Capacitance voltage-sharing circuit and module
By controlling capacitor discharge through a switch selection circuit and using a DC-DC circuit for voltage equalization, the problem of current imbalance caused by uneven capacitor voltage is solved, thus improving power supply efficiency.
Patent Information
- Application Number
- CN202520042293.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-08
- Publication Date
- 2026-01-30
- Estimated Expiration
- 2035-01-08
AI Technical Summary
In existing high-voltage input isolated DC-DC circuits, uneven voltage distribution in capacitors leads to current imbalance, resulting in additional losses and reduced power efficiency.
By controlling capacitor discharge through a switching selection circuit and using a DC-DC circuit for voltage equalization, additional losses are avoided and power efficiency is improved.
This achieves voltage equalization of capacitors, reduces additional losses, and improves power efficiency.
Smart Images
Figure CN223858837U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of voltage equalization, in particular to a capacitor voltage equalization circuit and module. BACKGROUND
[0002] A high-voltage input isolation DCDC circuit usually adopts a form of primary series and secondary parallel to solve the problem of high input voltage leading to high device stress. Common isolation circuit units include forward circuits, flyback circuits and LLC circuits. Due to the large parasitic parameters of the isolation transformer, it is difficult to keep the gains of the two circuits completely consistent, and therefore, the first and second currents are often unbalanced, leading to uneven voltage of the capacitors on the input side.
[0003] In order to solve the problem of voltage equalization of the input series capacitors, a common method is to increase voltage equalization resistors on both ends of the series capacitors to balance the voltage of the capacitors on the input side. However, this method will generate fixed losses, and even if the capacitors are evenly charged, the resistors will still generate additional losses, reducing the efficiency of the power supply. Therefore, how to ensure the voltage equalization of the capacitors while reducing or avoiding additional losses and improving the efficiency of the power supply has become a technical problem to be solved. CONTENT OF THE INVENTION
[0004] Therefore, it is necessary to provide a capacitor voltage equalization circuit and module in view of the above technical problems.
[0005] A capacitor voltage equalization circuit comprises:
[0006] a first capacitor;
[0007] a first DCDC circuit, a first end of the first DCDC circuit being connected to a first end of the first capacitor;
[0008] a second DCDC circuit, a first end of the second DCDC circuit being connected to a second end of the first DCDC circuit;
[0009] a second capacitor, a first end of the second capacitor being connected to a second end of the second DCDC circuit; and
[0010] a switch selection circuit, a first end of the switch selection circuit being connected to a second end of the second capacitor and a second end of the first capacitor, and a second end of the switch selection circuit being connected to the first end of the second DCDC circuit and the second end of the first DCDC circuit;
[0011] When the voltages on both ends of the first capacitor and the second capacitor are not equalized, the switch selection circuit controls the first capacitor or the second capacitor to discharge, so that the voltages on both ends of the first capacitor and the second capacitor are equalized.
[0012] In one of the embodiments, the switch selection circuit comprises:
[0013] a first switch circuit, a first end of the first switch circuit being connected to a second end of the second capacitor and a second end of the first capacitor;
[0014] a first unidirectional conducting circuit, a cathode of the first unidirectional conducting circuit being connected to a second end of the first switch circuit;
[0015] a second switch circuit, a first end of the second switch circuit being connected to the second end of the second capacitor and the second end of the first capacitor; and
[0016] a second unidirectional conducting circuit, an anode of the second unidirectional conducting circuit being connected to a second end of the second switch circuit, a cathode of the second unidirectional conducting circuit being connected to an anode of the first unidirectional conducting circuit, a first end of the second DCDC circuit and a second end of the first DCDC circuit;
[0017] when the first switch circuit is closed and the second switch circuit is opened, the first capacitor discharges, and when the first switch circuit is opened and the second switch circuit is closed, the second capacitor discharges.
[0018] In one of the embodiments, the first switch circuit and the second switch circuit are controllable switch tubes.
[0019] In one of the embodiments, the first unidirectional conducting circuit and the second unidirectional conducting circuit are diodes.
