Virtual trough detection method, electronic equipment and storage medium

Abstract

The embodiment of the invention discloses a virtual trough detection method, electronic equipment and a storage medium, and the method comprises the steps: starting timing and accumulating a trough count value when it is detected that a trough detection signal is changed from a high level to a low level; when it is detected that the trough detection signal is changed from low level to high level, the timing value is reset, and timing is stopped; generating a first virtual trough period according to the first time; generating a second virtual trough period according to the second time; when the wave trough detection signal is continuously at a low level, determining a wave trough detection moment based on a comparison result of the timing value and the first virtual wave trough period or the second virtual wave trough period; and when the timing value reaches the trough detection moment, accumulating a trough counting value, and resetting the timing value and restarting timing. According to the embodiment of the invention, the problem of trough detection failure caused by zero-cross detection sampling signal attenuation of the asymmetric half-bridge converter in the DCM mode is solved, and meanwhile, the trough detection accuracy is improved by adopting a double-cycle detection strategy.

Description

Technical Field

[0001] The embodiments of the present invention relate to a field, and in particular to a virtual trough detection method, an electronic device, and a storage medium. Background Art

[0002] Due to its simple structure and robust characteristics, the flyback converter has become one of the most widely used DC converter topologies in the low-power segment. Its multiple outputs and cost-effective design make it highly popular in applications such as personal computers, various home appliances, and office equipment. However, the main disadvantage of the flyback converter is hard switching. Typically, hard switching of the power switches leads to high switching losses, electromagnetic interference noise, and high switch voltage stress. The asymmetrical half-bridge converter (AHB), also known as the hybrid flyback converter, uses a half-bridge structure and resonant capacitors to achieve zero-voltage switching (ZVS) of the power switches and a wide output voltage range, and is currently gaining popularity.

[0003] In asymmetric half-bridge converter applications, to reduce the switching frequency at light loads, the converter is often operated in discontinuous conduction mode (DCM). In DCM mode, to reduce the turn-on losses when QH is conducting, the converter is often turned on at the moment when the VDS voltage is minimum. To achieve this, valley detection is required.

[0004] However, in the existing asymmetric half-bridge converter DCM mode, the valley detection has the following problems: when in DCM mode, when the set target valley number valleyset is large, as the valley number increases, the energy of the asymmetric half-bridge free resonance weakens, and the subsequent valley detection signal will not be detected normally; since the output voltage of AHB is often in a relatively wide range, in order to be compatible with high-voltage output, the zero-crossing detection sampling signal will be relatively weak under low-voltage output conditions. The increase in the number of valleys will cause the level of the valley detection signal to be continuously low, resulting in the inability to detect the valley normally; in the control of the lower tube of the asymmetric half-bridge, it is often difficult to make the excitation current at a suitable negative current level, which will result in that when the lower tube is turned off, if the excitation current is positive, or the negative current level is too small, the asymmetric half-bridge resonant cavity current is too small, which will also cause the valley to be unable to be detected normally. Summary of the Invention

[0005] The main technical problem solved by the embodiments of the present invention is to provide a virtual valley detection method, electronic equipment and storage medium, which can solve the problem of failure to detect valleys normally due to weak zero-crossing detection sampling signals.

[0006] In order to solve the above technical problems, a technical solution adopted in an embodiment of the present invention is: to provide a virtual valley detection method, which is applied to an asymmetric half-bridge converter, comprising: when a valley detection signal is detected to change from a high level to a low level, starting timing and accumulating valley count values; the valley detection signal is the output signal of the zero-crossing detection comparator of the asymmetric half-bridge converter; when the valley detection signal is detected to change from a low level to a high level, clearing the timing value and stopping timing; generating a first virtual valley period according to a first time; the first time is from the first detection of the valley detection signal changing from a high level to a second detection of the valley detection signal changing from a high level to a low level The time between detecting the valley detection signal changing from a high level to a low level is detected; a second virtual valley cycle is generated according to the second time; the second time is the time between detecting the valley detection signal changing from a high level to a low level for the second time and detecting the valley detection signal changing from a high level to a low level for the third time; when the valley detection signal continues to be a low level, the valley detection moment is determined based on the comparison result of the timing value and the first virtual valley cycle or the second virtual valley cycle; when the timing value reaches the valley detection moment, the valley count value is accumulated, the timing value is cleared and the timing is restarted.

[0007] In some embodiments, the method further includes: determining whether the valley count value is equal to a preset threshold; if so, ending the current valley detection cycle; and starting the next valley detection cycle after a first preset time delay.

[0008] In some embodiments, when the valley detection signal is continuously at a low level, the valley detection moment is determined based on the comparison result of the timing value and the virtual valley period, including: when the timing value reaches a second preset time, judging whether the valley detection signal is a high level; if not, judging whether the valley count value is the first preset value; if the valley count value is the first preset value, then when the timing value reaches the first virtual valley period, the timing value is used as the valley detection moment, and the count value is cleared; if the valley count value is not the first preset value, then when the timing value reaches the second virtual valley period, the timing value is used as the valley detection moment, and the count value is cleared.

