Converter and control method thereof

Abstract

The invention provides a converter and a control method thereof. The converter comprises a main switch tube, an auxiliary switch tube, a transformer and a controller. After the converter works, the controller obtains the output voltage of the converter and obtains a mode switching parameter based on the output voltage of the converter; and controlling the converter to switch between the first working mode and the second working mode according to the mode switching parameter. According to the invention, the efficiency of the converter under the full-range output voltage can be optimized.

Description

Converter and control method thereof Technical Field

[0001] The present application relates to the field of power supply technology, and in particular to a converter and a control method thereof. Background Art

[0002] To meet efficiency requirements under different loads, asymmetric half-bridge (AHB) converters typically use pulse width modulation (PWM), pulse frequency modulation (PFM), burst modulation (Burst-Mode), or a combination of these three modes. PWM fixes the converter's switching frequency and adjusts the output voltage by controlling the excitation current, for example. PFM adjusts the output voltage by varying the switching frequency. Burst-Mode adjusts the output voltage by controlling whether the converter switches.

[0003] At present, the AHB converter mainly controls the working mode of the AHB converter based on the input voltage and load of the AHB converter. Specifically, when the load of the AHB converter is greater than or equal to the first load setting value corresponding to the input voltage of the AHB converter, the AHB converter operates in an asymmetric half-bridge flyback mode with a fixed switching frequency, wherein the higher the input voltage of the AHB converter, the larger the first load setting value; when the above load is less than the first load setting value and greater than the second load setting value, the AHB converter operates in a clamped asymmetric half-bridge flyback mode, and the switching frequency of the AHB converter decreases linearly as the load decreases; when the above load is less than the second load setting value, the AHB converter operates in an intermittent wave mode. Since the mode switching point in the above control method is only related to the input voltage and load, when the AHB converter needs to output a wide range of output, the mode switching point of the above control method for all output voltages is the same, which will lead to low efficiency of the AHB converter under some output voltages.

[0004] Summary of the Invention

[0005] The present application provides a converter and a control method thereof, which can optimize the efficiency of the converter under a full range of output voltages.

[0006] In a first aspect, the present application provides a converter comprising a main switch, an auxiliary switch, a transformer, and a controller. The main switch and the auxiliary switch are connected in series between an input terminal of the converter and a reference ground, the input terminal of the transformer is connected to both ends of the auxiliary switch, and the output terminal of the transformer is connected to the output terminal of the converter. After the converter is in operation, the controller obtains the output voltage of the converter and obtains a mode switching parameter based on the output voltage of the converter; and controls the converter to switch between a first operating mode and a second operating mode according to the mode switching parameter. In the first operating mode, the switching frequency of the converter is negatively correlated with the output current of the converter, and in the second operating mode, the switching frequency of the converter remains unchanged within one operating cycle of the converter. Because the switching loss of a converter (such as an AHB converter) is often strongly correlated with the output voltage, the converter provided in the present application can adjust the mode switching parameters for switching between different operating modes according to different output voltages. That is, the converter adjusts its operating mode according to different output voltages, or adjusts its operating parameters when switching from the first operating mode to the second operating mode, to reduce switching losses, thereby optimizing the converter's efficiency over the full range of output voltages.

[0007] In conjunction with the first aspect, in a first possible implementation, the mode switching parameter is a first current threshold. The controller compares the output current of the converter with the first switching current threshold, and controls the converter to switch between the first operating mode and the second operating mode based on the comparison result. The converter provided in this application can adjust the mode switching point (i.e., the first switching current threshold) at which it switches between different operating modes according to different output voltages. That is, the converter adjusts its own operating mode according to different output voltages to reduce switching losses, thereby optimizing the efficiency of the converter under the full range of output voltages.

[0008] In conjunction with the first possible implementation of the first aspect, in a second possible implementation, the controller, based on the output voltage, obtains a first voltage interval in which the output voltage is located from a plurality of voltage intervals, and obtains a first switching current threshold corresponding to the first voltage interval from a plurality of switching current thresholds corresponding to the voltage intervals, wherein the plurality of voltage intervals correspond one-to-one to the plurality of switching current thresholds. Specifically, the higher the gear position in the first voltage interval in which the output voltage of the converter is located, the larger the first switching current threshold corresponding to the first voltage interval, thereby maintaining the switching frequency and operating frequency of the converter within a relatively appropriate range, thereby avoiding situations where the converter's switching frequency is too high, resulting in low converter efficiency, or avoiding situations where the converter's switching frequency is too low, resulting in audible noise in the converter's operating frequency.

[0009] In combination with the first possible implementation or the second possible implementation of the first aspect, in a third possible implementation, when the output current is less than or equal to the first switching current threshold and greater than the second switching current threshold, the controller controls the main switch and the auxiliary switch to be turned on a first number of times during one operating cycle of the converter, thereby placing the converter in a high-frequency intermittent ripple (HBURST) mode. Furthermore, when the output current is less than or equal to the second switching current threshold, the controller controls the main switch and the auxiliary switch to be turned on a second number of times during one operating cycle, wherein the second number of times is less than the first number of times. It is understood that when the converter is in HBURST mode, the converter can adjust the number of times the switch is turned on during the operating cycle based on changes in the load (i.e., the output current), ensuring on-demand output and avoiding output exceeding the load requirements, thereby reducing energy loss and switch losses, and thereby improving converter efficiency. Furthermore, since the number of times the switch is turned on during the operating cycle gradually decreases as the load gradually becomes lighter (i.e., the output current gradually decreases), the converter can also reduce the output voltage ripple of the converter under light load conditions, thus enhancing its applicability.

[0010] In combination with the first possible implementation or the second possible implementation of the first aspect, in a fourth possible implementation, the transformer includes an excitation inductor. When the output current is less than or equal to the first switching current threshold and greater than the second switching current threshold, the controller controls the current peak of the excitation inductor during one operating cycle of the converter to be a first current peak, thereby placing the converter in HBURST mode. Furthermore, when the output current is less than or equal to the second switching current threshold, the controller controls the current peak of the excitation inductor during one operating cycle to be a second current peak, wherein the second current peak is less than the first current peak. It is understood that when the converter is in HBURST mode, the converter can adjust the current peak of the excitation inductor during the operating cycle based on changes in the load, ensuring on-demand output and avoiding output exceeding the load requirements, thereby reducing energy loss and switching tube losses, and thereby improving converter efficiency. Furthermore, since the current peak of the excitation inductor during the operating cycle gradually decreases as the load gradually becomes lighter, the output voltage ripple of the converter under light load conditions can also be reduced, thus enhancing its applicability.

[0011] In combination with the first possible implementation or the second possible implementation of the first aspect, in a fifth possible implementation, when the output current is less than or equal to the first switching current threshold and greater than the third switching current threshold, the controller controls the main switch and the auxiliary switch to be turned on a third number of times in one operating cycle of the converter, so that the converter is in HBURST mode. Furthermore, when the output current is less than or equal to the third switching current threshold, the controller controls the main switch and the auxiliary switch to be turned on a fourth number of times in one operating cycle, and after a first operating cycle in which the number of turns on in one operating cycle is the third number of times, controls the main switch and the auxiliary switch to be turned on a fifth number of times in one operating cycle, so that the converter is in low-frequency intermittent wave generation (LBURST) mode, where the fourth number of turns on is less than or equal to the third number of turns on and greater than the fifth number of turns on. It can be understood that after the converter is in HBURST mode, this embodiment optimizes the operating mode of the converter under extremely light load conditions (i.e., the output current is less than or equal to the third switching current threshold), so that the converter is in HBURST mode to further reduce the output energy, thereby not only reducing energy loss and switching tube loss to improve the efficiency of the converter, but also reducing the output voltage ripple of the converter under extremely light load conditions.

[0012] In combination with the first possible implementation or the second possible implementation of the first aspect, in a sixth possible implementation, the transformer includes an excitation inductor. When the output current is less than or equal to the first switching current threshold and greater than the third switching current threshold, the controller controls the current peak of the excitation inductor during one operating cycle of the converter to be a third current peak, thereby placing the converter in HBURST mode. Furthermore, when the output current is less than or equal to the third switching current threshold, the controller controls the current peak of the excitation inductor during one operating cycle to be a fourth current peak. After a first number of operating cycles in which the current peak within one operating cycle is at the third current peak, the controller controls the current peak of the excitation inductor during one operating cycle to be a fifth current peak, thereby placing the converter in LBURST mode. The fourth current peak is less than or equal to the third current peak and greater than the fifth current peak. It will be appreciated that after the converter is in HBURST mode, this embodiment optimizes the converter's operating mode under extremely light load conditions, placing the converter in LBURST mode to further reduce output energy. This not only reduces energy loss and switching loss to improve converter efficiency, but also reduces output voltage ripple under extremely light load conditions.

[0013] In combination with the first possible implementation or the second possible implementation of the first aspect, in a seventh possible implementation, when the output current is less than or equal to the first switching current threshold, the controller controls the main switch and the auxiliary switch to be turned on a third number of times in one operating cycle of the converter (i.e., the high-frequency intermittent cycle), so that the converter is in HBURST mode. Furthermore, after the main switch and the auxiliary switch have been turned on a third number of times in one operating cycle, if the operating frequency of the converter (i.e., the frequency of the high-frequency intermittent cycle) is within a preset frequency range, the controller controls the main switch and the auxiliary switch to be turned on a fourth number of times in one operating cycle, and after a first operating cycle in which the number of turns on in one operating cycle is the fourth number of times, the controller controls the main switch and the auxiliary switch to be turned on a fifth number of times in one operating cycle, wherein the fourth number of turns on is less than or equal to the third number of turns on and greater than the fifth number of turns on. If the operating frequency of the converter is outside the preset frequency range, the controller controls the main switch and the auxiliary switch to be turned on a third number of times in one operating cycle. As will be appreciated, after the converter enters HBURST mode, this embodiment optimizes the converter's operating mode when the high-frequency intermittent period's frequency is within the human hearing range, placing the converter in LBURST mode. This reduces energy loss and switching losses, thereby improving converter efficiency. Furthermore, when the high-frequency intermittent period's frequency is within the human hearing range, operating the converter in LBURST mode effectively reduces converter switching noise.

[0014] In combination with the first possible implementation or the second possible implementation of the first aspect, in an eighth possible implementation, the transformer includes an excitation inductor. When the output current is less than or equal to the first switching current threshold, the controller controls the current peak of the excitation inductor in one working cycle of the converter to be a third current peak, so that the converter is in HBURST mode. The controller also controls the current peak of the excitation inductor in one working cycle to be a fourth current peak after the current peak of the excitation inductor in one working cycle is the third current peak, if the operating frequency of the converter is within a preset frequency range, and controls the current peak of the excitation inductor in one working cycle to be a fifth current peak after the first number of working cycles in which the current peak in one working cycle is the fourth current peak, wherein the fourth current peak is greater than the fifth current peak and less than or equal to the third current peak. If the operating frequency of the converter is outside the preset frequency range, the current peak of the excitation inductor in one working cycle is controlled to be the third current peak. As will be appreciated, after the converter enters HBURST mode, this embodiment optimizes the converter's operating mode when the high-frequency intermittent period's frequency is within the human hearing range, placing the converter in LBURST mode. This reduces energy loss and switching losses, thereby improving converter efficiency. Furthermore, when the high-frequency intermittent period's frequency is within the human hearing range, operating the converter in LBURST mode effectively reduces converter switching noise.

[0015] In combination with any one of the first possible implementation manner of the first aspect to the eighth possible implementation manner of the first aspect, in a ninth possible implementation manner, when the output current is greater than the first switching current threshold, and when the output currents are the first output current and the second output current, respectively, the controller controls the switching frequency of the converter to be the first switching frequency and the second switching frequency, wherein when the first output current is greater than the second output current, the first switching frequency is less than the second switching frequency.

[0016] In combination with any one of the first possible implementation manner of the first aspect to the ninth possible implementation manner of the first aspect, in a tenth possible implementation manner, the first operating mode includes a continuous resonance current flyback mode (CRM), and the second operating mode includes an intermittent wave mode. The controller controls the converter to operate in the CRM when the output current is greater than a first switching current threshold; or controls the converter to operate in the intermittent wave mode when the output current is less than or equal to the first switching current threshold.

[0017] In combination with the first aspect, in an eleventh possible implementation, the mode switching parameter is the first operating parameter of the converter in the second operating mode. The controller also obtains the switching frequency of the converter; when the switching frequency reaches the frequency threshold, the first operating parameter of the converter in the second operating mode is obtained according to the output voltage; based on the first operating parameter, the converter is controlled to switch from the first operating mode to the second operating mode, wherein the first operating parameter includes the number of times the main switch tube and the auxiliary switch tube are turned on in one operating cycle of the converter, or the current peak of the excitation inductance in one operating cycle. It can be understood that since the switching frequency and switching loss of the converter are often strongly correlated with the output voltage, the converter provided in the present application can adjust its operating parameters from the first operating mode to the second operating mode according to different output voltages to reduce the switching frequency and switching loss of the converter, thereby optimizing the efficiency of the converter under the full range of output voltages.

[0018] In combination with the eleventh possible implementation of the first aspect, in a twelfth possible implementation, when the switching frequency reaches the frequency threshold, the controller obtains a first voltage interval in which the output voltage is located from multiple voltage intervals; and obtains a first operating parameter corresponding to the first voltage interval from multiple operating parameters corresponding to the multiple voltage intervals, wherein the multiple voltage intervals correspond one-to-one to the multiple operating parameters.

[0019] In combination with the twelfth possible implementation of the first aspect, in the thirteenth possible implementation, the multiple voltage intervals further include a second voltage interval, and when any value in the second voltage interval is less than any value in the first voltage interval, the second operating parameter corresponding to the second voltage interval is less than the first operating parameter. Exemplarily, the first voltage interval and the second voltage interval are a high voltage interval and a medium voltage interval, respectively. Since the HBURST mode entry point (i.e., the second operating parameter) of the converter when the output voltage is in the medium voltage interval of the present application is lower than the HBURST mode entry point (i.e., the first operating parameter) of the converter when the output voltage is in the high voltage interval, compared to the HBURST mode entry point (i.e., the first operating parameter) of the converter when the output voltage is in the high voltage interval, compared to using the same HBURST mode entry point for different output voltages, the HBURST mode entry point of the present application when the output voltage is in the medium voltage interval is smaller, which can reduce the energy transmitted in each high-frequency intermittent cycle, thereby reducing the primary and secondary winding losses and the switch tube conduction loss, thereby improving the efficiency of the converter in HBURST mode.

[0020] In combination with any one of the eleventh to thirteenth possible implementations of the first aspect, in a fourteenth possible implementation, the first operating parameter includes a conduction number, and the conduction number is a first conduction number. The controller controls the conduction number of the main switch and the auxiliary switch in a working cycle to be the first conduction number, so that the converter switches to the HBURST mode. After the conduction number of the main switch and the auxiliary switch in a working cycle reaches the first conduction number, if the output current of the converter is less than or equal to the second switching current threshold, the main switch and the auxiliary switch are controlled to have a second conduction number in a working cycle, wherein the second conduction number is less than the first conduction number; if the output current of the converter is greater than the second switching current threshold and less than or equal to the first switching current threshold, the main switch and the auxiliary switch are controlled to have a first conduction number in a working cycle. It can be understood that after the converter switches to the HBURST mode, the converter can adjust the conduction number of the switch in a high-frequency intermittent cycle based on changes in the load to ensure output on demand and avoid outputting more than the load requires, thereby reducing energy loss and switch loss, and thereby improving converter efficiency. In addition, as the load gradually becomes lighter, the number of times the switch tube is turned on in a high-frequency intermittent cycle also gradually decreases. Therefore, the output voltage ripple of the converter under light load conditions can also be reduced, and the applicability is strong.

[0021] In combination with any one of the eleventh to thirteenth possible implementations of the first aspect, in a fifteenth possible implementation, the first switching parameter includes a current peak value, and the current peak value is a first current peak value. The controller controls the current peak value of the excitation inductor in one working cycle to be the first current peak value, so that the converter switches to HBURST mode. After the current peak value of the excitation inductor in one working cycle is the first current peak value, if the output current of the converter is less than or equal to the second switching current threshold, the current peak value of the excitation inductor in one working cycle is controlled to be the second current peak value, wherein the second current peak value is less than the first current peak value; if the output current of the converter is greater than the second switching current threshold and less than or equal to the first switching current threshold, the current peak value of the excitation inductor in one working cycle is controlled to be the first current peak value. It can be understood that after the converter switches to HBURST mode, the converter can adjust the current peak value of the excitation inductor in one high-frequency intermittent cycle based on changes in the load to ensure on-demand output and avoid outputting more than required by the load, thereby reducing energy loss and switching tube loss, and thereby improving the efficiency of the converter. In addition, as the load gradually becomes lighter, the current peak of the excitation inductance in a high-frequency intermittent cycle also gradually decreases. Therefore, the output voltage ripple of the converter under light load conditions can also be reduced, and the applicability is strong.

[0022] In combination with any one of the eleventh to thirteenth possible implementations of the first aspect, in a sixteenth possible implementation, the first switching parameter includes a conduction number, and the conduction number is a third conduction number. The controller controls the conduction number of the main switch and the auxiliary switch in one working cycle to be the third conduction number, so that the converter switches to the HBURST mode. After the conduction number of the main switch and the auxiliary switch in one working cycle reaches the third conduction number, if the output current of the converter is less than or equal to the third switching current threshold, the controller controls the conduction number of the main switch and the auxiliary switch in one working cycle to be a fourth conduction number, and after the first working cycle number in which the conduction number in one working cycle is the fourth conduction number, the controller controls the conduction number of the main switch and the auxiliary switch in one working cycle to be a fifth conduction number, so that the converter switches to the LBURST mode, wherein the fourth conduction number is less than or equal to the third conduction number and greater than the fifth conduction number; if the output current of the converter is greater than the third switching current threshold and less than or equal to the first switching current threshold, the controller controls the conduction number of the main switch and the auxiliary switch in one working cycle to be the third conduction number. It is understandable that after the converter switches to HBURST mode, compared to the implementation method that adjusts the number of times the switch tube is turned on in a high-frequency intermittent cycle based on the load to ensure that the converter is always in HBURST mode, this implementation further optimizes the converter's operating mode under extremely light load conditions (i.e., the output current is less than or equal to the third switching current threshold), placing the converter in LBURST mode. This can further reduce energy loss and switch tube loss, thereby further improving the converter's efficiency. In addition, because the converter is in LBURST mode under extremely light load conditions, the output energy is further reduced. Therefore, this implementation can further reduce the converter's output voltage ripple under extremely light load conditions, making it more applicable.

[0023] In combination with any one of the eleventh to thirteenth possible implementations of the first aspect, in a seventeenth possible implementation, the first switching parameter includes a current peak value, and the current peak value is a third current peak value. The controller controls the current peak value of the excitation inductor in one working cycle to be the third current peak value, so that the converter switches to the HBURST mode. After the current peak value of the excitation inductor in one working cycle is the third current peak value, if the output current of the converter is less than or equal to the third switching current threshold value, the current peak value of the excitation inductor in one working cycle is controlled to be the fourth current peak value; and after the first working cycle number in which the current peak value in the first working cycle is the fourth current peak value, the current peak value of the excitation inductor in one working cycle is controlled to be the fifth current peak value, so that the converter switches to the LBURST mode, wherein the fourth current peak value is less than or equal to the third current peak value and greater than the fifth current peak value; if the output current of the converter is greater than the third switching current threshold value and less than or equal to the first switching current threshold value, the current peak value of the excitation inductor in one working cycle is controlled to be the third current peak value. As can be understood, after the converter switches to HBURST mode, compared to implementations that adjust the peak current of the magnetizing inductor within a high-frequency intermittent cycle based on load to maintain the converter in HBURST mode, this implementation further optimizes the converter's operating mode under extremely light load conditions, placing the converter in LBURST mode. This further reduces energy loss and switching losses, thereby further improving converter efficiency. Furthermore, because the converter is in LBURST mode under extremely light load conditions, output energy is further reduced. Therefore, this embodiment can further reduce the converter's output voltage ripple under extremely light load conditions, making it more suitable for use.

[0024] In combination with any one of the eleventh to thirteenth possible implementations of the first aspect, in an eighteenth possible implementation, the first switching parameter includes a conduction number, and the conduction number is a third conduction number. The controller controls the main switch tube and the auxiliary switch tube to have the third conduction number in one working cycle, so that the converter switches to the HBURST mode. After the main switch tube and the auxiliary switch tube have the third conduction number in one working cycle, if the operating frequency of the converter is within a preset frequency range, the controller controls the main switch tube and the auxiliary switch tube to have the fourth conduction number in one working cycle; and after the first working cycle number of conduction times in one working cycle is the fourth conduction number, the controller controls the main switch tube and the auxiliary switch tube to have the fifth conduction number in one working cycle, so that the converter switches to the LBURST mode, wherein the fourth conduction number is less than or equal to the first conduction number and greater than the fifth conduction number; if the operating frequency of the converter is outside the preset frequency range, the controller controls the main switch tube and the auxiliary switch tube to have the third conduction number in one working cycle. It is understandable that after the converter switches to HBURST mode, compared to implementations that adjust the number of times the switch tube conducts during a high-frequency intermittent cycle based on load to ensure that the converter remains in HBURST mode, this implementation further optimizes the converter's operating mode when the frequency of the high-frequency intermittent cycle is within the human hearing range, placing the converter in LBURST mode. This further reduces energy loss and switch tube losses, thereby further improving converter efficiency. Furthermore, when the frequency of the high-frequency intermittent cycle is within the human hearing range, the converter is in LBURST mode, effectively reducing the converter's switching noise.

