Control method, control module and device of power converter and power converter

Abstract

The invention provides a control method, a control module and a device for a power converter and the power converter, and the method comprises the steps: collecting a first voltage and a second voltage collected by a first sampling module and a second sampling module corresponding to a branch based on a preset sampling frequency for any branch of a multi-path parallel three-level DCDC power converter; for any sampling moment, based on the first voltage and the second voltage, determining whether a midpoint circulation phenomenon occurs in the branch at the sampling moment; if yes, determining duty ratio compensation values corresponding to the upper and lower half switch tubes of the branch based on the first voltage and the second voltage for each sampling moment after the midpoint circulation phenomenon occurs, generating a control signal, and sending the control signal to a pulse width controller corresponding to the upper and lower half switch tubes of the branch, the pulse width controller adjusts the duty ratio of the upper half switch tube and the lower half switch tube of the branch according to the duty ratio compensation value until the midpoint circulation phenomenon does not occur in the branch. In this way, the midpoint circulation of the power converter can be suppressed by adjusting the duty ratio of the branch switch tube.

Description

Technical Field

[0001] The present application relates to the technical field of switching power supplies, and in particular to a control method, a control module, a device and a power converter for a power converter. Background Art

[0002] In the traditional DCDC switching power supply design process, due to the increasing design power requirements, the use of a single topology is becoming increasingly difficult in device selection and circuit design. Therefore, multi-channel parallel three-level DCDC power converters with low cost and relatively simple control have become the first choice for switching power supply design.

[0003] During the operation of the existing multi-channel parallel three-level DCDC power converter, due to the different time when the load devices of each branch are connected to the circuit, a phase difference will occur between the branches, and then a midpoint circulation phenomenon will occur, resulting in increased topological losses and reduced circuit efficiency. Summary of the invention

[0004] In view of this, the embodiments of the present application at least provide a control method, a control module, a device and a power converter of a power converter, which can suppress the midpoint circulating current of the power converter by adjusting the duty cycle of the branch switch tube.

[0005] This application mainly includes the following aspects:

[0006] In a first aspect, an embodiment of the present application provides a control method for a power converter, which is applied to a control module of a control device of a power converter, wherein the control device further includes at least two groups of first sampling modules and second sampling modules; each group of first sampling modules and second sampling modules corresponds to a branch of a multi-channel parallel three-level DCDC power converter; an input end of any first sampling module is electrically connected to both ends of an upper half capacitor of a corresponding branch; an input end of any second sampling module is electrically connected to both ends of a lower half capacitor of a corresponding branch; an output end of each first sampling module, an output end of each second sampling module, and a pulse width controller of a switch tube of each branch of the multi-channel parallel three-level DCDC power converter are electrically connected to the control module respectively; the control method includes:

[0007] For any branch of the multi-parallel three-level DCDC power converter, based on a preset sampling frequency, a first voltage collected by a first sampling module and a second voltage collected by a second sampling module corresponding to the branch are collected;

[0008] For any sampling moment, determining whether a midpoint circulation phenomenon occurs in the branch at the sampling moment based on the first voltage and the second voltage;

[0009] If so, for each sampling moment after the midpoint circulation phenomenon occurs, the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch is determined based on the first voltage and the second voltage, and a control signal is generated according to the duty cycle compensation value, and sent to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch.

[0010] In a second aspect, an embodiment of the present application further provides a control module, which is applied to a control device of a power converter, wherein the control device further includes at least two groups of first sampling modules and second sampling modules; each group of first sampling modules and second sampling modules corresponds to a branch of a multi-way parallel three-level DCDC power converter; the input end of any first sampling module is electrically connected to the ends of the upper half capacitor of the corresponding branch; the input end of any second sampling module is electrically connected to the ends of the lower half capacitor of the corresponding branch; the output end of each first sampling module, the output end of each second sampling module, and the pulse width controller of the switch tube of each branch of the multi-way parallel three-level DCDC power converter are electrically connected to the control module respectively; the control module includes:

[0011] A sampling unit, configured to collect, for any branch of the multi-channel parallel three-level DCDC power converter, a first voltage collected by a first sampling module and a second voltage collected by a second sampling module corresponding to the branch based on a preset sampling frequency;

[0012] A determination unit, configured to determine, at any sampling moment, whether a midpoint circulation phenomenon occurs in the branch at the sampling moment based on the first voltage and the second voltage;

[0013] The execution unit is used to determine the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first voltage and the second voltage at each sampling moment after the midpoint circulation phenomenon occurs, and generate a control signal according to the duty cycle compensation value, and send it to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch.

[0014] In a third aspect, an embodiment of the present application further provides a control device for a power converter, the control device comprising:

[0015] A midpoint circulating current detection circuit and a control module in the above-mentioned second aspect.

[0016] In a fourth aspect, an embodiment of the present application further provides a power converter, comprising the control device of the power converter in the third aspect above.

