A control method for a bidirectional voltage stabilizing circuit and a power converter

Abstract

The present application relates to the field of electric power conversion technology, and in particular to a control method and a power converter of a bidirectional voltage stabilizing circuit, wherein the bidirectional voltage stabilizing circuit includes a first three-level converter and a second three-level converter in parallel, wherein the first three-level converter includes a first flying capacitor, and the second three-level converter includes a second flying capacitor; the method includes: obtaining a first voltage fluctuation value of the first flying capacitor and a second voltage fluctuation value of the second flying capacitor; determining a control strategy corresponding to each three-level converter according to the first voltage fluctuation value and the second voltage fluctuation value, and controlling the first three-level converter and the second three-level converter based on the control strategy to adjust the output voltage of the bidirectional voltage stabilizing circuit. The present application not only realizes the stable control of the flying capacitor voltage, but also improves the stability and reliability of the circuit, and has high convenience, economy and safety.

Description

Technical Field

[0001] The present application relates to the technical field of electric power conversion, and in particular to a control method of a bidirectional voltage stabilizing circuit and a power converter. Background Art

[0002] In high-voltage power conversion, the traditional two-level conversion technology is limited by cost and design difficulty. Although the flying capacitor three-level technology solves some problems, it still faces challenges in controlling the voltage stability of the flying capacitor. In particular, unstable control under low current working conditions may cause large fluctuations in the flying capacitor voltage and even damage the power device, affecting the reliability and economy of the system. Summary of the invention

[0003] In view of this, an embodiment of the present application provides a control method for a bidirectional voltage stabilization circuit and a power converter, which can improve the stability of the circuit under a low current working state.

[0004] In a first aspect, an embodiment of the present application provides a control method for a bidirectional voltage regulator circuit, wherein the bidirectional voltage regulator circuit includes a first three-level converter and a second three-level converter connected in parallel, wherein the first three-level converter includes a first flying capacitor, and the second three-level converter includes a second flying capacitor; the method includes:

[0005] Acquire a first voltage fluctuation value of the first flying capacitor and a second voltage fluctuation value of the second flying capacitor;

[0006] A control strategy corresponding to each three-level converter is determined according to the first voltage fluctuation value and the second voltage fluctuation value, and the first three-level converter and the second three-level converter are controlled based on the control strategy to adjust the output voltage of the bidirectional voltage regulator circuit.

[0007] In some implementations, the bidirectional voltage stabilization circuit includes a trunk current sampler; and determining a control strategy corresponding to each three-level converter according to the first voltage fluctuation value and the second voltage fluctuation value includes:

[0008] If any of the voltage fluctuation values ​​does not fall within the preset fluctuation range, the trunk current sampling value of the trunk current sampler is obtained, and the fluctuation control strategy is determined according to the trunk current sampling value and the current state of the bidirectional voltage stabilization circuit, wherein the fluctuation control strategy includes a buck voltage stabilization control strategy, a boost voltage stabilization control strategy and a buck-boost voltage stabilization control strategy;

[0009] If all the voltage fluctuation values ​​belong to the preset fluctuation range, it is determined to adopt the non-fluctuation control strategy.

[0010] In some implementations, the current state includes a boost discharge state and a buck charge state; and determining the control strategy according to the trunk current sampling value and the current current state includes:

[0011] If the current current state is the step-down charging state, and the trunk current sampling value is not less than the preset current threshold, then determining that the control strategy is the step-down and voltage stabilization control strategy;

[0012] If the current current state is the boost discharge state, and the trunk current sampling value is not greater than the preset reverse current threshold, then determining that the control strategy is the boost voltage stabilization control strategy;

[0013] If the current current state is the step-down charging state and the main current sampling value is less than the preset current threshold, or the current current state is the step-up discharging state and the main current sampling value is greater than the preset reverse current threshold, then the control strategy is determined to be the step-up / step-down voltage regulation control strategy.

[0014] In some embodiments, the first three-level converter and the second three-level converter have the same structure; the first three-level converter includes a main switch tube group consisting of a first switch tube and a second switch tube connected in series, and a branch switch tube group consisting of a third switch tube and a fourth switch tube connected in series; a first end of the first flying capacitor is connected to the main switch tube group, and a second end of the first flying capacitor is connected to the branch switch tube group; positions of the second flying capacitor, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube in the second three-level converter correspond to positions of the first flying capacitor, the first switch tube to the fourth switch tube in sequence, respectively;

[0015] The step-down voltage regulation control strategy includes:

[0016] If both the first flying capacitor and the second flying capacitor are in an undervoltage state, controlling the first switch tube, the third switch tube, the fifth switch tube and the seventh switch tube to be closed, so as to charge the first flying capacitor and the second flying capacitor;

[0017] If both the first flying capacitor and the second flying capacitor are in an overvoltage state, the second switch tube, the fourth switch tube, the sixth switch tube and the eighth switch tube are controlled to be closed, so as to discharge the first flying capacitor and the second flying capacitor.

[0018] In some implementations, the first three-level converter and the second three-level converter each include a main circuit inductor; after charging the first flying capacitor and the second flying capacitor, further comprising:

[0019] The third switch tube, the fourth switch tube, the seventh switch tube and the eighth switch tube are controlled to be closed, so that each of the main circuit inductors can continue to flow.

[0020] In some embodiments, the first three-level converter and the second three-level converter have the same structure; the first three-level converter includes a main switch tube group consisting of a first switch tube and a second switch tube connected in series, and a branch switch tube group consisting of a third switch tube and a fourth switch tube connected in series; a first end of the first flying capacitor is connected to the main switch tube group, and a second end of the first flying capacitor is connected to the branch switch tube group; positions of the second flying capacitor, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube in the second three-level converter correspond to positions of the first flying capacitor, the first switch tube to the fourth switch tube in sequence, respectively;

[0021] The boost voltage regulation control strategy includes:

[0022] If both the first flying capacitor and the second flying capacitor are in an undervoltage state, controlling the second switch tube, the fourth switch tube, the sixth switch tube and the eighth switch tube to be closed to charge the first flying capacitor and the second flying capacitor;

[0023] If both the first flying capacitor and the second flying capacitor are in an overvoltage state, the first switch tube, the third switch tube, the fifth switch tube and the seventh switch tube are controlled to be closed, so as to discharge the first flying capacitor and the second flying capacitor.