[0009] In some embodiments, the second preset time is one quarter of the resonant period of the asymmetric half-bridge converter.

[0010] In some embodiments, generating the first virtual valley period according to the first time includes: filtering the first time to obtain a first filtered value; and adding a first preset margin to the first filtered value to obtain the first virtual valley period.

[0011] In some embodiments, obtaining the first time includes: when the valley count value is equal to 0 and the valley detection signal is detected to change from a high level to a low level, recording the current time as the first moment; when the valley count value is equal to the first preset value and the valley detection signal is detected to change from a high level to a low level, recording the current time as the second moment; obtaining the first time based on the first moment and the second moment.

[0012] In some embodiments, generating the second virtual valley period according to the second time includes: filtering the second time to obtain a second filtered value; and adding a second preset margin to the second filtered value to obtain the second virtual valley period.

[0013] In some embodiments, obtaining the second time includes: when the valley count value is equal to the first preset value and the valley detection signal is detected to change from a high level to a low level, recording the current time as the second moment; when the valley count value is equal to the second preset value and the valley detection signal is detected to change from a high level to a low level, recording the current time as the third moment; obtaining the second time based on the second moment and the third moment.

[0014] In order to solve the above technical problems, another technical solution adopted in the embodiment of the present invention is: to provide an electronic device, including: at least one processor; at least one network interface, the network interface is communicatively connected to the corresponding processor; and a memory communicatively connected to the at least one processor; wherein the network interface is used to establish a communication connection between the processor and other external devices; the memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute a virtual valley detection method as described above.

[0015] To solve the above technical problems, another technical solution adopted in the embodiment of the present invention is: providing a non-volatile computer storage medium, wherein the computer storage medium stores computer-executable instructions, and the computer-executable instructions are executed by one or more processors, enabling the one or more processors to execute a virtual valley detection method as described above.

[0016] The beneficial effects of the embodiments of the present invention are as follows: Different from the existing technology, the embodiments of the present invention have three main advantages: by introducing a virtual valley detection mechanism, the problem of valley detection failure caused by attenuation of the zero-crossing detection sampling signal is effectively solved; a dynamically updated dual-cycle detection strategy is adopted to improve the accuracy of valley detection; the virtual detection function is automatically shielded when the zero-crossing detection sampling signal is valid, realizing seamless switching between real valley detection and virtual valley detection, and ensuring stable operation of the asymmetric half-bridge converter under various working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a circuit diagram of an asymmetric half-bridge converter;

[0018] Figure 2 This is the operating waveform of the asymmetric half-bridge converter in discontinuous conduction mode;

[0019] Figure 3 This is the operating waveform diagram of the asymmetric half-bridge converter in discontinuous conduction mode where the valley cannot be detected normally;

[0020] Figure 4 It is a flow chart of a virtual trough detection method provided by the present invention;

[0021] Figure 5 It is a flow chart of another virtual trough detection method provided by the present invention;

[0022] Figure 6 yes Figure 4 The sub-process diagram of step S300 is shown;

[0023] Figure 7 yes Figure 4 A schematic diagram of a sub-process of step S400 is shown;

[0024] Figure 8 yes Figure 4 A schematic diagram of a sub-process of step S500 is shown;

[0025] Figure 9 is a working waveform diagram of an asymmetric half-bridge converter in discontinuous conduction mode using a virtual valley detection method;

[0026] Figure 10 Another working waveform diagram of an asymmetric half-bridge converter in discontinuous conduction mode using a virtual valley detection method;

[0027] Figure 11 It is a structural schematic diagram of an electronic device provided by the present invention. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as being "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The terms "upper", "lower", "inner", "outer", "bottom" and the like used in this specification indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0029] Unless otherwise defined, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the relevant listed items.

[0030] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0031] The technical solution in this application will be described below with reference to the accompanying drawings.

[0032] like Figure 1 As shown in Figure 1, the asymmetric half-bridge converter is widely used in the field of low-power power supply due to its simple structure and excellent performance characteristics. Its main structure includes input capacitor C in 、Original side pipe Q H and its freewheeling diode D H and equivalent junction capacitance C H 、Original side lower tube Q L and its freewheeling diode D L and equivalent junction capacitance C L , transformer TA, resonant capacitor Cr, secondary side freewheeling diode D S And the output filter capacitor C out The main advantage of this circuit is that through the cooperation of the half-bridge structure and the resonant capacitor Cr, zero voltage switching of the switch tube can be achieved, effectively reducing switching losses.

[0033] In order to reduce the switching frequency under light load conditions, the asymmetric half-bridge converter usually operates in discontinuous conduction mode. In discontinuous conduction mode, in order to reduce the primary side Q H The turn-on loss needs to be DS When the voltage is minimum, the primary side upper tube Q is turned on H , so it is necessary to implement the trough detection function.

