Switching power supply and control method thereof

Abstract

The invention discloses a switching power supply and a control method thereof. The switching power supply comprises at least one phase power conversion circuit and a control circuit. Wherein the control circuit is configured to compare the output voltage with an overvoltage threshold value in the discharging stage of each phase of power conversion circuit, and turn off the first switching device and the second switching device under the condition that the output voltage is greater than the overvoltage threshold value, so that the inductive current is discharged through a body diode of the second switching device; therefore, the discharging speed of the inductor can be increased when the load drops rapidly, energy in the inductor can be released rapidly, violent fluctuation of output voltage is avoided, and the stability of the system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, and more specifically, to a switching power supply and a control method thereof. Background Art

[0002] With the advancement of circuit electronic technology, switching power supplies are constantly developing towards high power density, high efficiency and high reliability. Switching converters are widely used in switching power supplies of various electronic products. Switching converters can adopt a variety of topologies, such as boost, buck, buck-boost, and flyback topologies. During operation, the switching converter uses, for example, pulse width modulation (PWM) to control the conduction state of the power switch tube, thereby controlling the power transmission from the input end to the output end to provide a stable output voltage and / or current.

[0003] For a synchronous rectifier BUCK converter, when the load current drops rapidly, the conventional practice is to continuously apply a low-level PWM signal to the power circuit in the BUCK converter before the output voltage drops to the target voltage, so that the inductor current is discharged through the low-side switch tube in the power circuit until the output voltage drops below the target threshold voltage. However, as the load current slew rate increases, relying solely on the discharge speed of the power switch tube can no longer meet the system requirements, which may cause the energy in the inductor to be unable to be released in time, resulting in increased fluctuations in the output voltage, thereby affecting the stability of the system. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a switching power supply and a control method thereof, and propose a new discharge control logic that can increase the inductor discharge speed and meet the system's requirements for the current change rate without causing overheating and damage to the system, thereby helping to improve the stability of the system.

[0005] According to one aspect of the present invention, there is provided a switching power supply, comprising: at least one phase power conversion circuit, each phase power conversion circuit comprising a first switching device and a second switching device connected in series between an input voltage and a ground, and an inductor connected between a switching node of the first switching device and the second switching device and an output voltage; a control circuit, for generating at least one switch control signal and a discharge enable signal to control the conduction state of the first switching device and the second switching device of the corresponding phase power conversion circuit, wherein the control circuit is further used to compare the output voltage with an overvoltage threshold value during a discharge phase of each phase power conversion circuit, and to turn off the first switching device when the output voltage is greater than the overvoltage threshold value, so that the inductor current is discharged through the body diode of the second switching device and one of the second switching devices.

[0006] Optionally, the control circuit is further configured to, when the output voltage is greater than the overvoltage threshold, turn off both the first switching device and the second switching device, so that the inductor current is discharged through the body diode of the second switching device.

[0007] Optionally, the control circuit is further configured to, when the output voltage is greater than the overvoltage threshold, turn off the first switching device and turn on the second switching device, so that the inductor current is discharged through the second switching device.

[0008] Optionally, the control circuit is further configured to enable the inductor current to discharge alternately via the body diode of the second switching device and the second switching device when the output voltage is greater than the overvoltage threshold.

[0009] Optionally, the control circuit includes: an overvoltage detection module, used to compare the output voltage with a first reference voltage representing the overvoltage threshold to output an overvoltage indication signal; a PWM control module, used to generate at least one pulse width modulation signal; and at least one switching signal generating module corresponding one-to-one to the at least one phase power conversion circuit, each switching signal generating module being used to generate a switching control signal and the discharge enable signal of the corresponding phase power conversion circuit according to the overvoltage indication signal and the corresponding pulse width modulation signal.

[0010] Optionally, each of the switch signal generating modules is used to set the switch control signal to be invalid when the overvoltage indication signal is valid, and to set the switch control signal to be the same as the corresponding pulse width modulation signal when the overvoltage indication signal is invalid.

[0011] Optionally, when the output voltage is greater than the over-voltage threshold, the control circuit is further used to compare the body diode temperature of the second switching device with an over-temperature threshold during the discharge phase, and when the body diode temperature of the second switching device is less than the over-temperature threshold, enable the inductor current to discharge through the body diode of the second switching device; and when the body diode temperature of the second switching device is greater than or equal to the over-temperature threshold, enable the inductor current to discharge through the second switching device.

[0012] Optionally, each of the switching signal generating modules is also used to compare the temperature detection signal of the corresponding phase power conversion circuit with a second reference voltage characterizing the over-temperature threshold. When the over-voltage indication signal is valid, when the temperature detection signal is less than the second reference voltage, the discharge enable signal is set to be valid; when the temperature detection signal is greater than or equal to the second reference voltage, the discharge enable signal is set to be invalid.

[0013] Optionally, each of the switch signal generating modules includes: a first AND gate, whose first input terminal is used to receive the corresponding pulse width modulation signal, whose second input terminal is used to receive the inverted signal of the overvoltage indication signal, and whose output terminal is used to output the switch control signal; a voltage comparator, whose non-phase input terminal is used to receive the second reference voltage, whose inverting input terminal is used to receive the temperature detection signal, and whose output terminal is used to output the first comparison signal; and a second AND gate, whose first input terminal is used to receive the overvoltage indication signal, whose second input terminal is used to receive the first comparison signal, and whose output terminal is used to output the discharge enable signal.

[0014] Optionally, when the output voltage is greater than the overvoltage threshold, the control circuit is further used to count in the discharge phase, and when the count value does not exceed the count reference value, the inductor current is discharged through the body diode of the second switching device, and when the count value exceeds the count reference value, the inductor current is discharged through the second switching device.

[0015] Optionally, each of the switch signal generating modules includes: a counter, used to perform cyclic counting in the discharge stage to generate the count value; a digital comparator, used to compare the count value with the count reference value to generate a second comparison signal; a third AND gate, whose first input end is used to receive the corresponding pulse width modulation signal, the second input end is used to receive the inverted signal of the overvoltage indication signal, and the output end is used to output the switch control signal; and a fourth AND gate, whose first input end is used to receive the overvoltage indication signal, the second input end is used to receive the second comparison signal, and the output end is used to output the discharge enable signal.

[0016] Optionally, the control circuit further includes: a duty cycle register, configured to generate the counting reference value.

[0017] Optionally, the control circuit is also used to generate the counting reference value according to the inductor current of each phase power conversion circuit, wherein the larger the inductor current is, the smaller the counting reference value is, so that the discharge time of the inductor current through the body diode of the second switching device is shorter.

[0018] Optionally, the control circuit further includes: a microcontroller, configured to provide a reference setting signal to the duty cycle register according to a sampling signal of the inductor current of the corresponding power conversion circuit, and the duty cycle register generates the counting reference value according to the reference setting signal.