[0025] In combination with any one of the eleventh to thirteenth possible implementations of the first aspect, in a nineteenth possible implementation, the first switching parameter includes a current peak value, and the current peak value is a third current peak value. The controller controls the current peak value of the excitation inductance in one working cycle to be the third current peak value, so that the converter switches to the HBURST mode. After the current peak value of the excitation inductance in one working cycle is the third current peak value, if the operating frequency of the converter is within a preset frequency range, the current peak value of the excitation inductance in one working cycle is controlled to be the fourth current peak value, and after the first number of working cycles in which the current peak value in one working cycle is the fourth current peak value, the current peak value of the excitation inductance in one working cycle is controlled to be the fifth current peak value, so that the converter switches to the LBURST mode, wherein the fourth current peak value is greater than the fifth current peak value and less than or equal to the first current peak value; if the operating frequency of the converter is outside the preset frequency range, the current peak value of the excitation inductance in one working cycle is controlled to be the third current peak value. It is understandable that after the converter switches to HBURST mode, compared to the implementation method that adjusts the peak current of the excitation inductance within a high-frequency intermittent cycle based on the load to ensure that the converter is always in HBURST mode, this implementation further optimizes the converter's operating mode when the frequency of the high-frequency intermittent cycle is within the human hearing range, placing the converter in LBURST mode. This further reduces energy loss and switching tube losses, thereby further improving converter efficiency. In addition, when the frequency of the high-frequency intermittent cycle is within the human hearing range, the converter is in LBURST mode, which effectively reduces the converter's switching noise.

[0026] In combination with any one of the eleventh to nineteenth possible implementations of the first aspect, in a twentieth possible implementation, the first operating mode includes CRM, and the second operating mode includes an intermittent wave mode.

[0027] In combination with the third possible implementation, the fifth possible implementation, the seventh possible implementation, the fourteenth possible implementation, the sixteenth possible implementation or the eighteenth possible implementation of the first aspect, in a twenty-first possible implementation, the duty cycle is determined by the number of times the main switch tube and the auxiliary switch tube are turned on in one duty cycle.

[0028] In combination with the fourth possible implementation, the sixth possible implementation, the eighth possible implementation, the fifteenth possible implementation, the seventeenth possible implementation or the nineteenth possible implementation of the first aspect, in a twenty-second possible implementation, the duty cycle is determined by the current peak value of the excitation inductance in one duty cycle.

[0029] In combination with any one of the first aspect to any one of the twenty-second possible implementations of the first aspect, in a twenty-third possible implementation, the transformer includes a primary winding, a secondary winding, an excitation inductor, a resonant inductor, and a resonant capacitor. The input end of the transformer includes a first input end and a second input end, and the output end of the transformer includes a first output end and a second output end. The primary winding is connected in parallel with the excitation inductor; one end of the resonant inductor is connected to the first input end of the transformer, the other end of the resonant inductor is connected to the input end of the converter or the same-name end of the primary winding, the opposite-name end of the primary winding is connected to the second input end of the transformer via the resonant capacitor, and the opposite-name end and the same-name end of the secondary winding are respectively connected to the first output end and the second output end of the transformer.

[0030] In conjunction with the twenty-third possible implementation of the first aspect, in a twenty-fourth possible implementation, the converter further includes a voltage sampling circuit, which is connected in parallel to both ends of the resonant capacitor and is used to collect the voltage of the resonant capacitor. The controller obtains the voltage of the resonant capacitor and obtains the output voltage of the converter based on the turns ratio of the secondary winding to the primary winding and the voltage of the resonant capacitor. It is understandable that the converter can obtain the output voltage of the converter by using the voltage of the resonant capacitor collected by the voltage sampling circuit. The output voltage acquisition method is simple and easy to control.

[0031] In conjunction with the twenty-third possible implementation of the first aspect, in a twenty-fifth possible implementation, the transformer further includes an auxiliary winding, and the converter further includes a voltage sampling circuit connected in parallel to both ends of the auxiliary winding for collecting the voltage of the auxiliary winding. The controller obtains the voltage of the auxiliary winding and, based on the turns ratio of the secondary winding to the auxiliary winding and the voltage of the auxiliary winding, obtains the output voltage of the converter. It will be appreciated that the converter can also obtain the output voltage of the converter using the voltage of the auxiliary winding collected by the voltage sampling circuit, resulting in diverse output voltage acquisition methods and high flexibility.

[0032] In a second aspect, the present application provides a control method for a converter, the converter comprising a main switch tube, an auxiliary switch tube, a transformer, and a controller. The main switch tube and the auxiliary switch tube are connected in series between the input terminal of the converter and a reference ground, the input terminal of the transformer is respectively connected to the two ends of the auxiliary switch tube, and the output terminal of the transformer is connected to the output terminal of the converter. The method comprises: the converter obtains its own output voltage, and obtains a mode switching parameter based on the output voltage of the converter; and controls the converter to switch between a first operating mode and a second operating mode according to the mode switching parameter, wherein the magnitude of the switching frequency of the converter in the first operating mode is negatively correlated with the magnitude of the output current of the converter, and the switching frequency of the converter remains unchanged within one operating cycle of the converter in the second operating mode.

[0033] In conjunction with the second aspect, in a first possible implementation, the mode switching parameter is a first switching current threshold. The converter compares its own output current with the first switching current threshold and controls the converter to switch between the first operating mode and the second operating mode based on the comparison result.

[0034] In combination with the first possible implementation of the second aspect, in a second possible implementation, the converter obtains a first voltage interval in which the output voltage is located from multiple voltage intervals based on the output voltage, and obtains a first switching current threshold corresponding to the first voltage interval from multiple switching current thresholds corresponding to the voltage intervals, wherein the multiple voltage intervals correspond one-to-one to the multiple switching current thresholds.

[0035] In combination with the first possible implementation manner or the second possible implementation manner of the second aspect, in a third possible implementation manner, when the output current of the converter is less than or equal to the first switching current threshold and greater than the second switching current threshold, the main switch and the auxiliary switch are controlled to be turned on a first number of times in one operating cycle of the converter, so that the converter is in a second operating state. Furthermore, when the output current is less than or equal to the second switching current threshold, the main switch and the auxiliary switch are controlled to be turned on a second number of times in one operating cycle, where the second number of times is less than the first number of times.

[0036] In combination with the first possible implementation or the second possible implementation of the second aspect, in a fourth possible implementation, the transformer includes an excitation inductor. When the output current of the converter is less than or equal to the first switching current threshold and greater than the second switching current threshold, the current peak value of the excitation inductor during one operating cycle of the converter is controlled to be a first current peak value, so that the converter is in the second operating mode. Furthermore, when the output current is less than or equal to the second switching current threshold, the current peak value of the excitation inductor during one operating cycle is controlled to be a second current peak value, where the second current peak value is less than the first current peak value.

[0037] In combination with the first possible implementation manner or the second possible implementation manner of the second aspect, in a fifth possible implementation manner, when the output current of the converter is less than or equal to the first switching current threshold and greater than the third switching current threshold, the main switch and the auxiliary switch are controlled to be turned on a third number of times in one operating cycle of the converter, so that the converter is in the second operating mode. Furthermore, when the output current is less than or equal to the third switching current threshold, the main switch and the auxiliary switch are controlled to be turned on a fourth number of times in one operating cycle, and after a first number of operating cycles in which the number of turns on in one operating cycle is the third number of times, the main switch and the auxiliary switch are controlled to be turned on a fifth number of times in one operating cycle, so that the converter is in the LBURST mode, where the fourth number of turns on is less than or equal to the third number of turns on and greater than the fifth number of turns on.

[0038] In combination with the first possible implementation or the second possible implementation of the second aspect, in a sixth possible implementation, the transformer includes an excitation inductor. When the output current of the converter is less than or equal to the first switching current threshold and greater than the third switching current threshold, the current peak value of the excitation inductor in one working cycle of the converter is controlled to be a third current peak value. When the output current is less than or equal to the third switching current threshold, the current peak value of the excitation inductor in one working cycle is controlled to be a fourth current peak value. After the first number of working cycles in which the current peak value in one working cycle is the third current peak value, the current peak value of the excitation inductor in one working cycle is controlled to be a fifth current peak value, wherein the fourth current peak value is less than or equal to the third current peak value and greater than the fifth current peak value.

[0039] In combination with the first possible implementation or the second possible implementation of the second aspect, in a seventh possible implementation, when the output current of the converter is less than or equal to the first switching current threshold, the main switch and the auxiliary switch are controlled to be turned on a third number of times in one operating cycle of the converter. After the main switch and the auxiliary switch are turned on a third number of times in one operating cycle, if the operating frequency of the converter is within a preset frequency range, the main switch and the auxiliary switch are controlled to be turned on a fourth number of times in one operating cycle. After the first operating cycle number of times in one operating cycle is the fourth number of times, the main switch and the auxiliary switch are controlled to be turned on a fifth number of times in one operating cycle, where the fourth number of times is less than or equal to the third number of times and greater than the fifth number of times. If the operating frequency of the converter is outside the preset frequency range, the main switch and the auxiliary switch are controlled to be turned on a third number of times in one operating cycle.

[0040] In combination with the first possible implementation or the second possible implementation of the second aspect, in an eighth possible implementation, the transformer includes an excitation inductor. When the output current of the converter is less than or equal to the first switching current threshold, the current peak value of the excitation inductor in one working cycle of the converter is controlled to be a third current peak value. After the current peak value of the excitation inductor in one working cycle is the third current peak value, if the operating frequency of the converter is within a preset frequency range, the current peak value of the excitation inductor in one working cycle is controlled to be a fourth current peak value, and after the first number of working cycles in which the current peak value in one working cycle is the fourth current peak value, the current peak value of the excitation inductor in one working cycle is controlled to be a fifth current peak value, wherein the fourth current peak value is greater than the fifth current peak value and less than or equal to the third current peak value. If the operating frequency of the converter is outside the preset frequency range, the current peak value of the excitation inductor in one working cycle is controlled to be the third current peak value.

[0041] In combination with any one of the first possible implementation manner of the second aspect to the eighth possible implementation manner of the second aspect, in a ninth possible implementation manner, when the output current of the converter is greater than the first switching current threshold, and when the output currents are the first output current and the second output current respectively, the switching frequency of the converter is controlled to be the first switching frequency and the second switching frequency respectively, wherein when the first output current is greater than the second output current, the first switching frequency is less than the second switching frequency.

[0042] In combination with any one of the first possible implementation manner of the second aspect to the ninth possible implementation manner of the second aspect, in a tenth possible implementation manner, the first operating mode includes a CRM mode, and the second operating mode includes an intermittent wave mode. When the output current of the converter is greater than a first switching current threshold, the converter is controlled to operate in the CRM mode; or when the output current is less than or equal to the first switching current threshold, the converter is controlled to operate in the intermittent wave mode.

[0043] In conjunction with the second aspect, in an eleventh possible implementation, the mode switching parameter is a first operating parameter of the converter in the second operating mode. The converter further obtains a switching frequency of the converter; when the switching frequency reaches a frequency threshold, obtains the first operating parameter of the converter in the second operating mode based on the output voltage; and controls the converter to switch from the first operating mode to the second operating mode based on the first operating parameter, wherein the first operating parameter includes the number of times the main switch and the auxiliary switch are turned on in one operating cycle of the converter, or the peak current of the excitation inductor in one operating cycle.

[0044] In combination with the eleventh possible implementation of the second aspect, in a twelfth possible implementation, when the switching frequency of the converter reaches a frequency threshold, the converter obtains a first voltage interval in which the output voltage is located from a plurality of voltage intervals; and obtains a first operating parameter corresponding to the first voltage interval from a plurality of operating parameters corresponding to the plurality of voltage intervals, wherein the plurality of voltage intervals correspond one-to-one to the plurality of operating parameters.

[0045] In combination with the twelfth possible implementation of the second aspect, in the thirteenth possible implementation, the multiple voltage intervals also include a second voltage interval, and when any value in the second voltage interval is smaller than any value in the first voltage interval, the second operating parameter corresponding to the second voltage interval is smaller than the first operating parameter.

[0046] In combination with any one of the eleventh possible implementation manner of the second aspect to the thirteenth possible implementation manner of the second aspect, in the fourteenth possible implementation manner, the first operating parameter includes the number of conduction times, and the number of conduction times is the first number of conduction times. The converter controls the number of conduction times of the main switch tube and the auxiliary switch tube in one working cycle to be the first number of conduction times. And after the number of conduction times of the main switch tube and the auxiliary switch tube in one working cycle is the first number of conduction times, if the output current of the converter is less than or equal to the second switching current threshold, the number of conduction times of the main switch tube and the auxiliary switch tube in one working cycle is controlled to be the second number of conduction times, wherein the second number of conduction times is less than the first number of conduction times; if the output current of the converter is greater than the second switching current threshold and less than or equal to the first switching current threshold, the number of conduction times of the main switch tube and the auxiliary switch tube in one working cycle is controlled to be the first number of conduction times.

[0047] In combination with any one of the eleventh possible implementation to the thirteenth possible implementation of the second aspect, in the fifteenth possible implementation, the first switching parameter includes a current peak value, and the current peak value is a first current peak value. The converter controls the current peak value of the excitation inductance in one working cycle to be the first current peak value. And after the current peak value of the excitation inductance in one working cycle is the first current peak value, if the output current of the converter is less than or equal to the second switching current threshold, the current peak value of the excitation inductance in one working cycle is controlled to be the second current peak value, wherein the second current peak value is less than the first current peak value; if the output current of the converter is greater than the second switching current threshold value and less than or equal to the first switching current threshold value, the current peak value of the excitation inductance in one working cycle is controlled to be the first current peak value.

[0048] In combination with any one of the eleventh to thirteenth possible implementations of the second aspect, in a sixteenth possible implementation, the first switching parameter includes a conduction number, and the conduction number is a third conduction number. The converter controls the main switch tube and the auxiliary switch tube to be on for the third conduction number in one working cycle. After the main switch tube and the auxiliary switch tube are on for the third conduction number in one working cycle, if the output current of the converter is less than or equal to the third switching current threshold, the main switch tube and the auxiliary switch tube are controlled to be on for the fourth conduction number in one working cycle; and after the first working cycle number in which the conduction number in one working cycle is the fourth conduction number, the main switch tube and the auxiliary switch tube are controlled to be on for the fifth conduction number in one working cycle, wherein the fourth conduction number is less than or equal to the third conduction number and greater than the fifth conduction number; if the output current of the converter is greater than the third switching current threshold and less than or equal to the first switching current threshold, the main switch tube and the auxiliary switch tube are controlled to be on for the third conduction number in one working cycle.

[0049] In combination with any one of the eleventh to thirteenth possible implementations of the second aspect, in a seventeenth possible implementation, the first switching parameter includes a current peak value, and the current peak value is a third current peak value. The converter controls the current peak value of the excitation inductance in one working cycle to be the third current peak value. And after the current peak value of the excitation inductance in one working cycle is the third current peak value, if the output current of the converter is less than or equal to the third switching current threshold value, the current peak value of the excitation inductance in one working cycle is controlled to be the fourth current peak value; and after the first working cycle number in which the current peak value in the first working cycle is the fourth current peak value, the current peak value of the excitation inductance in one working cycle is controlled to be the fifth current peak value, wherein the fourth current peak value is less than or equal to the third current peak value and greater than the fifth current peak value; if the output current of the converter is greater than the third switching current threshold value and less than or equal to the first switching current threshold value, the current peak value of the excitation inductance in one working cycle is controlled to be the third current peak value.

[0050] In combination with any one of the eleventh to thirteenth possible implementations of the second aspect, in an eighteenth possible implementation, the first switching parameter includes a conduction number, and the conduction number is a third conduction number. The converter controls the main switch tube and the auxiliary switch tube to have the third conduction number in one working cycle. After the main switch tube and the auxiliary switch tube have the third conduction number in one working cycle, if the operating frequency of the converter is within a preset frequency range, the main switch tube and the auxiliary switch tube are controlled to have the fourth conduction number in one working cycle; and after the first working cycle number of conduction times in one working cycle is the fourth conduction number, the main switch tube and the auxiliary switch tube are controlled to have the fifth conduction number in one working cycle, wherein the fourth conduction number is less than or equal to the first conduction number and greater than the fifth conduction number; if the operating frequency of the converter is outside the preset frequency range, the main switch tube and the auxiliary switch tube are controlled to have the third conduction number in one working cycle.

[0051] In combination with any one of the eleventh to thirteenth possible implementations of the second aspect, in a nineteenth possible implementation, the first switching parameter includes a current peak value, and the current peak value is a third current peak value. The converter controls the current peak value of the excitation inductance in one working cycle to be the third current peak value. And after the current peak value of the excitation inductance in one working cycle is the third current peak value, if the operating frequency of the converter is within the preset frequency range, the current peak value of the excitation inductance in one working cycle is controlled to be the fourth current peak value; and after the first number of working cycles in which the current peak value in one working cycle is the fourth current peak value, the current peak value of the excitation inductance in one working cycle is controlled to be the fifth current peak value, wherein the fourth current peak value is greater than the fifth current peak value and less than or equal to the first current peak value; if the operating frequency of the converter is outside the preset frequency range, the current peak value of the excitation inductance in one working cycle is controlled to be the third current peak value.

[0052] In combination with any one of the eleventh to nineteenth possible implementations of the second aspect, in a twentieth possible implementation, the first operating mode includes CRM, and the second operating mode includes an intermittent wave mode.

[0053] In combination with the third possible implementation, the fifth possible implementation, the seventh possible implementation, the fourteenth possible implementation, the sixteenth possible implementation or the eighteenth possible implementation of the second aspect, in a twenty-first possible implementation, the duty cycle is determined by the number of times the main switch tube and the auxiliary switch tube are turned on in one duty cycle.

[0054] In combination with the fourth possible implementation, the sixth possible implementation, the eighth possible implementation, the fifteenth possible implementation, the seventeenth possible implementation or the nineteenth possible implementation of the second aspect, in a twenty-second possible implementation, the duty cycle is determined by the current peak value of the excitation inductance in one duty cycle.

[0055] In combination with any one of the second aspect to any one of the twenty-second possible implementations of the second aspect, in a twenty-third possible implementation, the transformer includes a primary winding, a secondary winding, an excitation inductor, a resonant inductor, and a resonant capacitor. The input end of the transformer includes a first input end and a second input end, and the output end of the transformer includes a first output end and a second output end. The primary winding is connected in parallel with the excitation inductor; one end of the resonant inductor is connected to the first input end of the transformer, the other end of the resonant inductor is connected to the input end of the converter or the same-name end of the primary winding, the opposite-name end of the primary winding is connected to the second input end of the transformer via the resonant capacitor, and the opposite-name end and the same-name end of the secondary winding are respectively connected to the first output end and the second output end of the transformer.

[0056] In conjunction with the twenty-third possible implementation of the second aspect, in a twenty-fourth possible implementation, the converter further includes a voltage sampling circuit connected in parallel to both ends of the resonant capacitor for collecting the voltage of the resonant capacitor. The controller obtains the voltage of the resonant capacitor and, based on the turns ratio of the secondary winding to the primary winding and the voltage of the resonant capacitor, obtains the output voltage of the converter.

[0057] In conjunction with the twenty-third possible implementation manner of the second aspect, in a twenty-fifth possible implementation manner, the transformer further includes an auxiliary winding, and the converter further includes a voltage sampling circuit connected in parallel to both ends of the auxiliary winding for collecting the voltage of the auxiliary winding. The controller obtains the voltage of the auxiliary winding and, based on the turns ratio of the secondary winding to the auxiliary winding and the voltage of the auxiliary winding, obtains the output voltage of the converter.

[0058] In a third aspect, the present application provides a terminal device, which includes a battery and a converter provided by any possible implementation of the first aspect to the first aspect, wherein the converter is used to charge the battery.

[0059] It should be understood that the implementation and beneficial effects of the above-mentioned aspects of the present application can be referenced to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] FIG1 is a schematic diagram of an application scenario of a converter provided by the present application;

[0061] FIG2a is a schematic structural diagram of a converter provided by the present application;

[0062] FIG2b is another schematic structural diagram of the converter provided by the present application;

[0063] FIG3a is another schematic structural diagram of the converter provided by the present application;

[0064] FIG3 b is another schematic structural diagram of the converter provided by the present application;

[0065] FIG4 is a schematic diagram of three voltage intervals provided in this application;

[0066] FIG5 is a schematic diagram of mode switching of the converter provided by the present application;

[0067] FIG6 is a control timing diagram of the converter provided by the present application in a high-frequency intermittent wave mode;

[0068] FIG7 is a control timing diagram of the converter provided by the present application in a low-frequency intermittent wave mode;

[0069] FIG8a is another schematic structural diagram of the converter provided by the present application;

[0070] FIG8b is another schematic structural diagram of the converter provided by the present application;

[0071] FIG9 is a schematic diagram of converter efficiency at different output voltages provided by the present application;

[0072] FIG10 is a flow chart of a control method for a converter provided by the present application;

[0073] FIG11 is a schematic structural diagram of a terminal device provided in this application. DETAILED DESCRIPTION

[0074] The converter provided in this application can be applied to the fields of electronic equipment, industry (such as power adapters for lasers), aerospace (such as aerospace power supplies) and other fields. Specifically, the converter provided in this application can be applied to power adapters, industrial power supplies, aerospace power supplies, etc. of electronic devices (such as smart phones, tablet computers, laptops, desktop computers, smart speakers, smart watches and wearable devices, etc.) to convert direct current into voltage and current suitable for electronic equipment, industrial equipment, aerospace equipment, etc. The converter provided in this application is suitable for electronic equipment power supply scenarios, electric vehicle application scenarios or other application scenarios. The following is an example of an electronic equipment power supply scenario.