[0034] like Figure 1 As shown in the figure, the traditional valley detection circuit consists of the transformer auxiliary winding TB, the voltage divider resistor R ZCD1 and the voltage divider resistor R ZCD2 , filter capacitor C ZCD , clamping diode D ZCD And the zero-crossing detection comparator CMP1. Among them, the auxiliary winding TB is used to sample V DS Waveform information, through the voltage divider resistor R ZCD1 and the voltage divider resistor R ZCD2 After voltage division, we get the zero-crossing detection sampling signal V ZCD Filter capacitor C ZCD Used to filter out the zero-crossing detection sampling signal V ZCD The high frequency components in the clamping diode D ZCD For clamp protection, the zero-crossing detection comparator CMP1 will V ZCD The signal is compared with the reference level ZCD_REF, and the output valley detection signal ZCD indicates the arrival of the valley.

[0035] Table 1 is Figure 1 Definition of the labels shown.

[0036]

[0037]

[0038] Table 1

[0039] The operating waveform of the asymmetric half-bridge converter in discontinuous conduction mode is as follows Figure 2 As shown:

[0040] At t1, the upper tube drive signal GH of the asymmetric half-bridge converter is set high, and the primary upper tube Q H is turned on, at this time the excitation current I Lm Rising, excitation current I Lm Equal to I Lr .

[0041] At time t2, the excitation current I Lm When the target reference value is reached, the asymmetric half-bridge upper tube drive signal GH is set low, and the primary side upper tube Q H closure.

[0042] At time t3, the lower tube drive signal GL of the asymmetric half-bridge converter is set high, and the primary lower tube Q L is turned on, at this time the excitation current I Lm Starts to decline, during the time from t3 to t4, when the excitation current I Lm Not equal to the resonant current I Lr When the secondary side freewheeling diode D S The primary side transfers energy to the secondary side.

[0043] At time t4, the lower tube drive signal GL is set low, and the primary lower tube Q L Turn off, and the asymmetric half-bridge converter enters the free resonance state.

[0044] At time t5, the valley detection signal ZCD changes from high level to low level, and the first valley signal is detected. The valley number counter valley num =1.

[0045] At time t6, the valley detection signal ZCD changes from high level to low level for the second time, and the second valley signal is detected. The valley number counter valley num =2.

[0046] At time t7, the valley detection signal ZCD changes from high level to low level for the third time, and the third valley signal is detected. The valley number counter valley num =3.

[0047] At time t8, the valley detection signal ZCD changes from high level to low level for the nth time, and the nth valley signal is detected. num Reach the valley number set by the system set , end the trough detection.

[0048] At time t9, after a time delay set by the system, the upper tube drive signal GH of the asymmetric half-bridge converter is set high again, and the primary upper tube Q H Turn on again and start the next cycle.

[0049] However, this traditional trough detection solution has the following problems in practical applications:

[0050] First, in the discontinuous conduction mode, as the number of valleys increases, the energy of the asymmetric half-bridge free resonance gradually decays. ZCD When the amplitude drops below the reference level ZCD_REF, the zero-crossing detection comparator CMP1 will fail to flip, and the valley detection signal ZCD will remain at a low level, resulting in the inability to detect subsequent valleys.

[0051] Second, in order to adapt to a wider output voltage range, the voltage divider resistor RZCD1 and the voltage divider resistor R ZCD2 The voltage divider ratio is often large. At low voltage output, this will cause the zero-crossing detection sampling signal V ZCD The weaker the voltage, the more likely it is to fall below the reference level ZCD_REF due to attenuation of resonance energy, affecting the reliability of valley detection.

[0052] Third, due to the excitation current I of the primary lower tube QL when it is turned off Lm It is difficult to control accurately. If the excitation current I Lm If the positive or negative current is too small, it will cause the resonant cavity current to be too small, making the zero-crossing detection sampling signal V ZCD The attenuation is aggravated, affecting the accuracy of trough detection.

[0053] Figure 3 The figure shows that the asymmetric half-bridge converter cannot detect the valley normally in the discontinuous conduction mode. It can be seen that after time t8, due to the zero-crossing detection sampling signal V ZCD Gradually decays, resulting in zero-crossing detection sampling signal V ZCD The signal is always smaller than the ZCD_REF signal, so the valley detection signal ZCD cannot be reversed, and therefore valley detection cannot be performed by virtue of the signal reverse of the valley detection signal ZCD.

[0054] These issues severely restrict the performance of asymmetric half-bridge converters in discontinuous conduction mode. Therefore, a new valley detection scheme is urgently needed to overcome these drawbacks and ensure stable and reliable operation of the system under various operating conditions.

[0055] In view of the above situation, the embodiments of the present invention are based on Figure 1 The asymmetric half-bridge converter shown in FIG. 1 provides a virtual valley detection method, and its flow chart is shown in FIG. Figure 4 As shown, the method includes the following steps:

[0056] Step S100: When it is detected that the valley detection signal changes from a high level to a low level, timing is started and valley count values ​​are accumulated.

[0057] Specifically, in the initial state, the valley count value is 0. When the valley detection signal ZCD is detected to change from a high level to a low level for the first time, it indicates that the first valley has arrived, and the counter cnt starts timing, and the valley count value increases by 1 at the same time.