[0019] Optionally, each phase of the power conversion circuit further includes: a driving unit, configured to generate a first driving signal for driving the first switching device and a second driving signal for driving the second switching device according to a received switch control signal and a discharge enable signal.

[0020] Optionally, the driving unit includes: a fifth AND gate, whose first input terminal is used to receive the switch control signal, whose second input terminal is used to receive the inverted signal of the discharge enable signal, and whose output terminal is used to output the first drive signal; and a sixth AND gate, whose first input terminal is used to receive the inverted signal of the switch control signal, whose second input terminal is used to receive the inverted signal of the discharge enable signal, and whose output terminal is used to output the second drive signal.

[0021] Optionally, each phase of the power conversion circuit further includes: a temperature detection module, configured to detect the temperature of the second switching device to obtain the temperature detection signal.

[0022] Optionally, the topology structure of each phase power conversion circuit includes a buck topology, a boost topology or a flyback topology.

[0023] According to another aspect of the present invention, a control method for a switching power supply is provided, the switching power supply comprising at least one phase power conversion circuit, each phase power conversion circuit comprising a first switching device and a second switching device connected in series between an input voltage and a ground, and an inductor connected between a switching node of the first switching device and the second switching device and an output voltage, wherein the control method comprises: generating at least one switch control signal and a discharge enable signal to control the conduction state of the first switching device and the second switching device of the corresponding phase power conversion circuit; and comparing the output voltage with an overvoltage threshold value in the discharge stage of each phase power conversion circuit, and turning off the first switching device when the output voltage is greater than the overvoltage threshold value, so that the inductor current is discharged through the body diode of the second switching device and one of the second switching devices.

[0024] Optionally, the control method further includes: when the output voltage is greater than the overvoltage threshold, turning off both the first switching device and the second switching device, and discharging the inductor current through the body diode of the second switching device.

[0025] Optionally, the control method further includes: when the output voltage is greater than the overvoltage threshold, turning off the first switching device and turning on the second switching device, so that the inductor current is discharged through the second switching device.

[0026] Optionally, the control method further comprises: when the output voltage is greater than the overvoltage threshold, causing the inductor current to discharge alternately via the body diode of the second switching device and the second switching device.

[0027] Optionally, the step of generating at least one switch control signal and a discharge enable signal to control the conduction state of the first switch device and the second switch device of the corresponding phase power conversion circuit includes: comparing the output voltage with a first reference voltage characterizing the overvoltage threshold to output an overvoltage indication signal; generating at least one pulse width modulation signal; and generating the switch control signal and the discharge enable signal of the corresponding phase power conversion circuit based on the overvoltage indication signal and the corresponding pulse width modulation signal.

[0028] Optionally, when the overvoltage indication signal is valid, the switch control signal is set to be invalid, and when the overvoltage indication signal is invalid, the switch control signal is set to be the same as the corresponding pulse width modulation signal.

[0029] Optionally, the control method further includes: when the output voltage is greater than the over-voltage threshold, comparing the body diode temperature of the second switching device with an over-temperature threshold during the discharge phase, and when the body diode temperature of the second switching device is less than the over-temperature threshold, causing the inductor current to discharge through the body diode of the second switching device; and when the body diode temperature of the second switching device is greater than or equal to the over-temperature threshold, causing the inductor current to discharge through the second switching device.

[0030] Optionally, the control method also includes: comparing the temperature detection signal of the corresponding phase power conversion circuit with a second reference voltage representing the over-temperature threshold, and when the over-voltage indication signal is valid, when the temperature detection signal is less than the second reference voltage, setting the discharge enable signal to be valid; when the temperature detection signal is greater than or equal to the second reference voltage, setting the discharge enable signal to be invalid.

[0031] Optionally, the step of generating a switch control signal and a discharge enable signal of a corresponding phase power conversion circuit according to the overvoltage indication signal and the corresponding pulse width modulation signal includes: performing an AND logic operation on the corresponding pulse width modulation signal and an inverted signal of the overvoltage indication signal to generate the switch control signal; performing a voltage comparison between the second reference voltage and the temperature detection signal to generate a first comparison signal; and performing an AND logic operation between the overvoltage indication signal and the second comparison signal to generate the discharge enable signal.

[0032] Optionally, the control method further includes: when the output voltage is greater than the overvoltage threshold, counting is performed in the discharge phase, and when the count value does not exceed the count reference value, the inductor current is discharged through the body diode of the second switching device, and when the count value exceeds the count reference value, the inductor current is discharged through the second switching device.

[0033] Optionally, the step of generating a switch control signal of a corresponding phase power conversion circuit and a discharge enable signal according to the overvoltage indication signal and the corresponding pulse width modulation signal includes: performing an AND logic operation on the corresponding pulse width modulation signal and an inverted signal of the overvoltage indication signal to generate the switch control signal; performing cycle counting in the discharge phase to generate the count value; comparing the count value with the count reference value to generate a second comparison signal; and performing an AND logic operation on the overvoltage indication signal and the second comparison signal to generate the discharge enable signal.

[0034] Optionally, the control method further includes: generating the counting reference value through a duty cycle register.

[0035] Optionally, the control method further includes: providing a reference setting signal to the duty cycle register according to a sampling signal of the inductor current of the corresponding power conversion circuit through a microcontroller, and the duty cycle register generates the counting reference value according to the reference setting signal, wherein the larger the inductor current is, the smaller the counting reference value is, so that the discharge time of the inductor current through the body diode of the second switching device is shorter.

[0036] Optionally, the control method also includes: performing an AND logic operation on the switch control signal and the inverted signal of the discharge enable signal to provide a first drive signal to the first switch device; and performing an AND logic operation on the inverted signal of the switch control signal and the inverted signal of the discharge enable signal to provide a second drive signal to the second switch device.

[0037] To summarize, the control circuit of the switching power supply of the embodiment of the present invention compares the output voltage with the overvoltage threshold value during the discharge phase of the power conversion circuit, and turns off both the first switching device and the second switching device in the power conversion circuit when the output voltage is greater than the overvoltage threshold value, so that the inductor current can be discharged through the body diode of the second switching device, thereby accelerating the discharge speed of the inductor when the load drops rapidly, allowing the energy in the inductor to be quickly released, avoiding drastic fluctuations in the output voltage, and avoiding overvoltage damage to the system.

[0038] Furthermore, the control circuit of the switching power supply of the embodiment of the present invention also compares the body diode temperature of the second switching device with the over-temperature threshold during the discharge phase of the power conversion circuit, and turns on the second switching device again when the body diode temperature of the second switching device is greater than the over-temperature threshold, thereby discharging through the channel of the second switching device, avoiding damage to the switching device due to excessively long rapid discharge time, which is beneficial to improving the safety of the system.

