Power conversion system and method of controlling the same

Abstract

The present application relates to a power conversion system and a control method thereof. The power conversion system includes a first conversion module, a second conversion module and a load. The first conversion module receives an input voltage and converts the input voltage into a DC bus voltage. The second conversion module receives the DC bus voltage and converts the DC bus voltage into a DC output voltage for the load. The control method includes the following steps. First, the first conversion module is controlled to enter a voltage jitter mode according to a detection result of the load. Then, in the voltage jitter mode, the voltage ripple of the DC bus voltage is increased.

Description

Technical Field

[0001] This case relates to the field of power supply, and in particular to a power conversion system and its control method. Background Technology

[0002] The power conversion system comprises two stages of conversion modules: an AC / DC conversion module and a DC / DC conversion module. The AC / DC conversion module is located between the input of the power conversion system and the DC / DC conversion module, while the DC / DC conversion module is located between the AC / DC conversion module and the output of the power conversion system. However, the power conversion system may encounter special operating conditions. The first special operating condition is that the power conversion system must meet low power consumption requirements when operating under no-load conditions. The second special operating condition is that when multiple power conversion systems are connected in parallel, the main power conversion system is under load, and the slave power conversion systems enter sleep mode, and the slave power conversion systems must meet low power consumption requirements. When encountering these special operating conditions, traditional power conversion systems can only handle them by reducing the switching frequency of the downstream DC / DC conversion module or controlling the downstream DC / DC conversion module to enter burst mode. However, this control method still results in relatively high power consumption for traditional power conversion systems.

[0003] Therefore, it is necessary to develop a power conversion system and its control method to solve the problems faced by the prior art. Summary of the Invention

[0004] The purpose of this invention is to provide a power conversion system that utilizes a control module to control the voltage ripple of the DC bus voltage when the first conversion module enters a voltage jitter mode based on detection results. This power conversion system uses the increased voltage ripple of the DC bus voltage in the first conversion module to handle special operating conditions, reducing the number of switching operations of the first conversion module and thus lowering switching losses. Furthermore, since the DC bus voltage increases while the voltage gain of the second conversion module is within a certain range, the second conversion module will stop working when the DC bus voltage exceeds a certain value. This is equivalent to the second conversion module naturally entering an intermittent working mode, operating normally for part of the time and stopping for part of the time, further reducing system power consumption.

[0005] To achieve the above objectives, this invention provides a control method applied to a power conversion system. The power conversion system includes a first conversion module, a second conversion module, and a load. The first conversion module receives an input voltage and converts it into a DC bus voltage. The second conversion module receives the DC bus voltage and converts it into a DC output voltage to supply the load. The control method includes the following steps: First, based on the load's detection result, the first conversion module is controlled to enter a voltage jitter mode. Then, in the voltage jitter mode, the voltage ripple of the DC bus voltage is increased.

[0006] According to one embodiment of the present invention, the control method further includes controlling the rise of the DC bus voltage to increase within a first interval, wherein the first interval corresponds to the interval between the time of generation of the first pulse and the time of end of the tail pulse in each cycle, and the DC bus voltage at the time of end of the tail pulse is greater than the peak value of the DC bus voltage under normal operating mode of the first conversion module.

[0007] According to one embodiment of the present invention, the control method further includes, in voltage jitter mode, adjusting the first pulse generation time and the last pulse end time of the drive signal of the main power transistor in the first conversion module in each cycle corresponding to the voltage ripple of the DC bus voltage, thereby adjusting the rise amplitude of the DC bus voltage in the first interval.

[0008] According to one embodiment of the present invention, the control method further includes: acquiring a first feedback signal characterizing a DC bus voltage; calculating the difference between the first feedback signal and a reference voltage value, compensating for the difference, and generating a first reference current value; when the first reference current value rises to a level greater than a first current threshold, determining that this is the moment when the first pulse is generated, and generating and adjusting a drive signal based on the first reference current value and a second feedback signal characterizing the inductor current in the first conversion module; when the first reference current value falls to a level less than a second current threshold, determining that this is the moment when the tail pulse ends, and no drive signal is generated thereafter in this cycle; wherein the first current threshold is greater than the second current threshold, and the second current threshold is greater than zero.

[0009] According to one embodiment of the present invention, the control method further includes setting a first current threshold based on the desired power consumption of the power conversion system, wherein the first current threshold is positively correlated with the amplitude of the voltage ripple of the DC bus voltage.

