DC-DC multi-winding flyback battery equalization topology unit equalization topology structure

Abstract

The invention relates to the field of active equalization of a series lithium ion battery pack, in particular to an equalization topological structure of a DC-DC multi-winding flyback battery equalization topological unit. Comprising an inversion unit, a multi-winding transformer and M battery equalization topology units. The voltage of the battery pack is used for supplementing electric energy to the under-voltage battery after passing through the converter, so that the aim of equalization is fulfilled. Compared with the existing flyback equalization technology, the switching frequency is improved to ultrahigh frequency of 10MHz, the equalization response speed is greatly improved, and meanwhile, the soft switching technology is adopted, so that the full-control switches are switched on in a zero-voltage manner, and the diodes are switched off in a zero-current manner. Along with the improvement of the switching frequency, the passive device can be reduced into a small-capacity patch package, for example, a planar air-core transformer can be adopted as a transformer, so that the power density is effectively improved. The circuit has the advantages of simple and reliable structure, fast response capability, few passive devices, small circuit loss, strong expansibility and stable output of direct current.

Description

Technical Field

[0001] The invention relates to the field of active balancing of series-connected lithium-ion battery packs, and in particular to a DC-DC multi-winding flyback battery balancing topology unit balancing topology structure. Background Art

[0002] Lithium-ion batteries are widely used in energy applications such as electric vehicles and energy storage systems. However, due to various reasons such as the production process, the use environment and the properties of the materials themselves, the battery cells in the same battery pack will have differences in performance parameters such as voltage and capacity, which leads to the situation that some cells are filled or discharged first during the charge and discharge process of the battery pack, that is, the imbalance of the battery pack.

[0003] The imbalance of the battery pack will bring many disadvantages, such as reducing the efficiency of the entire battery pack, reducing the service life, and even causing safety accidents. Therefore, it has become an important task to take balanced management measures for the battery pack to maintain the capacity of the battery pack and extend the life of the battery pack.

[0004] Battery pack balancing technology can be mainly divided into passive balancing technology and active balancing technology. Passive balancing technology mainly achieves the purpose of balancing by releasing the electrical energy of higher voltage cells. This method has a simple structure, but has large losses and wastes energy. Active balancing technology achieves balancing by transferring electrical energy from high voltage cells to low voltage cells. This technology can effectively improve the utilization rate of electrical energy. One type of active balancing is one of the key research directions of active balancing in the future - using DC-DC converters for battery balancing. At present, this technology still has disadvantages such as large circuit size, complex control, and a large number of passive components.

[0005] Therefore, the very high frequency (VHF) DC converter technology based on the soft switching technology, that is, the switching frequency is increased to the megahertz level. The present invention proposes a DC-DC multi-winding flyback battery balancing topology unit balancing topology structure. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of large loss, large circuit volume, complex control and large number of passive components in the prior art, and to provide a DC-DC multi-winding flyback battery balancing topology unit balancing topology structure.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: A DC-DC multi-winding flyback battery balancing topology unit balancing topology structure includes an inverter unit, a multi-winding transformer, and M groups of battery balancing topology units, M≥2; The inverter unit is electrically connected to the primary side of the multi-winding transformer through a full-control switch; the inverter unit is used to convert the constant DC output of the battery balancing topology unit into an AC output; the switching frequency of the full-control switch is greater than or equal to 10 MHz; The secondary side of the multi-winding transformer is electrically connected to each of the battery balancing topology units respectively; Each group of the battery balancing topology units includes a rectifier unit, a gating switch and two balancing paths connected in sequence; the rectifier unit is used to convert the AC input voltage into a constant DC output; the gating switch is used to control the balancing path connected to the rectifier unit; the balancing path includes a single cell and a filter capacitor connected in parallel to the single cell; the single cells of different battery balancing topology units are connected in series in sequence.

[0008] As a preferred solution of the present invention, the secondary side of the multi-winding transformer includes M secondary windings, and each secondary winding is connected to a group of the battery balancing topology units.

[0009] As a preferred solution of the present invention, the balancing topology structure includes 2M single cells connected in series in sequence, and the positive electrode and the negative electrode of the series-connected battery group are respectively connected to the two ends of the inverter unit.