[0020] In one of the embodiments, the switch selection circuit comprises:
[0021] a third switch circuit;
[0022] a third unidirectional conducting circuit, an anode of the third unidirectional conducting circuit being connected to a first end of the third switch circuit, a second end of the second capacitor and a second end of the first capacitor;
[0023] a fourth switch circuit; and
[0024] a fourth unidirectional conducting circuit, a cathode of the fourth unidirectional conducting circuit being connected to a first end of the fourth switch circuit, a cathode of the third unidirectional conducting circuit and a second end of the third switch circuit, an anode of the fourth unidirectional conducting circuit being connected to a second end of the fourth switch circuit, the first end of the second DCDC circuit and the second end of the first DCDC circuit;
[0025] When the third switch circuit is closed and the fourth switch circuit is opened, the first capacitor discharges; and when the third switch circuit is opened and the fourth switch circuit is closed, the second capacitor discharges.
[0026] In one of the embodiments, the third switch circuit and the fourth switch circuit are both controllable switch tubes.
[0027] In one of the embodiments, the third unidirectional conducting circuit and the fourth unidirectional conducting circuit are both diodes.
[0028] In one of the embodiments, the capacitor voltage equalization circuit further comprises:
[0029] a first voltage sampling circuit, a first end of the first voltage sampling circuit being connected with a first end of the first capacitor, and a second end of the first voltage sampling circuit being connected with a second end of the first capacitor; and
[0030] a second voltage sampling circuit, a first end of the second voltage sampling circuit being connected with a first end of the second capacitor, and a second end of the second voltage sampling circuit being connected with a second end of the first capacitor.
[0031] In one of the embodiments, the capacitor voltage equalization circuit further comprises:
[0032] a control circuit, the control circuit being connected with the switch selection circuit, the first voltage sampling circuit and the second voltage sampling circuit respectively.
[0033] A capacitor voltage equalization module comprising the capacitor voltage equalization circuit in any of the above embodiments.
[0034] Compared with the prior art, the capacitor voltage equalization circuit and the module can control the first capacitor or the second capacitor to discharge and form a small discharge loop with the corresponding first DCDC circuit or second DCDC circuit through the switch selection circuit when the voltage across the first capacitor and the second capacitor is not equalized, so that the energy of the first capacitor or the second capacitor is transmitted to the output side through the DCDC circuit, thereby avoiding additional loss and improving power efficiency. BRIEF DESCRIPTION OF DRAWINGS
[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiment or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0036] Figure 1 A circuit schematic of a capacitor voltage equalization circuit is provided for an embodiment of the present application;
[0037] Figure 2 A circuit schematic of a capacitor voltage equalization circuit is provided for an embodiment of the present application;
[0038] Figure 3 A circuit schematic of a capacitor voltage equalization circuit is provided for another embodiment of the present application;
[0039] Figure 4 A circuit schematic of a capacitor voltage equalization circuit is provided for another embodiment of the present application;
[0040] Figure 5 A circuit schematic of a capacitor voltage equalization circuit is provided for another embodiment of the present application;
[0041] Figure 6 A circuit schematic of a capacitor voltage equalization module is provided for an embodiment of the present application. DETAILED DESCRIPTION
[0042] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the present application can be practiced in a variety of ways beyond the specific details disclosed herein without departing from the spirit and scope of the present application.
[0043] The serial numbers of components in the present application, such as "first", "second", etc., are only used to distinguish the described objects, and do not have any sequence or technical meaning. In the present application, "connection" and "coupling" include direct and indirect connection (coupling) unless otherwise specified. In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.
[0044] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0045] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.
[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0047] Please see Figure 1 This application provides a capacitor voltage equalization circuit 10 in one embodiment. The capacitor voltage equalization circuit 10 includes: a first capacitor C1, a first DC-DC circuit 100, a second DC-DC circuit 200, a second capacitor C2, and a switch selection circuit 300. A first terminal of the first DC-DC circuit 100 is connected to a first terminal of the first capacitor C1. A first terminal of the second DC-DC circuit 200 is connected to a second terminal of the first DC-DC circuit 100. A first terminal of the second capacitor C2 is connected to a second terminal of the second DC-DC circuit 200. A first terminal of the switch selection circuit 300 is connected to both the second terminal of the second capacitor C2 and the second terminal of the first capacitor C1. A second terminal of the switch selection circuit 300 is connected to both the first terminal of the second DC-DC circuit 200 and the second terminal of the first DC-DC circuit 100.