[0058] Step S200: when it is detected that the valley detection signal changes from a low level to a high level, the timing value is cleared and the timing is stopped.

[0059] That is, when the valley detection signal ZCD changes from a low level to a high level, it indicates that the current valley has ended, and the counter cnt is cleared and the counting is suspended. This step can avoid misjudgment during the period of valid valley signals.

[0060] Step S300: generating a first virtual valley period according to the first time.

[0061] The first time is defined as the time interval between the first detection of the valley detection signal changing from high level to low level and the second detection of the valley detection signal changing from high level to low level. This time corresponds to the first valley cycle. By measuring and processing it, the appropriate first virtual valley cycle valley can be obtained. period1 .

[0062] Step S400: generating a second virtual valley period according to the second time.

[0063] The second time is defined as the time interval between the second detection of the valley detection signal changing from high level to low level and the third detection of the valley detection signal changing from high level to low level. Since the subsequent valley cycles are similar, by measuring and processing the second time, a second virtual valley cycle suitable for subsequent valley detection can be obtained. period2 .

[0064] Step S500: When the valley detection signal is continuously at a low level, a valley detection moment is determined based on a comparison result between the timing value and the first virtual valley period or the second virtual valley period.

[0065] When the zero-crossing detection sampling signal V ZCD When the energy attenuation fails to cross the reference level ZCD_REF, the valley detection signal ZCD cannot be effectively flipped. By comparing the count value of the counter cnt with the corresponding virtual valley period, the arrival time of the valley is determined. period1 Make judgment; for subsequent troughs, use valley period2 Make a judgment.

[0066] Step S600: When the timing value reaches the valley detection time, the valley count value is accumulated, the timing value is reset and the timing is restarted.

[0067] That is, when the cnt count value is equal to the corresponding virtual valley period, it is considered that a new valley is detected, the valley count value is increased by 1, and cnt is cleared and restarted to prepare for the detection of the next valley.

[0068] This method replaces the traditional signal comparison method by using a virtual valley cycle mechanism, effectively overcoming the problem of zero-crossing detection sampling signal V ZCDTo address the problem of valley detection failure caused by attenuation, two different virtual valley periods are used, one for the second valley and the other for subsequent valley detection, to improve detection accuracy. Furthermore, during the period when the valley detection signal ZCD can normally flip, step S200 ensures that the virtual detection function is disabled to avoid interference with the normal valley detection process.

[0069] In a preferred embodiment, after completing each valley detection, the virtual valley detection method determines whether the current valley count value reaches a preset threshold value, and accordingly determines whether to start the next switching cycle. Figure 5 The complete workflow including this feature is shown in detail.

[0070] First, the method performs the basic valley detection process from steps S100 to S600. After the valley count value is accumulated in step S600, the method proceeds to step S700: determining whether the valley count value is equal to a preset threshold. The preset threshold represents the number of valleys to be detected and can be flexibly set based on actual application requirements.

[0071] If the judgment result is no, indicating that the expected number of valleys has not yet been reached, the method will return to step S500 to continue performing valley detection. Through this cyclic process, it is ensured that the system can detect a sufficient number of valleys, thereby achieving optimal switch timing control.

[0072] If the judgment result is yes, indicating that the expected number of valley detections has been completed, the method will proceed to step S800: ending the current valley detection cycle. After the current cycle ends, to ensure that the switch is turned on at the optimal time, the method will further proceed to step S900: delaying for a first predetermined time before starting the next valley detection cycle.

[0073] The setting of the first preset time directly affects switching losses and electromagnetic interference levels. Practice has shown that the first preset time is preferably set to 0.1 to 0.3 times the resonant period of the asymmetric half-bridge converter. By properly setting the first preset time, the switch can be turned on when the resonant voltage is close to its minimum value, minimizing switching losses while avoiding efficiency degradation caused by excessive delays.

[0074] It is worth noting that the virtual valley detection method adopts a dual protection mechanism: when the zero-crossing detection sampling signal V ZCD When valid, the valley detection is performed through the actual signal jump; the sampling signal V ZCD During attenuation, valley detection is performed using a virtual valley cycle. The two mechanisms switch seamlessly and complement each other, significantly improving system reliability.

[0075] Furthermore, the valley counting method in this method has been optimized. Valley counts are accumulated only when actual signal transitions or virtual valley periods are detected, avoiding the double counting and missed counting issues that can occur in traditional schemes. Furthermore, the valley count is automatically reset to zero at the beginning of each switching cycle, preparing for the next round of detection.

[0076] This design not only overcomes the limitations of traditional valley detection solutions but also provides flexible parameter configuration. Users can adjust the preset threshold and first preset time based on specific application scenarios to find the optimal balance between switching loss, electromagnetic interference, and system efficiency. Experimental results demonstrate that this method exhibits excellent stability and reliability under various operating conditions.

[0077] In a specific embodiment of the present invention, the process of generating the first virtual trough period involves multiple technical steps, the goal of which is to accurately capture the characteristics of the first trough period. Figure 6 The specific implementation of the generation process is shown in detail.