[0010] As a preferred solution of the present invention, the inverter unit includes a first resonant capacitor, a first resonant inductor and a full-control switch connected in series in sequence; One end of the first resonant capacitor is connected to the negative electrode of the series battery pack; the other end of the first resonant capacitor is connected to the first end of the full-control switch as the negative electrode of the AC output; One end of the first resonant inductor is connected to the positive electrode of the series battery pack, and the other end is the positive electrode of the AC output; The second end of the full-control switch is connected to the negative electrode of the series-connected battery pack.

[0011] As a preferred solution of the present invention, the fully-controlled switch adopts N-channel MOSFET, P-channel MOSFET or GaNFET, the first end of the fully-controlled switch is the drain, the second end is the source, and the third end is the gate.

[0012] As a preferred embodiment of the present invention, the multi-winding transformer includes a primary winding and M secondary windings; One end of the primary winding is connected to the positive electrode of the inverter unit; the other end of the primary winding is connected to the negative electrode of the inverter unit; and the primary winding of the multi-winding transformer also includes a leakage inductance, which is used to provide to the first resonant inductance; The first end of each secondary winding serves as the positive pole of the AC output, and the second end serves as the negative pole of the AC output.

[0013] As a preferred solution of the present invention, the rectifying unit comprises a second capacitor, a first gate switch, a second gate switch, a first diode and a second diode; One end of the second capacitor, the first end of the first gate switch and the cathode of the second diode are commonly connected to the positive electrode of the secondary winding; the other end of the second capacitor is connected to the negative electrode of the secondary winding as the negative electrode of the first output; The anode of the second diode is connected to the second end of the second gate switch; the first end of the second gate switch serves as the negative electrode of the second output of the rectifier unit; The second end of the first selection switch is connected to the anode of the first diode; the cathode of the first diode serves as the positive electrode of the first output of the rectifier unit; the negative electrode of the first output and the positive electrode of the second output are the same end; The positive pole of the first output of the kth rectifier unit is connected to the positive pole of the 2k-1th single cell; the positive pole of the second output of the kth rectifier unit is connected to the positive pole of the 2kth single cell; the negative pole of the second output of the kth rectifier unit is connected to the negative pole of the 2kth single cell.

[0014] As a preferred solution of the present invention, the gating switch is an N-channel MOSFET or a P-channel MOSFET, the first end of the gating switch is a drain, the second end is a source, and the third end is a gate.