[0075] Referring to FIG1 , FIG1 is a schematic diagram of an application scenario of the converter provided in the present application. As shown in FIG1 , in the electronic device power supply scenario, the converter provided in the present application can be the power adapter shown in FIG1 . The input end of the power adapter is connected to the power grid via an AC / DC converter, and the output end is connected to the electronic device. When powering the electronic device, the AC / DC converter first rectifies the AC voltage (e.g., 220V) provided by the power grid into a first DC voltage and outputs it to the input end of the power adapter. The power adapter performs a DC conversion on the first DC voltage at the input end to obtain a second DC voltage, and outputs the second DC voltage to the electronic device, thereby powering the electronic device. At the same time, while the power adapter is powering the electronic device, the power adapter obtains its current output voltage and obtains a mode switching parameter based on the current output voltage. The power adapter controls the converter to switch between a first operating mode and a second operating mode based on the mode switching parameter, wherein the switching frequency of the converter in the first operating mode is negatively correlated with the output current of the converter, and the switching frequency of the converter in the second operating mode remains unchanged within one operating cycle of the converter. Exemplarily, the first operating mode is CRM, and the second operating mode is intermittent wave mode.

[0076] Because the switching losses of a power adapter are often strongly correlated with the output voltage, the power adapter provided in this application can adjust the mode switching parameters for switching between different operating modes according to different output voltages. That is, the power adapter adjusts its own operating mode according to different output voltages, or adjusts its operating parameters when switching from a first operating mode to a second operating mode to reduce switching losses, thereby optimizing the efficiency of the power adapter over the full range of output voltages. The above is merely an example of the application scenarios of the converter provided in this application, and is not an exhaustive list. This application does not limit the application scenarios.

[0077] The working principle of the converter provided in this application is illustrated below with reference to FIG. 2 a to FIG. 9 .

[0078] Refer to Figure 2a, which is a structural diagram of the converter provided by the present application. As shown in Figure 2a, the converter 1 includes a main switch tube S1, an auxiliary switch tube S2, a transformer 11 and a controller 12. Among them, one end of the main switch tube S1 is connected to the input terminal in1 of the converter 1, and the other end of the main switch tube S1 is connected to the reference ground through the auxiliary switch tube S2. The input terminals in21 and in22 of the transformer are respectively connected to the two ends of the auxiliary switch tube S2, and the output terminal out2 of the transformer is connected to the output terminal out1 of the converter 1. The input terminal in1 of the converter 1 is connected to the AC power supply, and the output terminal out1 is connected to the DC load. Exemplarily, the converter 1 provided by the present application can be an AHB converter.

[0079] Optionally, the positions of the main switch S1 and the auxiliary switch S2 can be swapped, as shown in Figure 2b. As shown in Figure 2b, one end of the auxiliary switch S2 is connected to the input terminal in1 of the converter 1, and the other end of the auxiliary switch S2 is connected to the reference ground through the main switch S1.

[0080] In an optional embodiment, after converter 1 begins operation, controller 12 obtains the current output voltage of converter 1 and, based on the current output voltage, obtains a mode switching parameter. Controller 12 controls converter 1 to switch between a first operating mode and a second operating mode based on the mode switching parameter. In the first operating mode, the switching frequency of converter 1 is negatively correlated with the output current of converter 1. In the second operating mode, the switching frequency of converter 1 remains constant within one operating cycle of converter 1. Exemplarily, the first operating mode is CRM, and the second operating mode is intermittent wave generation mode.

[0081] In an embodiment of the present application, since the switching loss of the converter 1 is often strongly correlated with the output voltage, the converter 1 provided in the present application can adjust its mode switching parameters for switching between different operating modes according to different output voltages, that is, the converter 1 adjusts its own operating mode according to different output voltages, or the converter 1 adjusts its own operating parameters for switching from the first operating mode to the second operating mode to reduce the switching loss, thereby optimizing the efficiency of the converter 1 under the full range of output voltages.

[0082] Referring again to FIG. 2a , in an optional embodiment, after the converter 1 starts working, the controller 12 obtains the current output voltage of the converter 1 and obtains a first switching current threshold based on the current output voltage. The controller 12 obtains the current output current of the converter 1 and compares the current output current with the first switching current threshold, thereby controlling the converter 1 to switch between the first operating mode and the second operating mode according to the comparison result. It can be understood that since the switching loss of the converter 1 is often strongly correlated with the output voltage, the converter 1 provided in the present application can adjust its mode switching point (i.e., the switching current threshold) for switching between different operating modes (i.e., the first operating mode and the second operating mode) according to different output voltages, that is, the converter 1 adjusts its own operating mode according to different output voltages to reduce switching losses, thereby optimizing the efficiency of the converter 1 under the full range of output voltages.

[0083] In another optional embodiment, the transformer 11 includes an excitation inductor. After the converter 1 starts working, the controller 12 obtains the current switching frequency and the current output voltage of the converter 1, and when the current switching frequency reaches the frequency threshold, obtains the first operating parameter of the converter 1 in the second operating mode according to the current output voltage, thereby controlling the converter 1 to switch from the first operating mode to the second operating mode based on the first operating parameter. Wherein, the first operating parameter includes the first conduction times of the main switch tube S1 and the auxiliary switch tube S2 in one working cycle of the converter 1, or the current peak value of the excitation inductor in one working cycle of the converter 1. It can be understood that since the switching frequency and switching loss of the converter 1 are often strongly correlated with the output voltage, the converter 1 provided in the present application can adjust its operating parameters (i.e., the conduction times of the switch tube or the current peak value of the excitation inductor) when switching from the first operating mode to the second operating mode according to different output voltages to reduce the switching frequency and switching loss of the converter 1, thereby optimizing the efficiency of the converter 1 under the full range of output voltages.

[0084] In an embodiment of the present application, the converter 1 can reduce the switching loss of the converter 1 by adjusting the mode switching point based on the current output voltage, or by adjusting the operating parameters of the converter 1 to switch from the first operating mode to the second operating mode based on the current output voltage, thereby optimizing the efficiency of the converter 1 under the full range of output voltages.

[0085] See Figure 3a, which is another schematic diagram of the structure of the converter provided by this application. As shown in Figure 3a, the converter 1 includes a main switch tube S1, an auxiliary switch tube S2, a transformer 11, a controller 12 and a voltage sampling circuit 13. Optionally, the converter 1 also includes an input capacitor C in , output capacitor C o , rectifier diode D1, input voltage sampling module 14 and isolated secondary voltage sampling module 15.

[0086] Here, the main switch S1 and the auxiliary switch S2 can be field-effect transistors (FETs) made of silicon semiconductor materials (Si) or third-generation wide-bandgap semiconductor materials such as silicon carbide (SiC) or gallium nitride (GaN). This embodiment uses metal oxide semiconductor field effect transistors (MOSFETs) as an example to describe the main switch S1 and the auxiliary switch S2.

[0087] An input capacitor C is provided between the input terminal in1 of the converter 1 and the reference ground.in The input voltage sampling module 14 is provided with an input terminal and an output terminal. The input terminal of the input voltage sampling module 14 is connected to the input capacitor C in The positive electrode of the converter 1 is connected to the controller 12 at its output end, and is used to collect the input voltage of the converter 1 and output the input voltage to the controller 12 for input voltage protection and PWM volt-second balance control.

[0088] The drain of the main switch S1 is connected to the input terminal in1 of the converter 1 , the source of the main switch S1 is connected to the drain of the auxiliary switch S2 , and the source of the auxiliary switch S2 is connected to the reference ground. The gates of the main switch S1 and the auxiliary switch S2 are connected to the controller 12 .

[0089] The transformer 11 (ie, the flyback transformer) includes a primary winding N P , secondary winding N S , iron core T1, excitation inductance L m , resonant inductor L r (including the leakage inductance of transformer 11 and the added inductance, which can also be fully integrated into transformer 11) and the resonant capacitor C r The input terminal in2 of the transformer 11 includes a first input terminal in21 and a second input terminal in22, and the output terminal out2 of the transformer includes a first output terminal out21 and a second output terminal out22. r One end of the transformer 11 is connected to the drain of the auxiliary switch tube S2 through the first input terminal in21, and the resonant inductor L r The other end is connected to the primary winding N P The same-name end of the primary winding N P The opposite end is connected to the resonant capacitor C r One end of the resonant capacitor C r The other end is connected to the source of the auxiliary switch tube S2 through the second input terminal in22 of the transformer 11, and the excitation inductor L m With the primary winding N P Parallel. Secondary winding N S The opposite-name end and the same-name end of the primary winding N are connected to the first output end out21 and the second output end out22 of the transformer 11 respectively. P and the secondary winding N S are coupled to the core T1. Optional, resonant inductor L r It can also be connected between the input terminal in1 of the converter 1 and the first input terminal in21 of the transformer 11. Optionally, the two input terminals in21 and in22 of the transformer 11 can also be connected to both ends of the main switch tube S1 respectively.

[0090] The output terminal out1 of the converter 1 includes a first output terminal out11 and a second output terminal out12. The first output terminal out21 of the transformer 11 is connected to the first output terminal out11 of the converter 1 through a rectifier diode D1, and the second output terminal out22 of the transformer 11 is connected to the second output terminal out12 of the converter 1 and the reference ground. An output capacitor C is also provided between the first output terminal out21 and the second output terminal out22 of the transformer 11. o .

[0091] The voltage sampling circuit 13 includes sampling resistors R1 and R2, wherein one end of the sampling resistor R2 is connected to the resonant capacitor C r One end of the sampling resistor R2 is connected to the resonant capacitor C through the sampling resistor R1. r The other end of the sampling resistor R1 and the connection point between R2 are connected to the controller 12. The voltage sampling circuit 13 is used to collect the voltage of the resonant capacitor C r voltage, and the resonant capacitor C r The voltage is output to the controller 12.

[0092] The isolated secondary voltage sampling module 15 is a load sampling module. The isolated secondary voltage sampling module 15 has an input terminal and an output terminal. The input terminal is connected to the output capacitor C o The positive electrode of the output terminal is connected to the controller 12. The isolated secondary voltage sampling module 15 includes a phototransistor Q1, a light-emitting diode D2, and a breakdown diode D3. The phototransistor Q1 and the light-emitting diode D2 constitute an optocoupler, which converts the output voltage of the converter 1 into an optical signal through the light-emitting diode D2, and then the phototransistor Q1 converts the received optical signal into a current signal. The isolated secondary voltage sampling module 15 is used to collect the output voltage isolation feedback signal and output the output voltage isolation feedback signal to the controller 12. The output voltage isolation feedback signal is used to control the output voltage stability of the converter 1, and is also used to reflect load information for subsequent mode switching.

[0093] In an alternative embodiment, after converter 1 is operational, controller 12 obtains the current output voltage of converter 1 and, based on the current output voltage, determines a first switching current threshold. Controller 12 then obtains the current output current of converter 1 and compares the current output current with the first switching current threshold, thereby controlling converter 1 to switch between the first operating mode and the second operating mode based on the comparison result.

[0094] Specifically, the controller 12 may be the controller 12 shown in FIG3b . As shown in FIG3b , the controller 12 includes an input terminal VBULK, an input terminal FB, an input terminal VCR, an output terminal MDRV, an output terminal SDRV, a PWM control unit 121, and a curve control unit 122. The input terminals VBULK and FB are connected to the output terminal of the input voltage sampling module 14 and the output terminal of the isolated secondary voltage sampling module 15, respectively. The input terminal VCR is connected to the connection point between the sampling resistors R1 and R2. The output terminals MDRV and SDRV are connected to the gate of the main switch S1 and the gate of the auxiliary switch S2, respectively.

[0095] After the converter 1 starts working, the voltage sampling circuit 13 starts to collect the voltage V of the sampling resistor R2 in real time. R2 and the voltage V of the sampling resistor R2 R2 Output to the input terminal VCR of the controller 12. Among them, the voltage V R2 Can characterize the resonant capacitance C r The curve control unit 122 in the controller 12 is based on the voltage V of the sampling resistor R2. R2 Calculate the resonant capacitance C r The voltage V Cr =V R2 *(R1+R2) / R2, and then calculate the current output voltage V of converter 1 o =V Cr *P1, where P1 is the secondary winding N S With the primary winding N P The turns ratio between .

[0096] At the same time, after converter 1 starts operating, isolated secondary voltage sampling module 15 collects the output voltage isolation feedback signal in real time through an optocoupler and outputs the output voltage isolation feedback signal to input terminal FB of controller 12. Curve control unit 122 obtains the current output current of converter 1 based on the output voltage isolation feedback signal.

[0097] The curve control unit 122 determines the current output voltage V of the converter 1 from a plurality of preset voltage intervals. o The first voltage interval in which the voltage is located. The preset multiple voltage intervals may be the three voltage intervals shown in FIG4 , namely, the high voltage interval H, the medium voltage interval M and the low voltage interval L.

[0098] Specifically, taking the high voltage interval H as an example, when the output voltage gradually increases over time, if the current output voltage V o Greater than or equal to the voltage threshold V o_hh , the curve control unit 122 determines the output voltage V oFrom the medium voltage interval M to the high voltage interval H, that is, the first voltage interval is determined to be the high voltage interval H; in the case where the output voltage gradually decreases over time, if the current output voltage V o Greater than or equal to the voltage threshold V o_hl , the curve control unit 122 determines that the first voltage interval is the high voltage interval H. Taking the medium voltage interval M as an example, when the output voltage gradually increases over time, if the current output voltage V o Greater than or equal to the voltage threshold V o_mh And is less than the voltage threshold V o_hh , the curve control unit 122 determines that the first voltage interval is the medium voltage interval M; in the case where the output voltage gradually decreases over time, if the current output voltage V o Greater than or equal to the voltage threshold V o_ml And is less than the voltage threshold V o_hl , the curve control unit 122 determines that the first voltage interval is the medium voltage interval M. Taking the low voltage interval L as an example, when the output voltage gradually increases over time, if the current output voltage V o Greater than or equal to the voltage threshold V o_lh And is less than the voltage threshold V o_mh , the curve control unit 122 determines that the first voltage interval is the medium voltage interval M; in the case where the output voltage gradually decreases over time, if the current output voltage V o Greater than or equal to the voltage threshold V o_ll And is less than the voltage threshold V o_ml , the curve control unit 122 determines that the first voltage interval is the medium voltage interval M.

[0099] For ease of introduction, please refer to FIG5 , which is a schematic diagram of the mode switching of the converter provided by the present application. Afterwards, the curve control unit 122 selects the switching current thresholds I corresponding to the three voltage intervals, that is, the switching current threshold I corresponding to the high voltage interval H shown in FIG5 . o1 , the switching current threshold I corresponding to the medium voltage range M o2 The switching current threshold I corresponding to the low voltage interval L o3 In the embodiment, a first switching current threshold corresponding to the first voltage interval is determined.

[0100] In an optional embodiment, when the first voltage interval is the high voltage interval H, the curve control unit 122 determines that the first switching current threshold corresponding to the high voltage interval H is I shown in FIG. 5 . o1 The high voltage interval H corresponds to the first switching current threshold I o1 The first switching current threshold I corresponding to the high voltage interval H is sent to the PWM control unit 121. o1It is a mode switching point at which the converter 1 switches between the CRM mode and the HBURST mode when the output voltage of the converter 1 is in the high voltage range HIGH.

[0101] First, it should be noted that when the first voltage interval is the high voltage interval H, the first switching current threshold, the second switching current threshold, the third switching current threshold and the fourth switching current threshold are I o1 , I o2 , I o4 and I o3 The first conduction number, the second conduction number, the third conduction number, the fourth conduction number, the fifth conduction number and the sixth conduction number are N1, N2, N3, N4, N5 and N6 respectively, and the first current peak value, the second current peak value, the third current peak value, the fourth current peak value, the fifth current peak value and the sixth current peak value are I Lm_R1 , I Lm_R2 , I Lm_R3 , I Lm_R4 , I Lm_R5 and I Lm_R6 Among them, I o1 >I o2 >I o3 >0,I o1 >I o4 >0,I o2 with I o4 N1>N2>N6, N3≥N4, N5=0, N1, N2, N3, N4 and N6 are all positive integers. Lm_R1 >I Lm_R2 >I Lm_R6 >0,I Lm_R3 ≥I Lm_R4 >0,I Lm_R5 =0,I Lm_R1 , I Lm_R2 , I Lm_R3 , I Lm_R4 and I Lm_R6 The value of satisfies the switching frequency f of converter 1 SW Less than the maximum switching frequency f SW(MAX) And the operating frequency of the converter 1 (ie, the high frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST ) is outside the range of human hearing. For the sake of convenience, this embodiment uses N6=N3, I Lm_R6 =I Lm_R3 Take this as an example to introduce.

[0102] As shown in FIG5 , the current output current I o Greater than the first switching current threshold I o1In the case of SW (i.e. the switching frequency of the main switch tube S1) increases with the output current I o or control the switching frequency f of the converter 1. SW With the output current I o The switching frequency f of the converter 1 is increased by the decrease of the switching frequency f, so that the converter 1 is in CRM mode. SW With the output current I o decreases with the increase of the primary winding N P The average current of the secondary winding N is proportional to S The average current, therefore, the magnetizing inductance L m Peak current I Lm(PEAK) Also with the output current I o Similarly, when converter 1 is in CRM mode, the switching frequency f SW With the output current I o The excitation inductance L m Peak current I Lm(PEAK) Also with the output current I o decreases with the decrease of .

[0103] When the current output current of the converter 1 is less than or equal to the first switching current threshold I o1 In the case of , converter 1 is in HBURST mode:

[0104] Specifically, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o1 and is greater than the second switching current threshold I o2 In this case, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to operate in one working cycle of the converter 1 (ie, one high-frequency intermittent period T in the HBURST mode). HBURST ) conduction times N SW is the first conduction number N1 (such as 3), so that the converter 1 is in the HBURST mode. o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW The second conduction number N2 (eg, 2) is the second conduction number N2, and the converter 1 is still in the HBURST mode. oLess than or equal to the fourth switching current threshold I o3 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW The sixth conduction number N6 (eg, 1) indicates that the converter 1 is still in the HBURST mode. The specific implementation of the PWM control unit 121 controlling the converter 1 to be in the HBURST mode will be described in the subsequent embodiments and will not be further elaborated here.

[0105] It can be understood that when the converter 1 is in the HBURST mode, the converter 1 can be based on the load (ie, the output current I o ) changes to adjust the switching tube (i.e. the main switch tube S1 and the auxiliary switch tube S2) in a high-frequency intermittent period T HBURST The number of conduction times N SW , ensuring output on demand and avoiding the situation where the output is more than the load requires, thereby reducing energy loss and switch tube loss, and thus improving the efficiency of converter 1. In addition, as the load gradually becomes lighter (i.e., the output current I o In the process of gradually decreasing, the switch tube is in a high-frequency intermittent period T HBURST The number of conduction times N SW It also gradually decreases, therefore, the output voltage ripple of the converter 1 under light load conditions can also be reduced, and the applicability is strong.

[0106] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o1 In the case of m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , putting converter 1 in HBURST mode.

[0107] The current output current I o Less than or equal to the first switching current threshold I o1 and is greater than the second switching current threshold I o2 In the case of PWM control unit 121, the conduction time of main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 is in HBURST mode. At the current output current I o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold Io3 In the case of m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The second current peak value I Lm_R2 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the fourth switching current threshold I o3 In the case of m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The sixth current peak value I Lm_R6 , the converter 1 is still in the HBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the HBURST mode is described in the subsequent embodiments and will not be further described here.

[0108] It is understandable that when the converter 1 is in the HBURST mode, the converter 1 can adjust the excitation inductance L based on the change of the load. m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , ensuring output on demand and avoiding the situation where the output exceeds the load requirement, thereby reducing energy loss and switch tube loss, and thus improving the efficiency of converter 1. In addition, as the load gradually becomes lighter, the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) It also gradually decreases, therefore, the output voltage ripple of the converter 1 under light load conditions can also be reduced, and the applicability is strong.

[0109] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o1 In this case, the PWM control unit 121 can also simultaneously control the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent period T HBURST The number of conduction times within the circuit, and the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , putting converter 1 in HBURST mode.

[0110] The current output current I o Less than or equal to the first switching current threshold I o1 and is greater than the second switching current threshold Io2 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW is the first conduction number N1 (such as 3), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 is in HBURST mode. At the current output current I o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW is the second conduction number N2 (such as 2), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The second current peak value I Lm_R2 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the fourth switching current threshold I o3 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW is the sixth conduction number N6 (such as 1), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The sixth current peak value I Lm_R6 , converter 1 is still in HBURST mode.

[0111] For ease of understanding, the following assumes that the first conduction number is 3 and the first current peak is I Lm_R1 For example, the controller 12 simultaneously controls a high frequency intermittent period T HBURST The number of conduction times N SW and the peak current I Lm(PEAK) , the specific implementation method of making converter 1 in HBURST mode is introduced.

[0112] See Figure 6, which is a control timing diagram of the converter provided by this application in the HBURST mode. As shown in Figure 6, at time t0, the high-frequency intermittent period THBURST Initially, the PWM control unit 121 outputs a high level to the gate G_S2 of the auxiliary switch tube S2 to turn on the auxiliary switch tube S2 . At this time, the main switch tube S1 is in the off state.

[0113] During the time period t0-t1, the PWM control unit 121 still outputs a high level to the gate G_S2 of the auxiliary switch tube S2, and the auxiliary switch tube S2 is still in the on state, so that the resonant capacitor C r , the parasitic capacitance of the main switch tube S1, the parasitic capacitance of the auxiliary switch tube S2 and the resonant inductor L r Resonance occurs, achieving soft switching of the main switch tube S1. During this period, the main switch tube S1 is still in the off state.

[0114] At time t1 , the PWM control unit 121 stops outputting a high level to the gate G_S2 of the auxiliary switch S2 , so that the auxiliary switch S2 is turned off.