[0039] Furthermore, the control circuit of the switching power supply of the embodiment of the present invention also provides a counting reference value according to the duty cycle register, uses a counter to perform cyclic counting, compares the counting value with the counting reference value to generate a discharge enable signal with a certain duty cycle, and adjusts the counting reference value in the duty cycle register to adjust the duty cycle of the discharge enable signal, thereby adjusting the discharge time of the inductor current through the body diode of the second switching device. Since the temperature monitoring circuit is omitted, the discharge speed is balanced on the basis of reducing the circuit complexity.

[0040] Furthermore, the control circuit of the switching power supply in the embodiment of the present invention also adjusts the counting reference value provided by the duty cycle register according to the sampling signal of the inductor current of the corresponding power conversion circuit. Adjusting the duty cycle according to the inductor current sampling can obtain the maximum time that can be discharged through the body diode corresponding to the inductor current without adding additional circuits and without causing the body diode to overheat. Compared with simple duty cycle control, it can prevent the body diode from overheating and achieve a faster discharge speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0042] Figure 1 A schematic structural diagram of a single-phase switching power supply according to an embodiment of the present invention is shown;

[0043] Figure 2a A schematic circuit diagram of a switch signal generating module according to a first embodiment of the present invention is shown;

[0044] Figure 2b A schematic circuit diagram of a switch signal generating module according to a second embodiment of the present invention is shown;

[0045] Figure 2c A schematic circuit diagram of a switch signal generating module according to a third embodiment of the present invention is shown;

[0046] Figure 2d Show Figure 2b and Figure 2c A schematic waveform diagram of a switch signal generating module;

[0047] Figure 3 A schematic circuit diagram of a driving unit according to an embodiment of the present invention is shown;

[0048] Figure 4 A schematic diagram of a discharge path of a switching power supply according to an embodiment of the present invention is shown;

[0049] Figure 5 Show according to Figure 2aA schematic waveform diagram of a switch signal generating module;

[0050] Figure 6 A schematic structural diagram of a multi-phase switching power supply according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0051] Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, identical elements are represented by identical or similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale. In addition, some well-known parts may not be shown.

[0052] It should be understood that in the following description, a "circuit" may include a single or multiple combined hardware circuits, programmable circuits, state machine circuits, and / or elements capable of storing instructions executed by programmable circuits. When an element or circuit is said to be "connected to" another element or an element or circuit is said to be "connected between" two nodes, it may be directly coupled or connected to another element or there may be an intermediate element, and the connection between the elements may be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0053] At the same time, certain words are used in this patent specification and claims to refer to specific components. It should be understood by those skilled in the art that hardware manufacturers may use different terms to refer to the same component. This patent specification and claims do not use differences in names as a way to distinguish components, but rather use differences in components' functions as the criteria for distinction.

[0054] In addition, it should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the statement "comprise one..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements.

[0055] It should be noted that, in this article, the switching device is a transistor that works in a switching mode to provide a current path, including one selected from a bipolar transistor or a field effect transistor. The first end and the second end of the switching device are respectively a high potential end and a low potential end on the current path, and the control end of the switching device is used to receive a drive signal to control the on and off of the transistor. In addition, in the present application, the description of the on and off of the power conversion circuit corresponds to the on and off of the main switching device that receives the input voltage in the power conversion circuit. For example, turning on the power conversion circuit corresponds to turning on the main switching device in the power conversion circuit to connect the energy storage element in the circuit to the input for charging and energy storage, and start to provide power output to the load (that is, generate a corresponding output voltage according to the input voltage); turning off the power conversion circuit corresponds to turning off the main switching device in the power conversion circuit to end the charging and energy storage state of the energy storage element in the circuit, and stop providing power output to the load.

[0056] Figure 1 FIG. 2 shows a schematic structural diagram of a single-phase switching power supply according to an embodiment of the present invention. Figure 1 As shown, the switching power supply adopts a BUCK (step-down) topology architecture, including a power conversion circuit 110 and a control circuit 120. The power conversion circuit 110 includes one or more switching devices and energy storage elements (for example, inductors and capacitors, etc.), and the one or more switches and energy storage elements are configured to adjust the power transmission from the input end to the output end of the power circuit in response to one or more switch control signals from the control circuit 120. In some embodiments, one or more switches in the power circuit are integrated with the control circuit 120 to form an integrated circuit chip.

[0057] Further, the power conversion circuit includes a driving unit 111, a first switching device S1, a second switching device S2 and an inductor Lx. The power conversion circuit 110 is configured to convert the input voltage Vin into an output voltage Vout by alternately turning on the first switching device S1 and the second switching device S2. Specifically, the first switching device S1 and the second switching device S2 are connected between the input voltage Vin and the reference ground, the diodes D1 and D2 are the body diodes of the first switching device S1 and the second switching device S2, respectively, the first end of the inductor Lx is connected to the switch node between the first switching device S1 and the second switching device S2, the second end is connected to the first end of the output capacitor Cout, and the second end of the output capacitor Cout is grounded. The driving unit 111 is used to receive the switch control signal CTRL and the discharge enable signal DR_en provided by the control circuit 120, and generate corresponding drive signals GH and GL according to the received control signals to control the conduction and disconnection of the first switching device S1 and the second switching device S2 respectively, so as to charge the energy storage element Lx for a corresponding time to generate the output voltage Vout, and drive the load based on the output capacitor Cout.

[0058] Specifically, in the charging phase of each switching cycle, the control circuit 120 turns on the first switch device S1 in the power conversion circuit 110 and turns off the second switch device S2, and the input voltage Vin charges the inductor Lx, so the current on the inductor Lx continues to rise. In the discharge phase of each switching cycle, the control circuit 120 turns off the first switch device S1 in the power conversion circuit 110, turns on the second switch device S2, and the current in the inductor Lx is discharged through the second switch device S2, so the current in the inductor Lx decreases. However, relying solely on the discharge speed of the power switch tube in the discharge phase can no longer meet the existing system requirements, which may cause the energy in the inductor to be unable to be released in time, resulting in an increase in the fluctuation of the output voltage. Therefore, the switching power supply 100 of the embodiment of the present invention has made further improvements to the traditional discharge operation, which will be specifically described in the following description.

[0059] In this embodiment, the first switch device S1 and the second switch device S2 may be any controllable semiconductor switch device, such as a metal oxide semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), and the like.

[0060] It should be noted that although the power conversion circuit is described as having a buck topology layout (Buck), the technical solution of the present invention can be adopted for any type of layout design, such as boost, flyback, buck-boost, Cuk, Sepic and Zeta.

[0061] As mentioned above, the control circuit 120 of the present embodiment is also configured to compare the output voltage Vout with the overvoltage threshold during the discharge phase of the power conversion circuit 110, and to turn off the first switching device S1 when the output voltage Vout is greater than the overvoltage threshold, so that the inductor current is discharged through the second switching device S2 and one of the body diodes of the second switching device S2.