[0010] According to one embodiment of the present invention, the control method further includes adjusting the reference voltage value of the DC bus voltage to a first voltage threshold in a first interval and a second voltage threshold in a second interval, wherein the second interval corresponds to the interval after the end of the tail pulse when no drive signal is generated; wherein the first voltage threshold is greater than the rated value of the DC bus voltage of the first conversion module in normal operating mode, so as to increase the DC bus voltage, and the second voltage threshold is less than or equal to the rated value.

[0011] According to one embodiment of the present invention, the control method further includes determining the end time of the tail pulse based on the expected power consumption of the power conversion system.

[0012] According to one embodiment of the present invention, the control method further includes detecting the current or power of the load to obtain a detection result; and controlling the first conversion module to enter a voltage jitter mode when the detection result is less than a preset threshold.

[0013] According to one embodiment of the present invention, the control method further includes that the amplitude of the voltage ripple is determined by the desired power consumption of the power conversion system.

[0014] According to one embodiment of the present invention, the control method further includes, in voltage jitter mode, controlling the second conversion module to stop working in a portion of the period corresponding to the voltage ripple of the DC bus voltage.

[0015] To achieve the above objectives, this invention provides a power conversion system comprising a first conversion module, a second conversion module, and a control module. The first conversion module receives an input voltage and converts it into a DC bus voltage. The second conversion module is connected to the first conversion module to receive the DC bus voltage and convert it into a DC output voltage to supply the load. The control module controls the first conversion module to enter a voltage jitter mode based on the load detection result, and in the voltage jitter mode, controls the voltage ripple of the DC bus voltage to increase.

[0016] According to one embodiment of the present invention, the control module controls the rise of the DC bus voltage to increase within a first interval, the first interval corresponding to the interval between the generation time of the first pulse and the end time of the tail pulse in each cycle, and the DC bus voltage at the end time of the tail pulse is greater than the peak value of the DC bus voltage of the first conversion module in normal operating mode.

[0017] According to one embodiment of the present invention, the control module further includes a drive generation unit. In voltage jitter mode, the drive generation unit adjusts the first pulse generation time and the last pulse end time of the drive signal of the main power transistor in the first conversion module in each cycle corresponding to the voltage ripple of the DC bus voltage, thereby adjusting the rise amplitude of the DC bus voltage in the first interval.

[0018] According to one embodiment of the present invention, the drive generation unit includes a reference current generation unit and a driver. The reference current generation unit acquires a first feedback signal characterizing the DC bus voltage and calculates the difference between the first feedback signal and the reference voltage value. After compensating for the difference, a first reference current value is generated. When the first reference current value rises to a value greater than a first current threshold, the driver determines that this is the moment of first pulse generation and generates and adjusts a drive signal based on the first reference current value and a second feedback signal characterizing the inductor current in the first conversion module. When the first reference current value falls to a value less than a second current threshold, the driver determines that this is the moment of tail pulse end and no drive signal is generated thereafter in this cycle. The first current threshold is greater than the second current threshold, and the second current threshold is greater than zero.

[0019] According to one embodiment of the present invention, the control module further includes a numerical setter for setting a first current threshold according to the expected power consumption of the power conversion system, wherein the first current threshold is positively correlated with the amplitude of the voltage ripple of the DC bus voltage.

[0020] According to one embodiment of the present invention, the control module includes a reference voltage generation unit, which adjusts the reference voltage value corresponding to the DC bus voltage to a first voltage threshold in a first interval and a second voltage threshold in a second interval, wherein the second interval corresponds to the interval after the end of the tail pulse where no drive signal is generated, wherein the first voltage threshold is greater than the rated value of the DC bus voltage of the first conversion module in normal operating mode, so as to increase the DC bus voltage, and the second voltage threshold is less than or equal to the rated value.

[0021] According to one embodiment of the present invention, the end time of the tail pulse is determined based on the expected power consumption of the power conversion system.

[0022] According to one embodiment of the present invention, the control module further includes a detection unit and a mode switching unit. The detection unit is used to detect the current or power of the load to obtain the detection result. When the detection result is less than a preset threshold, the mode switching unit controls the first conversion module to enter the voltage jitter mode.

[0023] According to one embodiment of the present invention, the amplitude of the voltage ripple is determined by the desired power consumption of the power conversion system.