[0115] During the time period t1-t2, both the main switch S1 and the auxiliary switch S2 are in the off state, and this period is the dead time.

[0116] At time t2, the PWM control unit 121 outputs a high level to the gate G_S1 of the main switch S1 to turn on the main switch S1 and switches the main switch S1 to a high frequency intermittent period T HBURST The number of conduction times is recorded as 1. Correspondingly, at time t2, the excitation inductance L m The current I Lm Start to rise.

[0117] During the time period t2-t3, the PWM control unit 121 still outputs a high level to the gate G_S1 of the main switch tube S1, and the main switch tube S1 is still in the on state. m The current I Lm Continue to rise.

[0118] At time t3, the magnetizing inductance L m The current I Lm Reaching the first current peak I Lm_R1 , the PWM control unit 121 stops outputting a high level to the gate G_S1 of the main switch tube S1, so that the main switch tube S1 is turned off.

[0119] During the time period t3-t4, the main switch tube S1 and the auxiliary switch tube S2 are both in the off state. This period is the dead time. During this period, the excitation inductance L m The current I Lm From the first current peak I Lm_R1 Start to descend.

[0120] At time t4, the PWM control unit 121 outputs a high level to the gate G_S2 of the auxiliary switch tube S2 to turn on the auxiliary switch tube S2, and switches the auxiliary switch tube S2 to a high frequency intermittent period T HBURST The number of conduction times is recorded as 1. It should be noted that the high-frequency intermittent period T HBURST At the beginning, the auxiliary switch tube S2 is used to realize the conduction times of the main switch tube S1 soft switch, and the times are not recorded in the auxiliary switch tube S2 in a high frequency intermittent period T. HBURST within the conduction times.

[0121] During the time period t4-t5, the PWM control unit 121 still outputs a high level to the gate G_S2 of the auxiliary switch tube S2, so the auxiliary switch tube S2 is still in the on state and the main switch tube S1 is in the off state. m The current I Lm Still declining.

[0122] At t5, the magnetizing inductance L m When the volt-second balance is reached, the PWM control unit 121 stops outputting a high level to the gate G_S2 of the auxiliary switch tube S2 to turn off the auxiliary switch tube S2.

[0123] During the time period t5-t6, both the main switch tube S1 and the auxiliary switch tube S2 are in the off state, and this period is the dead time.

[0124] During the time period t6-t7, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to repeat the steps of the time period t2-t6 until the on-times of the main switch S1 and the auxiliary switch S2 are both 3.

[0125] At time t7, the number of times the main switch tube S1 and the number of times the auxiliary switch tube S2 are turned on are both 3, and the PWM control unit 121 no longer outputs a high level to the gate G_S1 of the main switch tube S1 and the gate G_S2 of the auxiliary switch tube S2, so that the main switch tube S1 and the auxiliary switch tube S2 are both turned off.

[0126] At time t7-t8, that is, at T SLEEP During the time period, both the main switch tube S1 and the auxiliary switch tube S2 are in the off state.

[0127] At time t8, the high-frequency intermittent period T HBURST Finish.

[0128] After time t8, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to operate according to a high-frequency intermittent period T between time t0 and time t8. HBURST Perform cycle work.

[0129] In the present application, the specific implementation of the converter 1 in the HBURST mode may refer to the description of the embodiment shown in FIG. 6 .

[0130] It is understandable that when the converter 1 is in the HBURST mode, the converter 1 can adjust the switching tube in a high frequency intermittent period T based on the change of the load. HBURST The number of conduction times N SW and the magnetizing inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , ensuring output on demand and avoiding the situation where the output exceeds the load requirement, thereby reducing energy loss and switch tube loss, and thus improving the efficiency of converter 1. In addition, as the load gradually becomes lighter, the switch tube is in a high-frequency intermittent period T HBURST The number of conduction times N SW and the magnetizing inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) Both gradually decrease, which can further reduce the energy output. Therefore, the output voltage ripple of the converter 1 under light load conditions can be further reduced, and the applicability is stronger.

[0131] The current output current I o Less than or equal to the first switching current threshold I o1 In the case of o Control converter 1 to be in HBURST mode or LBURST mode:

[0132] It should be noted that the converter 1 is based on the current output current I o The specific implementation steps of controlling the converter 1 to be in the HBURST mode or the LBURST mode are all obtained based on a combination of the steps corresponding to the following five current intervals.

[0133] At the current output current I o In the first current interval (I o2 ,I o1 ], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 ; At the current output current I o In the second current interval (I o3 ,I o2], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N2, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 ; At the current output current I o In the third current interval (I o4 ,I o1 ], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SW is the third conduction number N3, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The third current peak value I Lm_R3 ; At the current output current I o In the fourth current interval (0,I o4 ], the controller 12 is based on a high frequency intermittent period T HBURST The number of times the switch tube is turned on N SW is the fourth conduction number N4, and / or the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 , control converter 1 to be in LBURST mode; at the current output current I o In the fifth current interval (0,I o3 ], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SW is the sixth conduction number N6, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 .

[0134] Obviously, in the case where the above five current intervals are overlapped by multiple current intervals, when an overlapping current interval generated by the overlap of multiple current intervals appears between the above five current intervals, the PWM control unit 121 can select any current interval from the above overlapping multiple current intervals or a current interval that meets the actual working condition of the converter 1 as the target current interval, and o When the current is within the above-mentioned overlapping current range, the converter 1 is controlled to execute the current output current I o Based on this, it can be obtained that the control mode of the converter 1 in HBURST mode or LBURST mode is diverse and highly flexible. In addition, Io2 , I o4 with I o3 The size relationships among the three are diverse, so that the control methods of the converter 1 in the HBURST mode or the LBURST mode are more diverse and more flexible.

[0135] For the sake of ease of introduction, the following o2 >I o3 >I o4 As an example, the converter 1 is in HBURST mode or LBURST mode. o2 >I o3 >I o4 In this case, due to I o1 , I o2 and I o3 The size between them is fixed, that is, I o1 >I o2 >I o3 , so we can get the first current interval (I o2 ,I o1 ] and the third current interval (I o4 ,I o1 ] overlap and the overlapping current interval is (I o2 ,I o1 ], the controller 12 may select a first current interval (I o2 ,I o1 ] or the third current interval (I o4 ,I o1 ] as the overlapping current interval (I o2 ,I o1 ] target current interval, this embodiment takes the first current interval (I o2 ,I o1 ] is the overlapping current interval (I o2 ,I o1 ] is used as an example to introduce the target current interval; the second current interval (I o3 ,I o2 ] and the third current interval (I o4 ,I o1 ] overlap and the overlapping current interval is (I o3 ,I o2 ], the controller 12 may select a second current interval (I o3 ,I o2 ] or the third current interval (I o4 ,I o1 ] as the overlapping current interval (I o3 ,I o2 ] target current interval, this embodiment uses the second current interval (I o3 ,Io2 ] is the overlapping current interval (I o3 ,I o2 ] is used as an example to introduce the target current interval; the fifth current interval (0,I o3 ] and the third current interval (I o4 ,I o1 ] overlap and the overlapping current interval is (I o4 ,I o3 ], the controller 12 can select the fifth current interval (0,I o3 ] or the third current interval (I o4 ,I o1 ] as the overlapping current interval (I o4 ,I o3 ] target current interval, this embodiment uses the third current interval (I o4 ,I o1 ] is the overlapping current interval (I o4 ,I o3 ] is used as an example to introduce the target current interval; the fifth current interval (0,I o3 ] and the fourth current interval (0,I o4 ] overlap and the overlapping current interval is (0,I o4 ], the controller 12 can select the fifth current interval (0,I o3 ] or the fourth current interval (0,I o4 ] as the overlapping current interval (0,I o4 ] target current interval, this embodiment uses the fourth current interval (0,I o4 ] is the overlapping current interval (0,I o4 ] as an example to introduce the target current range.

[0136] Specifically, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o1 and is greater than the second switching current threshold I o2 In the case of the PWM control unit 121 executing the current output current I o In the first current interval (I o2 ,I o1 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1 (such as 3), so that the converter 1 is in the HBURST mode. o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3In the case of the PWM control unit 121 executing the current output current I o In the second current interval (I o3 ,I o2 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The second conduction number N2 (eg, 2) is the second conduction number N2, and the converter 1 is still in the HBURST mode. o Less than or equal to the fourth switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the third current interval (I o4 ,I o1 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The third conduction number N3 (eg, 1), the converter 1 is still in the HBURST mode. o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The fourth conduction number N4 (such as 1) is the same as the fourth conduction number N4 (such as 1), and after a high frequency intermittent period T HBURST The number of times the main switch tube S1 and the auxiliary switch tube S2 are turned on N SW After the first working cycle times of the fourth conduction times N4, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to perform a high-frequency intermittent period T HBURST The number of conduction times N SW The fifth conduction number N5 (ie 0) is the same, that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In the case of , the converter 1 is in the LBURST mode. The number of the first working cycles is a positive integer. For example, the number of the first working cycles is 3.

[0137] It can be understood that the current output current I o Less than or equal to the first switching current threshold Io1 In the case of load adjustment, the switch tube is adjusted in a high frequency intermittent cycle T HBURST The number of conduction times N SW For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, for extremely light load (i.e., output current I o Less than or equal to the third switching current threshold I o4 ) condition, the operating mode of converter 1 is further optimized, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube losses, thereby further improving converter 1's efficiency. Furthermore, because converter 1 is in LBURST mode under extremely light load conditions, output energy is further reduced. Therefore, this embodiment not only reduces converter 1's output voltage ripple under light load conditions, but also further reduces converter 1's output voltage ripple under extremely light load conditions, providing greater applicability.

[0138] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o1 In the case of m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0139] The current output current I o Less than or equal to the first switching current threshold I o1 and is greater than the second switching current threshold I o2 In the case of the PWM control unit 121 executing the current output current I o In the first current interval (I o2 ,I o1 ], that is, by controlling the conduction time of the main switch tube S1, so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 is in HBURST mode. At the current output current I o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 In the case of the PWM control unit 121 executing the current output current I o In the second current interval (I o3 ,I o2], that is, by controlling the conduction time of the main switch tube S1, so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The second current peak value I Lm_R2 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the fourth switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the third current interval (I o4 ,I o1 ], that is, by controlling the conduction time of the main switch tube S1, so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The third current peak value I Lm_R3 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, by controlling the conduction time of the main switch tube S1, so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fourth current peak value I Lm_R4 (such as I Lm_R4 =I Lm_R3 ), and after a high frequency intermittent period T HBURST The internal excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle times, the PWM control unit 121 controls the conduction time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In this case, converter 1 is in LBURST mode.

[0140] It can be understood that the current output current I o Less than or equal to the first switching current threshold I o1 In the case of load-based adjustment of the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) Regarding the embodiment in which converter 1 is always in HBURST mode, this embodiment further optimizes the operating mode of converter 1 under extremely light load conditions, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube losses, thereby further improving the efficiency of converter 1. Furthermore, because converter 1 is in LBURST mode under extremely light load conditions, output energy is further reduced. Therefore, this embodiment not only reduces converter 1's output voltage ripple under light load conditions, but also further reduces converter 1's output voltage ripple under extremely light load conditions, providing greater applicability.

[0141] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o1 In this case, the PWM control unit 121 can also simultaneously control the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW , and the magnetizing inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0142] The current output current I o Less than or equal to the first switching current threshold I o1 and is greater than the second switching current threshold I o2 In the case of the PWM control unit 121 executing the current output current I o In the first current interval (I o2 ,I o1 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1 (such as 3), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 is in HBURST mode. At the current output current I oLess than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 In the case of the PWM control unit 121 executing the current output current I o In the second current interval (I o3 ,I o2 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N2 (such as 2), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The second current peak value I Lm_R2 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the fourth switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the third current interval (I o4 ,I o1 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the third conduction number N3 (such as 1), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The third current peak value I Lm_R3 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The fourth conduction number N4 (such as 1) is used, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fourth current peak value I Lm_R4 (such as I Lm_R4 =I Lm_R3), and after a high frequency intermittent period T HBURST The number of conduction times of the switch tube in the circuit is the fourth conduction number N4 and the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle, that is, after the first working cycle, the number of conduction times of the switch tube is the fourth conduction number N4 and the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 The high-frequency intermittent period T HBURST After that, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to perform a high-frequency intermittent cycle T. HBURST The number of conduction times N SW The fifth conduction number N5 (ie 0) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In this case, converter 1 is in LBURST mode.

[0143] For ease of understanding, the following assumes that the number of the first working cycle and the fourth conduction number are both 1, and the fourth current peak is I Lm_R3 For example, the controller 12 simultaneously controls a high frequency intermittent period T HBURST The number of conduction times N SW and the peak current I Lm(PEAK) , the specific implementation method of putting converter 1 in LBURST mode is introduced.

[0144] Refer to Figure 7, which is a control timing diagram of the converter provided by the present application in the LBURST mode. As shown in Figure 7, at time t0', the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to turn on or off, so that the LBURST mode begins, that is, the converter 1 starts to operate in the first high-frequency intermittent wave cycle T HBURST , where, in a high frequency intermittent wave cycle T HBURST The number of times the main switch tube S1 and the auxiliary switch tube S2 are turned on is N. SW is 1, and the excitation inductance L m Peak current I Lm(PEAK) For I Lm_R3Here, the converter 1 works in a high frequency intermittent wave cycle T HBURST For the specific implementation method, please refer to the description of the corresponding part of the embodiment shown in Figure 6.

[0145] During the time period t0'-t1', the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be turned on or off, so that the converter 1 continuously operates for three high-frequency intermittent wave cycles T HBURST .

[0146] At time t1', converter 1 has been working continuously for three high-frequency intermittent wave cycles T HBURST , the PWM control unit 121 no longer outputs a high level to the gate G_S1 of the main switch tube S1 and the gate G_S2 of the auxiliary switch tube S2, so that both the main switch tube S1 and the auxiliary switch tube S2 are turned off.

[0147] After time t1 ′, the PWM control unit 121 no longer outputs a high level to the gate G_S1 of the main switch S1 and the gate G_S2 of the auxiliary switch S2 , so that both the main switch S1 and the auxiliary switch S2 are turned off.

[0148] In the present application, the specific implementation of the converter 1 in the LBURST mode may refer to the description of the embodiment shown in FIG. 7 .

[0149] It should be noted that when I o2 , I o3 and I o4 The relationship between the three is divided by I o2 >I o3 >I o4 For other size relationships except for the above, the specific implementation of the converter 1 in the HBURST mode or LBURST mode can be found in I o2 >I o3 >I o4 The description of the corresponding embodiment is omitted here.

[0150] It can be understood that the current output current I o Less than or equal to the first switching current threshold I o1 In the case of , compared with the load-based simultaneous adjustment of the number of switch on times N in a high-frequency intermittent cycle SW and the magnetizing inductance L m Peak current I Lm(PEAK)With regard to the embodiment in which converter 1 is always in HBURST mode, this embodiment further optimizes the operating mode of converter 1 under extremely light load conditions, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube loss, thereby further improving the efficiency of converter 1. Furthermore, since converter 1 is in LBURST mode under extremely light load conditions, the output energy is further reduced. Therefore, this embodiment not only reduces the output voltage ripple of converter 1 under light load conditions, but also further reduces the output voltage ripple of converter 1 under extremely light load conditions, making it more applicable.

[0151] The current output current I o Less than or equal to the first switching current threshold I o1 In the case of , according to the operating frequency of converter 1, converter 1 is controlled to be in HBURST mode or LBURST mode:

[0152] Specifically, please refer to FIG5 again, when the current output current I o Less than or equal to the first switching current threshold I o1 and is greater than the second switching current threshold I o2 In the case of o In the first current interval (I o2 ,I o1 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N1 (such as 3) is set to put the converter 1 in the HBURST mode. HBURST The number of conduction times N SW After the first conduction number N1 is reached, the PWM control unit 121 calculates the conduction number N of the switch tube (ie, the main switch tube S1 and the auxiliary switch tube S2). SW The high-frequency intermittent period T of the first conduction number N1 HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the circuit is within the human hearing range, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SWThe fourth conduction times N4 (such as 1) are all the same, and the conduction times N of the main switch tube S1 and the auxiliary switch tube S2 within a high-frequency intermittent period are SW After the first working cycle times of the fourth conduction times N4, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to conduct the number of times N in a high-frequency intermittent cycle. SW The fifth conduction number N5 (ie 0) is the same, that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, in the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the PWM control unit 121 controls the converter 1 to be in the LBURST mode. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1.

[0153] Assume that the number of times the switch tube is turned on is N SW The high-frequency intermittent period T of the first conduction number N1 HBURST Frequency f HBURST If the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1. And at the current output current I o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 In the case of o In the second current interval (I o3 ,I o2 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The second conduction number N2 (eg, 2) is the second conduction number, and the converter 1 is still in the HBURST mode. The main switch tube S1 and the auxiliary switch tube S2 are in a high frequency intermittent period T HBURST The number of conduction times N SW After the second conduction number N2 is reached, the PWM control unit 121 calculates the conduction number N of the switch tube. SW The high-frequency intermittent period T of the second conduction number N2 HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period THBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the corresponding part of the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N2.

[0154] Assume that the number of times the switch tube is turned on is N SW The high-frequency intermittent period T of the second conduction number N2 HBURST Frequency f HBURST If the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N2. And at the current output current I o Less than or equal to the fourth switching current threshold I o3 In the case of o In the fifth current interval (0,I o3 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The sixth conduction number N6 (eg, 1), the converter 1 is still in the HBURST mode. The main switch tube S1 and the auxiliary switch tube S2 are in a high frequency intermittent period T HBURST The number of conduction times N SW After the sixth conduction number N6, the PWM control unit 121 calculates the conduction number N of the switch tube. SW The high-frequency intermittent period T of the sixth conduction number N6 HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURSTWhen the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the corresponding part of the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW It is the sixth conduction number N6.

[0155] It can be understood that the current output current I o Less than or equal to the first switching current threshold I o1 In the case of load adjustment, the number of conduction times N of the switch tube in a high-frequency intermittent cycle is compared. SW For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURST The working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, which can further reduce energy loss and switch loss, and further improve the efficiency of the converter 1. In addition, during the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0156] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o1 In the case of m The peak current I in a high-frequency intermittent cycle Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0157] The current output current I o In the first current interval (I o2 ,I o1 ], the PWM control unit 121 controls the conduction time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 is in HBURST mode. And the excitation inductor L mThe peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 After that, the PWM control unit 121 calculates the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the voltage is within the human hearing range, the PWM control unit 121 controls the conduction time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fourth current peak value I Lm_R4 , and after a high-frequency intermittent cycle, the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle times, the PWM control unit 121 controls the conduction time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be in the off state. In other words, in the high-frequency intermittent period T HBURST Frequency f HBURST When the frequency is within the human hearing range, the converter 1 is in LBURST mode. HBURST Frequency f HBURST When the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 .

[0158] Assume that the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 The high-frequency intermittent period T HBURST Frequency f HBURST If the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 to make the excitation inductance Lm The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 . And the current output current I o In the second current interval (I o3 ,I o2 ], the PWM control unit 121 controls the conduction time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 , converter 1 is still in HBURST mode. And in the excitation inductor L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 After that, the PWM control unit 121 calculates the excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 .

[0159] Assume that the excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURST If the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK)The second current peak value I Lm_R2 . And the current output current I o In the fifth current interval (0,I o3 ], the PWM control unit 121 controls the conduction time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 =I Lm_R3 , converter 1 is still in HBURST mode. And in the excitation inductor L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 After that, the PWM control unit 121 calculates the excitation inductance L m Peak current I Lm(PEAK) The sixth current peak value I Lm_R6 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 .

[0160] It can be understood that the current output current I o Less than or equal to the first switching current threshold I o1 In the case of load-based adjustment of the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURSTThe working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, which can further reduce energy loss and switch loss, and further improve the efficiency of the converter 1. In addition, during the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0161] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o1 In the case of a high-frequency intermittent cycle, the PWM control unit 121 can also simultaneously control the conduction times N of the main switch tube S1 and the auxiliary switch tube S2. SW , and the magnetizing inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0162] The current output current I o In the first current interval (I o2 ,I o1 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N1 (such as 3) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 is in HBURST mode. And when the switch tube is in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1, and the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 After that, the PWM control unit 121 calculates the number of times the switch tube is turned on N. SW is the first conduction number N1 and the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURSTIs it within the range of human hearing? HBURST Frequency f HBURST When the circuit is within the human hearing range, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The fourth conduction number N4 (such as 1) is used, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fourth current peak value I Lm_R4 , and after a high-frequency intermittent cycle, the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 And the number of times the switch tube is turned on N SW After the first working cycle times of the fourth conduction times N4, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to conduct the number of times N in a high-frequency intermittent cycle. SW The fifth conduction number N5 (ie 0) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be in the off state. In other words, in the high-frequency intermittent period T HBURST Frequency f HBURST When the frequency is within the human hearing range, the converter 1 is in LBURST mode. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N1 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 .

[0163] Assume that the number of times the switch tube is turned on is N SW is the first conduction number N1 and the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 The high-frequency intermittent period T HBURST Frequency f HBURSTIf the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N1 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 . And the current output current I o In the second current interval (I o3 ,I o2 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The second conduction number N2 (such as 2) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 , converter 1 is still in HBURST mode. And when the switch tube is in a high frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N2 and the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 After that, the PWM control unit 121 calculates the number of times the switch tube is turned on N. SW is the second conduction number N2 and the excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURSTThe number of conduction times N SW The second conduction number N2 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 .