[0024] In some implementations, the first three-level converter and the second three-level converter each include a main circuit inductor; after charging the first flying capacitor and the second flying capacitor, further comprising:

[0025] The first switch tube, the second switch tube, the fifth switch tube and the sixth switch tube are controlled to be closed, so as to make each of the main circuit inductors continue to flow.

[0026] In some embodiments, the first three-level converter and the second three-level converter have the same structure; the first three-level converter includes a main switch tube group consisting of a first switch tube and a second switch tube connected in series, and a branch switch tube group consisting of a third switch tube and a fourth switch tube connected in series; a first end of the first flying capacitor is connected to the main switch tube group, and a second end of the first flying capacitor is connected to the branch switch tube group; positions of the second flying capacitor, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube in the second three-level converter correspond to positions of the first flying capacitor, the first switch tube to the fourth switch tube in sequence, respectively;

[0027] The buck-boost voltage stabilization control strategy includes:

[0028] If the first flying capacitor is in a stable state and the second flying capacitor is in an undervoltage state, controlling the first switch tube, the second switch tube, the sixth switch tube and the eighth switch tube to be closed, so as to charge the second flying capacitor;

[0029] If the first flying capacitor is in a stable state and the second flying capacitor is in an overvoltage state, controlling the first switch tube, the second switch tube, the fifth switch tube and the seventh switch tube to be closed to discharge the second flying capacitor;

[0030] If the first flying capacitor is in an undervoltage state and the second flying capacitor is in a stable state, controlling the first switch tube, the third switch tube, the fifth switch tube and the sixth switch tube to be closed, so as to charge the first flying capacitor;

[0031] If the first flying capacitor is in an overvoltage state and the second flying capacitor is in a stable state, controlling the second switch tube, the fourth switch tube, the fifth switch tube and the sixth switch tube to be closed to discharge the first flying capacitor;

[0032] If both the first flying capacitor and the second flying capacitor are in an undervoltage state, controlling the first switch tube, the third switch tube, the sixth switch tube and the eighth switch tube to be closed, so as to charge the first flying capacitor and the second flying capacitor;

[0033] If both the first flying capacitor and the second flying capacitor are in an overvoltage state, controlling the second switch tube, the fourth switch tube, the fifth switch tube and the seventh switch tube to be closed, so as to discharge the first flying capacitor and the second flying capacitor;

[0034] If the first flying capacitor is in an undervoltage state and the second flying capacitor is in an overvoltage state, controlling the first switch tube, the third switch tube, the fifth switch tube and the seventh switch tube to be closed, so that the first flying capacitor is charged and the second flying capacitor is discharged;

[0035] If the first flying capacitor is in an overvoltage state and the second flying capacitor is in an undervoltage state, the second switch tube, the fourth switch tube, the sixth switch tube and the eighth switch tube are controlled to be closed, so that the first flying capacitor is discharged and the second flying capacitor is charged.

[0036] In some embodiments, the first three-level converter includes a first current sampler, and the second three-level converter includes a second current sampler; the main current sampler is used to obtain the main current value of the main output;

[0037] The buck-boost voltage stabilization control strategy includes:

[0038] When the bidirectional voltage regulator circuit is in a charging output state, the first three-level converter and the second three-level converter are controlled so that the second sampling current of the second current sampler is a second preset current value, and the first sampling current of the first current sampler is a difference between the main current value and the second preset current value; wherein the main current value is a third preset current value, and the third preset current value is less than the preset current threshold;

[0039] When the bidirectional voltage regulator circuit is in a discharge input state, the first three-level converter and the second three-level converter are controlled so that the first sampling current of the first current sampler is a first preset current value, and the second sampling current of the second current sampler is a difference between the main current value and the first preset current value; wherein the main current value is a third preset reverse current value, and the third preset reverse current value is greater than a preset reverse current threshold.

[0040] In a second aspect, an embodiment of the present application further proposes a power converter, comprising a controller and a bidirectional voltage regulator circuit; the controller controls the bidirectional voltage regulator circuit according to the above-mentioned control method of the bidirectional voltage regulator circuit.

[0041] The embodiments of the present application have the following beneficial effects:

[0042] The embodiment of the present application provides a control method for a bidirectional voltage stabilization circuit, wherein the bidirectional voltage stabilization circuit includes a first three-level converter and a second three-level converter connected in parallel, wherein the first three-level converter includes a first flying capacitor, and the second three-level converter includes a second flying capacitor. By obtaining the first voltage fluctuation value of the first flying capacitor and the second voltage fluctuation value of the second flying capacitor; then determining the control strategy corresponding to each three-level converter according to the first voltage fluctuation value and the second voltage fluctuation value, and controlling the first three-level converter and the second three-level converter based on the control strategy to adjust the output voltage of the bidirectional voltage stabilization circuit. The present application not only realizes the stable control of the flying capacitor voltage, but also improves the stability and reliability of the circuit, and has high convenience, economy and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] 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.

[0044] Figure 1 A first structural schematic diagram of a bidirectional voltage stabilization circuit proposed in an embodiment of the present application is shown;

[0045] Figure 2 A second structural schematic diagram of the bidirectional voltage stabilization circuit proposed in an embodiment of the present application is shown;

[0046] Figure 3 A first flow chart of a control method for a bidirectional voltage stabilizing circuit according to an embodiment of the present application is shown;

[0047] Figure 4 A second flow chart of the control method of the bidirectional voltage stabilizing circuit proposed in the embodiment of the present application is shown;

[0048] Figure 5 A third flow chart of the control method of the bidirectional voltage stabilizing circuit proposed in the embodiment of the present application is shown.