[0017] The control method, control module, device and power converter of the power converter provided by the embodiment of the present application, wherein the control method is applied to the control module of the control device of the power converter, and the control device also includes at least two groups of first sampling modules and second sampling modules; each group of first sampling modules and second sampling modules corresponds to a branch of the multi-channel parallel three-level DCDC power converter; the input end of any first sampling module is electrically connected to the two ends of the upper half capacitor of the corresponding branch; the input end of any second sampling module is electrically connected to the two ends of the lower half capacitor of the corresponding branch; the output end of each first sampling module, the output end of each second sampling module and the pulse width controller of the switch tube of each branch of the multi-channel parallel three-level DCDC power converter are respectively electrically connected to the control module; the control method includes: for the multi-channel parallel For any branch of the three-level DCDC power converter, based on the preset sampling frequency, the first voltage collected by the first sampling module and the second voltage collected by the second sampling module corresponding to the branch are collected; for any sampling moment, based on the first voltage and the second voltage, whether the branch has a midpoint circulation phenomenon at the sampling moment is determined; if so, for each sampling moment after the midpoint circulation phenomenon occurs, based on the first voltage and the second voltage, the duty cycle compensation value corresponding to the upper switch tube and the lower switch tube of the branch is determined, and a control signal is generated according to the duty cycle compensation value and sent to the pulse width controller corresponding to the upper switch tube and the lower switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper switch tube and the lower switch tube of the branch according to the corresponding duty cycle compensation value until the branch does not have a midpoint circulation phenomenon. In this way, by adjusting the duty cycle of the branch switch tube, the midpoint circulation of the power converter can be suppressed.

[0018] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 One of the structural schematic diagrams of a control device of a power converter provided in an embodiment of the present application is shown;

[0021] Figure 2A second structural schematic diagram of a control device for a power converter provided in an embodiment of the present application is shown;

[0022] Figure 3 A flow chart showing a control method of a power converter provided in an embodiment of the present application is shown;

[0023] Figure 4 A flow chart showing another method for controlling a power converter provided in an embodiment of the present application is shown;

[0024] Figure 5 One of the functional module diagrams of a control module provided in an embodiment of the present application is shown;

[0025] Figure 6 A second functional module diagram of a control module provided in an embodiment of the present application is shown;

[0026] Figure 7 A schematic structural diagram of an electronic device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application usually described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0028] The following will be combined Figure 1 as well as Figure 2 The implementation of the embodiment of the present application is described in detail; a control method of a power converter provided in the embodiment of the present application is applied to a control module of a control device of a power converter.

[0029] See also Figure 1 , Figure 1 This is one of the structural schematic diagrams of a control device of a power converter provided in an embodiment of the present application. The control method of the power converter provided in an embodiment of the present application can be applied to Figure 1The control module in the control device of the power converter shown in the figure, the control device of the power converter also includes at least two groups of first sampling modules and second sampling modules, each group of first sampling modules and second sampling modules corresponds to a branch of the multi-way parallel three-level DCDC power converter. Figure 1 As shown, taking a two-way parallel three-level DCDC power converter as an example, the power converter has two branches, including an input power Bat common to the two branches, a first input capacitor C1, a first upper inductor L1, a first lower inductor L2, a first upper diode D1, a first lower diode D2, a first upper switch tube S1, a first lower switch tube S2, a first upper capacitor C2, a first lower capacitor C3, a first upper clamping resistor R1 and a first lower clamping resistor R2 of the first branch, and a second input capacitor C4, a second upper inductor L3, a second lower inductor L4, a second upper diode D3, a second lower diode D4, a second upper switch tube S3, a second lower switch tube S4, a second upper capacitor C5, a second lower capacitor C6, a second upper clamping resistor R3 and a second lower clamping resistor R4 of the second branch. Taking the first branch as an example, the resistance of the first upper clamp resistor R1 and the first lower clamp resistor R2 is generally around several hundred ohms. The working mode of the first branch is similar to that of an ordinary boost circuit. The first upper switch tube S1 and the first lower switch tube S2 are high-frequency switches. They are turned on or off at the same time, causing the first upper inductor L3 and the first lower inductor L4 to charge and discharge, thereby charging the first upper capacitor C2 and the first lower capacitor C3, achieving a boost effect, and obtaining three levels of OUT+, MID and OUT-. Figure 1 As shown, taking a two-way parallel three-level DCDC power converter as an example, the control device 100 of the power converter includes: a first sampling module 110 of the first branch, a second sampling module 120 of the first branch, a first sampling module 111 of the second branch, a second sampling module 121 of the second branch and a control module 130; the input end of the first sampling module 110 of the first branch is electrically connected to the two ends of the first upper half capacitor C2, the input end of the second sampling module 120 of the first branch is electrically connected to the two ends of the first lower half capacitor C3; the input end of the first sampling module 111 of the second branch is electrically connected to the two ends of the second upper half capacitor C3. The two ends of the half capacitor C5 are electrically connected, and the input end of the second sampling module 121 of the second branch is electrically connected to the two ends of the second lower half capacitor C6; the output ends of the first sampling module 110 of the first branch, the second sampling module 120 of the first branch, the first sampling module 111 of the second branch, and the second sampling module 121 of the second branch, as well as the pulse width controller 210 of the first upper half switch tube S1, the pulse width controller 220 of the first lower half switch tube S2, the pulse width controller 211 of the second upper half switch tube S3, and the pulse width controller 221 of the second lower half switch tube S4 are electrically connected to the control module 130 respectively.

[0030] The first sampling module 110 of the first branch is used to collect the voltage across the first upper capacitor C2.

[0031] The second sampling module 120 of the first branch is used to collect the voltage across the first lower half capacitor C3.

[0032] The first sampling module 111 of the second branch is used to collect the voltage across the second upper capacitor C5.