[0015] As a preferred solution of the present invention, the parasitic capacitance of the gate switch, the first diode and the second diode is absorbed by the second capacitor.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention relates to the field of active balancing of series-connected lithium-ion battery packs, and in particular to a DC-DC multi-winding flyback battery balancing topology unit balancing topology structure. It includes an inverter unit, a multi-winding transformer, and M groups of battery balancing topology units. The voltage of the battery pack is passed through a converter to supplement the undervoltage battery with electric energy, so as to achieve the purpose of balancing. Compared with the existing flyback balancing technology, the switching frequency is increased to an ultra-high frequency of 10MHz, which greatly improves the response speed of balancing. At the same time, the soft switching technology is adopted to enable the full-controlled switch to be turned on with zero voltage and the diode to be turned off with zero current. With the increase of the switching frequency, its passive components can be reduced to a small-capacity patch package. For example, the transformer can adopt a planar air-core transformer, thereby effectively improving the power density. It has the advantages of simple and reliable structure, fast response capability, few passive components, small circuit loss, strong expansibility and stable output of DC current. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1It is a structural electrical schematic diagram of a DC-DC multi-winding flyback battery balancing topology unit balancing topology structure described in Example 1 of the present invention; Figure 2 An electrical schematic diagram of a DC-DC multi-winding flyback battery balancing topology unit balancing topology structure according to Embodiment 2 of the present invention; Figure 3 A DC-DC three-winding flyback ultra-high frequency battery balancing circuit diagram in a DC-DC multi-winding flyback battery balancing topology unit balancing topology structure described in Embodiment 3 of the present invention; Figure 4 In the balancing topology structure of a DC-DC multi-winding flyback battery balancing topology unit described in Embodiment 3 of the present invention Figure 3 The first type of working mode diagram of the DC-DC three-winding flyback ultra-high frequency battery balancer provided; Figure 5 In the balancing topology structure of a DC-DC multi-winding flyback battery balancing topology unit described in Embodiment 3 of the present invention Figure 3 The second type of working mode diagram of the DC-DC three-winding flyback ultra-high frequency battery balancer provided; Figure 6 A simulation circuit diagram of a DC-DC three-winding flyback ultra-high frequency battery equalizer in a DC-DC multi-winding flyback battery equalization topology unit equalization topology structure described in Embodiment 3 of the present invention; Figure 7 In the balancing topology structure of a DC-DC multi-winding flyback battery balancing topology unit described in Embodiment 3 of the present invention Figure 6 The voltage and current waveforms of the first fully-controlled switch Q1 in the simulation circuit diagram shown; Figure 8 In the balancing topology structure of a DC-DC multi-winding flyback battery balancing topology unit described in Embodiment 3 of the present invention Figure 6 The current waveform diagram flowing through the diode D2 in the simulation circuit diagram shown; Fig. 9 In the balancing topology structure of a DC-DC multi-winding flyback battery balancing topology unit described in Embodiment 3 of the present invention Figure 6 The waveform of the balanced current output to B1 in the simulation circuit diagram shown. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with test examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0019] Example 1 like Figure 1As shown, a DC-DC multi-winding flyback battery balancing topology unit balancing topology structure includes an inverter unit, a multi-winding transformer, and M groups of battery balancing topology units, M≥2; The inverter unit is electrically connected to the primary side of the multi-winding transformer via a full-control switch; the inverter unit is used to convert the constant DC output of the battery balancing topology unit into an AC output; the switching frequency of the full-control switch is greater than or equal to 10 MHz.

[0020] The secondary sides of the multi-winding transformer are electrically connected to each of the battery balancing topology units respectively.

[0021] Each group of the battery balancing topology units includes a rectifier unit, a gating switch and two balancing paths connected in sequence; the rectifier unit is used to convert the AC input voltage into a constant DC output; the gating switch is used to control the balancing path connected to the rectifier unit; the balancing path includes a single cell and a filter capacitor connected in parallel to the single cell; the single cells of different battery balancing topology units are connected in series in sequence.

[0022] Example 2 This embodiment is a specific implementation of a DC-DC multi-winding flyback battery balancing topology unit balancing topology structure described in Example 1. The DC-DC multi-winding flyback battery balancing topology unit balancing topology structure includes an inverter unit, a multi-winding transformer, and M groups of battery balancing topology units, where M≥2.

[0023] Furthermore, the inverter unit is electrically connected to the primary side of the multi-winding transformer via a fully-controlled switch; the inverter unit is used to convert the constant DC output of the battery balancing topology unit into an AC output; and the switching frequency of the fully-controlled switch is greater than or equal to 10 MHz.

[0024] Furthermore, the inverter unit includes a first resonant capacitor, a first resonant inductor and a full-control switch connected in series in sequence; one end of the first resonant capacitor is connected to the negative electrode of the series battery group; the other end of the first resonant capacitor is connected to the first end of the full-control switch, serving as the negative electrode of the AC output; one end of the first resonant inductor is connected to the positive electrode of the series battery group, and the other end is the positive electrode of the AC output; the second end of the full-control switch is connected to the negative electrode of the series battery group.

[0025] Furthermore, the fully-controlled switch adopts N-channel MOSFET, P-channel MOSFET or GaN FET, the first end of the fully-controlled switch is the drain, the second end is the source, and the third end is the gate.

[0026] Furthermore, the secondary side of the multi-winding transformer is electrically connected to each of the battery balancing topology units respectively; the secondary side of the multi-winding transformer includes M secondary windings, and each secondary winding is connected to a group of the battery balancing topology units.

[0027] Furthermore, the multi-winding transformer includes a primary winding and M secondary windings; one end of the primary winding is connected to the positive pole of the inverter unit; the other end of the primary winding is connected to the negative pole of the inverter unit; and the primary winding of the multi-winding transformer also includes a leakage inductance, which is provided to the first resonant inductor; the first end of each secondary winding serves as the positive pole of the AC output, and the second end serves as the negative pole of the AC output.