[0048] When the voltages across the first capacitor C1 and the second capacitor C2 are not equal, the switch selection circuit 300 controls the first capacitor C1 or the second capacitor C2 to discharge so that the voltages across the first capacitor C1 and the second capacitor C2 are equal.
[0049] In some embodiments, the specific circuit topology of the first DCDC circuit 100 is not limited, for example, the first DCDC circuit 100 can be a forward circuit, a flyback circuit, an LLC circuit, etc. Similarly, the specific circuit topology of the second DCDC circuit 200 is not limited, and can also be a forward circuit, a flyback circuit, an LLC circuit, etc. The circuit topology of the first DCDC circuit 100 and the second DCDC circuit 200 can be selected according to actual needs, which is not limited here.
[0050] In some embodiments, the specific circuit topology of the switch selection circuit 300 is not limited, as long as it has the function of controlling the discharge of the first capacitor C1 or the second capacitor C2. Optionally, the switch selection circuit 300 can include controllable switching tubes and diodes in parallel. In some embodiments, the first capacitor C1, the first DCDC circuit 100, the second DCDC circuit 200, and the second capacitor C2 are connected in series to form a large loop.
[0051] When the voltages across the first capacitor C1 and the second capacitor C2 are not equal, for example, the voltage across the first capacitor C1 is higher than the voltage across the second capacitor C2, at this time the switch selection circuit 300 selects to control the first capacitor C1 to discharge (the second capacitor C2 does not discharge), and the specific discharge process is that the current flows from the first end (i.e. the positive electrode) of the first capacitor C1 through the first DCDC circuit 100, the switch selection circuit 300, and finally returns to the second end (i.e. the negative electrode) of the first capacitor C1, forming a discharge loop of the first capacitor C1. When the voltages across the first capacitor C1 and the second capacitor C2 are equal, the switch selection circuit 300 selects to control the first capacitor C1 to end the discharge, at this time the voltages across the first capacitor C1 and the second capacitor C2 achieve equalization.
[0052] When the voltages across the first capacitor C1 and the second capacitor C2 are not equal, for example, the voltage across the first capacitor C1 is lower than the voltage across the second capacitor C2, at this time the switch selection circuit 300 selects to control the second capacitor C2 to discharge (the first capacitor C1 does not discharge), and the specific discharge process is that the current flows from the first end (i.e. the positive electrode) of the second capacitor C2 through the switch selection circuit 300, the second DCDC circuit 200, and finally returns to the second end (i.e. the negative electrode) of the second capacitor C2, forming a discharge loop of the second capacitor C2. When the voltages across the first capacitor C1 and the second capacitor C2 are equal, the switch selection circuit 300 selects to control the second capacitor C2 to end the discharge, at this time the voltages across the first capacitor C1 and the second capacitor C2 achieve equalization.
[0053] Thus, the first capacitor or the second capacitor can be controlled to discharge by the switch selection circuit, and a discharge small loop is formed with the corresponding first DCDC circuit or second DCDC circuit, so that the energy of the first capacitor or the second capacitor is fully utilized by the DCDC circuit without additional loss, thereby improving the power supply efficiency.
[0054] In some embodiments, the switch selection circuit 300 comprises a first switch circuit 310, a first unidirectional conducting circuit 320, a second switch circuit 330, and a second unidirectional conducting circuit 340. The first end of the first switch circuit 310 is connected to the second end of the second capacitor C2 and the second end of the first capacitor C1. The cathode of the first unidirectional conducting circuit 320 is connected to the second end of the first switch circuit 310. The first end of the second switch circuit 330 is connected to the second end of the second capacitor C2 and the second end of the first capacitor C1. The anode of the second unidirectional conducting circuit 340 is connected to the second end of the second switch circuit 330. The cathode of the second unidirectional conducting circuit 340 is connected to the anode of the first unidirectional conducting circuit 320, the first end of the second DCDC circuit 200, and the second end of the first DCDC circuit 100.
[0055] When the first switch circuit 310 is closed and the second switch circuit 330 is opened, the first capacitor C1 discharges. When the first switch circuit 310 is opened and the second switch circuit 330 is closed, the second capacitor C2 discharges.