[0164] Assume that the number of times the switch tube is turned on is N SW is the second conduction number N2 and the excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURST If the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The second conduction number N2 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 . And the current output current I o In the fifth current interval (0,I o3 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The sixth conduction number N6 (such as 1) is used, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 , converter 1 is still in HBURST mode. And when the switch tube is in a high frequency intermittent period T HBURST The number of conduction times N SW The sixth conduction number N6 and the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 After that, the PWM control unit 121 calculates the number of times the switch tube is turned on N. SW The sixth conduction number N6 and the excitation inductance L m Peak current I Lm(PEAK) The sixth current peak value I Lm_R6 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency fHBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW The sixth conduction number N6 is obtained, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 .

[0165] It can be understood that the current output current I o Less than or equal to the switching current threshold I corresponding to the high voltage interval H o1 In the case of , compared with the load-based simultaneous adjustment of the number of switch on times N in a high-frequency intermittent cycle SW and the magnetizing inductance L m Peak current I Lm(PEAK) , so that the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURST The working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, which can further reduce energy loss and switch loss, and further improve the efficiency of the converter 1. In addition, during the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0166] It should be noted that the above embodiments are all based on the situation that the current output voltage is in the high voltage range H, and the current output current I o In the current range where the converter 1 is located, the converter 1 is controlled to be in CRM mode or intermittent wave mode. The following is a detailed description of the change trend of the output current of the converter 1. When the output current of the converter 1 drops to the first switching current threshold I o1, the converter 1 switches from the CRM mode to the HBURST mode; in order to further improve the efficiency of the converter 1 under extremely light load conditions, after the converter 1 is in the HBURST mode, the output current of the converter 1 continues to drop to the third switching current threshold I o4 When the converter 1 switches from the HBURST mode to the LBURST mode, the output current of the converter 1 rises to the third switching current threshold I o4 When the output current of the converter 1 continues to rise to the first switching current threshold I o1 When , converter 1 switches from HBURST mode to CRM mode.

[0167] In another optional embodiment, when the first voltage interval is the medium voltage interval M, the curve control unit 122 determines that the first switching current threshold corresponding to the medium voltage interval M is I shown in FIG. o2 and the first switching current threshold I corresponding to the medium voltage interval M o2 Sent to the PWM control unit 121. Among them, the first switching current threshold I corresponding to the medium voltage interval M o2 is the mode switching point at which the converter 1 switches between the CRM mode and the HBURST mode when the output voltage of the converter 1 is in the medium voltage range M.

[0168] First, it should be noted that when the first voltage interval is the medium voltage interval M, the first switching current threshold, the second switching current threshold, and the third switching current threshold are I o2 , I o3 and I o4 The first conduction number, the second conduction number, the third conduction number, the fourth conduction number and the fifth conduction number are N2, N6, N3, N4 and N5 respectively. The first current peak value, the second current peak value, the third current peak value, the fourth current peak value and the fifth current peak value are I Lm_R2 , I Lm_R6 , I Lm_R3 , I Lm_R4 and I Lm_R5 Among them, I o2 >I o3 >0,I o2 >I o4 >0,I o3 with I o4 N2>N6, N3≥N4, N5=0, N2, N3, N4 and N6 are all positive integers. Lm_R2 >I Lm_R6 >0,I Lm_R3 ≥I Lm_R4 >0,I Lm_R5 =0,ILm_R2 , I Lm_R3 , I Lm_R4 and I Lm_R6 The value of satisfies the switching frequency f of converter 1 SW Less than the maximum switching frequency f SW(MAX) And the high-frequency intermittent period T HBURST Frequency f HBURST For the convenience of introduction, this embodiment uses N6=N3, I Lm_R6 =I Lm_R3 Take this as an example to introduce.

[0169] As shown in FIG5 , the current output current I o Greater than the first switching current threshold I o2 In the case of SW With the output current I o or control the switching frequency f of the converter 1. SW With the output current I o In addition, when the converter 1 is in CRM mode, at the same output current value, when the output voltage is in the medium voltage range M, the switching frequency f of the converter 1 is SW is less than the switching frequency f of converter 1 when the output voltage is in the high voltage range H SW .

[0170] When the current output current of the converter 1 is less than or equal to the first switching current threshold I o2 In the case of , converter 1 is in HBURST mode:

[0171] Specifically, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o2 and is greater than the second switching current threshold I o3 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW is the first conduction number N2 (such as 2), so that the converter 1 is in the HBURST mode. o Less than or equal to the second switching current threshold I o3 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW The second conduction number N6 (eg, 1) is the second conduction number, and the converter 1 is still in the HBURST mode.

[0172] It is understandable that when the converter 1 is in the HBURST mode, the converter 1 can adjust the switching tube in a high frequency intermittent period T based on the change of the load. HBURST The number of conduction times N SW , ensuring output on demand and avoiding the situation where the output exceeds the load requirement, thereby reducing energy loss and switch tube loss, and thus improving the efficiency of converter 1. In addition, as the load gradually becomes lighter, the switch tube is in a high-frequency intermittent period T HBURST The number of conduction times N SW It also gradually decreases, therefore, the output voltage ripple of the converter 1 under light load conditions can also be reduced, and the applicability is strong.

[0173] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o2 In the case of m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , putting converter 1 in HBURST mode.

[0174] The current output current I o Less than or equal to the first switching current threshold I o2 and is greater than the second switching current threshold I o3 In the case of m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R2 , converter 1 is in HBURST mode. At the current output current I o Less than or equal to the second switching current threshold I o3 In the case of m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The second current peak value I Lm_R6 =I Lm_R3 , the converter 1 is still in the HBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the HBURST mode will be described in the subsequent embodiments and will not be further described here.

[0175] It is understandable that when the converter 1 is in the HBURST mode, the converter 1 can adjust the excitation inductance L based on the change of the load.m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , ensuring output on demand and avoiding the situation where the output exceeds the load requirement, thereby reducing energy loss and switch tube loss, and thus improving the efficiency of converter 1. In addition, as the load gradually becomes lighter, the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) It also gradually decreases, therefore, the output voltage ripple of the converter 1 under light load conditions can also be reduced, and the applicability is strong.

[0176] Optionally, the current output current I of the converter 1 o Less than or equal to the switching current threshold I o2 In this case, the PWM control unit 121 can also simultaneously control the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent period T HBURST The number of conduction times within the circuit, and the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , putting converter 1 in HBURST mode.

[0177] The current output current I o Less than or equal to the first switching current threshold I o2 and is greater than the second switching current threshold I o3 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW is the first conduction number N2 (such as 2), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The first current peak I Lm(PEAK) is the peak current I Lm_R2 , converter 1 is in HBURST mode. At the current output current I o Less than or equal to the second switching current threshold I o3 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW The second conduction number N6=N3 (such as 1), and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The second current peak I Lm(PEAK) is the peak current I Lm_R6 =ILm_R3 , converter 1 is still in HBURST mode.

[0178] It is understandable that when the converter 1 is in the HBURST mode, the converter 1 can adjust a high frequency intermittent period T based on the change of the load. HBURST The number of times the internal switch tube is turned on N SW and the magnetizing inductance L m Peak current I Lm(PEAK) , ensuring output on demand and avoiding the situation where the output exceeds the load requirement, thereby reducing energy loss and switch tube loss, and thus improving the efficiency of converter 1. In addition, as the load gradually becomes lighter, the switch tube is in a high-frequency intermittent period T HBURST The number of conduction times N SW and the magnetizing inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) Both gradually decrease, which can further reduce the energy output. Therefore, the output voltage ripple of the converter 1 under light load conditions can be further reduced, and the applicability is stronger.

[0179] The current output current I o Less than or equal to the first switching current threshold I o2 In the case of o Control converter 1 to be in HBURST mode or LBURST mode:

[0180] It should be noted that the converter 1 is based on the current output current I o The specific implementation steps of controlling the converter 1 to be in the HBURST mode or the LBURST mode are all obtained based on a combination of the steps corresponding to the following four current intervals.

[0181] At the current output current I o In the second current interval (I o3 ,I o2 ], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N2, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R2 ; At the current output current I o In the fourth current interval (0,I o4 ], the controller 12 is based on a high frequency intermittent period T HBURST The number of times the switch tube is turned on N SWis the fourth conduction number N4, and / or the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 , control converter 1 to be in LBURST mode; at the current output current I o In the fifth current interval (0,I o3 ], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N6, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R6 ; At the current output current I o In the sixth current interval (I o4 ,I o2 ], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SW is the third conduction number N3, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The third current peak value I Lm_R3 .

[0182] Obviously, in the case where the above four current intervals are overlapped by multiple current intervals, when an overlapping current interval generated by the overlap of multiple current intervals appears between the above four current intervals, the PWM control unit 121 can select any current interval from the above overlapping multiple current intervals or a current interval that meets the actual working condition of the converter 1 as the target current interval, and o When the current is within the above-mentioned overlapping current range, the converter 1 is controlled to execute the current output current I o Based on this, it can be obtained that the control mode of the converter 1 in HBURST mode or LBURST mode is diverse and highly flexible. In addition, I o3 with I o4 The size relationship between them is diverse, so that the control mode of the converter 1 in the HBURST mode or the LBURST mode is more diverse and more flexible.

[0183] For the sake of ease of introduction, the following o3 >I o4 As an example, the converter 1 is in HBURST mode or LBURST mode. o2 >I o4 In this case, due to I o2 >I o3 , Io2 >I o4 , so we can get the second current interval (I o3 ,I o2 ] and the sixth current interval (I o4 ,I o2 ] overlap and the overlapping current interval is (I o3 ,I o2 ], the controller 12 may select a second current interval (I o3 ,I o2 ] or the sixth current interval (I o4 ,I o2 ] as the overlapping current interval (I o3 ,I o2 ] target current interval, this embodiment uses the second current interval (I o3 ,I o2 ] is the overlapping current interval (I o3 ,I o2 ] is used as an example to introduce the target current interval; the fifth current interval (0,I o3 ] and the sixth current interval (I o4 ,I o2 ] overlap and the overlapping current interval is (I o4 ,I o3 ], the controller 12 can select the fifth current interval (0,I o3 ] or the sixth current interval (I o4 ,I o2 ] as the overlapping current interval (I o4 ,I o3 ] target current interval, this embodiment uses the sixth current interval (I o4 ,I o2 ] is the overlapping current interval (I o4 ,I o3 ] is used as an example to introduce the target current interval; the fifth current interval (0,I o3 ] and the fourth current interval (0,I o4 ] overlap and the overlapping current interval is (0,I o4 ], the controller 12 can select the fifth current interval (0,I o3 ] or the fourth current interval (0,I o4 ] as the overlapping current interval (0,I o4 ] target current interval, this embodiment uses the fourth current interval (0,I o4 ] is the overlapping current interval (0,I o4 ] as an example to introduce the target current range.

[0184] Specifically, the current output current I of the converter 1 oLess than or equal to the first switching current threshold I o2 and is greater than the second switching current threshold I o3 In the case of the PWM control unit 121 executing the current output current I o In the second current interval (I o3 ,I o2 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N2 (such as 2) is the first conduction number N2, and the converter 1 is in the HBURST mode. o Less than or equal to the second switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the sixth current interval (I o4 ,I o2 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The third conduction number N3 (eg, 1), the converter 1 is still in the HBURST mode. o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The fourth conduction number N4 (such as 1) is the same as the fourth conduction number N4 (such as 1), and after a high frequency intermittent period T HBURST The number of times the main switch tube S1 and the auxiliary switch tube S2 are turned on N SW After the first working cycle times of the fourth conduction times N4, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to perform a high-frequency intermittent period T HBURST The number of conduction times N SW The fifth conduction number N5 (ie 0) is the same, that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In the case of , the converter 1 is in the LBURST mode. The number of the first working cycles is a positive integer. For example, the number of the first working cycles is 3.

[0185] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the medium voltage range M o2 In the case of load adjustment, the switch tube is adjusted in a high frequency intermittent cycle T HBURST The number of conduction times N SW For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, for extremely light load (i.e., output current I o Less than or equal to the third switching current threshold I o4 ) condition, the operating mode of converter 1 is further optimized, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube losses, thereby further improving converter 1's efficiency. Furthermore, because converter 1 is in LBURST mode under extremely light load conditions, output energy is further reduced. Therefore, this embodiment not only reduces converter 1's output voltage ripple under light load conditions, but also further reduces converter 1's output voltage ripple under extremely light load conditions, providing greater applicability.

[0186] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o2 In the case of m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0187] The current output current I o Less than or equal to the first switching current threshold I o2 and is greater than the second switching current threshold I o3 In the case of the PWM control unit 121 executing the current output current I o In the second current interval (I o3 ,I o2 ], that is, by controlling the conduction time of the main switch tube S1, so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R2 , converter 1 is in HBURST mode. At the current output current I o Less than or equal to the second switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current Io In the sixth current interval (I o4 ,I o2 ], that is, by controlling the conduction time of the main switch tube S1, so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The third current peak value I Lm_R3 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, by controlling the conduction time of the main switch tube S1, so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fourth current peak value I Lm_R4 (such as I Lm_R4 =I Lm_R3 ), and after a high frequency intermittent period T HBURST The internal excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle times, the PWM control unit 121 controls the conduction time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In this case, converter 1 is in LBURST mode.

[0188] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the medium voltage range M o2 In the case of load-based adjustment of the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK)Regarding the embodiment in which converter 1 is always in HBURST mode, this embodiment further optimizes the operating mode of converter 1 under extremely light load conditions, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube losses, thereby further improving the efficiency of converter 1. Furthermore, because converter 1 is in LBURST mode under extremely light load conditions, output energy is further reduced. Therefore, this embodiment not only reduces converter 1's output voltage ripple under light load conditions, but also further reduces converter 1's output voltage ripple under extremely light load conditions, providing greater applicability.

[0189] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o2 In this case, the PWM control unit 121 can also simultaneously control the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW , and the magnetizing inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0190] The current output current I o Less than or equal to the first switching current threshold I o2 and is greater than the second switching current threshold I o3 In the case of the PWM control unit 121 executing the current output current I o In the second current interval (I o3 ,I o2 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N2 (such as 2), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R2 , converter 1 is in HBURST mode. At the current output current I o Less than or equal to the second switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the sixth current interval (I o4 ,I o2], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the third conduction number N3 (such as 1), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The third current peak value I Lm_R3 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The fourth conduction number N4 (such as 1) is used, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fourth current peak value I Lm_R4 (such as I Lm_R4 =I Lm_R3 ), and after a high frequency intermittent period T HBURST The number of conduction times of the switch tube in the circuit is the fourth conduction number N4 and the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle, that is, after the first working cycle, the number of conduction times of the switch tube is the fourth conduction number N4 and the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 The high-frequency intermittent period T HBURST After that, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to perform a high-frequency intermittent cycle T. HBURST The number of conduction times N SW The fifth conduction number N5 (ie 0) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current Io Less than or equal to the third switching current threshold I o4 In this case, converter 1 is in LBURST mode.

[0191] It should be noted that when I o4 >I o3 When the converter 1 is in the HBURST mode or the LBURST mode, please refer to I o3 >I o4 The description of the corresponding embodiment is omitted here.

[0192] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the medium voltage range M o2 In the case of , compared with the load-based simultaneous adjustment of the number of switch on times N in a high-frequency intermittent cycle SW and the magnetizing inductance L m Peak current I Lm(PEAK) With regard to the embodiment in which converter 1 is always in HBURST mode, this embodiment further optimizes the operating mode of converter 1 under extremely light load conditions, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube loss, thereby further improving the efficiency of converter 1. Furthermore, since converter 1 is in LBURST mode under extremely light load conditions, the output energy is further reduced. Therefore, this embodiment not only reduces the output voltage ripple of converter 1 under light load conditions, but also further reduces the output voltage ripple of converter 1 under extremely light load conditions, making it more applicable.

[0193] The current output current I o Less than or equal to the first switching current threshold I o2 In the case of , according to the operating frequency of converter 1, converter 1 is controlled to be in HBURST mode or LBURST mode:

[0194] Specifically, please refer to FIG5 again, when the current output current I o Less than or equal to the first switching current threshold I o2 and is greater than the second switching current threshold I o3 In the case of o In the second current interval (I o3 ,I o2 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The first conduction number N2 (such as 2), the converter 1 is in the HBURST mode. And the main switch tube S1 and the auxiliary switch tube S2 are in a high frequency intermittent period THBURST The number of conduction times N SW After the first conduction number N2 is reached, the PWM control unit 121 calculates the conduction number N of the switch tube. SW The high-frequency intermittent period T of the first conduction number N2 HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the circuit is within the human hearing range, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The fourth conduction times N4 (such as 1) are all the same, and the conduction times N of the main switch tube S1 and the auxiliary switch tube S2 within a high-frequency intermittent period are SW After the first working cycle times of the fourth conduction times N4, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to conduct the number of times N in a high-frequency intermittent cycle. SW The fifth conduction number N5 (ie 0) is the same, that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, in the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the PWM control unit 121 controls the converter 1 to be in the LBURST mode. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N2.

[0195] Assume that the number of times the switch tube is turned on is N SW The high-frequency intermittent period T of the first conduction number N2 HBURST Frequency f HBURST If the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N2. And at the current output current I o Less than or equal to the second switching current threshold I o3 In the case of o In the fifth current interval (0,I o3], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The second conduction number N6 = N3 (such as 1), the converter 1 is still in the HBURST mode. HBURST The number of conduction times N SW After the second conduction number N6 is reached, the PWM control unit 121 calculates the conduction number N of the switch tube. SW The high frequency intermittent period T of the second conduction number N6 HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the corresponding part of the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N6.

[0196] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the medium voltage range M o2 In the case of load adjustment, the number of conduction times N of the switch tube in a high-frequency intermittent cycle is compared. SW For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURST The working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, which can further reduce energy loss and switch loss, and further improve the efficiency of the converter 1. In addition, during the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0197] Optionally, the current output current I of the converter 1 oLess than or equal to the first switching current threshold I o2 In the case of m The peak current I in a high-frequency intermittent cycle Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0198] The current output current I o In the second current interval (I o3 ,I o2 ], the PWM control unit 121 controls the conduction time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R2 , converter 1 is in HBURST mode. And in the excitation inductor L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R2 After that, the PWM control unit 121 calculates the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R2 .

[0199] Assume that the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURSTIf the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R2 . And the current output current I o In the fifth current interval (0,I o3 ], the PWM control unit 121 controls the conduction time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R6 =I Lm_R3 , converter 1 is still in HBURST mode. And in the excitation inductor L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R6 After that, the PWM control unit 121 calculates the excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R6 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R6 .

[0200] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the medium voltage range M o2 In the case of load-based adjustment of the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK)For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURST The working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, which can further reduce energy loss and switch loss, and further improve the efficiency of the converter 1. In addition, during the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0201] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o2 In this case, the PWM control unit 121 can also simultaneously control the conduction times N of the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent cycle. SW , and the magnetizing inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0202] The current output current I o In the second current interval (I o3 ,I o2 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The first conduction number N2 (such as 2) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R2 , converter 1 is in HBURST mode. And when the switch tube is in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N2 and the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R2 After that, the PWM control unit 121 calculates the number of times the switch tube is turned on N. SW is the first conduction number N2 and the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / THBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N2 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R2 .

[0203] Assume that the number of times the switch tube is turned on is N SW is the first conduction number N2 and the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURST If the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N2 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R2 . And the current output current I o In the fifth current interval (0,I o3 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The second conduction number N6=N3 (such as 1), and the conduction time of the main switch tube S1 is controlled to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R6 =I Lm_R3, converter 1 is still in HBURST mode. And when the switch tube is in a high frequency intermittent period T HBURST The number of conduction times N SW The second conduction number N6 and the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R6 After that, the PWM control unit 121 calculates the number of times the switch tube is turned on N. SW The second conduction number N6 and the excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R6 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW The second conduction number N6 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R6 .

[0204] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the medium voltage range M o2 In the case of , compared with the load-based simultaneous adjustment of the number of switch on times N in a high-frequency intermittent cycle SW and the magnetizing inductance L m Peak current I Lm(PEAK) , so that the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURSTThe working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, which can further reduce energy loss and switch loss, and further improve the efficiency of the converter 1. In addition, during the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0205] It should be noted that the above embodiments are all based on the situation that the current output voltage is in the medium voltage range M, and the current output current I o In the current range where the converter 1 is located, the converter 1 is controlled to be in CRM mode or intermittent wave mode. The following is a detailed description of the change trend of the output current of the converter 1. When the output current of the converter 1 drops to the first switching current threshold I o2 , the converter 1 switches from the CRM mode to the HBURST mode; in order to further improve the efficiency of the converter 1 under extremely light load conditions, after the converter 1 is in the HBURST mode, the output current of the converter 1 continues to drop to the third switching current threshold I o4 When the output current of the converter 1 rises to the third switching current threshold I o4 When the output current of the converter 1 continues to rise to the first switching current threshold I o2 When , converter 1 switches from HBURST mode to CRM mode.

[0206] In another optional embodiment, when the first voltage interval is the low voltage interval L, the curve control unit 122 determines that the first switching current threshold corresponding to the low voltage interval L is I shown in FIG. o3 and the first switching current threshold I corresponding to the low voltage interval L o3 The first switching current threshold I corresponding to the low voltage interval L is sent to the PWM control unit 121. o3 It is a mode switching point at which the converter 1 switches between the CRM mode and the HBURST mode when the output voltage of the converter 1 is in the low voltage range L.

[0207] First, it should be noted that when the first voltage interval is the low voltage interval L, the first switching current threshold and the third switching current threshold are I o3 and I o4 The third conduction number, the fourth conduction number and the fifth conduction number are N3, N4 and N5 respectively, and the third current peak value, the fourth current peak value and the fifth current peak value are I Lm_R3 , ILm_R4 and I Lm_R5 Among them, I o3 >I o4 > 0. N3≥N4, N5=0, N3 and N4 are both positive integers. Lm_R3 ≥I Lm_R4 >0,I Lm_R5 =0,I Lm_R3 and I Lm_R4 The value of satisfies the switching frequency f of converter 1 SW Less than the maximum switching frequency f SW(MAX) And the high-frequency intermittent period T HBURST Frequency f HBURST The condition is beyond the range of human hearing.