[0078] First, step S310 is executed: when the valley count value is equal to 0 and it is detected that the valley detection signal changes from a high level to a low level, the current time is recorded as the first moment.

[0079] This step accurately captures the start of the first valley by monitoring the valley count value and the transition of the valley detection signal ZCD. The valley count value is initialized to 0 at startup to ensure that the first valley can be accurately identified.

[0080] Then, step S320 is executed: when the valley count value is equal to the first preset value and it is detected that the valley detection signal changes from a high level to a low level, the current time is recorded as the second moment.

[0081] The first preset value is usually set to 1, indicating that the first trough has been detected. By monitoring the starting time of the second trough, the time information required for calculating the first trough period is obtained.

[0082] Then, step S330 is executed: obtaining the first time according to the first moment and the second moment.

[0083] The specific calculation method is to subtract the first moment from the second moment, and the difference is the time interval between two adjacent troughs. This time interval contains the resonance characteristics of the asymmetric half-bridge converter under actual operating conditions.

[0084] In order to eliminate the influence of external interference and random fluctuations, step S340 is executed: filtering is performed on the first time to obtain a first filtered value.

[0085] Filtering uses a weighted average algorithm to process the first time of multiple consecutive measurements to extract stable periodic features. The filter coefficient can be adjusted according to actual application requirements. A larger filter coefficient is beneficial for suppressing interference, but it will reduce the system's response speed to changes in operating conditions.

[0086] Finally, step S350 is executed: the first filter value is added to the first preset margin to obtain a first virtual valley period.

[0087] The setting of the first preset margin has a significant impact on the performance of asymmetric half-bridge converters. Too little margin can cause premature triggering of virtual valley detection, while too much margin can miss the optimal switching moment. In practice, a suitable setting for the first preset margin is 20% to 30% of the first filter value.

[0088] The above generation process fully considers various factors in practical applications. Through precise time measurement, effective filtering, and appropriate margin settings, it ensures that the generated first virtual valley period accurately reflects system characteristics while also providing sufficient fault tolerance. This process is also relatively simple to implement, requiring no complex hardware circuitry and relying primarily on a digital controller, which helps reduce system costs.

[0089] It's particularly noteworthy that the generation process for the first virtual valley period utilizes a real-time update mechanism. Whenever a new valley is detected, the aforementioned steps are re-executed, continuously optimizing the value of the virtual valley period. This mechanism enables the asymmetric half-bridge converter to adapt to changing operating conditions, such as load variations and input voltage fluctuations, while maintaining stable and reliable operation.

[0090] In another specific embodiment of the present invention, the generation process of the second virtual valley period has a significant impact on system performance. Figure 7 The complete technical scheme for generating the second virtual trough period is presented in detail, which includes several key steps.

[0091] First, step S410 is executed: when the valley count value is equal to the first preset value and it is detected that the valley detection signal changes from a high level to a low level, the current time is recorded as the second moment.

[0092] The first preset value is usually set to 1, corresponding to the state where the first valley count is completed. The system captures the starting moment of the second valley by monitoring the jump of the valley detection signal ZCD.

[0093] Then, step S420 is executed: when the valley count value is equal to the second preset value and it is detected that the valley detection signal changes from a high level to a low level, the current time is recorded as a third moment.

[0094] The second preset value is usually set to 2, indicating that two troughs have been detected. The record of the third moment provides the necessary time reference for calculating subsequent trough cycles.

[0095] Then, step S430 is executed: obtaining a second time according to the second moment and the third moment.

[0096] The specific calculation method is to subtract the second time from the third time to obtain the time interval between two adjacent troughs. The second time reflects the resonant characteristics of the asymmetric half-bridge converter in stable operation. Its value is usually smaller than the first time due to the natural decay of the resonant energy.

[0097] In order to improve the anti-interference capability of the system, step S440 is executed: filtering is performed on the second time to obtain a second filtered value.

[0098] The filtering process uses a recursive averaging algorithm, which effectively suppresses the effects of external interference and random fluctuations. The filter design requires a balance between response speed and stability. Practice has shown that an 8th-order recursive averaging filter achieves good results.

[0099] Finally, step S450 is executed: a second preset margin is added to the second filtered value to obtain a second virtual valley period.

[0100] The setting of the second preset margin needs to consider multiple factors, including resonance characteristics, load conditions, operating frequency, etc. Generally, the second preset margin should be smaller than the first preset margin because the subsequent trough period is relatively stable and does not require an excessively large safety margin.

[0101] The mechanism for generating the second virtual trough period represents a significant technological innovation. Compared to traditional approaches, this mechanism is specifically optimized for the characteristics of subsequent troughs. Because the system enters a relatively stable operating state after the first trough, the periodicity of subsequent troughs varies less, enabling the use of more precise detection parameters.

[0102] It's worth noting that the second virtual valley period isn't fixed. The generation steps described above are repeated throughout each switching cycle, updating the value of the second virtual valley period in real time. This dynamic update mechanism allows for rapid adaptation to changing operating conditions, maintaining optimal detection results.