[0049] Explanation of main component symbols: 100-bidirectional voltage regulator circuit; 110-first three-level converter; 120-second three-level converter; 130-main current sampler; 140-switch module; Q1-first switch tube; Q2-second switch tube; Q3-third switch tube; Q4-fourth switch tube; Q5-fifth switch tube; Q6-sixth switch tube; Q7-seventh switch tube; Q8-eighth switch tube; L1-first main inductor; L2-second main inductor; CF1-first flying capacitor; CF2-second flying capacitor; HCT1-first current sampler; HCT2-second current sampler; 200-input power supply; 300-load. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0051] The components of the embodiments of the present application generally described and shown in the drawings herein may be arranged and designed in various 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.

[0052] Hereinafter, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are intended only to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions and cannot be understood as indicating or implying relative importance.

[0053] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as those generally understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meanings as the contextual meanings in the relevant technical field and will not be interpreted as having idealized meanings or overly formal meanings unless clearly defined in the various embodiments of the present application.

[0054] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0055] In high-voltage conversion circuits (such as bidirectional DC power conversion circuits above 1000V), due to magnetic field interference during operation, large current acquisition errors may occur, which will result in erroneous PWM signals, causing the flying capacitor voltage to quickly drop or surge, damaging the semiconductor power device. Even with a protection solution for the flying capacitor voltage control loop with driver limiting and pure KP, there is still unstable control under low current conditions. It may be necessary to select semiconductor power devices with higher voltage resistance to meet system operation, but this will increase costs. Not only that, the instability of the system under low current working conditions will cause fluctuations in the output when performing high-precision current control, which lacks market competitiveness.

[0056] Therefore, in order to solve the above problem, the present application proposes a control method for a bidirectional voltage stabilization circuit.

[0057] The control method of the bidirectional voltage stabilizing circuit is described below in conjunction with some specific embodiments.

[0058] Figure 1 A structural schematic diagram of a bidirectional voltage stabilizing circuit 100 according to an embodiment of the present application is shown.

[0059] Exemplarily, the bidirectional voltage regulator circuit 100 includes a first three-level converter 110, a second three-level converter 120, a main current sampler 130 and a switch module 140. The first three-level converter 110 and the second three-level converter 120 each include a first pin, a second pin and a third pin, and the first three-level converter 110 and the second three-level converter 120 are connected in parallel. The first pin of the first three-level converter 110 is connected to one end of the input power supply 200 through the switch module 140, and the third pin of the first three-level converter 110 is connected to the other end of the input power supply 200. The second pin of the first three-level converter 110 is connected to one end of the load 300 through the main current sampler 130, and the third pin of the first three-level converter 110 is connected to the other end of the load 300.

[0060] In some embodiments, Figure 2 As shown, based on the structure of the bidirectional voltage regulator circuit 100 described above, the first three-level converter 110 and the second three-level converter 120 have the same structure.

[0061] The first three-level converter 110 includes a first main inductor L1, a first main switch tube group consisting of a first switch tube Q1 and a second switch tube Q2 connected in series, and a first branch switch tube group consisting of a third switch tube Q3 and a fourth switch tube Q4 connected in series; a first end of a first flying capacitor CF1 is connected to a common node of the first switch tube Q1 and the second switch tube Q2, and a second end of the first flying capacitor CF1 is connected to a common node of the first switch tube Q1 and the second switch tube Q2.

[0062] One end of the first main switch tube group is respectively connected to one end of the first branch switch tube group and one end of the first main inductor L1, the other end of the first main switch tube group is connected to one end of the switch module 140, the other end of the first branch switch tube group is connected to the second three-level converter 120, and the other end of the first main inductor L1 is connected to the main current sampler 130; the other end of the main current sampler 130 and the other end of the first branch switch tube group are used to connect the two ends of the load 300; the other end of the switch module 140 and the other end of the first branch switch tube group are used to connect the two ends of the input power supply 200.

[0063] The second three-level converter 120 includes a second main inductor L2, a second main switch tube group consisting of a fifth switch tube Q5 and a sixth switch tube Q6 connected in series, and a second branch switch tube group consisting of a seventh switch tube Q7 and an eighth switch tube Q8 connected in series; a first end of a second flying capacitor CF2 is connected to a common node of the fifth switch tube Q5 and the sixth switch tube Q6, and a second end of the second flying capacitor CF2 is connected to a common node of the fifth switch tube Q5 and the sixth switch tube Q6.

[0064] One end of the second trunk switch tube group is respectively connected to one end of the second branch switch tube group and one end of the second trunk inductor L2, the other end of the second trunk switch tube group is connected to one end of the switch module 140, the other end of the second branch switch tube group is connected to the first three-level converter 110, and the other end of the second trunk inductor L2 is connected to the trunk current sampler 130; the other end of the trunk current sampler 130 and the other end of the second branch switch tube group are used to connect the two ends of the load 300; the other end of the switch module 140 and the other end of the second branch switch tube group are used to connect the two ends of the input power supply 200. Optionally, the load 300 can be a power supply, etc.

[0065] Furthermore, the other end of the main current sampler 130 and the other end of the second branch switch tube group are used to connect the two ends of the output capacitor for filtering and voltage stabilization; the other end of the switch module 140 and the other end of the second branch switch tube group are used to connect the two ends of the input capacitor for filtering and voltage stabilization.

[0066] Figure 3 The flow chart of the control method of the bidirectional voltage regulator circuit 100 is shown. Exemplarily, the control method is used in application scenarios such as electric vehicles, solar power generation, wind power generation, etc., such as high-voltage battery module test equipment that requires high-precision control.

[0067] In some embodiments, Figure 3 As shown, the bidirectional voltage regulator circuit 100 includes a first three-level converter 110 and a second three-level converter 120 connected in parallel, the first three-level converter 110 includes a first flying capacitor CF1, and the second three-level converter 120 includes a second flying capacitor CF2. The control method of the bidirectional voltage regulator circuit 100 includes:

[0068] S110 , obtaining a first voltage fluctuation value of the first flying capacitor CF1 and a second voltage fluctuation value of the second flying capacitor CF2 .

[0069] When the output current dynamically switches to a smaller current output, the voltage fluctuation of the flying capacitor is larger. Therefore, it can be determined whether the current output current is a small current according to the voltage fluctuation values ​​of the first flying capacitor CF1 and the second flying capacitor CF2.