[0062] For example, the control circuit 120 is used to turn off both the first switch device S1 and the second switch device S2 when the output voltage Vout is greater than the overvoltage threshold and the body diode temperature of the second switch device S2 is less than the overtemperature threshold, so that the inductor current can be discharged through the body diode D2 of the second switch device S2; and to turn off the first switch device S1 and turn on the second switch device S2 when the output voltage Vout is greater than the overvoltage threshold and the body diode temperature of the second switch device S2 is greater than the overtemperature threshold, so that the inductor current can be discharged through the second switch device S2.

[0063] For example, the control circuit 120 is further used to start cyclic counting when the output voltage Vout is greater than the overvoltage threshold value to obtain a count value, and when the count value does not exceed the count reference value, turn off both the first switch device S1 and the second switch device S2 to allow the inductor current to discharge through the body diode D2 of the second switch device S2, and when the count value exceeds the count reference value, turn off the first switch device S1 and turn on the second switch device S2 to allow the inductor current to discharge through the second switch device S2.

[0064] Specifically, the control circuit 120 includes an overvoltage detection module 121, a PWM control module 122, and a switch signal generation module 123. The overvoltage detection module 121 is used to compare the output voltage Vout with the first reference voltage Vref1 representing the overvoltage threshold, and output a valid (e.g., high level) overvoltage indication signal BRAKE_en when the output voltage Vout is overvoltage.

[0065] For example, the overvoltage detection module 121 can be implemented by a comparator, the positive input terminal of the comparator can be connected to the output voltage Vout, the negative input terminal of the comparator can be connected to the first reference voltage Vref1, and the output terminal of the comparator is used to output the overvoltage indication signal BRAKE_en. When the output voltage Vout is greater than the first reference voltage Vref1, the comparator sets the overvoltage indication signal BRAKE_en to be valid (for example, set to a high level). It should be noted that the overvoltage detection method of the present invention is not limited to the above embodiment, and those skilled in the art can also use other forms of overvoltage detection methods to implement it.

[0066] Furthermore, the first reference voltage Vref1 can be obtained by a DAC (digital-to-analog converter) controlled by a register, and different digital codes are provided to the DAC by configuring the register to obtain different voltage values ​​of the first reference voltage Vref1. Of course, the present invention is not limited to this.

[0067] The PWM control module 122 is used to generate a pulse width modulation signal PWM, wherein the PWM control module 122 can be implemented by a circuit or chip for generating a pulse width modulation (PWM) signal, which uses PWM modulation technology to control the average power of the output signal by changing the pulse width of the signal. The PWM control module and PWM modulation technology are conventional technologies in the art and will not be described in detail here.

[0068] The switch signal generation module 123 is used to generate the switch control signal CTRL and the discharge enable signal DR_en according to the overvoltage indication signal BRAKE_en and the pulse width modulation signal PWM. For example, the switch signal generation module 123 is used to set the switch control signal CTRL to be invalid (for example, a low level) when the overvoltage indication signal BRAKE_en is valid (for example, a high level), and to set the switch control signal CTRL to the same high and low level signals as the pulse width modulation signal PWM when the overvoltage indication signal BRAKE_en is invalid (for example, a low level).

[0069] For example, the power conversion circuit 110 also includes a temperature detection module 112, which is used to detect the temperature of the second switch device S2 to generate the temperature detection signal Tm. The temperature detection module 112 can be implemented by a thermistor NTC or a thermocouple, and the present invention does not limit this. In addition, the switch signal generation module 123 is also used to compare the temperature detection signal Tm with the second reference voltage Vref2 (not shown in the figure) representing the over-temperature threshold when the overvoltage indication signal BRAKE_en is valid. When the temperature detection signal Tm is less than the second reference voltage Vref2, the discharge enable signal DR_en is set to be valid (for example, a high level); when the temperature detection signal Tm is greater than the second reference voltage Vref2, the discharge enable signal DR_en is set to be invalid (for example, a low level).

[0070] Figure 2a FIG. 4 is a schematic circuit diagram of a switch signal generating module according to a first embodiment of the present invention. Figure 2a As shown, the switch signal generating module 123-1 includes AND gates AND1 and AND2, and a voltage comparator AMP. The first input terminal of the AND gate AND1 is used to receive the pulse width modulation signal PWM, the second input terminal of the AND gate AND1 is used to receive the inverted signal of the overvoltage indication signal BRAKE_en, and the output terminal of the AND gate AND1 is used to output the switch control signal CTRL. The positive input terminal of the voltage comparator AMP is used to receive the second reference voltage Vref2, the inverting input terminal of the voltage comparator AMP is used to receive the temperature detection signal Tm, and the output terminal of the voltage comparator AMP is used to output the comparison signal Cb1. The first input terminal of the AND gate AND2 is used to receive the overvoltage indication signal BRAKE_en, the second input terminal of the AND gate AND2 is used to receive the comparison signal Cb1 from the voltage comparator AMP, and the output terminal of the AND gate AND2 is used to output the discharge enable signal DR_en.

[0071] In this embodiment, the AND gate AND1 is configured to force the switch control signal CTRL to be set to a low level when the overvoltage indication signal BRAKE_en is at a valid level, and the high and low levels of the switch control signal CTRL are the same as the high and low levels of the input pulse width modulation signal PWM when the overvoltage indication signal BRAKE_en is at an invalid level. In the case where the overvoltage indication signal BRAKE_en is at a valid level, the AND gate AND2 is configured to set the discharge enable signal DR_en to a valid level when the temperature detection signal Tm is less than the second reference voltage Vref2, and to set the discharge enable signal DR_en to an invalid level when the temperature detection signal Tm is greater than the second reference voltage Vref2.

[0072] Figure 2bFIG. 2 shows an exemplary circuit diagram of a switch signal generating module according to a second embodiment of the present invention. Figure 2b As shown, the switch signal generating module 123-2 includes a counter 301, a digital comparator 303, and AND gates AND3 and AND4. The counter 301 is used to start cyclic counting when the output voltage Vout is greater than the overvoltage threshold value to generate a count value cnt. The digital comparator 303 is used to compare the count value cnt with the count reference value duty_th to generate a comparison signal Cb2. The first input end of the AND gate AND3 is used to receive the pulse width modulation signal PWM, the second input end of the AND gate AND3 is used to receive the inverted signal of the overvoltage indication signal BRAKE_en, and the output end of the AND gate AND3 is used to output the switch control signal CTRL. The first input end of the AND gate AND4 is used to receive the overvoltage indication signal BRAKE_en, the second input end of the AND gate AND4 is used to receive the comparison signal Cb2 from the digital comparator 303, and the output end of the AND gate AND4 is used to output the discharge enable signal DR_en.