[0033] The second sampling module 121 of the second branch is used to collect the voltage across the first lower half capacitor C6.

[0034] In one possible implementation, see Figure 2 , Figure 2 The second structural diagram of a control device of a power converter provided in an embodiment of the present application. The control method of the power converter provided in an embodiment of the present application can be applied to Figure 2 The control module in the control device of the power converter shown in the figure, the control device of the power converter further comprises at least two third sampling modules, each third sampling module corresponds to a branch of the multi-way parallel three-level DCDC power converter. Figure 2 As shown, taking two parallel three-level DCDC power converters as an example, the control device 100 of the power converter also includes: a third sampling module 140 of the first branch and a third sampling module 141 of the second branch; the input end of the third sampling module 140 of the first branch is electrically connected to the three-level neutral line of the first branch, and the input end of the third sampling module 141 of the second branch is electrically connected to the three-level neutral line of the second branch; the output ends of the third sampling module 140 of the first branch and the third sampling module 141 of the second branch are electrically connected to the control module 130 respectively.

[0035] The third sampling module 140 of the first branch is used to collect the three-level neutral line current of the first branch.

[0036] The third sampling module 141 of the second branch is used to collect the three-level neutral line current of the second branch.

[0037] A control method for a power converter provided in an embodiment of the present application is described in detail below. The control method for a power converter can be applied to a control module of the control device of the power converter.

[0038] See also Figure 3 , Figure 3 This is a flow chart of a control method of a power converter provided by an embodiment of the present application. Figure 3 As shown, the control method of the power converter provided in the embodiment of the present application includes the following steps:

[0039] S301 , for any branch of the multi-parallel three-level DCDC power converter, based on a preset sampling frequency, collecting a first voltage collected by a first sampling module and a second voltage collected by a second sampling module corresponding to the branch.

[0040] Here, if Figure 1 As shown, during the operation of the multi-way parallel three-level DCDC power converter, if the switch tubes S1 and S2 of the first branch and the switch tubes S3 and S4 of the second branch are turned on or off at the same time, and the two branches charge the inductor at the same time, then a loop of Bat, L1, S1, S2, L2 will be formed in the first branch, and a loop of Bat, L3, S3, S4, L4 will be formed in the second branch, and there will be no midpoint circulation phenomenon. If there is a phase difference between S1, S2 and S3, S4, when S1 and S2 are turned on, S3 and S4 may be disconnected. At this time, the inductor of the first branch is charged and the inductor of the second branch is not charged. The inductor current of the first branch is greater than the inductor current of the second branch, and a loop of Bat, L1, D1, C5, S4, L4 will be formed. The first branch will charge the second upper half capacitor C5 of the second branch, so that the midpoint circulation phenomenon exists in the second branch. Similarly, when S3 and S4 are turned on, S1 and S2 may be disconnected. At this time, the inductor of the second branch is charged while the inductor of the first branch is not charged. The inductor current of the second branch is greater than the inductor current of the first branch, forming a loop of Bat, L3, D3, C2, S2, and L2. The second branch will charge the first upper capacitor C2 of the first branch, causing the first branch to have a midpoint circulation phenomenon. In both cases, the current passing through the first lower half switch tube S2 and the second lower half switch tube S4 is the superposition of the charging current of the inductor from the input power supply Bat and the midpoint circulation, which will increase the loss of the switch tube. From the above analysis, it can be seen that when a midpoint circulation occurs in a branch, the upper capacitor or the lower capacitor of the branch will be charged. Therefore, it is possible to determine whether the corresponding branch has a midpoint circulation phenomenon by detecting the voltage across the upper capacitor and the lower capacitor of each branch. Specifically, for any branch of the multi-way parallel three-level DCDC power converter, based on the preset sampling frequency, the first voltage collected by the first sampling module corresponding to the branch and the second voltage collected by the second sampling module are collected. The preset sampling frequency is specifically set according to the actual situation and is not specifically limited here.

[0041] S302: For any sampling moment, determine whether a midpoint circulation phenomenon occurs in the branch at the sampling moment based on the first voltage and the second voltage.

[0042] Here, according to the analysis in S301, for any branch of the multi-parallel three-level DCDC power converter, for any sampling moment, it can be determined whether the midpoint circulation phenomenon occurs in the branch at the sampling moment based on the first voltage and the second voltage of the branch collected at the sampling moment.

[0043] S303, if yes, for each sampling moment after the midpoint circulation phenomenon occurs, the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch is determined based on the first voltage and the second voltage, and a control signal is generated according to the duty cycle compensation value, and sent to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch.

[0044] Here, if it is determined that the branch has a midpoint circulation phenomenon at the sampling moment, the midpoint circulation control of the branch can be converted into a balance control of the voltage across the upper capacitor and the voltage across the lower capacitor of the branch, that is, for each sampling moment after the midpoint circulation phenomenon occurs, the duty cycle compensation value corresponding to the upper switch tube and the lower switch tube of the branch is determined based on the first voltage and the second voltage. Then, according to the calculated duty cycle compensation value, a corresponding control signal is generated, and these signals will be sent to the pulse width controller corresponding to the upper switch tube and the lower switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper switch tube and the lower switch tube of the branch according to the corresponding duty cycle compensation value, to perform closed-loop balance control on the voltage across the upper capacitor and the voltage across the lower capacitor of the branch, and this process will continue until the difference between the voltage across the upper capacitor and the voltage across the lower capacitor of the branch is close to zero or within an acceptable range, and the midpoint circulation phenomenon does not occur in the branch. In this way, the midpoint circulation phenomenon in the parallel three-level DCDC power converter can be effectively controlled to improve the stability and efficiency of the power converter control.