[0070] S210 , determining a control strategy corresponding to each three-level converter according to the first voltage fluctuation value and the second voltage fluctuation value, and controlling the first three-level converter 110 and the second three-level converter 120 based on the control strategy to adjust the output voltage of the bidirectional voltage regulator circuit 100 .

[0071] Since there are many situations during the operation of the circuit, corresponding adjustments need to be made according to each specific situation in order to make the output voltage reach the target value.

[0072] In some embodiments, Figure 4 As shown, the bidirectional voltage regulator circuit 100 includes a main current sampler 130. A control strategy corresponding to each three-level converter is determined according to the first voltage fluctuation value and the second voltage fluctuation value, including:

[0073] S211: If all voltage fluctuation values ​​are within a preset fluctuation range, it is determined to adopt a non-fluctuation control strategy.

[0074] When the voltage fluctuation values ​​of the first flying capacitor CF1 and the second flying capacitor CF2 are both within the preset fluctuation range, it means that the current bidirectional voltage stabilization circuit 100 is in a normal voltage stabilization state, and the non-fluctuation control strategy can basically meet the large current and steady-state output.

[0075] Optionally, when the structure of the bidirectional voltage regulator circuit 100 satisfies:

[0076] The first three-level converter 110 and the second three-level converter 120 have the same structure; the first three-level converter 110 includes a main switch tube group consisting of a first switch tube Q1 and a second switch tube Q2 connected in series, and a branch switch tube group consisting of a third switch tube Q3 and a fourth switch tube Q4 connected in series. The first end of the first flying capacitor CF1 is connected to the main switch tube group, and the second end of the first flying capacitor CF1 is connected to the branch switch tube group. The positions of the second flying capacitor CF2, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8 in the second three-level converter 120 correspond to the positions of the first flying capacitor CF1 and the first switch tube Q1 to the fourth switch tube Q4 in sequence.

[0077] Then the non-fluctuating control strategy can be:

[0078] The first case: If the current current state is the buck charging state (i.e. charging the load 300), the buck charging is performed alternately in the following two ways:

[0079] Method 1: Control the first switch tube Q1, the second switch tube Q2, the fifth switch tube Q5 and the sixth switch tube Q6 to be closed.

[0080] Mode 2: Control the third switch tube Q3, the fourth switch tube Q4, the seventh switch tube Q7 and the eighth switch tube Q8 to be closed.

[0081] In some embodiments, Figure 2 As shown, the first main inductor L1 and the second main inductor L2 are charged by the first method, wherein the current direction of one loop is: flowing from the first switch tube Q1, the second switch tube Q2 and the first main inductor L1 in sequence; the current direction of the other loop is: flowing from the fifth switch tube Q5, the sixth switch tube Q6 and the second main inductor L2 in sequence. The second method is adopted to make the first main inductor L1 and the second main inductor L2 carry out freewheeling to achieve the voltage reduction effect, wherein the current direction of one loop is: flowing from the fourth switch tube Q4, the third switch tube Q3 and the first main inductor L1 in sequence; the current direction of the other loop is: flowing from the eighth switch tube Q8, the seventh switch tube Q7 and the second main inductor L2 in sequence.

[0082] The second case: If the current state is the boost discharge state (i.e. the load 300 is discharging), the boost discharge is performed alternately in the following two ways:

[0083] Method 1: Control the first switch tube Q1, the second switch tube Q2, the fifth switch tube Q5 and the sixth switch tube Q6 to be closed.

[0084] Mode 2: Control the third switch tube Q3, the fourth switch tube Q4, the seventh switch tube Q7 and the eighth switch tube Q8 to be closed.

[0085] In some embodiments, Figure 2 As shown, the first trunk inductor L1 and the second trunk inductor L2 are charged by the second method, wherein the current direction of one loop is: flowing from the first trunk inductor L1, the third switch tube Q3 and the fourth switch tube Q4 in sequence; the current direction of the other loop is: flowing from the second trunk inductor L2, the seventh switch tube Q7 and the eighth switch tube Q8 in sequence. The first method is adopted to discharge the first trunk inductor L1 and the second trunk inductor L2 to achieve a boosting effect, wherein the current direction of one loop is: flowing from the first trunk inductor L1, the second switch tube Q2 and the first switch tube Q1 in sequence; the current direction of the other loop is: flowing from the second trunk inductor L2, the sixth switch tube Q6 and the fifth switch tube Q5 in sequence.

[0086] S212 , if any voltage fluctuation value does not belong to the preset fluctuation range, obtain the trunk current sampling value of the trunk current sampler 130 , and determine to adopt the fluctuation control strategy according to the trunk current sampling value and the current state of the bidirectional voltage regulator circuit 100 .

[0087] If the first voltage fluctuation value or the second voltage fluctuation value does not fall within the preset fluctuation range, it means that the current bidirectional voltage regulator circuit 100 is in a situation of large fluctuation, and the voltage regulation control cannot be satisfied by relying solely on the non-fluctuation control strategy. It is necessary to obtain the trunk current sampling value of the trunk current sampler 130, and further analyze the current situation to determine the corresponding fluctuation control strategy, so as to control in a more accurate manner. Among them, the fluctuation control strategy includes a buck voltage regulation control strategy, a boost voltage regulation control strategy, and a buck-boost voltage regulation control strategy. In some embodiments, Figure 5 As shown, the current state includes a boost discharge state and a buck charge state. The control strategy is determined according to the trunk current sampling value and the current current state, including:

[0088] S2121: If the current current state is a step-down charging state, and the trunk current sampling value is not less than a preset current threshold, then the control strategy is determined to be a step-down and voltage stabilization control strategy.

[0089] S2122: If the current state is a boost discharge state and the trunk current sampling value is not greater than a preset reverse current threshold, then the control strategy is determined to be a boost voltage stabilization control strategy.

[0090] When the voltage fluctuation of the flying capacitor is large, it is necessary to further implement different voltage stabilization strategies according to the current state and the size of the main current sampling value to ensure stable output. If the current sampling value of several channels is large, the voltage stabilization control strategy corresponding to the current state can be adopted to meet the stable output.

[0091] S2123. If the current state is a buck charging state and the trunk current sampling value is less than a preset current threshold, or the current state is a boost discharging state and the trunk current sampling value is greater than a preset reverse current threshold, then determine that the control strategy is a buck-boost voltage stabilization control strategy.