[0056] In one embodiment, the specific circuit topology of the first switch circuit 310 is not limited, for example, the first switch circuit 310 can be a controllable switch tube such as a relay switch, an IGBT (Insulate-Gate Bipolar Transistor), a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), etc. Similarly, the specific circuit topology of the second switch circuit 330 is not limited, for example, the second switch circuit 330 can be a controllable switch tube such as a relay switch, an IGBT, a MOSFET, etc.
[0057] In some embodiments, the specific circuit topology of the first unidirectional conducting circuit 320 is not limited, as long as it has the function of allowing current to flow from its anode to its cathode, but preventing current from flowing from its cathode to its anode. For example, the first unidirectional conducting circuit 320 can be a diode. Similarly, the specific circuit topology of the second unidirectional conducting circuit 340 is not limited, as long as it has the function of allowing current to flow from its anode to its cathode, but preventing current from flowing from its cathode to its anode. For example, the second unidirectional conducting circuit 340 can be a diode.
[0058] When an imbalance in voltage is detected between the first capacitor C1 and the second capacitor C2, such that the voltage across the first capacitor C1 is higher than that across the second capacitor C2, the first switch circuit 310 is closed and the second switch circuit 330 is opened. This discharges the first capacitor C1. Specifically, the discharge process involves current flowing from the first terminal (positive) of the first capacitor C1 through the first DC-DC circuit 100, the first unidirectional conduction circuit 320, and the first switch circuit 310, finally returning to the second terminal (negative) of the first capacitor C1, forming a discharge circuit for the first capacitor C1. When the voltages across the first capacitor C1 and the second capacitor C2 are equal, the first switch circuit 310 is opened, thus ending the discharge of the first capacitor C1. At this point, the voltages across the first capacitor C1 and the second capacitor C2 are equalized.
[0059] When the voltages across the first capacitor C1 and the second capacitor C2 are not equal, such as when the voltage across the first capacitor C1 is lower than the voltage across the second capacitor C2, the first switching circuit 310 can be opened and the second switching circuit 330 can be closed to discharge the second capacitor C2. Specifically, the discharge process involves current flowing from the first terminal (positive) of the second capacitor C2 through the second switching circuit 330, the second unidirectional conduction circuit 340, and the second DC-DC circuit 200, finally returning to the second terminal (negative) of the second capacitor C2, forming a discharge circuit for the second capacitor C2. When the voltages across the first capacitor C1 and the second capacitor C2 are equal, the second switching circuit 330 is opened, thus ending the discharge of the second capacitor C2. At this point, the voltages across the first capacitor C1 and the second capacitor C2 are equalized.
[0060] In some embodiments, such as Figure 2 As shown, when the number of capacitors connected in series increases, such as three capacitors connected in series, the voltage equalization adjustment process is the same as in the above embodiment, and will not be repeated here.
[0061] In some embodiments, such as Figure 3As shown, the switch selection circuit 300 includes a third switch circuit 350, a third unidirectional conducting circuit 360, a fourth switch circuit 370, and a fourth unidirectional conducting circuit 380. The anode of the third unidirectional conducting circuit 360 is connected to the first terminal of the third switch circuit 350, the second terminal of the second capacitor C2, and the second terminal of the first capacitor C1. The cathode of the fourth unidirectional conducting circuit 380 is connected to the first terminal of the fourth switch circuit 370, the cathode of the third unidirectional conducting circuit 360, and the second terminal of the third switch circuit 350. The anode of the fourth unidirectional conducting circuit 380 is connected to the second terminal of the fourth switch circuit 370, the first terminal of the second DCDC circuit 200, and the second terminal of the first DCDC circuit 100. When the third switch circuit 350 is closed and the fourth switch circuit 370 is open, the first capacitor C1 discharges. When the third switch circuit 350 is open and the fourth switch circuit 370 is closed, the second capacitor C2 discharges.
[0062] In one embodiment, the specific circuit topology of the third switch circuit 350 is not limited, for example, the third switch circuit 350 can be a relay switch, an IGBT (Insulate-Gate Bipolar Transistor), a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), or the like controllable switch tube. Similarly, the specific circuit topology of the fourth switch circuit 370 is not limited, for example, the fourth switch circuit 370 can be a relay switch, an IGBT, a MOSFET, or the like controllable switch tube.