[0024] According to one embodiment of the present invention, in voltage jitter mode, the control module controls the second conversion module to stop working in a certain interval within the period corresponding to the voltage ripple of the DC bus voltage. Attached Figure Description

[0025] Figure 1 This is the circuit topology diagram of the power conversion system in this case;

[0026] Figure 2 for Figure 1 The detailed circuit topology of the first conversion module of the power conversion system shown;

[0027] Figure 3 for Figure 1 A schematic diagram of the control module portion of the power conversion system shown.

[0028] Figure 4 for Figure 1 A detailed schematic diagram of the drive generation unit of the control module of the power conversion system shown.

[0029] Figure 5 for Figure 1 The diagram shows the operating waveforms of the first conversion module in the power conversion system.

[0030] Figure 6 for Figure 1 A detailed schematic diagram of the drive generation unit of the control module of another embodiment of the power conversion system shown.

[0031] Figure 7 for Figure 1 The diagram shows the operating waveforms of the first conversion module in another embodiment of the power conversion system; and

[0032] Figure 8 for Figure 1 The flowchart shown is a control method flowchart for the power conversion system.

[0033] The reference numerals in the attached figures are explained as follows:

[0034] 1: Power Conversion System

[0035] Vin: Input voltage

[0036] Vbulk: DC bus voltage

[0037] Vout: DC output voltage

[0038] 2: First conversion module

[0039] 21: Inductor

[0040] 22: Diode

[0041] 23: Main power transistor

[0042] 3: Second conversion module

[0043] A: Connection point

[0044] 4: Load

[0045] 5: Control Module

[0046] 50: Numerical Setter

[0047] 51: Detection Unit

[0048] 52: Mode switching unit

[0049] 53, 53a: Drive generation unit

[0050] 54: Reference Current Generation Unit

[0051] 541: The First Subtractor

[0052] 542: First compensator

[0053] 55: Control Unit

[0054] 551: Multiplier

[0055] 552: Second Subtractor

[0056] 553: Second compensator

[0057] 56, 58: Drivers

[0058] 57: Reference Voltage Generation Unit

[0059] Iref1: First current threshold

[0060] Iref2: Second current threshold

[0061] Vref: Reference voltage value

[0062] F1: First feedback signal

[0063] Error 1, Error 2: Difference

[0064] Idc_ref: First reference current value

[0065] Iac_ref: Second reference current value

[0066] F2: Second feedback signal

[0067] D: Duty cycle signal

[0068] Vg: Drive signal

[0069] t0, t1, t2, t3: Time points

[0070] Vref1: First voltage threshold

[0071] Vref2: Second voltage threshold

[0072] S1, S2: Steps Detailed Implementation

[0073] Some typical embodiments that embody the features and advantages of this invention will be described in detail in the following description. It should be understood that this invention can have various variations in different forms, all of which do not depart from the scope of this invention, and the descriptions and drawings therein are for illustrative purposes only and not for limiting this invention.

[0074] Please see Figures 1 to 3 ,in Figure 1 This is the circuit topology diagram of the power conversion system in this case. Figure 2 for Figure 1 The diagram shows the detailed circuit topology of the first conversion module of the power conversion system. Figure 3 for Figure 1 The diagram shown is a partial schematic of the control module in the power conversion system. Specifically, it is a structural block diagram of the control module of the power conversion system, specifically the part used to control the first conversion module and detect load information. The structures of other parts are not the focus of this case and are not shown. As shown in the figure, the power conversion system 1 of this case receives an input voltage Vin and includes a first conversion module 2, a second conversion module 3, a load 4, and a control module 5. The input voltage Vin can be a DC input voltage or an AC input voltage. The first conversion module 2 can be, but is not limited to, an AC / DC conversion module, such as a boost power factor correction circuit or a totem-pole power factor correction circuit, and is used to receive the input voltage Vin and convert it into a DC bus voltage Vbulk. The DC bus voltage has voltage ripple, that is, the DC bus voltage has a rated value and a peak value caused by superimposed ripple. In this embodiment, as shown... Figure 2 As shown, the first conversion module 2 is a boost power factor correction circuit, and includes an inductor 21, a diode 22, and a main power transistor 23. The first end of the inductor 21 is connected to the positive input terminal that provides the input voltage Vin. The diode 22 and the main power transistor 23 are connected in series, and the two ends of the series-connected diode 22 and the main power transistor 23 provide the DC bus voltage Vbulk. The connection between the diode 22 and the main power transistor 23 forms connection point A, which is connected to the second end of the inductor 21. Figure 1 As shown, the second conversion module 3 can be, but is not limited to, a DC / DC conversion module, such as an LLC converter, connected to the first conversion module 2 to receive the DC bus voltage Vbulk and convert it into a DC output voltage Vout. The load 4 is connected to the second conversion module 3 to receive the DC output voltage Vout.