[0092] When the trunk current sampling value is small, it is necessary to further determine the corresponding control strategy according to the voltage fluctuation state of the first flying capacitor CF1 and the second flying capacitor CF2, wherein the voltage fluctuation state includes an undervoltage state and an overvoltage state.

[0093] For example, if the preset current threshold is I th , then the preset reverse current threshold is -I th , that is, the magnitude of the preset reverse current threshold is the same as the magnitude of the preset current threshold, but in the opposite direction.

[0094] In some embodiments, the first three-level converter 110 and the second three-level converter 120 have the same structure; the first three-level converter 110 includes a main switch tube group consisting of a first switch tube Q1 and a second switch tube Q2 connected in series, and a branch switch tube group consisting of a third switch tube Q3 and a fourth switch tube Q4 connected in series; the first end of the first flying capacitor CF1 is connected to the main switch tube group, and the second end of the first flying capacitor CF1 is connected to the branch switch tube group; the positions of the second flying capacitor CF2, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8 in the second three-level converter 120 correspond to the positions of the first flying capacitor CF1 and the first switch tube Q1 to the fourth switch tube Q4, respectively.

[0095] Buck regulation control strategies include:

[0096] If both the first flying capacitor CF1 and the second flying capacitor CF2 are in an undervoltage state, the third method is adopted to charge the first flying capacitor CF1 and the second flying capacitor CF2.

[0097] The third method is to control the first switch tube Q1, the third switch tube Q3, the fifth switch tube Q5 and the seventh switch tube Q7 to be closed.

[0098] For example, Figure 2 As shown, the third method is used to charge the first flying capacitor CF1 and the second flying capacitor CF2. The current direction of one loop is: flowing from the first switch tube Q1, the first flying capacitor CF1, the third switch tube Q3 and the first trunk inductor L1 in sequence; the current direction of the other loop is: flowing from the fifth switch tube Q5, the second flying capacitor CF2, the seventh switch tube Q7 and the second trunk inductor L2 in sequence.

[0099] If both the first flying capacitor CF1 and the second flying capacitor CF2 are in an overvoltage state, the fourth method is adopted to discharge the first flying capacitor CF1 and the second flying capacitor CF2.

[0100] The fourth method is to control the second switch tube Q2, the fourth switch tube Q4, the sixth switch tube Q6 and the eighth switch tube Q8 to be closed.

[0101] For example, Figure 2 As shown, the fourth method is used to discharge the first flying capacitor CF1 and the second flying capacitor CF2. The current direction of one loop is: flowing from the second switch tube Q2, the first flying capacitor CF1, the fourth switch tube Q4 and the first main inductor L1 in sequence; the current direction of the other loop is: flowing from the sixth switch tube Q6, the second flying capacitor CF2, the eighth switch tube Q8 and the second main inductor L2 in sequence.

[0102] In some embodiments, the first three-level converter 110 and the second three-level converter 120 each include a main circuit inductor; after charging the first flying capacitor CF1 and the second flying capacitor CF2, further include:

[0103] Method 2 is adopted to discharge each trunk inductor.

[0104] The second method is to control the third switch tube Q3, the fourth switch tube Q4, the seventh switch tube Q7 and the eighth switch tube Q8 to be closed.

[0105] In some embodiments, Figure 2 As shown, the second method is adopted to discharge the first trunk inductor L1 and the second trunk inductor L2 to prevent the damage of the device caused by excessive trunk inductor energy. The current direction of one loop is: flowing through the fourth switch tube Q4, the third switch tube Q3 and the first trunk inductor L1 in sequence; the current direction of the other loop is: flowing through the eighth switch tube Q8, the seventh switch tube Q7 and the second trunk inductor L2 in sequence.

[0106] In some embodiments, the first three-level converter 110 and the second three-level converter 120 have the same structure; the first three-level converter 110 includes a main switch tube group consisting of a first switch tube Q1 and a second switch tube Q2 connected in series, and a branch switch tube group consisting of a third switch tube Q3 and a fourth switch tube Q4 connected in series; the first end of the first flying capacitor CF1 is connected to the main switch tube group, and the second end of the first flying capacitor CF1 is connected to the branch switch tube group; the positions of the second flying capacitor CF2, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8 in the second three-level converter 120 correspond to the positions of the first flying capacitor CF1 and the first switch tube Q1 to the fourth switch tube Q4, respectively.

[0107] The boost voltage regulation control strategy includes:

[0108] If both the first flying capacitor CF1 and the second flying capacitor CF2 are in an undervoltage state, the fourth method is adopted to charge the first flying capacitor CF1 and the second flying capacitor CF2.

[0109] The fourth method is to control the second switch tube Q2, the fourth switch tube Q4, the sixth switch tube Q6 and the eighth switch tube Q8 to be closed.

[0110] For example, Figure 2As shown, the first flying capacitor CF1 and the second flying capacitor CF2 are charged by using mode 4. The current direction of one loop is: flowing from the second switch tube Q2, the first flying capacitor CF1, the fourth switch tube Q4 and the first trunk inductor L1 in sequence; the current direction of the other loop is: flowing from the sixth switch tube Q6, the second flying capacitor CF2, the eighth switch tube Q8 and the second trunk inductor L2 in sequence.

[0111] If both the first flying capacitor CF1 and the second flying capacitor CF2 are in an overvoltage state, the third method is adopted to discharge the first flying capacitor CF1 and the second flying capacitor CF2.

[0112] The third method is to control the first switch tube Q1, the third switch tube Q3, the fifth switch tube Q5 and the seventh switch tube Q7 to be closed.

[0113] For example, Figure 2 As shown, the third method is used to discharge the first flying capacitor CF1 and the second flying capacitor CF2. The current direction of one loop is: flowing from the first switch tube Q1, the first flying capacitor CF1, the third switch tube Q3 and the first trunk inductor L1 in sequence; the current direction of the other loop is: flowing from the fifth switch tube Q5, the second flying capacitor CF2, the seventh switch tube Q7 and the second trunk inductor L2 in sequence.