[0073] Among them, the AND gate AND3 is configured to force the switch control signal CTRL to be set to a low level when the overvoltage indication signal BRAKE_en is at a valid level, and the high and low levels of the switch control signal CTRL are the same as the high and low levels of the input pulse width modulation signal PWM when the overvoltage indication signal BRAKE_en is at an invalid level. In the case where the overvoltage indication signal BRAKE_en is at a valid level, the AND gate AND4 is configured to set the discharge enable signal DR_en to a valid level when the count value cnt is less than the count reference value duty_th, and to set the discharge enable signal DR_en to an invalid level when the count value cnt is greater than or equal to the count reference value duty_th.

[0074] Furthermore, the control circuit 120 of the present invention further includes a duty cycle register 302, and the duty cycle register 302 is used to generate the counting reference value duty_th. For example, the duty cycle register 302 can also be located in the switch signal generating module 123-2, and the present invention does not limit this. Furthermore, the duty cycle register 302 can be set to be storable and programmable by the user, so that the user can adjust the value of the counting reference value duty_th.

[0075] Figure 2c FIG. 4 shows an exemplary circuit diagram of a switch signal generating module according to a third embodiment of the present invention. Figure 2cAs shown, in the third embodiment of the present invention, the control circuit 120 may further include a microcontroller (MCU for short) 304, and the microcontroller 304 is used to provide a reference setting signal duty_ctrl to the duty cycle register 302 according to the sampling signal CS of the inductor current of the corresponding power conversion circuit, and the duty cycle register 302 generates the counting reference value duty_th according to the reference setting signal duty_ctrl. For example, the microcontroller 304 may store a mapping table of the sampling signal CS of the inductor current and the reference setting signal duty_ctrl, and the microcontroller 304 is used to look up the table according to the sampling signal CS to output the corresponding reference setting signal duty_ctrl. Among them, the larger the sampling signal CS of the inductor current of the corresponding power conversion circuit, the smaller the counting reference value duty_th, so that the discharge time of the inductor current through the body diode of the second switching device is shorter, so as to improve the discharge speed without causing the body diode to overheat.

[0076] Figure 2d Show Figure 2b and Figure 2c Schematic waveform diagram of the switch signal generation module. Figure 2d The waveforms of the overvoltage indication signal BRAKE_en, the discharge enable signal DR_en, the switch control signal CTRL, the count value cnt and the count reference value duty_th are shown in FIG. Figure 2b to Figure 2d The discharge process of the second and third embodiments of the present invention is described in detail.

[0077] like Figure 2d As shown, in the time period t1-t2, when the overvoltage indication signal BRAKE_en flips from a low level to a high level, the switch control signal CTRL is forced to be pulled down to a low level, and the counter 301 starts counting. At this time, the count value cnt is less than the count reference value duty_th, so the discharge enable signal DR_en is a high level, and the first switch device S1 and the second switch device S2 in the control power conversion circuit 110 are both turned off. At this time, the current will discharge through the body diode D2.

[0078] In the time period t2-t3, the count value cnt rises to the count reference value duty-th, so the discharge enable signal DR_en is at a low level. Since the switch control signal CTRL is also at a low level, the first switch device S1 in the power conversion circuit 110 is turned off and the second switch device S2 is turned on. At this time, the current will discharge through the second switch device S2.

[0079] At the same time, the counter 301 continues to count, and at time t3, the count value cnt reaches the maximum value, the count value of the counter 301 is cleared, and the counting starts again. At this time, the count value cnt is less than the count reference value duty_th, so the discharge enable signal DR_en flips to a high level again. At time t4, the overvoltage indication signal BRAKE_en flips from a high level to a low level, so the discharge enable signal DR_en also flips to a low level. Figure 3 FIG. 2 shows a schematic circuit diagram of a driving unit according to an embodiment of the present invention. Figure 3 As shown, the driving unit 111 of this embodiment includes AND gates AND7 and AND8. The first input end of the AND gate AND7 is used to receive the switch control signal CTRL, the second input end of the AND gate AND7 is used to receive the inverted signal of the discharge enable signal DR_en, and the output end of the AND gate AND7 is used to output the first drive signal GH that controls the on and off of the first switch device S1. The first input end of the AND gate AND8 is used to receive the inverted signal of the discharge enable signal DR_en, the second input end of the AND gate AND8 is used to receive the inverted signal of the switch control signal CTRL, and the output end of the AND gate AND8 is used to output the second drive signal GL that controls the on and off of the second switch device S2.

[0080] Among them, the driving unit 111 of this embodiment is configured to set the first driving signal GH and the second driving signal GL to a low level when the switch control signal CTRL is at an invalid level and the discharge enable signal DR_en is at a valid level, so that the first switching device S1 and the second switching device S2 are both turned off, so that the inductor current discharges through the body diode D2 of the second switching device S2; when the switch control signal CTRL and the discharge enable signal DR_en are both at invalid levels, the driving unit 111 sets the first driving signal GH to a low level and sets the second driving signal GL to a high level, so that the first switching device S1 is turned off and the second switching device S2 is turned on, so that the inductor current discharges through the second switching device S2.

[0081] Figure 4 and Figure 5 A schematic diagram of a discharge path and a schematic waveform diagram of a switching power supply according to an embodiment of the present invention are respectively shown. Figure 5 The waveforms of the overvoltage indication signal BRAKE_en, the discharge enable signal DR_en, the switch control signal CTRL, the temperature detection signal Tm and the inductor current IL are shown in FIG. Figure 4 and Figure 5 The discharging process of the switching power supply according to the embodiment of the present invention is described in detail.

[0082] In the time period t1-t2, when the overvoltage indication signal BRAKE_en is flipped from a low level to a high level, the switch control signal CTRL is forced to be pulled down to a low level, and the temperature detection signal Tm from the power conversion circuit 110 is detected. If the temperature detection signal Tm is less than the second reference voltage Vref2, the discharge enable signal DR_en is set to a high level, and the first switch device S1 and the second switch device S2 in the power conversion circuit 110 are controlled to be turned off. At this time, the current will be discharged through the body diode D2, and its discharge path is as follows: Figure 4 As shown by the dotted line in .

[0083] In the time period t2-t3, the temperature detection signal Tm is greater than the second reference voltage Vref2, so the discharge enable signal DR_en is at a low level. Since the switch control signal CTRL is also at a low level, the first switch device S1 in the power conversion circuit 110 is turned off and the second switch device S2 is turned on. At this time, the current will be discharged through the second switch device S2. The discharge path is as follows: Figure 4 The process of time period t1-t2 and time period t2-t3 is repeated continuously in the following time, until the overvoltage indication signal BRAKE_en is flipped to a low level again at time t4, at which time the waveform of the switch control signal CTRL will be the same as the pulse width modulation signal PWM generated by the system.