[0075] The control module 5 is connected to the load 4 and the first conversion module 2. It detects data from the load 4 to obtain detection results and, based on these results, determines whether to control the first conversion module 2 to enter voltage jitter mode. When the first conversion module 2 enters voltage jitter mode, it controls the voltage ripple of the DC bus voltage Vbulk to increase. In this embodiment, as... Figure 3As shown, the control module 5 further includes a detection unit 51, a mode switching unit 52, and a drive generation unit 53. The detection unit 51 detects the current or power of the load 4 to obtain a detection result. The mode switching unit 52 receives the detection result provided by the detection unit 51 and, when confirming that the detection result is less than a preset threshold within the mode switching unit 52, controls the first conversion module 2 to enter a voltage jitter mode. Based on the confirmation result from the mode switching unit 52, i.e., when confirming that the first conversion module 2 has entered the voltage jitter mode, the drive generation unit 53 adjusts the voltage ripple of the DC bus voltage Vbulk to increase. Specifically, the voltage ripple of the DC bus voltage Vbulk can be increased by controlling the duty cycle of the duty cycle signal D corresponding to the main power transistor 23 in the first conversion module 2; or by adjusting the generation time of the first pulse and the end time of the last pulse of the drive signal in each cycle, the rise amplitude of the DC bus voltage within the drive signal generation interval can be increased, thereby increasing the voltage ripple of the DC bus voltage Vbulk; or, by adjusting the reference voltage value corresponding to the drive signal generation interval to be greater than the normal rated voltage value, the loop can automatically adjust the voltage ripple of the DC bus voltage Vbulk to increase. In this embodiment, the specific amplitude of the voltage ripple is determined by the desired power consumption of the power conversion system 1. Specifically, the power conversion system 1 also needs to detect its power consumption and control the voltage ripple of the DC bus voltage Vbulk to increase until the power consumption of the power conversion system 1 reaches the desired power consumption. Of course, the specific increase in voltage ripple can also be determined by other specific conditions, such as voltage withstand voltage limits, etc., which are not limited here.

[0076] As can be seen from the above, the power conversion system 1 in this case utilizes the control module 5 to control the voltage ripple of the DC bus voltage Vbulk by controlling the first conversion module 2 to enter the voltage jitter mode based on the detection results. Compared to traditional power conversion systems that only adjust the second conversion module 3 without adjusting the first conversion module 2, resulting in a still relatively high overall power consumption of the power conversion system 1, the power conversion system 1 in this case uses the increased voltage ripple of the DC bus voltage Vbulk of the first conversion module 2 to handle special operating conditions, thereby reducing the number of switching operations of the first conversion module 2 and thus lowering switching losses. Furthermore, since the DC bus voltage Vbulk increases while the voltage gain of the second conversion module 3 is within a certain range, when the DC bus voltage Vbulk exceeds a certain value, the second conversion module 3 will stop working to maintain a stable DC output voltage Vout. This is equivalent to the second conversion module 3 naturally entering an intermittent working mode, that is, working normally for part of the time and stopping for part of the time, thus further reducing system power consumption.

[0077] In this embodiment, as Figure 3As shown, the control module 5 further includes a numerical setter 50, which is used to set a first current threshold Iref1 and a second current threshold Iref2 according to the expected power consumption of the power conversion system 1. The first current threshold Iref1 is positively correlated with the amplitude of the voltage ripple of the DC bus voltage Vbulk. The first current threshold Iref1 is greater than the second current threshold Iref2, and the second current threshold Iref2 is greater than or equal to zero.

[0078] Please see Figure 4 and cooperate Figures 1 to 3 ,in Figure 4 for Figure 1 This is a schematic diagram of the drive generation unit of the control module in the power conversion system. Figure 3 As shown, the drive generation unit 53 includes a reference current generation unit 54, a control unit 55, and a driver 56. The reference current generation unit 54 includes a first subtractor 541 and a first compensator 542. The first subtractor 541 receives a first feedback signal F1 representing the DC bus voltage Vbulk and a preset reference voltage value Vref, and subtracts them to obtain the difference error1 between the first feedback signal F1 representing the DC bus voltage Vbulk and the reference voltage value Vref. The first compensator 542 generates a first reference current value Idc_ref after compensation.