[0114] In some embodiments, the first three-level converter 110 and the second three-level converter 120 each include a main circuit inductor; after charging the first flying capacitor CF1 and the second flying capacitor CF2, further include:

[0115] The first method is adopted to discharge each main circuit inductor, wherein the first method is to control the first switch tube Q1, the second switch tube Q2, the fifth switch tube Q5 and the sixth switch tube Q6 to be closed.

[0116] In some embodiments, Figure 2 As shown, the first main inductor L1 and the second main inductor L2 are discharged by using method 1 to prevent the main inductor energy from being too high and causing damage to the device. The current direction of one loop is: flowing from the first main inductor L1, the second switch tube Q2 and the first switch tube Q1 in sequence; the current direction of the other loop is: flowing from the second main inductor L2, the sixth switch tube Q6 and the fifth switch tube Q5 in sequence.

[0117] In some embodiments, Figure 2 As shown, the first three-level converter 110 includes a first current sampler HCT1, and the second three-level converter 120 includes a second current sampler HCT2; the main current sampler 130 is used to obtain the main current value of the main output;

[0118] The buck-boost voltage regulation control strategy includes:

[0119] When the bidirectional voltage regulator circuit 100 is in the charging output state, the first three-level converter 110 and the second three-level converter 120 are controlled so that the second sampling current of the second current sampler HCT2 is a second preset current value, and the first sampling current of the first current sampler HCT1 is a difference between the main current value and the second preset current value; wherein the main current value is a third preset current value, and the third preset current value is less than the preset current threshold.

[0120] Exemplarily, if the second preset current value is -I2 and the main current value is I3, then the first sampling current is I3+I2.

[0121] When the bidirectional voltage regulator circuit 100 is in the discharge input state, the first three-level converter 110 and the second three-level converter 120 are controlled so that the first sampling current of the first current sampler HCT1 is the first preset current value, and the second sampling current of the second current sampler HCT2 is the difference between the main current value and the first preset current value; wherein the main current value is the third preset reverse current value, and the third preset reverse current value is greater than the preset reverse current threshold. wherein the preset reverse current threshold is the same as the preset current threshold, but in the opposite direction.

[0122] Exemplarily, if the first preset current value is I1 and the trunk current value is -I3, then the second sampled current is -I3-I1.

[0123] In some embodiments, the first three-level converter 110 and the second three-level converter 120 have the same structure; the first three-level converter 110 includes a main switch tube group consisting of a first switch tube Q1 and a second switch tube Q2 connected in series, and a branch switch tube group consisting of a third switch tube Q3 and a fourth switch tube Q4 connected in series; a first end of the first flying capacitor CF1 is connected to the main switch tube group, and a second end of the first flying capacitor CF1 is connected to the branch switch tube group; positions of the second flying capacitor CF2, the fifth switch tube Q5, the sixth switch tube Q6, the seventh switch tube Q7 and the eighth switch tube Q8 in the second three-level converter 120 correspond to positions of the first flying capacitor CF1 and the first switch tube Q1 to the fourth switch tube Q4 in sequence;

[0124] The buck-boost voltage regulation control strategy includes:

[0125] If the first flying capacitor CF1 is in a stable state and the second flying capacitor CF2 is in an undervoltage state, the fifth method is adopted to charge the second flying capacitor CF2.

[0126] The fifth method is to control the first switch tube Q1, the second switch tube Q2, the sixth switch tube Q6 and the eighth switch tube Q8 to be closed.

[0127] For example, Figure 2 As shown, the fifth method is used to charge the first flying capacitor CF1 and the second flying capacitor CF2.

[0128] If the first flying capacitor CF1 is in a stable state and the second flying capacitor CF2 is in an overvoltage state, the sixth method is adopted to discharge the second flying capacitor CF2.

[0129] Wherein, the sixth method is to control the first switch tube Q1, the second switch tube Q2, the fifth switch tube Q5 and the seventh switch tube Q7 to be closed.

[0130] For example, Figure 2 As shown, the sixth mode is used to discharge the second flying capacitor CF2 so that the second flying capacitor CF2 returns to a normal state.

[0131] If the first flying capacitor CF1 is in an undervoltage state and the second flying capacitor CF2 is in a stable state, the seventh method is adopted to charge the first flying capacitor CF1.

[0132] Wherein, the seventh method is to control the first switch tube Q1, the third switch tube Q3, the fifth switch tube Q5 and the sixth switch tube Q6 to be closed.

[0133] For example, Figure 2 As shown, the seventh mode is used to charge the first flying capacitor CF1 so as to restore the first flying capacitor CF1 to a normal state.

[0134] If the first flying capacitor CF1 is in an overvoltage state and the second flying capacitor CF2 is in a stable state, the eighth method is adopted to discharge the first flying capacitor CF1.

[0135] The eighth method is to control the second switch tube Q2, the fourth switch tube Q4, the fifth switch tube Q5 and the sixth switch tube Q6 to be closed.

[0136] For example, Figure 2 As shown, the eighth mode is used to discharge the first flying capacitor CF1 so that the first flying capacitor CF1 returns to a normal state.

[0137] If both the first flying capacitor CF1 and the second flying capacitor CF2 are in an undervoltage state, the ninth method is adopted to charge the first flying capacitor CF1 and the second flying capacitor CF2.

[0138] Wherein, the ninth method is to control the first switch tube Q1, the third switch tube Q3, the sixth switch tube Q6 and the eighth switch tube Q8 to be closed.

[0139] For example, Figure 2As shown, the ninth mode is used to charge the first flying capacitor CF1 and the second flying capacitor CF2, so that the first flying capacitor CF1 and the second flying capacitor CF2 are restored to a normal state.

[0140] If both the first flying capacitor CF1 and the second flying capacitor CF2 are in an overvoltage state, method 10 is adopted to discharge the first flying capacitor CF1 and the second flying capacitor CF2.

[0141] Wherein, the tenth method is to control the second switch tube Q2, the fourth switch tube Q4, the fifth switch tube Q5 and the seventh switch tube Q7 to be closed.

[0142] For example, Figure 2 As shown, the tenth mode is used to discharge the first flying capacitor CF1 and the second flying capacitor CF2, so that the first flying capacitor CF1 and the second flying capacitor CF2 are restored to a normal state.