[0084] In addition, Figure 5 In the waveform of the inductor current ILx, the dotted line represents the conventional inductor current discharge waveform, and the solid line represents the inductor current discharge waveform of the embodiment of the present invention. Figure 5 As shown, compared with the traditional inductor current discharge method, the inductor current discharge speed of the embodiment of the present invention is faster, and the energy in the inductor can be released in time during the discharge process, avoiding drastic fluctuations in the output voltage and improving the stability of the system.

[0085] Figure 6 A schematic structural diagram of a multi-phase switching power supply according to an embodiment of the present invention is shown. The multi-phase switching power supply (hereinafter referred to as a multi-phase power supply) of the embodiment of the present invention includes a control circuit of the multi-phase power supply and an N-phase power conversion circuit, where N is an integer greater than 1, and the control circuit of the multi-phase power supply is used to control the conduction sequence and charging time of the N-phase power conversion circuit to jointly provide an output voltage Vout.

[0086] Specifically, refer to Figure 6 The multi-phase power supply 200 includes N-phase parallel coupled power conversion circuits 201 - 20N (N is the number of phases set by the multi-phase power supply, and N is an integer greater than 1) and a control circuit (hereinafter referred to as the control circuit) 300 of the multi-phase power supply.

[0087] Each phase power conversion circuit includes a driving unit, a first switch device S1, a second switch device S2, and an inductor Lx, wherein the first switch device S1 and the second switch device S2 are connected between the input voltage Vin and the reference ground, the diodes D1 and D2 are body diodes of the first switch device S1 and the second switch device S2, respectively, the first end of the inductor Lx is connected to the middle node of the first switch device S1 and the second switch device S2, the second end is connected to the first end of the output capacitor Cout, and the second end of the output capacitor Cout is grounded. The driving units in each phase power conversion circuit 201-20N receive the switch control signals CTRL1-CTRLN and the discharge enable signals DR_en1-DR_enN provided by the control circuit 300, and control the conduction and shutdown of the corresponding switch device according to the received control signal, charge the energy storage element of the current phase for a corresponding time, and provide an output current to the output end of the multi-phase power conversion circuit, so that the output end of the multi-phase power conversion circuit outputs the output voltage Vout, and drives the load based on the output capacitor Cout.

[0088] It should be noted that although each phase power conversion circuit can refer to Figure 6 The structure of the power conversion circuit 201 in the embodiment can be understood. In this embodiment, each phase inductor corresponding to each phase power conversion circuit in the N-phase power conversion circuit 201-20N can be discrete or mutually coupled (for example, the first phase inductor is coupled with the second phase inductor; the third phase inductor is coupled with the fourth phase inductor, and so on). At the same time, although the power conversion circuit is described as having a buck topology layout (Buck), the technical solution of the present invention can be adopted for any type of layout design, such as boost, flyback, buck-boost, Cuk, Sepic and Zeta.

[0089] Furthermore, the control circuit 300 is also configured to compare the output voltage Vout with a first reference voltage Vref1 representing an overvoltage threshold during the discharge phase of each phase power conversion circuit, and when the output voltage Vout is greater than the first reference voltage Vref1, turn off the first switching device S1 in the power conversion circuit of the corresponding phase, so that the inductor current is discharged through the second switching device S2 of the power conversion circuit of that phase and one of the body diodes of the second switching device S2.

[0090] By way of example, the control circuit 300 is used to, when the output voltage Vout is greater than the first reference voltage Vref1 and the body diode temperature of the second switch device S2 is less than an over-temperature threshold, turn off both the first switch device S1 and the second switch device S2 of the corresponding phase power conversion circuit so that the inductor current can be discharged through the body diode D2 of the second switch device S2; and, when the output voltage Vout is greater than the first reference voltage Vref1 and the body diode temperature of the second switch device S2 of the phase power conversion circuit is greater than the over-temperature threshold, turn off the first switch device S1 of the corresponding phase power conversion circuit and turn on the second switch device S2 so that the inductor current can be discharged through the second switch device S2.

[0091] For example, the control circuit 300 is further used to start cyclic counting when the output voltage Vout is greater than the first reference voltage Vref1 to obtain a count value, and when the count value does not exceed the count reference value, turn off both the first switch device S1 and the second switch device S2 to allow the inductor current to discharge through the body diode D2 of the second switch device S2, and when the count value exceeds the count reference value, turn off the first switch device S1 and turn on the second switch device S2 to allow the inductor current to discharge through the second switch device S2.

[0092] Specifically, the control circuit 300 includes an overvoltage detection module 310, a PWM control module 320, and N switch signal generation modules 331-33N (N is an integer greater than 1) corresponding to the N-phase power conversion circuits 201-20N. The overvoltage detection module 310 is used to compare the output voltage Vout with the first reference voltage Vref1 representing the overvoltage threshold, and output a valid overvoltage indication signal BRAKE_en when the output voltage Vout is overvoltage. It should be noted that the overvoltage detection module 310 of this embodiment can be implemented using the same circuit as the overvoltage detection module 121 of the above embodiment, which will not be repeated here.

[0093] The PWM control module 320 is used to generate N pulse width modulation signals PWM1-PWMN corresponding to the N-phase power conversion circuits 201-20N. The circuit structure of the PWM control module 320 is conventional in the art and will not be described in detail here.

[0094] Each switch signal generating module 33x (x=1, 2, 3, ..., N) is used to generate a switch control signal CTRLx (x=1, 2, 3, ..., N) and a discharge enable signal DR_enx (x=1, 2, 3, ..., N) of the corresponding phase power conversion circuit according to the overvoltage indication signal BRAKE_en, the corresponding pulse width modulation signal PWMx (x=1, 2, 3, ..., N) and the temperature detection signal Tmx (x=1, 2, 3, ..., N) of the body diode temperature of the second switch device S2 in the corresponding power conversion circuit 20x (x=1, 2, 3, ..., N). For example, each power conversion circuit 20x also includes a temperature detection module (for example, a temperature detection module 2012), which is used to detect the temperature of the second switch device S2 to generate the temperature detection signal Tmx. The temperature detection module can be implemented by a thermistor NTC or a thermocouple, which is not limited by the present invention.

[0095] For example, each of the switch signal generating modules 33x is used to set the switch control signal CTRLx of the corresponding phase power conversion circuit 20x to invalid (for example, low level) when the overvoltage indication signal BRAKE_en is valid (for example, high level), and to set the switch control signal CTRLx to the same high and low level signal as the pulse width modulation signal PWMx when the overvoltage indication signal BRAKE_en is invalid (for example, low level). In addition, each switch signal generating module 33x is also used to compare the temperature detection signal Tmx output by the corresponding phase power conversion circuit 20x with the second reference voltage Vref2 (not shown in the figure) representing the over-temperature threshold when the overvoltage indication signal BRAKE_en is valid, and to set the discharge enable signal DR_enx to valid (for example, high level) when the temperature detection signal Tmx is less than the second reference voltage Vref2; and to set the discharge enable signal DR_enx to invalid (for example, low level) when the temperature detection signal Tmx is less than the second reference voltage Vref2.