[0028] Furthermore, each group of the battery balancing topology units includes a rectifier unit, a gating switch and two balancing paths connected in sequence; the rectifier unit is used to convert the AC input voltage into a constant DC output; the gating switch is used to control the balancing path connected to the rectifier unit; the balancing path includes a single cell and a filter capacitor connected in parallel to the single cell; the single cells of different battery balancing topology units are connected in series in sequence.

[0029] Furthermore, the balancing topology structure includes 2M single cells connected in series in sequence, and the positive electrode and the negative electrode of the series-connected battery group are respectively connected to the two ends of the inverter unit.

[0030] Further, the rectifying unit includes a second capacitor, a first gate switch, a second gate switch, a first diode and a second diode; One end of the second capacitor, the first end of the first gate switch and the cathode of the second diode are commonly connected to the positive electrode of the secondary winding; the other end of the second capacitor is connected to the negative electrode of the secondary winding as the negative electrode of the first output; The anode of the second diode is connected to the second end of the second gate switch; the first end of the second gate switch serves as the negative electrode of the second output of the rectifier unit; The second end of the first selection switch is connected to the anode of the first diode; the cathode of the first diode serves as the positive electrode of the first output of the rectifier unit; the negative electrode of the first output and the positive electrode of the second output are the same end; The positive pole of the first output of the kth rectifier unit is connected to the positive pole of the 2k-1th single cell; the positive pole of the second output of the kth rectifier unit is connected to the positive pole of the 2kth single cell; the negative pole of the second output of the kth rectifier unit is connected to the negative pole of the 2kth single cell.

[0031] Furthermore, the gating switch is an N-channel MOSFET or a P-channel MOSFET, the first end of the gating switch is a drain, the second end is a source, and the third end is a gate.

[0032] Furthermore, the parasitic capacitance of the gate switch, the first diode and the second diode is absorbed by the second capacitor.

[0033] like Figure 2 As shown, the figure provides a DC-DC multi-winding flyback ultra-high frequency battery balancing structure, including two or more battery balancing topology units, the energy required for single cell balancing comes from the series battery group, which is isolated by a multi-winding transformer, and a first fully controlled switch is connected in series with the primary side of the multi-winding transformer, which generates AC through a high-frequency switch, thereby transferring energy to the secondary side of the multi-winding transformer. If there are 2M (M≥2) single cells, the secondary side of the multi-winding transformer has M windings, each winding provides two channels for balancing two batteries, and each balancing path is equipped with a gating switch, which controls whether the balancing path is turned on or not, and only one balancing path is turned on at one time. Example 3 like Figure 3 As shown, this embodiment proposes a DC-DC multi-winding flyback ultra-high frequency battery balancing structure with M=2, and the multi-winding transformer adopts a three-winding transformer T 1 .

[0034] The series battery pack includes four batteries connected in series in sequence, which are B 1 , B 2 , B 3 , B 4 ,in B 1 positive electrode is used as the positive electrode of the series battery pack, B 4 The negative electrode is used as the negative electrode of the series battery pack. At the same time, each single cell is connected in parallel with a filter capacitor, which are C O1 , C O2 , C O3 , C O4 .

[0035] The inverter unit includes a first inductor L 1 , the first full control switch Q 1 , the first capacitor C1 The first inductor L 1 One end of the first fully controlled switch is connected to the positive electrode of the battery pack, and the other end is connected to the primary side of the three-winding transformer. Q 1 The first end is connected to the other primary side of the three-winding transformer, and the first fully controlled switch Q 1 The second end is connected to the negative electrode of the battery pack, and at the same time, the first full-control switch Q 1 The first capacitor is connected in parallel on both sides C 1 。 In the first full control switch Q 1 Under high-frequency switching, the inverter unit is connected to the first resonant inductor L 1 With the first resonant capacitor C 1 The resonance outputs an AC voltage through a transformer.