[0143] If the first flying capacitor CF1 is in an undervoltage state and the second flying capacitor CF2 is in an overvoltage state, the third method is adopted to charge the first flying capacitor CF1 and discharge the second flying capacitor CF2.

[0144] The third method is to control the first switch tube Q1, the third switch tube Q3, the fifth switch tube Q5 and the seventh switch tube Q7 to be closed.

[0145] For example, Figure 2 As shown, the third pair of modes is applied to charge the first flying capacitor CF1 and discharge the first flying capacitor CF1 , so that the first flying capacitor CF1 and the second flying capacitor CF2 return to a normal state.

[0146] If the first flying capacitor CF1 is in an overvoltage state and the second flying capacitor CF2 is in an undervoltage state, the fourth method is adopted to discharge the first flying capacitor CF1 and charge the second flying capacitor CF2.

[0147] The fourth method is to control the second switch tube Q2, the fourth switch tube Q4, the sixth switch tube Q6 and the eighth switch tube Q8 to be closed.

[0148] For example, Figure 2 As shown, the fourth pair of modes is used to discharge the first flying capacitor CF1 and charge the first flying capacitor CF1 , so that the first flying capacitor CF1 and the second flying capacitor CF2 return to normal state.

[0149] It is understandable that, during the operation of any of the above-mentioned bidirectional voltage stabilization circuits, the switch module 140 is in a closed state.

[0150] This application realizes stable control of the output voltage, and realizes that the flying capacitor voltage is always controlled to be maintained at the target voltage (which can be set to half of the input voltage) under different working states and different working currents, ensuring that the switching device will not be damaged due to excessive voltage stress, thereby improving the reliability of use. And due to the stability and reliability brought by this technical solution. It can also achieve high frequency and modular design through the new generation of semiconductor material silicon carbide. The converter is easy to operate in parallel with multiple machines, and has high economy, convenience and safety in use. The application of this technical solution in the field of high-voltage battery module automatic testing equipment has obvious advantages.

[0151] Another embodiment of the present application further provides a power converter, including a controller and a bidirectional voltage regulator circuit 100; the controller controls the bidirectional voltage regulator circuit 100 according to the control method of the bidirectional voltage regulator circuit 100 described above.

[0152] It should be noted that a power converter is an energy conversion device that can convert one form of energy into another form to meet different application requirements. In the automotive field, power converters are used in vehicle lighting systems such as headlights and interior lighting. They are also used in solar power generation, wind power generation and other fields. In addition, power converters can also be used in special occasions such as medical equipment, ships, and military vehicles. In summary, as an application of the power converter, the charging device also belongs to the category of the power converter in this embodiment.

[0153] It can be understood that the bidirectional voltage regulator circuit 100 in the device of this embodiment corresponds to the bidirectional voltage regulator circuit 100 in the above embodiment; the control method of the bidirectional voltage regulator circuit 100 in the device of this embodiment corresponds to the control method of the bidirectional voltage regulator circuit 100 in the above embodiment; the optional items in the above embodiment are also applicable to this embodiment, so they will not be repeated here.

[0154] The present application also provides a computer-readable storage medium for storing a computer program used in the above controller. For example, the computer-readable storage medium may include, but is not limited to, 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.

[0155] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and structure diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in an alternative implementation, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the structure diagram and / or the flow diagram, and the combination of boxes in the structure diagram and / or the flow diagram, can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0156] In addition, the functional modules or units in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0157] If the functions are implemented in the form of software function modules 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 enabling a computer device (which can be a smart phone, a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application.

[0158] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A control method for a bidirectional voltage stabilizing circuit, characterized in that: The bidirectional voltage stabilization circuit comprises a first three-level converter and a second three-level converter connected in parallel, the first three-level converter comprises a first flying capacitor, and the second three-level converter comprises a second flying capacitor; the method comprises: Acquire a first voltage fluctuation value of the first flying capacitor and a second voltage fluctuation value of the second flying capacitor; Determining a control strategy corresponding to each three-level converter according to the first voltage fluctuation value and the second voltage fluctuation value, and controlling the first three-level converter and the second three-level converter based on the control strategy to adjust the output voltage of the bidirectional voltage regulator circuit; The bidirectional voltage stabilization circuit includes a main current sampler; the control strategy corresponding to each three-level converter is determined according to the first voltage fluctuation value and the second voltage fluctuation value, including: If any of the voltage fluctuation values ​​does not fall within the preset fluctuation range, the trunk current sampling value of the trunk current sampler is obtained, and the fluctuation control strategy is determined according to the trunk current sampling value and the current state of the bidirectional voltage stabilization circuit, wherein the fluctuation control strategy includes a buck voltage stabilization control strategy, a boost voltage stabilization control strategy and a buck-boost voltage stabilization control strategy; If all the voltage fluctuation values ​​fall within the preset fluctuation range, it is determined to adopt a non-fluctuation control strategy; The current state includes a boost discharge state and a buck charge state; the control strategy is determined according to the trunk current sampling value and the current current state, including: If the current current state is the step-down charging state, and the trunk current sampling value is not less than the preset current threshold, determining that the control strategy is the step-down and voltage stabilization control strategy; If the current current state is the boost discharge state, and the trunk current sampling value is not greater than the preset reverse current threshold, then determining that the control strategy is the boost voltage stabilization control strategy; If the current current state is the buck charging state and the trunk current sampling value is less than the preset current threshold, or the current current state is the boost discharging state and the trunk current sampling value is greater than the preset reverse current threshold, then the control strategy is determined to be the buck-boost voltage stabilization control strategy; The first three-level converter and the second three-level converter have the same structure; the first three-level converter includes a trunk switch tube group consisting of a first switch tube and a second switch tube connected in series, and a branch switch tube group consisting of a third switch tube and a fourth switch tube connected in series; a first end of the first flying capacitor is connected to the trunk switch tube group, and a second end of the first flying capacitor is connected to the branch switch tube group; the positions of the second flying capacitor, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube in the second three-level converter correspond to the positions of the first flying capacitor and the first switch tube to the fourth switch tube in sequence; The control strategy includes a step-down and voltage stabilization control strategy, and the step-down and voltage stabilization control strategy includes: If both the first flying capacitor and the second flying capacitor are in an undervoltage state, controlling the first switch tube, the third switch tube, the fifth switch tube and the seventh switch tube to be closed, so as to charge the first flying capacitor and the second flying capacitor; If both the first flying capacitor and the second flying capacitor are in an overvoltage state, the second switch tube, the fourth switch tube, the sixth switch tube and the eighth switch tube are controlled to be closed, so as to discharge the first flying capacitor and the second flying capacitor.