[0096] It should be noted that each switch signal generating module 33x can be implemented using the same circuit as the switch signal generating module 123 in the above embodiment, and the driving unit (for example, the driving unit 2011) in each power conversion circuit 20x can be implemented using the same circuit as the driving unit 111 in the above embodiment, which will not be repeated here.

[0097] In summary, the control circuit of the switching power supply of the embodiment of the present invention compares the output voltage with the overvoltage threshold value during the discharge stage of the power conversion circuit, and turns off both the first switching device and the second switching device in the power conversion circuit when the output voltage is greater than the overvoltage threshold value, so that the inductor current can be discharged through the body diode of the second switching device, thereby accelerating the discharge speed of the inductor when the load drops rapidly, allowing the energy in the inductor to be quickly released, avoiding drastic fluctuations in the output voltage, and improving the stability of the system.

[0098] Furthermore, the control circuit of the switching power supply of the embodiment of the present invention also compares the body diode temperature of the second switching device with the over-temperature threshold during the discharge phase of the power conversion circuit, and turns on the second switching device again when the body diode temperature of the second switching device is greater than the over-temperature threshold, thereby discharging through the channel of the second switching device, avoiding damage to the switching device due to excessively long rapid discharge time, which is beneficial to improving the safety of the system.

[0099] In the above description, the well-known structural elements and steps are not described in detail. However, it should be understood by those skilled in the art that the corresponding structural elements and steps can be realized by various technical means. In addition, in order to form the same structural elements, those skilled in the art can also design methods that are not completely the same as the methods described above. In addition, although each embodiment is described above respectively, this does not mean that the measures in each embodiment cannot be advantageously used in combination.

[0100] According to the embodiments of the present invention, as described above, these embodiments do not describe all the details in detail, nor do they limit the invention to specific embodiments. Obviously, many modifications and changes can be made based on the above description. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and the modified use based on the present invention. The scope of protection of the present invention shall be based on the scope defined by the claims of the present invention.

Claims

1. A switching power supply, comprising: At least one-phase power conversion circuit, each phase power conversion circuit includes a first switching device and a second switching device connected in series between an input voltage and ground, and an inductor connected between a switch node of the first switching device and the second switching device and an output voltage; a control circuit, configured to generate at least one switch control signal and a discharge enable signal to control the conduction state of the first switch device and the second switch device of the corresponding phase power conversion circuit, The control circuit is also used to compare the output voltage with an overvoltage threshold during the discharge phase of each phase power conversion circuit, and to turn off the first switching device when the output voltage is greater than the overvoltage threshold, so that the inductor current is discharged through the body diode of the second switching device and one of the second switching devices.

2. The switching power supply according to claim 1, wherein: The control circuit is further configured to, when the output voltage is greater than the overvoltage threshold, turn off both the first switching device and the second switching device, so that the inductor current is discharged through the body diode of the second switching device.

3. The switching power supply according to claim 1, wherein: The control circuit is further configured to, when the output voltage is greater than the overvoltage threshold, turn off the first switch device and turn on the second switch device, so that the inductor current is discharged through the second switch device.

4. The switching power supply according to claim 1, wherein: The control circuit is further configured to enable the inductor current to discharge alternately via the body diode of the second switching device and the second switching device when the output voltage is greater than the overvoltage threshold.

5. The switching power supply according to claim 4, wherein: The control circuit comprises: an overvoltage detection module, configured to compare the output voltage with a first reference voltage representing the overvoltage threshold value, so as to output an overvoltage indication signal; A PWM control module, configured to generate at least one pulse width modulation signal; and At least one switching signal generating module corresponding one-to-one to the at least one phase power conversion circuit, each switching signal generating module is used to generate a switching control signal and the discharge enable signal of the corresponding phase power conversion circuit according to the overvoltage indication signal and the corresponding pulse width modulation signal.

6. The switching power supply according to claim 5, wherein: Each of the switch signal generating modules is used to set the switch control signal to be invalid when the overvoltage indication signal is valid, and to set the switch control signal to be the same as the corresponding pulse width modulation signal when the overvoltage indication signal is invalid.

7. The switching power supply according to claim 5, wherein: When the output voltage is greater than the overvoltage threshold, The control circuit is further configured to compare the body diode temperature of the second switching device with an over-temperature threshold value during the discharge phase, and, when the body diode temperature of the second switching device is less than the over-temperature threshold value, discharge the inductor current through the body diode of the second switching device, and When the body diode temperature of the second switching device is greater than or equal to the over-temperature threshold, the inductor current is discharged via the second switching device.

8. The switching power supply according to claim 7, wherein: Each of the switching signal generating modules is also used to compare the temperature detection signal of the corresponding phase power conversion circuit with a second reference voltage representing the over-temperature threshold. When the over-voltage indication signal is valid, when the temperature detection signal is less than the second reference voltage, the discharge enable signal is set to be valid; when the temperature detection signal is greater than or equal to the second reference voltage, the discharge enable signal is set to be invalid.

9. The switching power supply according to claim 8, wherein: Each of the switch signal generating modules comprises: A first AND gate, wherein a first input terminal is used to receive the corresponding pulse width modulation signal, a second input terminal is used to receive the inverted signal of the overvoltage indication signal, and an output terminal is used to output the switch control signal; a voltage comparator, wherein the non-phase input terminal is used to receive the second reference voltage, the inverting input terminal is used to receive the temperature detection signal, and the output terminal is used to output the first comparison signal; and The second AND gate has a first input terminal for receiving the overvoltage indication signal, a second input terminal for receiving the first comparison signal, and an output terminal for outputting the discharge enable signal.

10. The switching power supply according to claim 5, wherein: When the output voltage is greater than the overvoltage threshold, The control circuit is further configured to count during the discharge phase, and when the count value does not exceed the count reference value, enable the inductor current to discharge via the body diode of the second switch device, and When the count value exceeds the count reference value, the inductor current is discharged via the second switching device.

11. The switching power supply according to claim 10, wherein: Each of the switch signal generating modules comprises: A counter, used for performing cycle counting in the discharging stage to generate the count value; a digital comparator, configured to compare the count value with the count reference value to generate a second comparison signal; A third AND gate, whose first input terminal is used to receive the corresponding pulse width modulation signal, whose second input terminal is used to receive the inverted signal of the overvoltage indication signal, and whose output terminal is used to output the switch control signal; and A fourth AND gate has a first input terminal for receiving the overvoltage indication signal, a second input terminal for receiving the second comparison signal, and an output terminal for outputting the discharge enable signal.