[0208] As shown in FIG5 , the current output current I o Greater than the first switching current threshold I o3 In the case of SW With the output current I o or control the switching frequency f of the converter 1. SW With the output current I o In addition, when the converter 1 is in CRM mode, at the same output current value, when the output voltage is in the low voltage range L, the switching frequency f of the converter 1 is SW is less than the switching frequency f of converter 1 when the output voltage is in the medium voltage range M SW .

[0209] When the current output current of the converter 1 is less than or equal to the first switching current threshold I o3 In the case of , converter 1 is in HBURST mode:

[0210] Specifically, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o3 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW The third conduction number N3 (eg, 1) is set to put the converter 1 in the HBURST mode.

[0211] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o3 In the case of mIn a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The third current peak value I Lm_R3 , converter 1 is in HBURST mode. Lm_R3 Satisfy the switching frequency f of converter 1 SW Less than the maximum switching frequency f SW(MAX) And the high-frequency intermittent period T HBURST Frequency f HBURST Conditions outside the range of human hearing.

[0212] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o3 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SW is the third conduction number N3 (such as 1), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The third current peak value I Lm_R3 , converter 1 is in HBURST mode.

[0213] It can be understood that the converter 1 can be based on adjusting the switching tube in a high frequency intermittent period T HBURST The number of conduction times N SW and / or magnetizing inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , puts converter 1 in HBURST mode, with diverse control methods and high flexibility.

[0214] The current output current I o Less than or equal to the first switching current threshold I o3 In the case of o Control converter 1 to be in HBURST mode or LBURST mode:

[0215] Specifically, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of o In the seventh current interval (I o4 ,I o3], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The third conduction number N3 (such as 1) indicates that the converter 1 is in the HBURST mode. o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The fourth conduction number N4 (such as 1) is the same as the fourth conduction number N4 (such as 1), and after a high frequency intermittent period T HBURST The number of times the main switch tube S1 and the auxiliary switch tube S2 are turned on N SW After the first working cycle times of the fourth conduction times N4, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to perform a high-frequency intermittent period T HBURST The number of conduction times N SW The fifth conduction number N5 (ie 0) is the same, that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In the case of , the converter 1 is in the LBURST mode. The number of the first working cycles is a positive integer. For example, the number of the first working cycles is 3.

[0216] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the low voltage interval L o3 In the case of load adjustment, the switch tube is adjusted in a high frequency intermittent cycle T HBURST The number of conduction times N SW For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, for extremely light load (i.e., output current I o Less than or equal to the switching current threshold I o4) condition, the operating mode of converter 1 is further optimized, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube losses, thereby further improving converter 1's efficiency. Furthermore, because converter 1 is in LBURST mode under extremely light load conditions, output energy is further reduced. Therefore, this embodiment not only reduces converter 1's output voltage ripple under light load conditions, but also further reduces converter 1's output voltage ripple under extremely light load conditions, providing greater applicability.

[0217] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o3 In the case of m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0218] The current output current I o Less than or equal to the first switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of PWM control unit 121, the conduction time of main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The third current peak value I Lm_R3 , converter 1 is in HBURST mode. At the current output current I o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, by controlling the conduction time of the main switch tube S1, so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fourth current peak value I Lm_R4 (such as I Lm_R4 =I Lm_R3 ), and after a high frequency intermittent period T HBURST The internal excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle times, the PWM control unit 121 controls the conduction time of the main switch S1 to make the excitation inductance Lm The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In this case, converter 1 is in LBURST mode.

[0219] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the low voltage interval L o3 In the case of load-based adjustment of the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) Regarding the embodiment in which converter 1 is always in HBURST mode, this embodiment further optimizes the operating mode of converter 1 under extremely light load conditions, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube losses, thereby further improving the efficiency of converter 1. Furthermore, because converter 1 is in LBURST mode under extremely light load conditions, output energy is further reduced. Therefore, this embodiment not only reduces converter 1's output voltage ripple under light load conditions, but also further reduces converter 1's output voltage ripple under extremely light load conditions, providing greater applicability.

[0220] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o3 In this case, the PWM control unit 121 can also simultaneously control the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW , and the magnetizing inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0221] The current output current I o Less than or equal to the first switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times N SWis the third conduction number N3 (such as 1), and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R3 , converter 1 is in HBURST mode. At the current output current I o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The fourth conduction number N4 (such as 1) is used, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fourth current peak value I Lm_R4 (such as I Lm_R4 =I Lm_R3 ), and after a high frequency intermittent period T HBURST The number of conduction times of the switch tube in the circuit is the fourth conduction number N4 and the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle, that is, after the first working cycle, the number of conduction times of the switch tube is the fourth conduction number N4 and the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 The high-frequency intermittent period T HBURST After that, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to perform a high-frequency intermittent cycle T. HBURST The number of conduction times N SW The fifth conduction number N5 (ie 0) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In this case, converter 1 is in LBURST mode.

[0222] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the low voltage interval L o3 In the case of , compared with the load-based simultaneous adjustment of the number of switch on times N in a high-frequency intermittent cycle SW and the magnetizing inductance L m Peak current I Lm(PEAK) With regard to the embodiment in which converter 1 is always in HBURST mode, this embodiment further optimizes the operating mode of converter 1 under extremely light load conditions, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube loss, thereby further improving the efficiency of converter 1. Furthermore, since converter 1 is in LBURST mode under extremely light load conditions, the output energy is further reduced. Therefore, this embodiment not only reduces the output voltage ripple of converter 1 under light load conditions, but also further reduces the output voltage ripple of converter 1 under extremely light load conditions, making it more applicable.

[0223] The current output current I o Less than or equal to the first switching current threshold I o3 In the case of , according to the operating frequency of converter 1, converter 1 is controlled to be in HBURST mode or LBURST mode:

[0224] Specifically, please refer to FIG5 again, when the current output current I o Less than or equal to the first switching current threshold I o3 In the case of o In the fifth current interval (0,I o3 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The third conduction number N3 (e.g., N3=N4=1), the converter 1 is in the HBURST mode. HBURST The number of conduction times N SW After the third conduction number N3, the PWM control unit 121 calculates the conduction number N of the switch tube. SW The high frequency intermittent period T of the third conduction number N3 HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURSTWhen the circuit is within the human hearing range, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The fourth conduction times N4 (such as 1) are all the same, and the conduction times N of the main switch tube S1 and the auxiliary switch tube S2 within a high-frequency intermittent period are SW After the first working cycle times of the fourth conduction times N4, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to conduct the number of times N in a high-frequency intermittent cycle. SW The fifth conduction number N5 (ie 0) is the same, that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, in the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the PWM control unit 121 controls the converter 1 to be in the LBURST mode. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW is the third conduction number N3.

[0225] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the low voltage interval L o3 In the case of load adjustment, the number of conduction times N of the switch tube in a high-frequency intermittent cycle is compared. SW For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURST The working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, which can further reduce energy loss and switch loss, and further improve the efficiency of the converter 1. In addition, during the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0226] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o3 In the case of m The peak current I in a high-frequency intermittent cycle Lm(PEAK), so that converter 1 is in HBURST mode or LBURST mode.

[0227] The current output current I o In the fifth current interval (0,I o3 ], the PWM control unit 121 controls the conduction time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The third current peak value I Lm_R3 , converter 1 is in HBURST mode. And in the excitation inductor L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The third current peak value I Lm_R3 After that, the PWM control unit 121 calculates the excitation inductance L m Peak current I Lm(PEAK) The third current peak value I Lm_R3 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The third current peak value I Lm_R3 .

[0228] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the low voltage interval L o3 In the case of load-based adjustment of the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURSTThe working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, which can further reduce energy loss and switch loss, and further improve the efficiency of the converter 1. In addition, during the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0229] Optionally, the current output current I of the converter 1 o Less than or equal to the first switching current threshold I o3 In this case, the PWM control unit 121 can also simultaneously control the conduction times N of the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent cycle. SW , and the magnetizing inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) , so that converter 1 is in HBURST mode or LBURST mode.

[0230] The current output current I o In the fifth current interval (0,I o3 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The third conduction number N3 (such as N3 = N4 = 1) is set, and the conduction time of the main switch tube S1 is controlled to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The third current peak value I Lm_R3 (such as I Lm_R3 =I Lm_R4 ), the converter 1 is in HBURST mode. And the switch tube is in a high frequency intermittent period T HBURST The number of conduction times N SW The third conduction number N3 and the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The third current peak value I Lm_R3 After that, the PWM control unit 121 calculates the number of times the switch tube is turned on N. SW The third conduction number N3 and the excitation inductance L m Peak current I Lm(PEAK) The third current peak value I Lm_R3 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency fHBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW The third conduction number N3 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The third current peak value I Lm_R3 .

[0231] It can be understood that the current output current I o Less than or equal to the first switching current threshold I corresponding to the low voltage interval L o3 In the case of , compared with the load-based simultaneous adjustment of the number of switch on times N in a high-frequency intermittent cycle SW and the magnetizing inductance L m Peak current I Lm(PEAK) , so that the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURST The working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, which can further reduce energy loss and switch loss, and further improve the efficiency of the converter 1. In addition, during the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0232] It should be noted that the above embodiments are all based on the situation that the current output voltage is in the low voltage range L, and the current output current I o In the current range where the converter 1 is located, the converter 1 is controlled to be in CRM mode or intermittent wave mode. The following is a detailed description of the change trend of the output current of the converter 1. When the output current of the converter 1 drops to the first switching current threshold I o3, the converter 1 switches from the CRM mode to the HBURST mode; in order to further improve the efficiency of the converter 1 under extremely light load conditions, after the converter 1 is in the HBURST mode, the output current of the converter 1 drops to the third switching current threshold I o4 When the output current of the converter 1 rises to the third switching current threshold I o4 When the output current of the converter 1 rises to the first switching current threshold I o3 When , converter 1 switches from HBURST mode to CRM mode.

[0233] In summary, the first switching current threshold I corresponding to the medium voltage range M is o2 Less than the first switching current threshold I corresponding to the high voltage interval H o1 And greater than the first switching current threshold I corresponding to the low voltage interval L o3 In other words, when the converter 1 switches between the CRM mode and the HBURST mode, the mode switching point when the output voltage is in the medium voltage range M is smaller than the mode switching point when the output voltage is in the high voltage range H, and is larger than the mode switching point when the output voltage is in the low voltage range L.

[0234] The first conduction number N2 corresponding to the medium voltage interval M is less than the first conduction number N1 corresponding to the high voltage interval H and greater than the third conduction number N3 corresponding to the low voltage interval L. The first current peak value I Lm_R2 Less than the first current peak value I corresponding to the high voltage interval H Lm_R1 And greater than the third current peak value I corresponding to the low voltage interval L Lm_R3 . In other words, when the converter 1 enters the HBURST mode from the CRM mode, as the gear position of the voltage range in which the output voltage is located gradually becomes lower, the operating parameters when entering the HBURST mode also gradually decrease, wherein the operating parameters are the number of conduction times of the switch tube within a high-frequency gap cycle and / or the current peak of the excitation inductance. For the convenience of description, the operating parameters when entering the HBURST mode will be referred to as the HBURST mode entry point below. The HBURST mode entry point when the output voltage is in the medium voltage range M is smaller than the HBURST mode entry point when the output voltage is in the high voltage range H, and is larger than the HBURST mode entry point when the output voltage is in the low voltage range L.

[0235] Since the mode switching point and HBURST mode entry point of the converter 1 when the output voltage is in the medium voltage range M are lower than when the output voltage is in the high voltage range H, compared to using the same mode switching point and HBURST mode entry point for different output voltages, the mode switching point and HBURST mode entry point of the converter 1 when the output voltage is in the medium voltage range M are lower, and the HBURST mode entry point is smaller, which can reduce the energy transmitted in each high-frequency intermittent cycle, thereby reducing the primary and secondary winding losses and the switch tube conduction loss, thereby improving the efficiency of the converter 1 in the HBURST mode. Since the mode switching point and HBURST mode entry point of the converter 1 when the output voltage is in the low voltage range L are lower than when the output voltage is in the medium voltage range M, the energy transmitted in each high-frequency intermittent cycle can be further reduced, thereby further reducing the primary and secondary winding losses and the switch tube conduction loss, thereby further improving the efficiency of the converter 1 in the HBURST mode. In addition, since the energy transmitted in each high-frequency intermittent cycle is further reduced when the output voltage is in the low-voltage range L, the load point at which the HBURST mode frequency (the frequency of the high-frequency intermittent cycle) reaches the audible frequency point can be lowered to a lower level, thereby optimizing the power supply ripple under extremely low loads.

[0236] In this embodiment, converter 1 adjusts its mode switching point and HBURST mode entry point based on different output voltages, thereby reducing primary and secondary winding losses and switch conduction losses, thereby optimizing converter 1's efficiency across the full output voltage range. Furthermore, while in HBURST mode, converter 1 can adjust the number of switch conduction cycles and / or the peak current in the magnetizing inductor within a high-frequency intermittent cycle based on load variations, thereby reducing output voltage ripple under extremely light load conditions.

[0237] In another optional embodiment, after converter 1 begins operation, controller 12 obtains converter 1's current switching frequency and output voltage. When the current switching frequency reaches a frequency threshold, controller 12 obtains a first operating parameter for converter 1 in the second operating mode based on the current output voltage, thereby controlling converter 1 to switch from the first operating mode to the second operating mode based on the first operating parameter. The first operating parameter includes the number of times the main switch S1 and the auxiliary switch S2 are turned on within a high-frequency intermittent cycle, or the peak current of the magnetizing inductor within a high-frequency intermittent cycle.

[0238] Specifically, after the converter 1 starts working, the curve control unit 122 collects the voltage V of the sampling resistor R2 collected by the voltage sampling circuit 13. R2 , calculate the current output voltage V of converter 1 o At the same time, the curve control unit 122 obtains the current switching frequency f of the converter 1 SW. And at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) In the case of the above, the curve control unit 122 determines the output voltage V of the converter 1 from the three voltage intervals (ie, the high voltage interval H, the medium voltage interval M and the low voltage interval L) shown in FIG4. o The first voltage range in which the output voltage is located is determined, thereby determining the first operating parameter corresponding to the first voltage range from the three operating parameters corresponding to the three voltage ranges. Converter 1 is then controlled to switch from CRM mode to HBURST mode based on the first operating parameter. The operating parameter corresponding to medium voltage range M is smaller than the operating parameter corresponding to high voltage range H and larger than the operating parameter corresponding to low voltage range L. Specifically, the HBURST mode entry point when the output voltage is in medium voltage range M is smaller than the HBURST mode entry point when the output voltage is in high voltage range H and larger than the HBURST mode entry point when the output voltage is in low voltage range L.

[0239] In an optional embodiment, please refer to FIG5 again, at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) In the case of the curve control unit 122, the output voltage V of the converter 1 is determined from the three voltage intervals shown in FIG4. o The first voltage interval is the high voltage interval H.

[0240] First, it should be noted that when the first voltage interval is the high voltage interval H, the first switching current threshold, the second switching current threshold, the third switching current threshold and the fourth switching current threshold are I o1 , I o2 , I o4 and I o3 The first conduction number, the second conduction number, the third conduction number, the fourth conduction number, the fifth conduction number and the sixth conduction number are N1, N2, N3, N4, N5 and N6 respectively, and the first current peak value, the second current peak value, the third current peak value, the fourth current peak value, the fifth current peak value and the sixth current peak value are I Lm_R1 , I Lm_R2 , I Lm_R3 , I Lm_R4 , I Lm_R5 and I Lm_R6 Among them, I o1 >I o2 >I o3 >0,I o1 >I o4 >0,I o2 with I o4 N1>N2>N6, N3≥N4, N5=0, N1, N2, N3, N4 and N6 are all positive integers. Lm_R1 >ILm_R2 >I Lm_R6 >0,I Lm_R3 ≥I Lm_R4 >0,I Lm_R5 =0,I Lm_R1 , I Lm_R2 , I Lm_R3 , I Lm_R4 and I Lm_R6 The value of satisfies the switching frequency f of converter 1 SW Less than the maximum switching frequency f SW(MAX) And the high-frequency intermittent period T HBURST Frequency f HBURST The condition is beyond the range of human hearing.

[0241] Then, the curve control unit 122 determines that the working parameter corresponding to the high-voltage interval H is a high-frequency intermittent period T shown in FIG5 . HBURST The first conduction number N1 of the switch tube and / or the excitation inductance L m The first current peak I Lm_R1 and sends the operating parameters corresponding to the high voltage interval H to the PWM control unit 121.

[0242] Specifically, the operating parameters corresponding to the high-voltage interval H are as follows: the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent period T HBURST Taking the first conduction number N1 as an example, after receiving the working parameter, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to perform a high-frequency intermittent cycle T HBURST The number of conduction times N SW The first conduction number N1 (such as 3) is used to switch the converter 1 from the CRM mode to the HBURST mode. HBURST The number of conduction times N SW After the first conduction number N1, the PWM control unit 121 compares the current output current I o and the second switching current threshold I o2 , the fourth switching current threshold I o3 The current output current I o Greater than the second switching current threshold I o2 and is less than or equal to the first switching current threshold I o1 When the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1. At the current output current I o Less than or equal to the second switching current threshold I o2and is greater than the fourth switching current threshold I o3 When the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N2 (such as 2). At the current output current I o Less than or equal to the fourth switching current threshold I o3 When the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the sixth conduction number N6 (eg 1).

[0243] It is understandable that at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) When the converter 1 is switched from CRM mode to HBURST mode, the switching frequency f of the converter 1 can be effectively reduced. SW , thereby reducing switching losses and improving the efficiency of converter 1. In addition, after converter 1 switches to HBURST mode, converter 1 can adjust the switching tube in a high-frequency intermittent period T based on the change of load. HBURST The number of conduction times N SW , ensuring output on demand and avoiding the situation where the output exceeds the load requirement, thereby reducing energy loss and switch loss, and thus improving the efficiency of converter 1. Furthermore, as the load gradually becomes lighter, the switch tube is in a high-frequency intermittent period T HBURST The number of conduction times N SW It also gradually decreases, therefore, the output voltage ripple of the converter 1 under light load conditions can also be reduced, and the applicability is strong.

[0244] Optionally, the operating parameter corresponding to the high voltage range H can also be the excitation inductance L m In a high-frequency intermittent period T HBURST The first current peak I Lm_R1 .

[0245] After receiving the operating parameters corresponding to the high voltage interval H, the PWM control unit 121 controls the conduction time of the main switch S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 switches from CRM mode to HBURST mode. And in the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1After that, the PWM control unit 121 compares the current output current I o and the second switching current threshold I o2 , the fourth switching current threshold I o3 The current output current I o Greater than the second switching current threshold I o2 and is less than or equal to the first switching current threshold I o1 When the PWM control unit 121 continues to control the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 . The current output current I o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 When the PWM control unit 121 controls the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The second current peak value I Lm_R2 . The current output current I o Less than or equal to the fourth switching current threshold I o3 When the PWM control unit 121 controls the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The sixth current peak value I Lm_R6 .

[0246] It is understandable that at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) When the converter 1 is switched from CRM mode to HBURST mode, the switching frequency f of the converter 1 can be effectively reduced. SW , thereby reducing switching losses and improving the efficiency of the converter 1. In addition, after the converter 1 switches to the HBURST mode, the converter 1 can adjust the excitation inductance L based on the change of the load. m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) , ensuring output on demand and avoiding the situation where the output exceeds the load requirement, thereby reducing energy loss and switch tube loss, and thus improving the efficiency of converter 1. Furthermore, as the load gradually becomes lighter, the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) It also gradually decreases, therefore, the output voltage ripple of the converter 1 under light load conditions can also be reduced, and the applicability is strong.

[0247] Optionally, the operating parameter corresponding to the high voltage range H can also be the excitation inductance L m In a high-frequency intermittent period T HBURST The first current peak I Lm_R1 , and the switch tube in a high frequency intermittent period T HBURST The first conduction number N1 of .

[0248] After receiving the operating parameters corresponding to the high voltage interval H, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to operate in a high frequency intermittent period T. HBURST The number of conduction times N SW is the first conduction number N1, and controls the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 switches from CRM mode to HBURST mode. And when the switch tube is in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1, and the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 After that, the PWM control unit 121 compares the current output current I o and the second switching current threshold I o2 , the fourth switching current threshold I o3 The current output current I o Greater than the second switching current threshold I o2 and is less than or equal to the first switching current threshold I o1 When the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N1, and continue to control the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 . The current output current I o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 When the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SWis the second conduction number N2, and controls the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The second current peak value I Lm_R2 . The current output current I o Less than or equal to the fourth switching current threshold I o3 When the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The sixth conduction number N6, and controls the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The sixth current peak value I Lm_R6 .

[0249] It should be noted that after the converter 1 switches from the CRM mode to the HBURST mode, the above embodiments are all based on the current output current I o In the current range where the converter 1 is located, the converter 1 is controlled to be in the HBURST mode. The following is an example of the change trend of the output current of the converter 1. After the converter 1 switches from the CRM mode to the HBURST mode, the converter 1 reduces the operating parameters in the HBURST mode during the process of reducing the output current. For example, when the output current drops to the second switching current threshold I o2 When the converter 1 reduces a high frequency intermittent period T HBURST The output current continues to drop to the fourth switching current threshold I o3 When the converter 1 further reduces a high frequency intermittent period T HBURST The number of times the switch is turned on and / or the peak current of the excitation inductor.