[0103] Experimental data demonstrates that the second virtual valley period generated using this scheme is highly accurate and stable. It maintains reliable valley detection across various load conditions and input voltage ranges, effectively improving the performance of an asymmetric half-bridge converter operating in DCM mode.

[0104] In a preferred embodiment of the present invention, a multi-level judgment mechanism is used to determine the trough detection moment. Figure 8 A detailed technical solution for determining the trough detection moment is presented, which ensures the accuracy of the detection results through a reasonable judgment process.

[0105] First, step S510 is executed: when the timing value reaches the second preset time, it is determined whether the valley detection signal is at a high level.

[0106] The second preset time is set to one-quarter of the resonant period of the asymmetric half-bridge converter. There is sufficient technical justification for selecting this time point: at this point, if the asymmetric half-bridge converter is in normal resonance, the valley detection signal must have transitioned from a low level to a high level. Therefore, by performing level determination at this point, it is possible to effectively distinguish between normal resonance and signal attenuation.

[0107] If the valley detection signal remains high, the asymmetric half-bridge converter still has sufficient resonant energy. Valley detection should continue through actual signal transitions, eliminating the need to initiate the virtual valley detection mechanism. Conversely, if the valley detection signal remains low, the asymmetric half-bridge converter has entered the signal attenuation phase, requiring the subsequent virtual valley detection process.

[0108] After confirming that virtual valley detection is required, step S520 is executed: determining whether the valley count value is a first preset value.

[0109] This judgment is used to distinguish whether the second trough detection is in progress. The first preset value is usually set to 1, indicating that the first trough detection has been completed. The purpose of distinguishing different trough numbers is to use different virtual trough periods in a targeted manner.

[0110] If the valley count value is equal to the first preset value, step S530 is executed: when the timing value reaches the first virtual valley period, the timing value is used as the valley detection moment, and the count value is cleared.

[0111] The first virtual valley period is specifically optimized for the characteristics of the second valley. Its value is generated based on the actual valley period measured for the first time, and can better match the resonant characteristics of the asymmetric half-bridge converter at this stage.

[0112] If the valley count value is not equal to the first preset value, step S540 is executed: when the timing value reaches the second virtual valley period, the timing value is used as the valley detection moment, and the count value is cleared.

[0113] The second virtual valley period is suitable for detecting the third and subsequent valleys, and its value is usually smaller than the first virtual valley period, which is more consistent with the characteristics of the asymmetric half-bridge converter in the stable working stage.

[0114] The aforementioned mechanism for determining the valley detection moment offers significant technical advantages. By determining the second preset time, signal attenuation can be promptly identified, avoiding signal detection blind spots. The use of two different virtual valley periods fully accounts for the characteristics of the asymmetric half-bridge converter in different operating phases, improving detection accuracy. Furthermore, this mechanism establishes seamless switching between actual signal detection and virtual valley detection, ensuring reliable operation of the asymmetric half-bridge converter under various operating conditions.

[0115] Practical application results show that an asymmetric half-bridge converter based on this detection mechanism exhibits excellent performance. Even under light-load conditions, it can accurately implement valley conduction control, significantly reducing switching losses. Even under sudden load changes, it can quickly adjust detection parameters to maintain stable operation.

[0116] An embodiment of the present invention details the specific application process of the virtual valley detection method in an asymmetric half-bridge converter. Figure 9 The working process including the complete waveform is demonstrated, and the timing relationship between various control signals is clearly presented.

[0117] At t1, the upper tube drive signal GH of the asymmetric half-bridge converter is set high, and the upper tube Q H is turned on, at this time the excitation current I Lm Rising, excitation current I Lm Equal to I Lr .

[0118] At time t2, the excitation current I Lm Reaching the target reference value, the asymmetric half-bridge upper tube drives GH low, and the upper tube Q H closure.

[0119] At time t3, the lower tube drive signal GL of the asymmetric half-bridge converter is set high, and the lower tube Q L is turned on, at this time the excitation current I Lm Starts to decline, during the time from t3 to t4, when the excitation current I Lm Not equal to the resonant current I Lr When the secondary side freewheeling diode D S The primary side transfers energy to the secondary side.

[0120] At time t4, the lower tube drive signal GL is set low, and the lower tube Q L Turn off, and the asymmetric half-bridge converter enters the free resonance state.

[0121] At time t5, the valley detection signal ZCD changes from high level to low level, the asymmetric half-bridge converter detects the first valley signal, and the valley number counter valley num = 1. At this time, the counter cnt starts counting.

[0122] At time t6, the valley detection signal ZCD changes from low to high, at which time the cnt counter is cleared and stops counting.

[0123] At time t7, the valley detection signal ZCD changes from high to low for the second time, and the asymmetric half-bridge converter detects the second valley signal. The valley number counter valley num =2. At the same time, record the time from t5 to t7 as T period1 At this time, the cnt counter starts counting again.