[0063] In some embodiments, the specific circuit topology of the third unidirectional conducting circuit 360 is not limited, as long as it has the function of allowing current to flow from its anode to its cathode, but not allowing current to flow from its cathode to its anode. For example, the third unidirectional conducting circuit 360 can be a diode. Similarly, the specific circuit topology of the fourth unidirectional conducting circuit 380 is not limited, as long as it has the function of allowing current to flow from its anode to its cathode, but not allowing current to flow from its cathode to its anode. For example, the fourth unidirectional conducting circuit 380 can be a diode.
[0064] When the voltage across the first capacitor C1 and the second capacitor C2 is not equal, for example, the voltage across the first capacitor C1 is higher than the voltage across the second capacitor C2, at this time, the third switch circuit 350 can be controlled to be closed and the fourth switch circuit 370 can be controlled to be opened, and the first capacitor C1 is selected to be discharged. The specific discharge process is that the current flows from the first end (i.e., the positive electrode) of the first capacitor C1, through the first DC-DC circuit 100, the fourth unidirectional conducting circuit 380, the third switch circuit 350, and finally returns to the second end (i.e., the negative electrode) of the first capacitor C1, forming a discharge loop of the first capacitor C1. When the voltage across the first capacitor C1 and the second capacitor C2 is equal, the third switch circuit 350 is controlled to be opened, i.e., the discharge of the first capacitor C1 is controlled to be completed, and the voltage across the first capacitor C1 and the second capacitor C2 is equalized.
[0065] When the voltage across the first capacitor C1 and the second capacitor C2 is not equal, for example, the voltage across the first capacitor C1 is lower than the voltage across the second capacitor C2, at this time, the third switch circuit 350 can be controlled to be opened and the fourth switch circuit 370 can be controlled to be closed, and the second capacitor C2 is selected to be discharged. The specific discharge process is that the current flows from the first end (i.e., the positive electrode) of the second capacitor C2, through the third unidirectional conducting circuit 360, the fourth switch circuit 370, and the second DC-DC circuit 200, and finally returns to the second end (i.e., the negative electrode) of the second capacitor C2, forming a discharge loop of the second capacitor C2. When the voltage across the first capacitor C1 and the second capacitor C2 is equal, the fourth switch circuit 370 is controlled to be opened, i.e., the discharge of the second capacitor C2 is controlled to be completed, and the voltage across the first capacitor C1 and the second capacitor C2 is equalized.
[0066] In some embodiments, as shown in FIG. 6, when the number of series-connected capacitors is three, the voltage equalization adjustment process is consistent with the above-mentioned embodiments, which will not be repeated here. Figure 4
[0067] In some embodiments, as shown in FIG. 6, when the number of series-connected capacitors is three, the voltage equalization adjustment process is consistent with the above-mentioned embodiments, which will not be repeated here. Figure 5
[0068] In some embodiments, the specific circuit topology of the first voltage sampling circuit 410 is not limited, as long as it has the function of collecting the voltage across the first capacitor C1. Optionally, the first voltage sampling circuit 410 can be a voltage dividing resistor sampling circuit. Similarly, the specific circuit topology of the second voltage sampling circuit 420 is not limited, as long as it has the function of collecting the voltage across the second capacitor C2. Optionally, the second voltage sampling circuit 420 can also be a voltage dividing resistor sampling circuit.
[0069] In some embodiments, the capacitor voltage equalization circuit 10 further comprises a control circuit 500. The control circuit 500 is connected to the switch selection circuit 300, the first voltage sampling circuit 410 and the second voltage sampling circuit 420, respectively. In some embodiments, the specific circuit topology of the control circuit 500 is not limited, for example, the control circuit 500 can be a controller, an integrated chip, etc. The control circuit 500 can determine whether to output a driving signal according to the voltages collected by the first voltage sampling circuit 410 and the second voltage sampling circuit 420, so as to control the switch selection circuit 300 to act according to the preset logic, so that the voltages across the first capacitor C1 and the second capacitor C2 are equalized.
[0070] Please refer to Figure 6 An embodiment of the present application provides a capacitor voltage equalization module 20. The capacitor voltage equalization module 20 comprises the capacitor voltage equalization circuit 10 in any of the above embodiments. The capacitor voltage equalization module 20 can control the first capacitor or the second capacitor to discharge through the switch selection circuit, and form a discharge small loop with the corresponding first DCDC circuit or second DCDC circuit, so as to utilize the corresponding first DCDC circuit or second DCDC circuit for voltage equalization, so that the energy of the first capacitor or the second capacitor is fully utilized through the DCDC circuit, without additional loss, thereby improving the power supply efficiency.