[0250] It is understandable that at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) When the converter 1 is switched from CRM mode to HBURST mode, the switching frequency f of the converter 1 can be effectively reduced. SW , thereby reducing switching losses and improving the efficiency of the converter 1. In addition, after the converter 1 switches to the HBURST mode, the converter 1 can adjust a high-frequency intermittent period T based on the change of the load. HBURST The number of times the internal switch tube is turned on N SW and the magnetizing inductance L m Peak current I Lm(PEAK), ensuring output on demand and avoiding the situation where the output exceeds the load requirement, thereby reducing energy loss and switch loss, and thus improving the efficiency of converter 1. Furthermore, as the load gradually becomes lighter, the switch tube is in a high-frequency intermittent period T HBURST The number of conduction times N SW and the magnetizing inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) Both gradually decrease, which can further reduce the energy output. Therefore, the output voltage ripple of the converter 1 under light load conditions can be further reduced, and the applicability is stronger.

[0251] At the current switching frequency f SW Reaching the frequency threshold f SW(MAX) In the case of , the converter 1 is controlled to be in HBURST mode, and after the converter 1 is in HBURST mode, according to the current output current I o The specific implementation of controlling the converter 1 to be in the HBURST mode or the LBURST mode may be a combination of the following two optional embodiments:

[0252] In an optional embodiment, the operating parameters corresponding to the high-voltage interval H include a high-frequency intermittent period T HBURST The first conduction number N1 of the inner switch tube, and / or the excitation inductance L m The first current peak I Lm_R1 ;

[0253] At the current switching frequency f SW Reaching the frequency threshold f SW(MAX) In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times is the first conduction time N1, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 . And in a high frequency intermittent period T HBURST The number of times the main switch tube S1 and the auxiliary switch tube S2 are turned on is the first number of times N1, and / or the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 After that, if the output current I o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 When the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURSTThe number of conduction times is the second conduction number N2, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R2 ; If the output current I of converter 1 o Less than or equal to the fourth switching current threshold I o3 When the main switch tube S1 and the auxiliary switch tube S2 are controlled in a high frequency intermittent period T HBURST The number of conduction times is the sixth conduction time N6, and / or, a high frequency intermittent period T is controlled. HBURST The excitation inductance L m Peak current I Lm(PEAK) The sixth current peak value I Lm_R6 ; If the output current of the converter I o Greater than the second switching current threshold I o2 and is less than or equal to the first switching current threshold I o1 , then the main switch tube S1 and the auxiliary switch tube S2 are controlled in a high frequency intermittent period T HBURST The number of conduction times is the first conduction time N1, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 .

[0254] In another optional embodiment, the operating parameters corresponding to the high-voltage interval H include a high-frequency intermittent period T HBURST The third conduction number N3 of the inner switch tube is N1, and / or the excitation inductance L m The third current peak I Lm_R3 =I Lm_R1 ;

[0255] At the current switching frequency f SW Reaching the frequency threshold f SW(MAX) In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times is the first conduction time N1, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The third current peak value I Lm_R1 . And in a high frequency intermittent period T HBURST The number of times the main switch tube S1 and the auxiliary switch tube S2 are turned on is the first number of times N1, and / or the excitation inductance L m Peak current I Lm(PEAK) The third current peak value ILm_R1 After that, if the output current I o Less than or equal to the third switching current threshold I o4 , the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent period T HBURST The number of conduction times is the fourth conduction number N4, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 ; and after a high-frequency intermittent period T HBURST The number of times the switch is turned on is the fourth number of times N4, and / or a high frequency intermittent period T HBURST The excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle, the main switch tube S1 and the auxiliary switch tube S2 are controlled to be in a high frequency intermittent period T HBURST The number of conduction times is the fifth conduction time N5, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The fifth current peak value I Lm_R5 ; If the output current of the converter I o Less than or equal to the first switching current threshold I o1 and is greater than the third switching current threshold I o4 , the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent period T HBURST The number of conduction times is the first conduction time N1, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The third current peak value I Lm_R1 .

[0256] Specifically, after the converter 1 switches to the HBURST mode, according to the current output current I o The specific implementation steps of controlling the converter 1 to be in the HBURST mode or the LBURST mode are all obtained based on a combination of the steps corresponding to the following five current intervals.

[0257] At the current output current I o In the first current interval (I o2 ,I o1 ], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SWis the first conduction number N1, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 . The current output current I o In the second current interval (I o3 ,I o2 ], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N2, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 . The current output current I o In the third current interval (I o4 ,I o1 ], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The third current peak value I Lm_R1 . The current output current I o In the fourth current interval (0,I o4 ], the controller 12 is based on a high frequency intermittent period T HBURST The number of times the switch tube is turned on N SW is the fourth conduction number N4, and / or the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 , control converter 1 to be in LBURST mode. At the current output current I o In the fifth current range (-0,I o3 ], the controller 12 controls the switch tube in a high frequency intermittent period T HBURST The number of conduction times N SW is the sixth conduction number N6, and / or controls the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 .

[0258] Obviously, in the case where the above five current intervals are overlapped by multiple current intervals, when an overlapping current interval generated by the overlap of multiple current intervals appears between the above five current intervals, the PWM control unit 121 can select any current interval from the above overlapping multiple current intervals or a current interval that meets the actual working condition of the converter 1 as the target current interval, and o When the current is within the above-mentioned overlapping current range, the converter 1 is controlled to execute the current output current I o Based on this, it can be obtained that the control mode of the converter 1 in HBURST mode or LBURST mode is diverse and highly flexible. In addition, I o4 , I o2 and I o3 The size relationships among the three are diverse, so that the control methods of the converter 1 in the HBURST mode or the LBURST mode are more diverse and more flexible.

[0259] For the sake of ease of introduction, the following o2 >I o3 >I o4 As an example, the converter 1 is in HBURST mode or LBURST mode. o2 >I o3 >I o4 In the case of the first current interval (I o2 ,I o1 ] and the third current interval (I o4 ,I o1 ] overlap and the overlapping current interval is (I o2 ,I o1 ], the controller 12 may select a first current interval (I o2 ,I o1 ] or the third current interval (I o4 ,I o1 ] as the overlapping current interval (I o2 ,I o1 ] target current interval, this embodiment takes the first current interval (I o2 ,I o1 ] is the overlapping current interval (I o2 ,I o1 ] is used as an example to introduce the target current interval; the second current interval (I o3 ,I o2 ] and the third current interval (I o4 ,I o1 ] overlap and the overlapping current interval is (I o3 ,I o2], the controller 12 may select a second current interval (I o3 ,I o2 ] or the third current interval (I o4 ,I o1 ] as the overlapping current interval (I o3 ,I o2 ] target current interval, this embodiment uses the second current interval (I o3 ,I o2 ] is the overlapping current interval (I o3 ,I o2 ] is used as an example to introduce the target current interval; the fifth current interval (0,I o3 ] and the third current interval (I o4 ,I o1 ] overlap and the overlapping current interval is (I o4 ,I o3 ], the controller 12 can select the fifth current interval (0,I o3 ] or the third current interval (I o4 ,I o1 ] as the overlapping current interval (I o4 ,I o3 ] target current interval, this embodiment uses the fifth current interval (0,I o3 ] is the overlapping current interval (I o4 ,I o3 ] is used as an example to introduce the target current interval; the fifth current interval (0,I o3 ] and the fourth current interval (0,I o4 ] overlap and the overlapping current interval is (0,I o4 ], the controller 12 can select the fifth current interval (0,I o3 ] or the fourth current interval (0,I o4 ] as the overlapping current interval (0,I o4 ] target current interval, this embodiment uses the fourth current interval (0,I o4 ] is the overlapping current interval (0,I o4 ] as an example to introduce the target current range.

[0260] At the current switching frequency f SW Reaching the frequency threshold f SW(MAX) In the case of the curve control unit 122, the output voltage V of the converter 1 is determined from the three voltage intervals shown in FIG4. o The first voltage interval is the high voltage interval H. Then, the curve control unit 122 determines that the working parameter corresponding to the high voltage interval H is a high frequency intermittent period T shown in FIG5 . HBURST The first conduction number N1 of the switch tube and / or the excitation inductance Lm The first current peak I Lm_R1 and sends the operating parameters to the PWM control unit 121.

[0261] Specifically, the working parameter corresponding to the high-voltage interval H is a high-frequency intermittent period T HBURST As an example, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to conduct in a high-frequency intermittent period T after receiving the working parameters. HBURST The number of conduction times N SW The first conduction number N1 (such as 3) is used to switch the converter 1 from the CRM mode to the HBURST mode. HBURST The number of conduction times N SW After the first conduction number N1, the PWM control unit 121 compares the current output current I o and the second switching current threshold I o2 , the third switching current threshold I o4 and the fourth switching current threshold I o3 The current output current I o Less than or equal to the first switching current threshold I o1 and is greater than the second switching current threshold I o2 In this case, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N1, the converter 1 is still in the HBURST mode. o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 In the case of the PWM control unit 121 executing the current output current I o In the second current interval (I o3 ,I o2 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The second conduction number N2 (eg, 2) is the second conduction number N2, and the converter 1 is still in the HBURST mode. o Less than or equal to the fourth switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fifth current interval (0,I o3], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The sixth conduction number N6 (eg, 1), the converter 1 is still in the HBURST mode. o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The fourth conduction number N4 (such as 1) is the same as the fourth conduction number N4 (such as 1), and after a high frequency intermittent period T HBURST The number of times the main switch tube S1 and the auxiliary switch tube S2 are turned on N SW After the first working cycle times of the fourth conduction times N4, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to perform a high-frequency intermittent period T HBURST The number of conduction times N SW The fifth conduction number N5 (ie 0) is the same, that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In the case of , the converter 1 is in the LBURST mode. The number of the first working cycles is a positive integer. For example, the number of the first working cycles is 3.

[0262] It is understandable that at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) When the converter 1 is switched from CRM mode to HBURST mode, the switching frequency f of the converter 1 can be effectively reduced. SW , thereby reducing switching losses and improving the efficiency of the converter 1. In addition, after the converter 1 switches to the HBURST mode, compared with the load-adjusted switching mode based on a high-frequency intermittent period T HBURST The number of conduction times N SW For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, for extremely light load (i.e., output current I o Less than or equal to the third switching current threshold I o4) condition, the operating mode of converter 1 is further optimized, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube losses, thereby further improving converter 1's efficiency. Furthermore, because converter 1 is in LBURST mode under extremely light load conditions, output energy is further reduced. Therefore, this embodiment can further reduce converter 1's output voltage ripple under extremely light load conditions, enhancing its applicability.

[0263] Optionally, the operating parameter corresponding to the high voltage range H can also be the excitation inductance L m In a high-frequency intermittent period T HBURST The first current peak I Lm_R1 .

[0264] After receiving the operating parameters corresponding to the high voltage interval H, the PWM control unit 121 controls the conduction time of the main switch S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 switches from CRM mode to HBURST mode. And in the excitation inductor L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 After that, the PWM control unit 121 compares the current output current I o and the second switching current threshold I o2 , the third switching current threshold I o4 and the fourth switching current threshold I o3 The current output current I o Less than or equal to the first switching current threshold I o1 and is greater than the second switching current threshold I o2 In the case of m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 In the case of the PWM control unit 121 executing the current output current I o In the second current interval (I o3 ,I o2], that is, controlling the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The second current peak value I Lm_R2 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the fourth switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fifth current interval (0,I o3 ], that is, controlling the conduction time of the main switch tube S1 so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The sixth current peak value I Lm_R6 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, by controlling the conduction time of the main switch tube S1, so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fourth current peak value I Lm_R4 (such as I Lm_R4 =I Lm_R6 ), and after a high frequency intermittent period T HBURST The internal excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle times, the PWM control unit 121 controls the conduction time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In the case of , the converter 1 is in the LBURST mode. The number of the first working cycles is a positive integer. For example, the number of the first working cycles is 3.

[0265] It is understandable that at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) When the converter 1 is switched from CRM mode to HBURST mode, the switching frequency f of the converter 1 can be effectively reduced. SW , thereby reducing switching losses and improving the efficiency of the converter 1. In addition, after the converter 1 switches to the HBURST mode, compared with the load-based adjustment of the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) Regarding the embodiment in which converter 1 is always in HBURST mode, this embodiment further optimizes the operating mode of converter 1 under extremely light load conditions, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube losses, thereby further improving the efficiency of converter 1. Furthermore, because converter 1 is in LBURST mode under extremely light load conditions, output energy is further reduced. Therefore, this embodiment can further reduce the output voltage ripple of converter 1 under extremely light load conditions, making it more suitable for use.

[0266] Optionally, the operating parameter corresponding to the high voltage range H can also be the excitation inductance L m In a high-frequency intermittent period T HBURST The first current peak I Lm_R1 , and the switch tube in a high frequency intermittent period T HBURST The first conduction number N1 of .

[0267] After receiving the operating parameters corresponding to the high voltage interval H, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to operate in a high frequency intermittent period T. HBURST The number of conduction times N SW The first conduction number N1 (such as 3) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 switches from CRM mode to HBURST mode. And when the switch tube is in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1, and the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 After that, the PWM control unit 121 compares the current output current I oand the second switching current threshold I o2 , the third switching current threshold I o4 and the fourth switching current threshold I o3 The current output current I o Less than or equal to the first switching current threshold I o1 and is greater than the second switching current threshold I o2 In this case, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N1 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The first current peak value I Lm_R1 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 In the case of the PWM control unit 121 executing the current output current I o In the second current interval (I o3 ,I o2 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The second conduction number N2 (such as 2) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The second current peak value I Lm_R2 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the fourth switching current threshold I o3 and is greater than the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fifth current interval (0,I o3 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The sixth conduction number N6 (such as 1) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The sixth current peak value ILm_R6 , converter 1 is still in HBURST mode. At the current output current I o Less than or equal to the third switching current threshold I o4 In the case of the PWM control unit 121 executing the current output current I o In the fourth current interval (0,I o4 ], that is, controlling the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The fourth conduction number N4 (such as 1) is used, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m In a high-frequency intermittent period T HBURST The peak current I Lm(PEAK) The fourth current peak value I Lm_R4 (such as I Lm_R4 =I Lm_R6 ), and after a high frequency intermittent period T HBURST The number of times the switch tube is turned on N SW The fourth conduction number N4 and the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle times, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to perform a high-frequency intermittent period T HBURST The number of conduction times N SW The fifth conduction number N5 (ie 0) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, at the current output current I o Less than or equal to the third switching current threshold I o4 In the case of , the converter 1 is in the LBURST mode. The number of the first working cycles is a positive integer. For example, the number of the first working cycles is 3.

[0268] It should be noted that after the converter 1 switches from the CRM mode to the HBURST mode, the above embodiments are all based on the current output current I oIn the current range where the converter 1 is located, the converter 1 is controlled to be in the HBURST mode or the LBURST mode. The following is an example of the change trend of the output current of the converter 1. After the converter 1 switches from the CRM mode to the HBURST mode, the converter 1 reduces the operating parameters in the HBURST mode during the process of reducing the output current. For example, when the output current drops to the switching current threshold I o2 When the converter 1 reduces a high frequency intermittent period T HBURST The number of times the switch is turned on and / or the current peak of the excitation inductor; when the output current continues to drop to the switching current threshold I o3 When the converter 1 further reduces a high frequency intermittent period T HBURST The number of times the switch is turned on and / or the current peak of the excitation inductor is reached. o4 When the converter 1 switches from HBURST mode to LBURST mode, the output current of the converter 1 rises to the switching current threshold I o4 , converter 1 switches from LBURST mode to HBURST mode.

[0269] In addition, when I o4 , I o2 and I o3 The relationship between the three is divided by I o2 >I o3 >I o4 When the asymmetric converter 1 is in the HBURST mode, the converter 1 is based on the output current I o For the specific implementation of the HBURST mode or the LBURST mode, please refer to the embodiment I o2 >I o3 >I o4 The corresponding description of is not repeated here.

[0270] It is understandable that at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) When the converter 1 is switched from CRM mode to HBURST mode, the switching frequency f of the converter 1 can be effectively reduced. SW , thereby reducing switching losses and improving the efficiency of converter 1. In addition, after converter 1 switches to HBURST mode, compared with adjusting the number of switch on times N of the switch tube in a high-frequency intermittent cycle based on the load, SW and the magnetizing inductance L m Peak current I Lm(PEAK)Regarding the embodiment in which converter 1 is always in HBURST mode, this embodiment further optimizes the operating mode of converter 1 under extremely light load conditions, placing converter 1 in LBURST mode. This further reduces energy loss and switching tube losses, thereby further improving the efficiency of converter 1. Furthermore, because converter 1 is in LBURST mode under extremely light load conditions, output energy is further reduced. Therefore, this embodiment can further reduce the output voltage ripple of converter 1 under extremely light load conditions, making it more suitable for use.

[0271] At the current switching frequency f SW Reaching the frequency threshold f SW(MAX) In the case of, the converter 1 is controlled to be in HBURST mode, and after the converter 1 is in HBURST mode, according to the high frequency intermittent period T HBURST Frequency f HBURST The specific implementation of controlling the converter 1 to be in the HBURST mode or the LBURST mode may be a combination of the following two optional embodiments:

[0272] In an optional embodiment, the operating parameters corresponding to the high-voltage interval H include a high-frequency intermittent period T HBURST The first conduction number N1 of the inner switch tube, and / or the excitation inductance L m The first current peak I Lm_R1 ;

[0273] At the current switching frequency f SW Reaching the frequency threshold f SW(MAX) In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times is the first conduction time N1, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 . And in a high frequency intermittent period T HBURST The number of times the main switch tube S1 and the auxiliary switch tube S2 are turned on is the first number of times N1, and / or the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 After that, if the output current I o Greater than the second switching current threshold I o2 and is less than or equal to the first switching current threshold I o1 , then the main switch tube S1 and the auxiliary switch tube S2 are controlled in a high frequency intermittent period T HBURST The number of conduction times is the first conduction time N1, and / or, a high frequency intermittent period T is controlledHBURST The excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 ; If the output current I of converter 1 o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 When the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times is the second conduction number N2, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R2 ; If the output current I of converter 1 o Less than or equal to the fourth switching current threshold I o3 When the main switch tube S1 and the auxiliary switch tube S2 are controlled in a high frequency intermittent period T HBURST The number of conduction times is the sixth conduction time N6, and / or, a high frequency intermittent period T is controlled. HBURST The excitation inductance L m Peak current I Lm(PEAK) The sixth current peak value I Lm_R6 .

[0274] In another optional embodiment, the operating parameters corresponding to the high-voltage interval H include a high-frequency intermittent period T HBURST The third conduction number N3 of the inner switch tube = N1, N2 or N6, and / or the excitation inductance L m The third current peak I Lm_R3 =I Lm_R1 , I Lm_R2 or I Lm_R6 ;

[0275] At the current switching frequency f SW Reaching the frequency threshold f SW(MAX) In the case of a high frequency intermittent period T, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2. HBURST The number of conduction times is the third conduction number N3, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The third current peak value I Lm_R3 . And in a high frequency intermittent period T HBURST The number of times the internal main switch tube S1 and the auxiliary switch tube S2 are turned on is the third number of times N3, and / or the excitation inductance L m Peak current I Lm(PEAK)The third current peak value I Lm_R3 After that, if the number of conduction times of the switch tube is the third conduction number N3 and / or the excitation inductance L m Peak current I Lm(PEAK) The third current peak value I Lm_R3 The high-frequency intermittent period T HBURST Frequency f HBURST If the frequency is within the preset range, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to operate in a high frequency intermittent period T HBURST The number of conduction times is the fourth conduction number N4, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 ; and after a high-frequency intermittent period T HBURST The number of times the switch is turned on is the fourth number of times N4, and / or a high frequency intermittent period T HBURST The excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle, the main switch tube S1 and the auxiliary switch tube S2 are controlled to be in a high frequency intermittent period T HBURST The number of conduction times is the fifth conduction time N5, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The fifth current peak value I Lm_R5 If the number of conduction times of the switch tube is the third conduction number N3 and / or the excitation inductance L m Peak current I Lm(PEAK) The third current peak value I Lm_R3 The high-frequency intermittent period T HBURST Frequency f HBURST If the frequency is outside the preset range, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to operate in a high frequency intermittent period T HBURST The number of conduction times is the third conduction number N3, and / or, a high frequency intermittent period T is controlled HBURST The excitation inductance L m Peak current I Lm(PEAK) The third current peak value I Lm_R3 .

[0276] Specifically, at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) In the case of the curve control unit 122, the output voltage V of the converter 1 is determined from the three voltage intervals shown in FIG4. oThe first voltage interval is the high voltage interval H. Then, the curve control unit 122 determines that the working parameter corresponding to the high voltage interval H is a high frequency intermittent period T shown in FIG5 . HBURST The first conduction number N1 of the switch tube in.

[0277] After receiving the working parameters, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to operate in a high-frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N1 (such as 3) is used to switch the converter 1 from the CRM mode to the HBURST mode. HBURST The number of conduction times N SW After the first conduction number N1 is reached, the PWM control unit 121 calculates the conduction number N of the switch tube. SW The high-frequency intermittent period T of the first conduction number N1 HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the circuit is within the human hearing range, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The fourth conduction times N4 (such as 1) are all the same, and the conduction times N of the main switch tube S1 and the auxiliary switch tube S2 within a high-frequency intermittent period are SW After the first working cycle times of the fourth conduction times N4, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to conduct the number of times N in a high-frequency intermittent cycle. SW The fifth conduction number N5 (ie 0) is the same, that is, the PWM control unit 121 controls the main switch S1 and the auxiliary switch S2 to be in the off state. In other words, in the high-frequency intermittent period T HBURST Frequency f HBURST When the voltage is within the human hearing range, the PWM control unit 121 controls the converter 1 to be in the LBURST mode. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1.