[0079] like Figure 4As shown, the control unit 55 includes a multiplier 551, a second subtractor 552, and a second compensator 553. The multiplier 551 multiplies the first reference current value Idc_ref by the absolute value of the input voltage Vin (since the absolute value is taken, the Vin waveform becomes a dotted wave) to obtain the second reference current Iac_ref, which is also a dotted wave and can be used as a reference value for the inductor current flowing through the inductor 21 in the first conversion module 2. The second subtractor 552 receives the second reference current value Iac_ref and the second feedback signal F2, and subtracts them to obtain the difference error2 between the second feedback signal F2, which represents the inductor current flowing through the inductor 21 in the first conversion module 2. The second compensator 553 compensates for the difference error2 and outputs the duty cycle signal D. The driver 56 receives the duty cycle signal D and adjusts the duty cycle of the drive signal Vg according to the duty cycle signal D, and outputs the drive signal Vg. The duty cycle of the drive signal Vg is positively correlated with the first reference current value Idc_ref. Furthermore, when the first conversion module 2 is a DC / DC converter, the control unit 55 may not include a multiplier 551. Therefore, the first reference current value Idc_ref generated by the first compensator 542 is directly subtracted from the second feedback signal F2, which represents the inductor current flowing through the inductor 21 in the first conversion module 2, by the second subtractor 552 to generate a difference error2. The second compensator 553 compensates for this difference error2 to generate the duty cycle signal D.

[0080] The following further describes how the duty cycle signal D is controlled based on the relationship between the first reference current value Idc_ref and the first current threshold Iref1. Please refer to [link / reference]. Figure 5 and cooperate Figures 1 to 4 ,in Figure 5 for Figure 1 The diagram shows the operating waveforms of the first conversion module 2 in the power conversion system. Figure 5 As shown, in voltage jitter mode, the period corresponding to the voltage ripple of the DC bus voltage Vbulk (i.e., time t1 to time t4) includes a first interval and a second interval, where the first interval is the interval where the drive signal is generated. Figure 5 The time intervals t1 to t3 shown are (or Figure 7The time intervals t1 to t2 are shown. t1 corresponds to the time when the first pulse of the current cycle is generated, and t3 corresponds to the time when the last pulse of the current cycle ends. That is, when the first reference current value Idc_ref rises to a range greater than the first current threshold Iref1, the drive generation unit 53 generates the drive signal Vg of the main power transistor 23 in the first conversion module 2 within the first range. If this scheme is not adopted, the drive signal Vg should start generating at time t0 (the time when the first feedback signal F1 of the DC bus voltage Vbulk decreases to the reference voltage value Vref), and the duty cycle is extremely small. However, with this scheme, since the drive signal Vg only starts generating when the first reference current value Idc_ref exceeds the first current threshold Iref1, and the duty cycle of the drive signal Vg is significantly increased compared to the case without this scheme, the DC bus voltage Vbulk increases, and the rate of increase is faster. At time t2, the first feedback signal F1 of the DC bus voltage Vbulk is greater than the reference voltage value Vref. Afterwards, the first reference current value Idc_ref begins to decrease until time t3, when the first reference current value Idc_ref drops below the second current threshold Iref2. At this point, the drive generation unit 53 stops generating the drive signal, and the DC bus voltage Vbulk gradually decreases. The second interval is... Figure 5 The intervals shown are t3-t4. Furthermore, due to the increased DC bus voltage Vbulk, the length of the second interval is also longer compared to when this scheme is not used. In summary, the magnitude of the first current threshold Iref1 determines the timing and pulse width (i.e., duty cycle) of the drive signal Vg, while the second current threshold Iref2 determines the timing when the drive signal Vg stops generating.

[0081] In this embodiment, when the control module 5 is in voltage jitter mode, the second conversion module 3 stops working in a certain range within the period corresponding to the voltage ripple of the DC bus voltage Vbulk. As a result, the second conversion module 3 automatically enters intermittent mode to maintain the stability of the DC output voltage of the second conversion module 3 and further reduce power consumption.