2. The control method of the bidirectional voltage stabilizing circuit according to claim 1, characterized in that: The first three-level converter and the second three-level converter each include a main circuit inductor; after charging the first flying capacitor and the second flying capacitor, further include: The third switch tube, the fourth switch tube, the seventh switch tube and the eighth switch tube are controlled to be closed, so that each of the main circuit inductors can continue to flow.

3. The control method of the bidirectional voltage stabilizing circuit according to claim 1, characterized in that: The first three-level converter and the second three-level converter have the same structure; the first three-level converter includes a trunk switch tube group consisting of a first switch tube and a second switch tube connected in series, and a branch switch tube group consisting of a third switch tube and a fourth switch tube connected in series; a first end of the first flying capacitor is connected to the trunk switch tube group, and a second end of the first flying capacitor is connected to the branch switch tube group; the positions of the second flying capacitor, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube in the second three-level converter correspond to the positions of the first flying capacitor and the first switch tube to the fourth switch tube in sequence; The boost voltage regulation control strategy includes: If both the first flying capacitor and the second flying capacitor are in an undervoltage state, controlling the second switch tube, the fourth switch tube, the sixth switch tube and the eighth switch tube to be closed to charge the first flying capacitor and the second flying capacitor; If both the first flying capacitor and the second flying capacitor are in an overvoltage state, the first switch tube, the third switch tube, the fifth switch tube and the seventh switch tube are controlled to be closed, so as to discharge the first flying capacitor and the second flying capacitor.

4. The control method of the bidirectional voltage stabilizing circuit according to claim 3, characterized in that: The first three-level converter and the second three-level converter each include a main circuit inductor; after charging the first flying capacitor and the second flying capacitor, further include: The first switch tube, the second switch tube, the fifth switch tube and the sixth switch tube are controlled to be closed, so as to make each of the main circuit inductors continue to flow.

5. The control method of the bidirectional voltage stabilizing circuit according to claim 1, characterized in that: The first three-level converter and the second three-level converter have the same structure; the first three-level converter includes a trunk switch tube group consisting of a first switch tube and a second switch tube connected in series, and a branch switch tube group consisting of a third switch tube and a fourth switch tube connected in series; a first end of the first flying capacitor is connected to the trunk switch tube group, and a second end of the first flying capacitor is connected to the branch switch tube group; the positions of the second flying capacitor, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube in the second three-level converter correspond to the positions of the first flying capacitor and the first switch tube to the fourth switch tube in sequence; The buck-boost voltage stabilization control strategy includes: If the first flying capacitor is in a stable state and the second flying capacitor is in an undervoltage state, controlling the first switch tube, the second switch tube, the sixth switch tube and the eighth switch tube to be closed, so as to charge the second flying capacitor; If the first flying capacitor is in a stable state and the second flying capacitor is in an overvoltage state, controlling the first switch tube, the second switch tube, the fifth switch tube and the seventh switch tube to be closed to discharge the second flying capacitor; If the first flying capacitor is in an undervoltage state and the second flying capacitor is in a stable state, controlling the first switch tube, the third switch tube, the fifth switch tube and the sixth switch tube to be closed, so as to charge the first flying capacitor; If the first flying capacitor is in an overvoltage state and the second flying capacitor is in a stable state, controlling the second switch tube, the fourth switch tube, the fifth switch tube and the sixth switch tube to be closed to discharge the first flying capacitor; If both the first flying capacitor and the second flying capacitor are in an undervoltage state, controlling the first switch tube, the third switch tube, the sixth switch tube and the eighth switch tube to be closed, so as to charge the first flying capacitor and the second flying capacitor; If both the first flying capacitor and the second flying capacitor are in an overvoltage state, controlling the second switch tube, the fourth switch tube, the fifth switch tube and the seventh switch tube to be closed, so as to discharge the first flying capacitor and the second flying capacitor; If the first flying capacitor is in an undervoltage state and the second flying capacitor is in an overvoltage state, controlling the first switch tube, the third switch tube, the fifth switch tube and the seventh switch tube to be closed, so that the first flying capacitor is charged and the second flying capacitor is discharged; If the first flying capacitor is in an overvoltage state and the second flying capacitor is in an undervoltage state, the second switch tube, the fourth switch tube, the sixth switch tube and the eighth switch tube are controlled to be closed, so that the first flying capacitor is discharged and the second flying capacitor is charged.

6. The control method of the bidirectional voltage stabilizing circuit according to claim 1, characterized in that: The first three-level converter includes a first current sampler, and the second three-level converter includes a second current sampler; the main current sampler is used to obtain the main current value of the main output; The buck-boost voltage stabilization control strategy includes: When the bidirectional voltage regulator circuit is in a charging output state, the first three-level converter and the second three-level converter are controlled so that the second sampling current of the second current sampler is a second preset current value, and the first sampling current of the first current sampler is a difference between the main current value and the second preset current value; wherein the main current value is a third preset current value, and the third preset current value is less than the preset current threshold; When the bidirectional voltage regulator circuit is in a discharge input state, the first three-level converter and the second three-level converter are controlled so that the first sampling current of the first current sampler is a first preset current value, and the second sampling current of the second current sampler is a difference between the main current value and the first preset current value; wherein the main current value is a third preset reverse current value, and the third preset reverse current value is greater than a preset reverse current threshold.

7. A power converter, characterized in that: It comprises a controller and a bidirectional voltage stabilizing circuit; the controller controls the bidirectional voltage stabilizing circuit according to the control method of the bidirectional voltage stabilizing circuit according to any one of claims 1 to 6.

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