[0124] At time t8, the valley detection signal ZCD changes from low to high, at which time the cnt counter is cleared and stops counting.

[0125] At time t9, the valley detection signal ZCD changes from high to low for the third time, and the asymmetric half-bridge converter detects the third valley signal. The valley number counter valley num =3. At the same time, record the time from t7 to t9 as T period2 At this time, the cnt counter starts counting again.

[0126] In the subsequent valley detection, if the valley detection signal ZCD turns high, the cnt counter is cleared and stops counting. If the valley detection signal ZCD changes from high to low, the valley signal is detected and the next valley detection cycle begins, and the cnt counter starts counting.

[0127] In t 10 At this moment, the last time the valley detection signal ZCD is detected to flip, the subsequent zero-crossing detection sampling signal V ZCD The attenuation of the zero-crossing detection comparator CMP1 cannot be flipped, so the valley detection signal ZCD remains at a low level. At this time, the cnt counter starts counting.

[0128] In t 11 At this moment, when the cnt counter is equal to the virtual valley period valley period2 When a valley is detected, num The counter is incremented by 1. At the same time, the cnt counter is cleared.

[0129] In t 12 At this moment, when the cnt counter is equal to the virtual valley period valley period2 When a valley is detected, num The counter is incremented by 1. At the same time, the cnt counter is cleared. At this point, Valleynum equals the preset valley number valleyset, and valley detection ends.

[0130] In t 13At this moment, the upper tube drive signal GH is set high and enters the next switching cycle. 12 to t 13 The delay time between them is configurable to achieve the optimal valley conduction moment.

[0131] If the zero-crossing detection sampling signal V ZCD The attenuation is serious. After the valley detection signal ZCD changes from high to low for the first time, the reversal of the valley detection signal ZCD cannot be detected again. Figure 10 The working process in such cases is demonstrated, and the timing relationship between various control signals is clearly presented.

[0132] At t1, the upper tube drive signal GH of the asymmetric half-bridge converter is set high, and the upper tube Q H is turned on, at this time the excitation current I Lm Rising, excitation current I Lm Equal to I Lr .

[0133] At time t2, the excitation current I Lm Reaching the target reference value, the asymmetric half-bridge upper tube drives GH low, and the upper tube Q H closure.

[0134] At time t3, the lower tube drive signal GL of the asymmetric half-bridge converter is set high, and the lower tube Q L is turned on, at this time the excitation current I Lm Starts to decline, during the time from t3 to t4, when the excitation current I Lm Not equal to the resonant current I Lr When the secondary side freewheeling diode D S The primary side transfers energy to the secondary side.

[0135] At time t4, the lower tube drive signal GL is set low, and the lower tube Q L Turn off, and the asymmetric half-bridge converter enters the free resonance state.

[0136] At time t5, the valley detection signal ZCD changes from high level to low level, the asymmetric half-bridge converter detects the first valley signal, and the valley number counter valley num = 1. At this time, the counter cnt starts counting.

[0137] During the time period from t5 to t6, due to the zero-crossing detection sampling signal V ZCD It is always smaller than the reference signal ZCD_REF of the comparator, so the valley detection signal ZCD is always at a low level, and the cnt counter keeps counting.

[0138] At t6, cnt is equal to the virtual valley period valley period1At this time, it is considered that the second valley is detected, and the valley number counter valley num = 2. The cnt counter is cleared and starts counting again.

[0139] After the second valley is detected, the cnt counter will no longer be in the same valley. period1 Instead of comparing with valley period2 Compare, whenever cnt is equal to valley period2 When the trough is detected, num Add 1.

[0140] At t8, cnt equals valley period2 , cnt counter cleared, valley num Add 1, which is equal to the valley number set by the system. set .

[0141] After a delay, at time t9, the high-side tube drive signal GH is set high, entering the next switching cycle.

[0142] Throughout the entire operating process, smooth switching between actual and virtual valley detection is achieved. When the resonant signal amplitude is sufficient, detection is performed using signal transitions; during signal attenuation, detection is performed using virtual valley cycles. This dual detection mechanism ensures stable operation across the system's full operating range.

[0143] As can be seen from the waveform diagram, the proposed virtual valley detection method not only solves the detection failure problem caused by signal attenuation in traditional solutions, but also improves detection accuracy through a dual-cycle detection strategy, enabling the system to exhibit excellent control characteristics. This method is also relatively simple to implement, relying primarily on a digital controller to perform all its functions, and has high engineering application value.

[0144] The embodiment of the present invention also provides an electronic device based on the above virtual valley detection method, the structural diagram of which is shown in FIG. Figure 11 As shown, the electronic device 700 includes:

[0145] One or more processors 701, network interface 702, and memory 703, Figure 11 In the figure, a processor 701, a network interface 702 and a memory 703 are taken as an example.

[0146] The network interface 702 is in communication with the corresponding processor 701, and the processor 701 and the memory 702 can be connected via a bus or other means. Figure 11 The bus connection is taken as an example.