12. The switching power supply according to claim 11, wherein: The control circuit further comprises: The duty cycle register is used to generate the counting reference value.

13. The switching power supply according to claim 12, wherein: The control circuit is further configured to generate the counting reference value according to the inductor current of each phase power conversion circuit. The larger the inductor current is, the smaller the counting reference value is, so that the discharge time of the inductor current through the body diode of the second switching device is shorter.

14. The switching power supply according to claim 13, wherein: The control circuit further comprises: The microcontroller is used for providing a reference setting signal to the duty cycle register according to a sampling signal of the inductor current of the corresponding power conversion circuit, and the duty cycle register generates the counting reference value according to the reference setting signal.

15. The switching power supply according to any one of claims 5 to 14, wherein: Each phase of the power conversion circuit further includes: The driving unit is used to generate a first driving signal for driving the first switching device and a second driving signal for driving the second switching device according to the received switch control signal and the discharge enable signal.

16. The switching power supply according to claim 15, wherein: The driving unit comprises: a fifth AND gate, whose first input terminal is used to receive the switch control signal, whose second input terminal is used to receive the inverted signal of the discharge enable signal, and whose output terminal is used to output the first drive signal; and A sixth AND gate has a first input terminal for receiving an inverted signal of the switch control signal, a second input terminal for receiving an inverted signal of the discharge enable signal, and an output terminal for outputting the second drive signal.

17. The switching power supply according to claim 8 or 9, wherein: Each phase of the power conversion circuit further includes: The temperature detection module is used to detect the temperature of the second switch device to obtain the temperature detection signal.

18. The switching power supply according to claim 1, wherein: The topology of each phase power conversion circuit includes a buck topology, a boost topology or a flyback topology.

19. A method for controlling a switching power supply, the switching power supply comprising at least one phase power conversion circuit, each phase power conversion circuit comprising a first switching device and a second switching device connected in series between an input voltage and ground, and an inductor connected between a switch node of the first switching device and the second switching device and an output voltage, in, The control method comprises: generating at least one switch control signal and a discharge enable signal to control the conduction state of the first switch device and the second switch device of the corresponding phase power conversion circuit; and The output voltage is compared with an overvoltage threshold during a discharge phase of each phase power conversion circuit, and when the output voltage is greater than the overvoltage threshold, the first switching device is turned off so that the inductor current is discharged through the body diode of the second switching device and one of the second switching devices.

20. The control method according to claim 19, wherein: Also includes: When the output voltage is greater than the overvoltage threshold, both the first switching device and the second switching device are turned off, and the inductor current is discharged through the body diode of the second switching device.

21. The control method according to claim 19, wherein: Also includes: When the output voltage is greater than the overvoltage threshold, the first switch device is turned off and the second switch device is turned on, so that the inductor current is discharged through the second switch device.

22. The control method according to claim 19, wherein: Also includes: When the output voltage is greater than the overvoltage threshold, the inductor current is discharged alternately via the body diode of the second switching device and the second switching device.

23. The control method according to claim 22, wherein: The step of generating at least one switch control signal and a discharge enable signal to control the conduction state of the first switch device and the second switch device of the corresponding phase power conversion circuit comprises: Comparing the output voltage with a first reference voltage representing the overvoltage threshold to output an overvoltage indication signal; generating at least one pulse width modulated signal; and A switch control signal of a corresponding phase power conversion circuit and the discharge enable signal are generated according to the overvoltage indication signal and the corresponding pulse width modulation signal.

24. The control method according to claim 23, wherein: When the overvoltage indication signal is valid, the switch control signal is set to be invalid, and When the overvoltage indication signal is invalid, the switch control signal is set to be the same as the corresponding pulse width modulation signal.

25. The control method according to claim 23, wherein: Also includes: When the output voltage is greater than the overvoltage threshold, the body diode temperature of the second switching device is compared with the overtemperature threshold during the discharge phase, and when the body diode temperature of the second switching device is less than the overtemperature threshold, the inductor current is discharged through the body diode of the second switching device, and When the body diode temperature of the second switching device is greater than or equal to the over-temperature threshold, the inductor current is discharged via the second switching device.

26. The control method according to claim 25, wherein: Also includes: The temperature detection signal of the corresponding phase power conversion circuit is compared with a second reference voltage representing the over-temperature threshold. When the over-voltage indication signal is valid, when the temperature detection signal is less than the second reference voltage, the discharge enable signal is set to be valid; when the temperature detection signal is greater than or equal to the second reference voltage, the discharge enable signal is set to be invalid.

27. The control method according to claim 26, wherein: The step of generating a switch control signal of a corresponding phase power conversion circuit and the discharge enable signal according to the overvoltage indication signal and the corresponding pulse width modulation signal comprises: Performing an AND logic operation on the corresponding pulse width modulation signal and the inverted signal of the overvoltage indication signal to generate the switch control signal; performing a voltage comparison between the second reference voltage and the temperature detection signal to generate a first comparison signal; and Performing an AND logic operation on the overvoltage indication signal and the second comparison signal to generate the discharge enable signal.

28. The control method according to claim 23, wherein: Also includes: When the output voltage is greater than the overvoltage threshold, counting is performed in the discharge phase, and when the count value does not exceed the count reference value, the inductor current is discharged through the body diode of the second switch device, and When the count value exceeds the count reference value, the inductor current is discharged via the second switching device.

29. The control method according to claim 28, wherein: The step of generating a switch control signal of a corresponding phase power conversion circuit and the discharge enable signal according to the overvoltage indication signal and the corresponding pulse width modulation signal comprises: Performing an AND logic operation on the corresponding pulse width modulation signal and the inverted signal of the overvoltage indication signal to generate the switch control signal; Performing cycle counting during the discharging phase to generate the count value; comparing the count value with the count reference value to generate a second comparison signal; and Performing an AND logic operation on the overvoltage indication signal and the second comparison signal to generate the discharge enable signal.

30. The control method according to claim 29, wherein: Also includes: The counting reference value is generated by a duty cycle register.

31. The control method according to claim 30, wherein: Also includes: The microcontroller provides a reference setting signal to the duty cycle register according to a sampling signal of the inductor current of the corresponding power conversion circuit, and the duty cycle register generates the counting reference value according to the reference setting signal. The larger the inductor current is, the smaller the counting reference value is, so that the discharge time of the inductor current through the body diode of the second switching device is shorter.

32. The control method according to any one of claims 23 to 31, wherein: Also includes: Performing an AND logic operation on the switch control signal and an inverted signal of the discharge enable signal to provide a first drive signal to the first switch device; as well as An AND logic operation is performed on the inverted signal of the switch control signal and the inverted signal of the discharge enable signal to provide a second drive signal to the second switch device.

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