[0045] Further, the determining whether a midpoint circulation phenomenon occurs in the branch at the sampling moment based on the first voltage and the second voltage includes:

[0046] Step a1: if the first voltage is greater than or less than the second voltage, it is determined that a midpoint circulation phenomenon occurs in the branch at the sampling moment.

[0047] Here, according to the analysis in S301, if the first voltage is greater than or less than the second voltage, it means that the midpoint circulating current charges the upper half capacitor or the lower half capacitor of the branch, and the midpoint circulating current phenomenon occurs in the branch at the sampling moment.

[0048] Step a2: if the first voltage is equal to the second voltage, it is determined that no midpoint circulation phenomenon occurs in the branch at the sampling moment.

[0049] Here, according to the analysis in S301, if the first voltage is equal to the second voltage, the upper and lower capacitors of the branch are normally turned on and charged, and it is determined that no midpoint circulation phenomenon occurs in the branch at the sampling moment.

[0050] Furthermore, for each sampling moment after the midpoint circulation phenomenon occurs, determining the duty cycle compensation values ​​corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first voltage and the second voltage includes:

[0051] Step b1, determining the duty cycle compensation values ​​corresponding to the upper half switch tube and the lower half switch tube of the branch at the sampling moment according to the voltage difference between the first voltage and the second voltage and a proportional integral control algorithm.

[0052] Here, the voltage difference between the first voltage and the second voltage is first calculated, and this voltage difference reflects the degree of imbalance between the upper capacitor voltage and the lower capacitor voltage of the branch. Then the proportional-integral (PI) control algorithm is used to process this voltage difference. The PI control algorithm includes two main parts. The first is the proportional part, which calculates an adjustment amount according to the voltage difference and the proportional gain (Kp). This adjustment amount is proportional to the voltage difference and is used to quickly respond to voltage imbalance. Then, the integral part is used to integrate the voltage difference and multiply it by the integral gain (Ki) to accumulate historical errors, thereby eliminating steady-state errors. Then, the results of the proportional part and the integral part are added to obtain a total control signal. This total control signal is used to generate the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch to adjust the PWM duty cycle to reduce voltage imbalance and suppress the midpoint circulation phenomenon. According to the calculated duty cycle compensation value, the corresponding control signal is generated, and these signals will be sent to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch. The pulse width controller adjusts the PWM duty ratio of the upper half switch tube and the lower half switch tube according to the received control signal.

[0053] Step b2: if the first voltage is greater than the second voltage, determine that the duty cycle of the upper half switch tube of the branch is reduced by a corresponding duty cycle compensation value, and the duty cycle of the lower half switch tube is increased by a corresponding duty cycle compensation value.

[0054] Specifically, if the first voltage is higher than the second voltage, the duty cycle of the upper half of the switch tube is reduced and the duty cycle of the lower half of the switch tube is increased, and it is determined that the duty cycle of the upper half of the switch tube of the branch is reduced by a corresponding duty cycle compensation value, and the duty cycle of the lower half of the switch tube is increased by a corresponding duty cycle compensation value.

[0055] Step b3: if the first voltage is less than the second voltage, determine that the duty cycle of the upper half switch tube of the branch is increased by a corresponding duty cycle compensation value, and the duty cycle of the lower half switch tube is reduced by a corresponding duty cycle compensation value.

[0056] Specifically, if the first voltage is lower than the second voltage, the duty cycle of the upper half switch is increased and the duty cycle of the lower half switch is reduced. It is determined that the duty cycle of the upper half switch of the branch is increased by a corresponding duty cycle compensation value, and the duty cycle of the lower half switch is reduced by a corresponding duty cycle compensation value.

[0057] This process will continue until the midpoint circulation phenomenon no longer occurs in the branch, that is, the difference between the first voltage and the second voltage is close to zero or within an acceptable range. Through the PI control algorithm, the midpoint circulation phenomenon in the parallel three-level DCDC converter can be effectively controlled to improve the stability and efficiency of the power converter control.

[0058] In one possible implementation, see Figure 4 , Figure 4 This is a flow chart of another power converter control method provided by an embodiment of the present application. Figure 4 As shown, the control method also includes:

[0059] S401 , for any branch of the multi-parallel three-level DCDC power converter, based on a preset sampling frequency, sampling a first current collected by a third sampling module corresponding to the branch.

[0060] Here, according to the analysis in S301, it can also be determined whether the corresponding branch has a midpoint circulation phenomenon by detecting the current of the three-level neutral line of each branch. Specifically, for any branch of the multi-way parallel three-level DCDC power converter, based on the preset sampling frequency, the first current collected by the third sampling module corresponding to the branch is collected.

[0061] S402: For any sampling moment, determine whether a midpoint circulation phenomenon occurs in the branch at the sampling moment based on the first current.

[0062] Here, according to the analysis in S401, for any branch of the multi-parallel three-level DCDC power converter, for any sampling moment, it can be determined whether the branch has a midpoint circulation phenomenon at the sampling moment based on the first current of the branch collected at the sampling moment.