[0147] The network interface 702 is used to establish a communication connection between the processor 701 and other external devices, and includes the following types of interfaces: RJ-45 interface, SC fiber optic interface, AUI interface, FDDI interface, and Console interface.

[0148] Memory 703, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer executable programs, and modules. Processor 701 executes the non-volatile software programs, instructions, and units stored in memory 703 to perform various functional applications and data processing of the electronic device, thereby implementing the virtual valley detection method of the above-described method embodiment.

[0149] The memory 103 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and applications required for at least one function; the data storage area may store data created based on the use of the electronic device, etc. In addition, the memory 703 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 703 may optionally include a memory remotely located relative to the processor 701, and these remote memories may be connected to the electronic device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0150] The one or more units are stored in the memory 703, and when executed by the one or more processors 701, perform the virtual valley detection method in any of the above method embodiments, for example, perform the above described Figure 4 Method steps S100 to S600.

[0151] The electronic device can execute the virtual trough detection method provided by the embodiment of the present invention, and has the corresponding program module and beneficial effects of the execution method. For technical details not fully described in the electronic device embodiment, please refer to the virtual trough detection method provided by the embodiment of the present invention.

[0152] Embodiments of the present invention also provide a non-volatile computer-readable storage medium. This non-volatile computer-readable storage medium may be included in the device described in the above embodiments, or may exist independently and not incorporated into the device. This non-volatile computer-readable storage medium carries one or more programs. When executed, these one or more programs implement the virtual valley detection method of the disclosed embodiments.

[0153] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Based on the idea of ​​the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present application as above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A virtual valley detection method, applied to an asymmetric half-bridge converter, characterized in that: include: When it is detected that the valley detection signal changes from a high level to a low level, the timing is started and the valley count value is accumulated; the valley detection signal is the output signal of the zero-crossing detection comparator of the asymmetric half-bridge converter; When it is detected that the valley detection signal changes from a low level to a high level, the timing value is cleared and the timing is stopped; Generate a first virtual valley period according to a first time; the first time is the time between the first detection of the valley detection signal changing from a high level to a low level and the second detection of the valley detection signal changing from a high level to a low level; Generate a second virtual valley period according to a second time; the second time is the time between the second detection of the valley detection signal changing from a high level to a low level and the third detection of the valley detection signal changing from a high level to a low level; When the valley detection signal is continuously at a low level, determining a valley detection moment based on a comparison result of a timing value and the first virtual valley period or the second virtual valley period; When the timing value reaches the valley detection moment, the valley count value is accumulated, the timing value is cleared, and the timing is restarted.

2. The method according to claim 1, characterized in that Also includes: Determining whether the valley count value is equal to a preset threshold; If yes, then end the current trough detection cycle; After a delay of the first preset time, the next valley detection cycle is started.

3. The method according to claim 1, characterized in that When the valley detection signal is continuously at a low level, determining the valley detection moment based on a comparison result between the timing value and the virtual valley period includes: When the timing value reaches a second preset time, determining whether the valley detection signal is at a high level; If not, determining whether the valley count value is the first preset value; If the valley count value is the first preset value, when the timing value reaches the first virtual valley period, the timing value is used as the valley detection moment, and the count value is cleared; If the valley count value is not the first preset value, when the timing value reaches the second virtual valley period, the timing value is used as the valley detection moment, and the count value is cleared.

4. The method according to claim 3, characterized in that The second preset time is one quarter of the resonant period of the asymmetric half-bridge converter.

5. The method according to claim 1, wherein Generating a first virtual trough period according to the first time includes: performing filtering on the first time to obtain a first filtered value; The first filtered value is added to a first preset margin to obtain the first virtual valley period.

6. The method according to claim 5, characterized in that The obtaining of the first time includes: When the valley count value is equal to 0 and the valley detection signal is detected to change from a high level to a low level, the current time is recorded as the first moment; When the valley count value is equal to the first preset value and the valley detection signal is detected to change from a high level to a low level, the current time is recorded as a second moment; The first time is obtained according to the first moment and the second moment.

7. The method according to claim 1, characterized in that Generating a second virtual trough period according to the second time includes: performing filtering on the second time to obtain a second filtered value; The second filtered value is added to a second preset margin to obtain the second virtual valley period.

8. The method according to claim 7, characterized in that The obtaining of the second time includes: When the valley count value is equal to the first preset value and the valley detection signal is detected to change from a high level to a low level, the current time is recorded as a second moment; When the valley count value is equal to the second preset value and the valley detection signal is detected to change from a high level to a low level, the current time is recorded as a third moment; The second time is obtained according to the second moment and the third moment.

9. An electronic device, characterized in that: include: at least one processor; at least one network interface, the network interface being communicatively connected to a corresponding processor; as well as, a memory communicatively connected to the at least one processor; wherein, The network interface is used to establish a communication connection between the processor and other external devices; The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the virtual valley detection method according to any one of claims 1 to 8.

10. A non-volatile computer storage medium, characterized in that The computer storage medium stores computer-executable instructions, which are executed by one or more processors, enabling the one or more processors to execute a virtual trough detection method according to any one of claims 1 to 8.

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