[0082] Please see Figure 6 and Figure 7 and cooperate Figure 1 ,in Figure 6 for Figure 1 A detailed schematic diagram of the drive generation unit of the control module in another embodiment of the power conversion system shown. Figure 7 for Figure 1 The diagram shows the operating waveforms of another embodiment of the first conversion module 2. Compared to... Figure 3The control module 5 shown in this embodiment includes a drive generation unit 53a comprising a reference voltage generation unit 57 and a driver 58. The reference voltage generation unit 57 generates a reference voltage value corresponding to the DC bus voltage Vbulk, wherein the reference voltage value falls within a first interval, i.e. Figure 7 The times shown, from t1 to t2, represent the first voltage threshold Vref1, where Vref1 is greater than the rated value Vbus of the DC bus voltage Vbulk of the first conversion module 2 under normal operating mode. Time t2 is determined based on the expected power consumption of the power conversion system. The reference voltage value is in the second interval, i.e. Figure 7 At times t2 to t3, the second voltage threshold Vref2 is less than or equal to the rated value Vbus, and no drive signal Vg is generated. Driver 58 provides a drive signal based on the reference voltage value. Since the reference voltage value increases compared to not using this scheme in the first interval, the duty cycle of the control drive signal Vg increases compared to not using this scheme in the first interval, thereby increasing the DC bus voltage Vbulk.

[0083] In summary, this invention provides two methods for controlling the first conversion module 2 to enter voltage jitter mode and increase the ripple of the DC bus voltage. It should be understood that this invention is not limited to these methods, and any other methods that can achieve the same function are within the protection scope of this invention.

[0084] Please see Figure 8 , it is Figure 1 The flowchart of the control method for the power conversion system is shown. First, step S1 is executed, controlling the first conversion module 2 to enter voltage jitter mode based on the detection result of load 4. Next, step S2 is executed, controlling the voltage ripple of the DC bus voltage Vbulk to increase in voltage jitter mode.

[0085] In summary, the power conversion system of this invention utilizes a control module to control the voltage ripple of the DC bus voltage when the first conversion module 2 enters voltage jitter mode based on detection results. This power conversion system uses the increased voltage ripple of the DC bus voltage in the first conversion module 2 to handle special operating conditions, reducing the number of switching operations of the first conversion module 2 and thus lowering switching losses. Furthermore, since the DC bus voltage increases, and the voltage gain of the second conversion module is within a certain range, when the DC bus voltage exceeds a certain value, the second conversion module will stop working. This is equivalent to the second conversion module naturally entering an intermittent working mode, operating normally for part of the time and stopping for part of the time, further reducing system power consumption.

Claims

1. A control method applied to a power conversion system, wherein the power conversion system includes a first conversion module and a second conversion module, the first conversion module receiving an input voltage and converting it into a DC bus voltage, and the second conversion module receiving the DC bus voltage and converting it into a DC output voltage to supply a load, wherein the control method includes: Based on a detection result of the load, the first conversion module is controlled to enter a voltage jitter mode; and In this voltage jitter mode, the voltage ripple controlling the DC bus voltage increases.

2. The control method as described in claim 1, further comprising: The rise rate of the DC bus voltage is increased within a first interval, wherein the first interval corresponds to the interval between the time of generation of the first pulse and the time of end of the last pulse in each cycle, and the DC bus voltage at the time of end of the last pulse is greater than the peak value of the DC bus voltage in the normal operating mode of the first conversion module.

3. The control method as described in claim 2, further comprising: In this voltage jitter mode, the timing of the first pulse generation and the timing of the last pulse end of the drive signal of a main power transistor in the first conversion module in each cycle corresponding to the voltage ripple of the DC bus voltage are adjusted, thereby adjusting the rise amplitude of the DC bus voltage in the first interval.

4. The control method as described in claim 3, further comprising: Obtain a first feedback signal characterizing the DC bus voltage; Calculate the difference between the first feedback signal and a reference voltage value, and generate a first reference current value after compensating for the difference; When the first reference current value rises to a value greater than a first current threshold, it is determined that this is the moment when the first pulse is generated. Based on the first reference current value and a second feedback signal representing the inductor current in an inductor in the first conversion module, the drive signal is generated and the drive signal is adjusted. as well as When the first reference current value drops to less than a second current threshold, it is determined that this is the end time of the tail pulse, and no drive signal will be generated thereafter in this cycle. Wherein, the first current threshold is greater than the second current threshold, and the second current threshold is greater than zero.

5. The control method as described in claim 4, further comprising: The first current threshold is set according to a desired power consumption of the power conversion system, wherein the first current threshold is positively correlated with the amplitude of the voltage ripple of the DC bus voltage.