[0063] S403, if yes, for each sampling moment after the midpoint circulation phenomenon occurs, based on the first current, the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch is determined, and a control signal is generated according to the duty cycle compensation value, and sent to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch.

[0064] Here, if it is determined that the branch has a midpoint circulation phenomenon at the sampling moment, the midpoint circulation control of the branch can be converted into a balanced control of the three-level neutral line current of the branch, that is, for each sampling moment after the midpoint circulation phenomenon occurs, based on the first current, the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch is determined. Then, according to the calculated duty cycle compensation value, a corresponding control signal is generated, and these signals will be sent to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value, so as to perform closed-loop balanced control on the three-level neutral line current of the branch, and this process will continue until the three-level neutral line current of the branch is close to zero or within an acceptable range, and the midpoint circulation phenomenon does not occur in the branch. In this way, the midpoint circulation phenomenon in the parallel three-level DCDC power converter can be effectively controlled, and the stability and efficiency of the power converter control can be improved.

[0065] Further, the determining, based on the first current, whether a midpoint circulation phenomenon occurs in the branch at the sampling moment includes:

[0066] Step c1: if the first current is greater than a preset neutral line current threshold, it is determined that a midpoint circulation phenomenon occurs in the branch at the sampling moment.

[0067] Here, according to the analysis in S401, if the first current is greater than the preset neutral current threshold, it indicates that there is a circulation phenomenon on the three-level neutral line of the branch, that is, the midpoint circulation phenomenon occurs in the branch at the sampling moment. Here, the preset neutral current threshold is the minimum current for the midpoint circulation to occur on the three-level neutral line set according to the actual situation.

[0068] Step c2: if the first current is less than or equal to the neutral line current threshold, it is determined that no midpoint circulation phenomenon occurs in the branch at the sampling moment.

[0069] Here, according to the analysis in S401, if the first current is less than or equal to the preset neutral line current threshold, it means that there is no circulating current phenomenon on the three-level neutral line of the branch, that is, there is no midpoint circulating current phenomenon in the branch at the sampling moment.

[0070] Furthermore, for each sampling moment after the midpoint circulation phenomenon occurs, determining the duty cycle compensation values ​​corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first current includes:

[0071] Step d1, determining the duty cycle compensation values ​​corresponding to the upper half switch tube and the lower half switch tube of the branch at the sampling moment according to the first current, the preset neutral line current threshold and the proportional integral control algorithm.

[0072] Here, the current difference between the first current and the preset neutral current threshold is first calculated, and this current difference reflects the imbalance degree of the midpoint circulating current of the three-level neutral line of the branch. Then the proportional integral control algorithm is used to process this current difference. The PI control algorithm includes two main parts. The first is the proportional part, which calculates an adjustment amount according to the current difference and the proportional gain (Kp). This adjustment amount is proportional to the current difference and is used to quickly respond to the current imbalance. Then, the integral part is used to integrate the current difference and multiply it by the integral gain (Ki) to accumulate historical errors, thereby eliminating steady-state errors. Then, the results of the proportional part and the integral part are added to obtain a total control signal. This total control signal is used to generate the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch to adjust the PWM duty cycle to reduce the imbalance of the three-level neutral line of the branch to suppress the midpoint circulating current phenomenon. According to the calculated duty cycle compensation value, the corresponding control signal is generated, and these signals will be sent to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch. The pulse width controller adjusts the PWM duty ratio of the upper half switch tube and the lower half switch tube according to the received control signal.

[0073] Step d2, if the current direction of the first current is to flow into the input end of the multi-parallel three-level DCDC power converter, determine that the duty cycle of the upper half of the switch tube of the branch is reduced by a corresponding duty cycle compensation value, and the duty cycle of the lower half of the switch tube is increased by a corresponding duty cycle compensation value.

[0074] Specifically, if the current direction of the first current is to flow into the input end of a multi-parallel three-level DCDC power converter, the duty cycle of the upper half of the switch tube is reduced and the duty cycle of the lower half of the switch tube is increased, and the duty cycle of the upper half of the switch tube of the branch is determined to be reduced by a corresponding duty cycle compensation value, and the duty cycle of the lower half of the switch tube is increased by a corresponding duty cycle compensation value.

[0075] Step d3, if the current direction of the first current is to flow toward the output end of the multi-parallel three-level DCDC power converter, determine that the duty cycle of the upper half switch tube of the branch increases by a corresponding duty cycle compensation value, and the duty cycle of the lower half switch tube decreases by a corresponding duty cycle compensation value.

[0076] Specifically, if the current direction of the first current is to flow toward the output end of the multi-channel parallel three-level DCDC power converter, the duty cycle of the upper half switch tube is increased and the duty cycle of the lower half switch tube is reduced. It is determined that the duty cycle of the upper half switch tube of the branch increases by a corresponding duty cycle compensation value, and the duty cycle of the lower half switch tube decreases by a corresponding duty cycle compensation value.

[0077] This process will continue until the midpoint circulation phenomenon no longer occurs in the branch, that is, the first current is close to zero or within an acceptable range. Through the PI control algorithm, the midpoint circulation phenomenon in the parallel three-level DCDC converter can be effectively controlled to improve the stability and efficiency of the power converter control.

[0078] Furthermore, a first-order low-pass filter circuit with a cutoff frequency of 500 Hz to 1 kHz can be added between each third sampling module and the three-level neutral line of the corresponding branch to filter out the high-frequency signal brought by the switching frequency of the switching tube, thereby obtaining a more stable current value, improving the accuracy of PI control, and further improving the stability and efficiency of the power converter control.