[0278] Assume that the number of times the switch tube is turned on is NSW The high-frequency intermittent period T of the first conduction number N1 HBURST Frequency f HBURST If the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1. And at the current output current I o Less than or equal to the second switching current threshold I o2 and is greater than the fourth switching current threshold I o3 In the case of o In the second current interval (I o3 ,I o2 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The second conduction number N2 (eg, 2) is the second conduction number, and the converter 1 is still in the HBURST mode. The main switch tube S1 and the auxiliary switch tube S2 are in a high frequency intermittent period T HBURST The number of conduction times N SW After the second conduction number N2 is reached, the PWM control unit 121 calculates the conduction number N of the switch tube. SW The high-frequency intermittent period T of the second conduction number N2 HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the corresponding part of the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N2.

[0279] Assume that the number of times the switch tube is turned on is N SW The high-frequency intermittent period T of the second conduction number N2 HBURST Frequency f HBURSTIf the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N2. And at the current output current I o Less than or equal to the fourth switching current threshold I o3 In the case of o In the fifth current interval (0,I o3 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The sixth conduction number N6 (eg, 1), the converter 1 is still in the HBURST mode. The main switch tube S1 and the auxiliary switch tube S2 are in a high frequency intermittent period T HBURST The number of conduction times N SW After the sixth conduction number N6, the PWM control unit 121 calculates the conduction number N of the switch tube. SW The high-frequency intermittent period T of the sixth conduction number N6 HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the corresponding part of the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW It is the sixth conduction number N6.

[0280] It is understandable that at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) When the converter 1 is switched from CRM mode to HBURST mode, the switching frequency f of the converter 1 can be effectively reduced. SW , thereby reducing switching losses and improving the efficiency of converter 1. In addition, after converter 1 switches to HBURST mode, compared with the number of conduction times N of the switch tube in a high-frequency intermittent cycle based on load adjustment, SWFor the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURST The working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, thereby further reducing energy loss and switch loss, and further improving the efficiency of the converter 1. HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0281] Optionally, the operating parameter corresponding to the high voltage range H can also be the excitation inductance L m The first current peak value I in a high-frequency intermittent period Lm_R1 .

[0282] After receiving the working parameters corresponding to the high voltage interval H, the PWM control unit 121 controls the conduction time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 is in HBURST mode. And the excitation inductor L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 After that, the PWM control unit 121 calculates the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the voltage is within the human hearing range, the PWM control unit 121 controls the conduction time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fourth current peak value I Lm_R4 , and after a high-frequency intermittent cycle, the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 After the first working cycle times, the PWM control unit 121 controls the conduction time of the main switch S1 to make the excitation inductance Lm The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be in the off state. In other words, in the high-frequency intermittent period T HBURST Frequency f HBURST When the frequency is within the human hearing range, the converter 1 is in LBURST mode. HBURST Frequency f HBURST When the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 .

[0283] Assume that the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 The high-frequency intermittent period T HBURST Frequency f HBURST If the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 . And the current output current I o In the second current interval (I o3 ,I o2 ], the PWM control unit 121 controls the conduction time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 , converter 1 is still in HBURST mode. And in the excitation inductor L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) is the peak current I Lm_R2 After that, the PWM control unit 121 calculates the excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing?HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 .

[0284] Assume that the excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURST If the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 to make the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 . And the current output current I o In the fifth current interval (0,I o3 ], the PWM control unit 121 controls the conduction time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 , converter 1 is still in HBURST mode. And in the excitation inductor L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 After that, the PWM control unit 121 calculates the excitation inductance L m Peak current I Lm(PEAK) The sixth current peak value I Lm_R6 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURSTWhen the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the voltage is not within the human hearing range, the PWM control unit 121 continues to control the on-time of the main switch S1 so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The sixth current peak value I Lm_R6 .

[0285] It is understandable that at the current switching frequency f SW Reaching the frequency threshold f SW(MAX) When the converter 1 is switched from CRM mode to HBURST mode, the switching frequency f of the converter 1 can be effectively reduced. SW , thereby reducing switching losses and improving the efficiency of the converter 1. In addition, after the converter 1 switches to the HBURST mode, compared with the load-based adjustment of the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) For the embodiment in which the converter 1 is always in the HBURST mode, in this embodiment, the high frequency intermittent period T HBURST Frequency f HBURST The working mode of the converter 1 is further optimized when it is within the range of human hearing, so that the converter 1 is in LBURST mode, thereby further reducing energy loss and switch loss, and further improving the efficiency of the converter 1. HBURST Frequency f HBURST When the voltage is within the human hearing range, the converter 1 is in the LBURST mode, which can effectively reduce the switching noise of the converter 1 .

[0286] Optionally, the operating parameter corresponding to the high voltage range H can also be the excitation inductance L m In a high-frequency intermittent period T HBURST The first current peak I Lm_R1 , and the switch tube in a high frequency intermittent period T HBURST The first conduction number N1 of .

[0287] After receiving the operating parameters corresponding to the high voltage interval H, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to operate in a high frequency intermittent period T. HBURST The number of conduction times N SW The first conduction number N1 (such as 3) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance Lm The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 , so that the converter 1 is in HBURST mode. And when the switch tube is in a high frequency intermittent period T HBURST The number of conduction times N SW is the first conduction number N1, and the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 After that, the PWM control unit 121 calculates the number of times the switch tube is turned on N. SW is the first conduction number N1 and the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the circuit is within the human hearing range, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The fourth conduction number N4 (such as 1) is used, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fourth current peak value I Lm_R4 , and after a high-frequency intermittent cycle, the excitation inductance L m Peak current I Lm(PEAK) The fourth current peak value I Lm_R4 And the number of times the switch tube is turned on N SW After the first working cycle times of the fourth conduction times N4, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to conduct the number of times N in a high-frequency intermittent cycle. SW The fifth conduction number N5 (ie 0) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The fifth current peak value I Lm_R5 (ie 0), that is, the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be in the off state. In other words, in the high-frequency intermittent period T HBURST Frequency f HBURSTWhen the frequency is within the human hearing range, the converter 1 is in LBURST mode. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N1 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 .

[0288] Assume that the number of times the switch tube is turned on is N SW is the first conduction number N1 and the excitation inductance L m Peak current I Lm(PEAK) The first current peak value I Lm_R1 The high-frequency intermittent period T HBURST Frequency f HBURST If the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch tube S1 and the auxiliary switch tube S2 in a high frequency intermittent period T HBURST The number of conduction times N SW The first conduction number N1 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The first current peak value I Lm_R1 . And the current output current I o In the second current interval (I o3 ,I o2 ], the PWM control unit 121 controls the main switch tube S1 and the auxiliary switch tube S2 to be turned on for a number of times N in a high-frequency intermittent cycle. SW The second conduction number N2 (such as 2) is set, and the conduction time of the main switch tube S1 is controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 , converter 1 is still in HBURST mode. And when the switch tube is in a high frequency intermittent period T HBURST The number of conduction times N SW is the second conduction number N2 and the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 After that, the PWM control unit 121 calculates the number of times the switch tube is turned on N. SW is the second conduction number N2 and the excitation inductance Lm Peak current I Lm(PEAK) The second current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBURST =1 / T HBURST , and determine the high-frequency intermittent period T HBURST Frequency f HBURST Is it within the range of human hearing? HBURST Frequency f HBURST When the PWM control unit 121 is within the hearing range of the human ear, the converter 1 is in the LBURST mode. Here, the specific implementation of the PWM control unit 121 controlling the converter 1 to be in the LBURST mode can be found in the description of the corresponding part in the above embodiment, which will not be repeated here. HBURST Frequency f HBURST When the switch is not within the human hearing range, the PWM control unit 121 continues to control the main switch S1 and the auxiliary switch S2 in a high-frequency intermittent period T HBURST The number of conduction times N SW The second conduction number N2 is set, and the conduction time of the main switch tube S1 is continuously controlled so that the excitation inductance L m The peak current I in a high-frequency intermittent cycle Lm(PEAK) The second current peak value I Lm_R2 .

[0289] Assume that the number of times the switch tube is turned on is N SW is the second conduction number N2 and the excitation inductance L m Peak current I Lm(PEAK) The second current peak value I Lm_R2 The high-frequency intermittent period T HBURST Frequency f HBU...

Claims

1. A converter, characterized in that: The converter includes a main switch tube, an auxiliary switch tube, a transformer and a controller, wherein: The main switch tube and the auxiliary switch tube are connected in series between the input terminal of the converter and the reference ground, the input terminal of the transformer is connected to both ends of the auxiliary switch tube respectively, and the output terminal of the transformer is connected to the output terminal of the converter; The controller is used to obtain the output voltage of the converter and obtain a mode switching parameter based on the output voltage of the converter; and control the converter to switch between a first operating mode and a second operating mode according to the mode switching parameter, wherein the switching frequency of the converter in the first operating mode is negatively correlated with the output current of the converter, and the switching frequency of the converter remains unchanged within one operating cycle of the converter in the second operating mode.

2. The converter according to claim 1, characterized in that The mode switching parameter is a first current threshold; The controller is used to compare the output current of the converter with the first switching current threshold, and control the converter to switch between the first working mode and the second working mode according to the comparison result.

3. The converter according to claim 2, characterized in that The controller is used to obtain a first voltage interval in which the output voltage is located from multiple voltage intervals based on the output voltage; and obtain the first switching current threshold corresponding to the first voltage interval from multiple switching current thresholds corresponding to the voltage intervals, wherein the multiple voltage intervals correspond one-to-one to the multiple switching current thresholds.

4. The converter according to claim 2 or 3, characterized in that The controller is configured to control the main switch tube and the auxiliary switch tube to be turned on a first number of times in one working cycle of the converter when the output current is less than or equal to the first switching current threshold and greater than a second switching current threshold; The controller is also used to control the main switch tube and the auxiliary switch tube to be turned on a second number of times in one working cycle when the output current is less than or equal to the second switching current threshold, wherein the second number of times of conduction is less than the first number of conduction.

5. The converter according to claim 2 or 3, characterized in that The transformer includes an excitation inductor; The controller is configured to control the current peak value of the excitation inductor in one working cycle of the converter to be a first current peak value when the output current is less than or equal to the first switching current threshold and greater than a second switching current threshold; The controller is further configured to control the current peak of the excitation inductor in one working cycle to be a second current peak when the output current is less than or equal to the second switching current threshold, wherein the second current peak is less than the first current peak.

6. The converter according to claim 2 or 3, characterized in that: The controller is configured to control the main switch tube and the auxiliary switch tube to be turned on a third number of times in one working cycle of the converter when the output current is less than or equal to the first switching current threshold and greater than a third switching current threshold; The controller is further configured to control the main switch tube and the auxiliary switch tube to be turned on a fourth number of times in one working cycle when the output current is less than or equal to the third switching current threshold; And after the first working cycle number in which the number of conduction times in the one working cycle is the third conduction number, the main switch tube and the auxiliary switch tube are controlled to be the fifth conduction number in the one working cycle, wherein the fourth conduction number is less than or equal to the third conduction number and greater than the fifth conduction number.

7. The converter according to claim 2 or 3, characterized in that: The transformer includes an excitation inductor; The controller is configured to control the current peak value of the excitation inductor in one working cycle of the converter to be a third current peak value when the output current is less than or equal to the first switching current threshold and greater than a third switching current threshold; The controller is further configured to control the current peak value of the excitation inductor in the one working cycle to be a fourth current peak value when the output current is less than or equal to the third switching current threshold; And after the first working cycle number in which the current peak in the one working cycle is the third current peak, the current peak of the excitation inductance in the one working cycle is controlled to be the fifth current peak, wherein the fourth current peak is less than or equal to the third current peak and greater than the fifth current peak.

8. The converter according to claim 2 or 3, characterized in that The controller is configured to control the main switch tube and the auxiliary switch tube to be turned on a third number of times in one working cycle of the converter when the output current is less than or equal to the first switching current threshold; The controller is further configured to, after the main switch and the auxiliary switch are both turned on a third number of times in one working cycle, control the main switch and the auxiliary switch to be turned on a fourth number of times in one working cycle if the operating frequency of the converter is within a preset frequency range; and after a first working cycle number of conduction times in the one working cycle equal to the fourth conduction times, controlling the main switch tube and the auxiliary switch tube to be both conducted at a fifth conduction times in the one working cycle, wherein the fourth conduction times is less than or equal to the third conduction times and greater than the fifth conduction times; The controller is also used to control the main switch tube and the auxiliary switch tube to be turned on the third number of times in one working cycle after the number of times the main switch tube and the auxiliary switch tube are turned on the third number of times in one working cycle, if the operating frequency of the converter is outside the preset frequency range.

9. The converter according to claim 2 or 3, characterized in that: The transformer includes an excitation inductor; The controller is configured to control the current peak value of the excitation inductor in one working cycle of the converter to be a third current peak value when the output current is less than or equal to the first switching current threshold; The controller is further configured to, after the current peak value of the excitation inductor in the one working cycle reaches the third current peak value, control the current peak value of the excitation inductor in the one working cycle to reach a fourth current peak value if the operating frequency of the converter is within a preset frequency range; and after a first number of working cycles in which the current peak value in the one working cycle is the fourth current peak value, controlling the current peak value of the excitation inductor in the one working cycle to be a fifth current peak value, wherein the fourth current peak value is greater than the fifth current peak value and less than or equal to the third current peak value; The controller is also used to control the current peak of the excitation inductor in the one working cycle to be the third current peak if the operating frequency of the converter is outside the preset frequency range after the current peak of the excitation inductor in the one working cycle is the third current peak.

10. The converter according to claim 1, wherein: The mode switching parameter is a first operating parameter of the converter in the second operating mode; The controller is further configured to obtain a switching frequency of the converter; The controller is used to obtain the first operating parameter based on the output voltage when the switching frequency reaches a frequency threshold; and control the converter to switch from the first operating mode to the second operating mode based on the first operating parameter, wherein the first operating parameter includes the number of times the main switch tube and the auxiliary switch tube are turned on in one working cycle of the converter, or the current peak of the excitation inductor in the one working cycle.

11. The converter according to claim 10, characterized in that The controller is used to obtain a first voltage interval in which the output voltage is located from multiple voltage intervals when the switching frequency reaches the frequency threshold; and obtain the first operating parameter corresponding to the first voltage interval from multiple operating parameters corresponding to the multiple voltage intervals, wherein the multiple voltage intervals correspond to the multiple operating parameters one-to-one.

12. The converter according to claim 11, characterized in that The multiple voltage intervals further include a second voltage interval. When any value in the second voltage interval is smaller than any value in the first voltage interval, a second operating parameter corresponding to the second voltage interval is smaller than the first operating parameter.

13. The converter according to any one of claims 10 to 12, characterized in that: The first operating parameter includes the conduction number, and the conduction number is a first conduction number; The controller is used to control the main switch tube and the auxiliary switch tube to be turned on a first number of times in one working cycle; The controller is further configured to, after the main switch and the auxiliary switch have been turned on a first number of times in one working cycle, control the main switch and the auxiliary switch to be turned on a second number of times in one working cycle if the output current of the converter is less than or equal to a second switching current threshold, wherein the second number of times of conduction is less than the first number of times of conduction; The controller is also used to control the main switch tube and the auxiliary switch tube to be turned on the first number of times in one working cycle, if the output current of the converter is greater than the second switching current threshold and less than or equal to the first switching current threshold, after the main switch tube and the auxiliary switch tube are turned on the first number of times in one working cycle.

14. The converter according to any one of claims 10 to 12, characterized in that: The first switching parameter includes the current peak value, and the current peak value is a first current peak value; The controller is used to control the current peak value of the excitation inductor in the one working cycle to be the first current peak value; The controller is further configured to, after the current peak value of the excitation inductor in one working cycle reaches the first current peak value, control the current peak value of the excitation inductor in one working cycle to be a second current peak value if the output current of the converter is less than or equal to a second switching current threshold, wherein the second current peak value is less than the first current peak value; The controller is also used to control the current peak of the excitation inductor in the one working cycle to be the first current peak if the output current of the converter is greater than the second switching current threshold and less than or equal to the first switching current threshold after the current peak of the excitation inductor in the one working cycle is the first current peak.

15. A method for controlling a converter, characterized in that: The converter includes a main switch tube, an auxiliary switch tube and a transformer, wherein the main switch tube and the auxiliary switch tube are connected in series between the input terminal of the converter and a reference ground, the input terminal of the transformer is respectively connected to both ends of the auxiliary switch tube, and the output terminal of the transformer is connected to the output terminal of the converter; The method comprises: obtaining an output voltage of the converter, and obtaining a mode switching parameter based on the output voltage of the converter; The converter is controlled to switch between a first operating mode and a second operating mode according to the mode switching parameter, wherein the switching frequency of the converter in the first operating mode is negatively correlated with the output current of the converter, and the switching frequency of the converter remains unchanged within one operating cycle of the converter in the second operating mode.

16. The method according to claim 15, characterized in that The mode switching parameter is a first switching current threshold; The step of controlling the converter to switch between the first operating mode and the second operating mode according to the mode switching parameter includes: The output current of the converter is compared with the first switching current threshold, and the converter is controlled to switch between the first operating mode and the second operating mode according to the comparison result.

17. The method according to claim 16, characterized in that The obtaining of a mode switching parameter based on the output voltage of the converter includes: Based on the output voltage, obtaining a first voltage interval in which the output voltage is located from a plurality of voltage intervals; The first switching current threshold corresponding to the first voltage interval is obtained from a plurality of switching current thresholds corresponding to the voltage intervals, wherein the plurality of voltage intervals correspond to the plurality of switching current thresholds in a one-to-one correspondence.

18. The method according to claim 16 or 17, characterized in that The step of controlling the converter to switch between the first operating mode and the second operating mode according to the comparison result includes: When the output current is less than or equal to the first switching current threshold and greater than a second switching current threshold, controlling the main switch tube and the auxiliary switch tube to be turned on a first number of times in one working cycle of the converter; The method further comprises: When the output current is less than or equal to the second switching current threshold, the main switch tube and the auxiliary switch tube are controlled to be turned on a second number of times in one working cycle, wherein the second number of times of conduction is less than the first number of times of conduction.

19. The method according to claim 16 or 17, characterized in that The transformer includes an excitation inductor; The step of controlling the converter to switch between the first operating mode and the second operating mode according to the comparison result includes: When the output current is less than or equal to the first switching current threshold and greater than a second switching current threshold, controlling the current peak value of the excitation inductor in one working cycle of the converter to be a first current peak value; The method further comprises: When the output current is less than or equal to the second switching current threshold, the current peak of the excitation inductor in one working cycle is controlled to be a second current peak, wherein the second current peak is less than the first current peak.

20. The method according to claim 15, wherein The mode switching parameter is a first operating parameter of the converter in the second operating mode; the method further includes: Obtaining a switching frequency of the converter; The obtaining of a mode switching parameter based on the output voltage of the converter includes: When the switching frequency reaches a frequency threshold, obtaining the first operating parameter according to the output voltage; The step of controlling the converter to switch between the first operating mode and the second operating mode according to the mode switching parameter includes: The converter is controlled to switch from the first operating mode to the second operating mode based on the first operating parameter, wherein the first operating parameter includes the number of times the main switch tube and the auxiliary switch tube are turned on in one operating cycle of the converter, or the current peak value of the excitation inductor in the one operating cycle.

21. The method according to claim 20, characterized in that When the switching frequency reaches a frequency threshold, obtaining the first operating parameter according to the output voltage includes: When the switching frequency reaches the frequency threshold, obtaining a first voltage interval in which the output voltage is located from a plurality of voltage intervals; The first operating parameter corresponding to the first voltage interval is obtained from a plurality of operating parameters corresponding to the plurality of voltage intervals, wherein the plurality of voltage intervals correspond to the plurality of operating parameters in a one-to-one correspondence.

22. The method according to claim 21, characterized in that The multiple voltage intervals further include a second voltage interval. When any value in the second voltage interval is smaller than any value in the first voltage interval, a second operating parameter corresponding to the second voltage interval is smaller than the first operating parameter.

23. The method according to any one of claims 20 to 22, characterized in that The first operating parameter includes the conduction number, and the conduction number is a first conduction number; The controlling the converter to switch from the first operating mode to the second operating mode based on the first operating parameter includes: Controlling the main switch tube and the auxiliary switch tube to be turned on a first number of times in one working cycle; The method further comprises: After the main switch and the auxiliary switch are turned on a first number of times in one working cycle, if the output current of the converter is less than or equal to a second switching current threshold, controlling the main switch and the auxiliary switch to be turned on a second number of times in one working cycle, wherein the second number of times of conduction is less than the first number of times of conduction; The method further comprises: After the main switch tube and the auxiliary switch tube are turned on the first number of times in the one working cycle, if the output current of the converter is greater than the second switching current threshold and less than or equal to the first switching current threshold, the main switch tube and the auxiliary switch tube are controlled to be turned on the first number of times in the one working cycle.

24. The method according to any one of claims 20 to 22, characterized in that The first operating parameter includes the current peak value, and the current peak value is a first current peak value; The controlling the converter to switch from the first operating mode to the second operating mode based on the first operating parameter includes: controlling the current peak value of the excitation inductor in the one working cycle to be the first current peak value; The method further comprises: After the current peak value of the excitation inductor in the one working cycle reaches the first current peak value, if the output current of the converter is less than or equal to a second switching current threshold, controlling the current peak value of the excitation inductor in the one working cycle to be a second current peak value, wherein the second current peak value is less than the first current peak value; The method further comprises: After the current peak of the excitation inductor in the one working cycle is the first current peak, if the output current of the converter is greater than the second switching current threshold and less than or equal to the first switching current threshold, the current peak of the excitation inductor in the one working cycle is controlled to be the first current peak.

25. A terminal device, characterized in that: The terminal device comprises a battery and a converter according to any one of claims 1 to 14, wherein the converter is used to charge the battery.

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