[0071] The technical features of the above embodiments can be combined in any way. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not exist, they should be considered as the scope of the present application.
[0072] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the utility model patent. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.
Claims
1. A capacitor voltage equalization circuit, characterized by, comprise: a first capacitor; a first DCDC circuit, a first end of the first DCDC circuit being connected with a first end of the first capacitor; a second DCDC circuit, a first end of the second DCDC circuit being connected with a second end of the first DCDC circuit; a second capacitor, a first end of the second capacitor being connected with a second end of the second DCDC circuit; and a switch selection circuit, a first end of the switch selection circuit being connected with a second end of the second capacitor and a second end of the first capacitor, a second end of the switch selection circuit being connected with the first end of the second DCDC circuit and the second end of the first DCDC circuit; when voltages across the first capacitor and the second capacitor are not equal, the switch selection circuit controls the first capacitor or the second capacitor to discharge, so that the voltages across the first capacitor and the second capacitor are equal.
2. The capacitor voltage equalization circuit of claim 1, wherein, The switch selection circuit comprises: a first switch circuit, a first end of the first switch circuit being connected with a second end of the second capacitor and a second end of the first capacitor; a first unidirectional conduction circuit, a cathode of the first unidirectional conduction circuit being connected with a second end of the first switch circuit; a second switch circuit, a first end of the second switch circuit being connected with the second end of the second capacitor and the second end of the first capacitor; and a second unidirectional conduction circuit, an anode of the second unidirectional conduction circuit being connected with a second end of the second switch circuit, a cathode of the second unidirectional conduction circuit being connected with an anode of the first unidirectional conduction circuit, the first end of the second DCDC circuit and the second end of the first DCDC circuit; when the first switch circuit is closed and the second switch circuit is open, the first capacitor discharges, and when the first switch circuit is open and the second switch circuit is closed, the second capacitor discharges.
3. The capacitor voltage equalization circuit of claim 2, wherein, The first switch circuit and the second switch circuit are both controllable switch tubes.
4. The capacitor voltage equalization circuit of claim 2, wherein, The first unidirectional conduction circuit and the second unidirectional conduction circuit are both diodes.
5. The capacitor voltage equalization circuit of claim 1, wherein, The switch selection circuit comprises: a third switch circuit; a third unidirectional conduction circuit, an anode of the third unidirectional conduction circuit being connected with a first end of the third switch circuit, a second end of the second capacitor and a second end of the first capacitor; a fourth switch circuit; and a fourth unidirectional conduction circuit, a cathode of the fourth unidirectional conduction circuit being connected with a first end of the fourth switch circuit, a cathode of the third unidirectional conduction circuit and a second end of the third switch circuit, an anode of the fourth unidirectional conduction circuit being connected with a second end of the fourth switch circuit, the first end of the second DCDC circuit and the second end of the first DCDC circuit; when the third switch circuit is closed and the fourth switch circuit is open, the first capacitor discharges, and when the third switch circuit is open and the fourth switch circuit is closed, the second capacitor discharges.
6. The capacitor voltage equalization circuit of claim 5, wherein, The third switch circuit and the fourth switch circuit are both controllable switch tubes.
7. The capacitor voltage equalization circuit of claim 5, wherein, The third unidirectional conduction circuit and the fourth unidirectional conduction circuit are both diodes.
8. The capacitor voltage equalization circuit of claim 1, wherein, Further comprising: a first voltage sampling circuit, a first end of the first voltage sampling circuit being connected with a first end of the first capacitor, and a second end of the first voltage sampling circuit being connected with a second end of the first capacitor; and a second voltage sampling circuit, a first end of the second voltage sampling circuit being connected with a first end of the second capacitor, and a second end of the second voltage sampling circuit being connected with a second end of the first capacitor.
9. The capacitor voltage equalization circuit of claim 8, wherein, Further comprising: a control circuit, the control circuit being connected with the switch selection circuit, the first voltage sampling circuit and the second voltage sampling circuit respectively.
10. A capacitor voltage equalization module, comprising: The capacitor voltage equalization circuit comprises the capacitor voltage equalization circuit according to any one of claims 1-9.