[0079] The embodiment of the present application provides a control method for a power converter, which is applied to a control module of a control device of the power converter, wherein the control device further comprises at least two groups of first sampling modules and second sampling modules; each group of first sampling modules and second sampling modules corresponds to a branch of a multi-channel parallel three-level DCDC power converter; the input end of any first sampling module is electrically connected to the two ends of the upper half capacitor of the corresponding branch; the input end of any second sampling module is electrically connected to the two ends of the lower half capacitor of the corresponding branch; the output end of each first sampling module, the output end of each second sampling module and the pulse width controller of the switch tube of each branch of the multi-channel parallel three-level DCDC power converter are electrically connected to the control module respectively; the control method comprises: for the multi-channel parallel three-level DCDC power converter For any branch of the source converter, based on the preset sampling frequency, the first voltage collected by the first sampling module and the second voltage collected by the second sampling module corresponding to the branch are collected; for any sampling moment, based on the first voltage and the second voltage, whether the branch has a midpoint circulation phenomenon at the sampling moment is determined; if so, for each sampling moment after the midpoint circulation phenomenon occurs, based on the first voltage and the second voltage, the duty cycle compensation value corresponding to the upper switch tube and the lower switch tube of the branch is determined, and a control signal is generated according to the duty cycle compensation value and sent to the pulse width controller corresponding to the upper switch tube and the lower switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper switch tube and the lower switch tube of the branch according to the corresponding duty cycle compensation value until the branch does not have a midpoint circulation phenomenon. In this way, by adjusting the duty cycle of the branch switch tube, the midpoint circulation of the power converter can be suppressed.

[0080] Based on the same application concept, a control module corresponding to the control method of the power converter provided in the above embodiment is also provided in the embodiment of the present application. Since the principle of solving the problem by the control module in the embodiment of the present application is similar to the control method of the power converter in the above embodiment of the present application, the implementation of the control module can refer to the implementation of the method, and the repeated parts will not be repeated.

[0081] See also Figure 5 , Figure 5 This is one of the functional module diagrams of a control module provided in an embodiment of the present application, such as Figure 5 As shown, the control module 130 includes:

[0082] The sampling unit 131 is used to collect, for any branch of the multi-parallel three-level DCDC power converter, a first voltage collected by a first sampling module and a second voltage collected by a second sampling module corresponding to the branch based on a preset sampling frequency.

[0083] A determination unit 132, configured to determine, for any sampling moment, based on the first voltage and the second voltage, whether a midpoint circulation phenomenon occurs in the branch at the sampling moment;

[0084] The execution unit 133 is used to determine the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first voltage and the second voltage at each sampling moment after the midpoint circulation phenomenon occurs, and generate a control signal according to the duty cycle compensation value, and send it to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch.

[0085] Further, when the determining unit 132 is used to determine whether a midpoint circulation phenomenon occurs in the branch at the sampling moment based on the first voltage and the second voltage, the determining unit 132 is specifically used to:

[0086] If the first voltage is greater than or less than the second voltage, it is determined that a midpoint circulation phenomenon occurs in the branch at the sampling moment;

[0087] If the first voltage is equal to the second voltage, it is determined that no midpoint circulation phenomenon occurs in the branch at the sampling moment.

[0088] Further, for each sampling moment after the midpoint circulation phenomenon occurs, when the execution unit 133 is used to determine the duty cycle compensation values ​​corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first voltage and the second voltage, the execution unit 133 is specifically used to:

[0089] Determine the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch at the sampling moment according to the voltage difference between the first voltage and the second voltage and the proportional integral control algorithm;

[0090] If the first voltage is greater than the second voltage, determining that the duty cycle of the upper half switch tube of the branch is reduced by a corresponding duty cycle compensation value, and the duty cycle of the lower half switch tube is increased by a corresponding duty cycle compensation value;

[0091] If the first voltage is less than the second voltage, it is determined that the duty cycle of the upper switch tube of the branch is increased by a corresponding duty cycle compensation value, and the duty cycle of the lower switch tube is decreased by a corresponding duty cycle compensation value.

[0092] In one possible implementation, see Figure 6 , Figure 6 This is a second functional module diagram of a control module provided in an embodiment of the present application. Figure 6 As shown, the control module 130 also includes:

[0093] The second sampling unit 134 is configured to collect, for any branch of the multi-parallel three-level DCDC power converter, the first current collected by the third sampling module corresponding to the branch based on a preset sampling frequency.

[0094] The second determining unit 135 is configured to determine, at any sampling moment, based on the first current, whether a midpoint circulating current phenomenon occurs in the branch at the sampling moment.

[0095] The second execution unit 136 is used to determine the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first current at each sampling moment after the midpoint circulation phenomenon occurs, and generate a control signal according to the duty cycle compensation value, and send it to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch.

[0096] Further, when the second determining unit 135 is used to determine whether a midpoint circulating current phenomenon occurs in the branch at the sampling moment based on the first current, the second determining unit 135 is specifically used to:

[0097] If the first current is greater than a preset neutral line current threshold, it is determined that a midpoint circulation phenomenon occurs in the branch at the sampling moment;

[0098] If the first current is less than or equal to the neutral line current threshold, it is determined that no midpoint circulation phenomenon occurs in the branch at the sampling moment.