6. The control method as described in claim 2, further comprising: A reference voltage value for adjusting the DC bus voltage is a first voltage threshold in the first interval and a second voltage threshold in a second interval, wherein the second interval corresponds to the interval in which no drive signal is generated after the end of the tail pulse; in, The first voltage threshold is greater than a rated value of the DC bus voltage of the first conversion module in the normal operating mode, so as to increase the DC bus voltage, and the second voltage threshold is less than or equal to the rated value.

7. The control method of claim 2, wherein the end time of the tail pulse is determined based on a desired power consumption of the power conversion system.

8. The control method as described in claim 1, further comprising: The detection result is obtained by detecting a current or a power of the load; and When the detection result is less than a preset threshold, the first conversion module is controlled to enter the voltage jitter mode.

9. The control method of claim 1, wherein the amplitude of the voltage ripple is determined by a desired power consumption of the power conversion system.

10. The control method as described in claim 1, further comprising: In this voltage jitter mode, the second conversion module is controlled to stop working in a certain range within the period corresponding to the voltage ripple of the DC bus voltage.

11. A power conversion system, comprising: A first conversion module receives an input voltage and converts it into a DC bus voltage; A second conversion module, connected to the first conversion module, receives the DC bus voltage and converts it into a DC output voltage to supply a load; and A control module controls the first conversion module to enter a voltage jitter mode based on a detection result of the load, and in the voltage jitter mode, controls the voltage ripple of the DC bus voltage to increase.

12. The power conversion system of claim 11, wherein the control module controls the DC bus voltage to increase its rise within a first interval, the first interval corresponding to the interval between the time of generation of the first pulse and the time of end of the last pulse in each cycle, and the DC bus voltage at the time of end of the last pulse is greater than the peak value of the DC bus voltage of the first conversion module in normal operating mode.

13. The power conversion system of claim 12, wherein the control module further includes a drive generation unit, which, in the voltage jitter mode, adjusts the first pulse generation time and the last pulse end time of a drive signal of a main power transistor in the first conversion module in each cycle corresponding to the voltage ripple of the DC bus voltage, thereby adjusting the rise amplitude of the DC bus voltage in the first interval.

14. The power conversion system of claim 13, wherein the drive generation unit includes a reference current generation unit and a driver, the reference current generation unit acquires a first feedback signal characterizing the DC bus voltage, calculates the difference between the first feedback signal and a reference voltage value, and generates a first reference current value after compensating for the difference. When the first reference current value rises to a value greater than a first current threshold, the driver determines that this is the moment when the first pulse is generated, and generates and adjusts the drive signal based on the first reference current value and a second feedback signal that characterizes the current of an inductor in the first conversion module. When the first reference current value drops to less than a second current threshold, the driver determines that this is the end time of the tail pulse, and does not generate the drive signal thereafter in this cycle, wherein the first current threshold is greater than the second current threshold, and the second current threshold is greater than zero.

15. The power conversion system of claim 14, wherein the control module further includes a numerical setting unit for setting the first current threshold according to a desired power consumption of the power conversion system, wherein the first current threshold is positively correlated with the amplitude of the voltage ripple of the DC bus voltage.

16. The power conversion system of claim 12, wherein the control module includes a reference voltage generation unit, adjusting a reference voltage value corresponding to the DC bus voltage to a first voltage threshold in the first interval and a second voltage threshold in a second interval, wherein the second interval corresponds to the interval where no drive signal is generated after the end of the tail pulse, wherein the first voltage threshold is greater than a rated value of the DC bus voltage of the first conversion module in the normal operating mode, so as to increase the DC bus voltage, and the second voltage threshold is less than or equal to the rated value.

17. The power conversion system of claim 12, wherein the end time of the tail pulse is determined based on a desired power consumption of the power conversion system.

18. The power conversion system of claim 11, wherein the control module further includes a detection unit and a mode switching unit, the detection unit being used to detect a current or a power of the load to obtain the detection result, and the mode switching unit controlling the first conversion module to enter the voltage jitter mode when the detection result is less than a preset threshold.

19. The power conversion system of claim 11, wherein the amplitude of the voltage ripple is determined by a desired power consumption of the power conversion system.

20. The power conversion system of claim 11, wherein the control module controls the second conversion module to stop operating in a portion of the period corresponding to the voltage ripple of the DC bus voltage during the voltage jitter mode.

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