[0099] Further, for each sampling moment after the midpoint circulation phenomenon occurs, when the second execution unit 136 is used to determine the duty cycle compensation values ​​corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first current, the second execution unit 136 is specifically used to:

[0100] Determine the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch at the sampling moment according to the first current, the preset neutral line current threshold and the proportional integral control algorithm;

[0101] If the current direction of the first current is to flow into the input end of the multi-parallel three-level DCDC power converter, determine that the duty cycle of the upper switch tube of the branch is reduced by a corresponding duty cycle compensation value, and the duty cycle of the lower switch tube is increased by a corresponding duty cycle compensation value;

[0102] If the current direction of the first current is to flow toward the output end of the multi-parallel three-level DCDC power converter, determine that the duty cycle of the upper half of the switch tube on the branch increases by a corresponding duty cycle compensation value, and the duty cycle of the lower half of the switch tube decreases by a corresponding duty cycle compensation value.

[0103] The control module provided in the embodiment of the present application is applied to a control device of a power converter, and the control device also includes at least two groups of first sampling modules and second sampling modules; each group of first sampling modules and second sampling modules corresponds to a branch of a multi-channel parallel three-level DCDC power converter; the input end of any first sampling module is electrically connected to the two ends of the upper half capacitor of the corresponding branch; the input end of any second sampling module is electrically connected to the two ends of the lower half capacitor of the corresponding branch; the output end of each first sampling module, the output end of each second sampling module and the pulse width controller of the switch tube of each branch of the multi-channel parallel three-level DCDC power converter are electrically connected to the control module respectively; the control module includes: a sampling unit, which is used for any branch of the multi-channel parallel three-level DCDC power converter, Based on the preset sampling frequency, the first voltage collected by the first sampling module and the second voltage collected by the second sampling module corresponding to the acquisition branch are collected; the determination unit is used to determine whether the midpoint circulation phenomenon occurs in the branch at any sampling moment based on the first voltage and the second voltage; the execution unit is used to determine the duty cycle compensation value corresponding to the upper switch tube and the lower switch tube of the branch based on the first voltage and the second voltage for each sampling moment after the midpoint circulation phenomenon occurs, and generate a control signal according to the duty cycle compensation value, and send it to the pulse width controller corresponding to the upper switch tube and the lower switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper switch tube and the lower switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch. In this way, by adjusting the duty cycle of the branch switch tube, the midpoint circulation of the power converter can be suppressed.

[0104] Based on the same application concept, an embodiment of the present application also provides a power converter, which includes a control device for the power converter as described above, and uses the control method for the power converter as described above to control the power converter, and the repeated parts will not be repeated.

[0105] Based on the same application idea, please refer to Figure 7 , Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Figure 7As shown, the electronic device 700 includes a processor 710 , a memory 720 and a bus 730 .

[0106] The memory 720 stores machine-readable instructions executable by the processor 710. When the electronic device 700 is running, the processor 710 communicates with the memory 720 through the bus 730. When the processor 710 is running, the machine-readable instructions are executed by the steps of the control method of the power converter provided in the above embodiment. The specific implementation method can be found in the method embodiment, which will not be repeated here.

[0107] An embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the control method for the power converter provided in the above embodiment are executed. The specific implementation method can be found in the method embodiment, which will not be repeated here.

[0108] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0109] In the embodiments provided in the present application, it should be understood that the disclosed methods, modules and devices can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0110] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0111] In addition, each functional unit in the embodiments provided in the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0112] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0113] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and are not to be understood as indicating or implying relative importance.

[0114] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-mentioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-mentioned embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application. They should all be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A control method for a power converter, characterized in that: A control module for a control device applied to a power converter, the control device further comprising at least two groups of first sampling modules and second sampling modules; each group of first sampling modules and second sampling modules corresponds to a branch of a multi-channel parallel three-level DCDC power converter; the input end of any first sampling module is electrically connected to the two ends of the upper half capacitor of the corresponding branch; the input end of any second sampling module is electrically connected to the two ends of the lower half capacitor of the corresponding branch; the output end of each first sampling module, the output end of each second sampling module and the pulse width controller of the switch tube of each branch of the multi-channel parallel three-level DCDC power converter are electrically connected to the control module respectively; the control method comprises: For any branch of the multi-parallel three-level DCDC power converter, based on a preset sampling frequency, a first voltage collected by a first sampling module and a second voltage collected by a second sampling module corresponding to the branch are collected; For any sampling moment, based on the first voltage and the second voltage, determining whether a midpoint circulation phenomenon occurs in the branch at the sampling moment; If so, for each sampling moment after the midpoint circulation phenomenon occurs, the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch is determined based on the first voltage and the second voltage, and a control signal is generated according to the duty cycle compensation value, and sent to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch.

2. The control method according to claim 1, characterized in that: The determining, based on the first voltage and the second voltage, whether a midpoint circulation phenomenon occurs in the branch at the sampling moment includes: If the first voltage is greater than or less than the second voltage, it is determined that a midpoint circulation phenomenon occurs in the branch at the sampling moment; If the first voltage is equal to the second voltage, it is determined that no midpoint circulation phenomenon occurs in the branch at the sampling moment.

3. The control method according to claim 1, characterized in that: For each sampling moment after the midpoint circulation phenomenon occurs, determining the duty cycle compensation values ​​corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first voltage and the second voltage includes: Determine the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch at the sampling moment according to the voltage difference between the first voltage and the second voltage and the proportional integral control algorithm; If the first voltage is greater than the second voltage, determining that the duty cycle of the upper half switch tube of the branch is reduced by a corresponding duty cycle compensation value, and the duty cycle of the lower half switch tube is increased by a corresponding duty cycle compensation value; If the first voltage is less than the second voltage, it is determined that the duty cycle of the upper switch tube of the branch is increased by a corresponding duty cycle compensation value, and the duty cycle of the lower switch tube is decreased by a corresponding duty cycle compensation value.

4. The control method according to claim 1, characterized in that: The control device further includes at least two third sampling modules; each third sampling module corresponds to a branch of a multi-way parallel three-level DCDC power converter; the input end of any third sampling module is electrically connected to the three-level neutral line of the corresponding branch; the output end of each third sampling module is electrically connected to the control module respectively; the control method further includes: For any branch of the multi-parallel three-level DCDC power converter, based on a preset sampling frequency, a first current collected by a third sampling module corresponding to the branch is collected; For any sampling moment, based on the first current, determining whether a midpoint circulation phenomenon occurs in the branch at the sampling moment; If so, for each sampling moment after the midpoint circulation phenomenon occurs, based on the first current, the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch is determined, and a control signal is generated according to the duty cycle compensation value, and sent to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch.

5. The control method according to claim 4, characterized in that: The determining, based on the first current, whether a midpoint circulation phenomenon occurs in the branch at the sampling moment includes: If the first current is greater than a preset neutral line current threshold, it is determined that a midpoint circulation phenomenon occurs in the branch at the sampling moment; If the first current is less than or equal to the neutral line current threshold, it is determined that no midpoint circulation phenomenon occurs in the branch at the sampling moment.

6. The control method according to claim 5, characterized in that: For each sampling moment after the midpoint circulation phenomenon occurs, determining the duty cycle compensation values ​​corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first current includes: Determine the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch at the sampling moment according to the first current, the preset neutral line current threshold and the proportional integral control algorithm; If the current direction of the first current is to flow into the input end of the multi-parallel three-level DCDC power converter, determine that the duty cycle of the upper switch tube of the branch is reduced by a corresponding duty cycle compensation value, and the duty cycle of the lower switch tube is increased by a corresponding duty cycle compensation value; If the current direction of the first current is to flow toward the output end of the multi-parallel three-level DCDC power converter, determine that the duty cycle of the upper half of the switch tube on the branch increases by a corresponding duty cycle compensation value, and the duty cycle of the lower half of the switch tube decreases by a corresponding duty cycle compensation value.

7. A control module, characterized in that: A control device applied to a power converter, the control device also includes at least two groups of first sampling modules and second sampling modules; each group of first sampling modules and second sampling modules corresponds to a branch of a multi-channel parallel three-level DCDC power converter; the input end of any first sampling module is electrically connected to the two ends of the upper half capacitor of the corresponding branch; the input end of any second sampling module is electrically connected to the two ends of the lower half capacitor of the corresponding branch; the output end of each first sampling module, the output end of each second sampling module and the pulse width controller of the switch tube of each branch of the multi-channel parallel three-level DCDC power converter are electrically connected to the control module respectively; the control module includes: A sampling unit, configured to collect, for any branch of the multi-channel parallel three-level DCDC power converter, a first voltage collected by a first sampling module and a second voltage collected by a second sampling module corresponding to the branch based on a preset sampling frequency; A determination unit, configured to determine, at any sampling moment, whether a midpoint circulation phenomenon occurs in the branch at the sampling moment based on the first voltage and the second voltage; The execution unit is used to determine the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first voltage and the second voltage at each sampling moment after the midpoint circulation phenomenon occurs, and generate a control signal according to the duty cycle compensation value, and send it to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch.

8. The control module according to claim 7, characterized in that: The control device further includes at least two third sampling modules; each third sampling module corresponds to a branch of a multi-way parallel three-level DCDC power converter; the input end of any third sampling module is electrically connected to the three-level neutral line of the corresponding branch; the output end of each third sampling module is electrically connected to the control module respectively; the control module further includes: A second sampling unit is used to collect, for any branch of the multi-parallel three-level DCDC power converter, the first current collected by the third sampling module corresponding to the branch based on a preset sampling frequency; A second determining unit is used to determine, for any sampling moment, based on the first current, whether a midpoint circulation phenomenon occurs in the branch at the sampling moment; The second execution unit is used to determine the duty cycle compensation value corresponding to the upper half switch tube and the lower half switch tube of the branch based on the first current at each sampling moment after the midpoint circulation phenomenon occurs, and generate a control signal according to the duty cycle compensation value, and send it to the pulse width controller corresponding to the upper half switch tube and the lower half switch tube of the branch, so that the corresponding pulse width controller adjusts the duty cycle of the upper half switch tube and the lower half switch tube of the branch according to the corresponding duty cycle compensation value until the midpoint circulation phenomenon does not occur in the branch.

9. A control device for a power converter, characterized in that: The control device comprises: A midpoint circulating current detection circuit and a control module as claimed in any one of claims 7 to 8.

10. A power converter, characterized in that: A control device comprising the power converter as claimed in claim 9.

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