[0036] The DC-DC three-winding flyback ultra-high frequency battery balancing circuit includes two rectifier units. The first rectifier unit includes a second capacitor C 2. First selection switch S 1. Second selection switch S 2. The first diode D 1 and the second diode D 2 The second capacitor C 2 One end and the first gate switch S 1 The first end of the second diode D 2 The cathodes of the second diodes are connected to the positive electrode of the secondary winding of the three-winding transformer. D 2 The anode of the second gate switch S 2 The second gate switch S 2 The first end of the second capacitor is used as the negative electrode of the second output of the rectifier unit. C 2 The other end of is connected to the negative electrode of the secondary winding of the three-winding as the negative electrode of the first output. The negative electrode of the first output is the same as the positive electrode of the second output. S 1 The second end and the first diode D 1 The anode of the first diode is connected.D 1 The cathode of the second rectifier unit is used as the positive electrode of the first output of the rectifier unit. The second rectifier unit includes a third capacitor C 3 , the third selection switch S 3 , the fourth selection switch S 4 , the third diode D 3 and the fourth diode D 4 The third capacitor C 3 One end and the third gate switch S 3 The first end of the fourth diode D 4 The cathodes of the fourth diode are connected to the positive electrode of the secondary winding of the three-winding transformer. D 4 The anode of the fourth gate switch S 4 The fourth selection switch S 4 The first end of the fourth capacitor is used as the negative electrode of the fourth output of the rectifier unit. C 4 The other end of is connected to the negative electrode of the secondary winding of the three windings as the negative electrode of the third output. The negative electrode of the third output and the positive electrode of the fourth output are the same end. S 3 The second end and the third diode D 3 The anode of the third diode D 3 The cathode serves as the positive electrode of the third output of the rectifier unit.

[0037] Preferably, the filter capacitor is used to filter the output voltage and remove clutter to ensure the stability of the output current.

[0038] like Figure 4 and Figure 5 As shown, this embodiment takes three windings as an example to illustrate two types of working modes of a multi-winding flyback ultra-high frequency battery balancing circuit, and each case is described in detail below.

[0039] 1) The first type of working mode like Figure 4 As shown, when the battery B1 needs to be balanced, the first full-control switch Q1 and the gate switch S1 are turned on to charge and balance the battery cell B1 with a constant current of 0.1c.

[0040] 2) The second working mode like Figure 5 As shown, when the battery B2 needs to be balanced, the first full-control switch Q1 and the gate switch S2 are turned on to charge and balance the battery cell B2 with a constant current of 0.1c.

[0041] The same is true when other batteries need to be balanced. The battery balancing is simple and direct, and the circuit is simple, the response speed is fast, and the loss is small. In addition, a single secondary winding can manage two battery cells through a gate switch, and the winding utilization rate is high.

[0042] On the basis of the above embodiment, the first fully-controlled switch Q1 is an N-channel MOSFET. When the type of the fully-controlled switch is an N-channel MOSFET, the specific connection relationship is as follows: the gate of the N-channel MOSFET serves as the third terminal of the fully-controlled switch, the source of the N-channel MOSFET serves as the first terminal of the fully-controlled switch, and the drain of the N-channel MOSFET serves as the second terminal of the fully-controlled switch.

[0043] On the basis of the above embodiment, the first fully-controlled switch Q1 is a P-channel MOSFET. When the type of the fully-controlled switch is a P-channel MOSFET, the specific connection relationship is as follows: the gate of the P-channel MOSFET serves as the third terminal of the fully-controlled switch, the drain of the P-channel MOSFET serves as the first terminal of the fully-controlled switch, and the source of the N-channel MOSFET serves as the second terminal of the fully-controlled switch.

[0044] On the basis of the above embodiment, the first fully-controlled switch Q1 is a GaN FET. When the type of the fully-controlled switch is a GaN FET, the specific connection relationship is as follows: the gate of the GaN FET serves as the third terminal of the fully-controlled switch, the drain of the GaN FET serves as the first terminal of the fully-controlled switch, and the source of the GaN FET serves as the second terminal of the fully-controlled switch.

[0045] It is understandable that, in addition to the above-mentioned types of fully-controlled switches, other types of switch devices may also be used, which will not be described in detail in the present invention.

[0046] This embodiment takes three windings as an example to conduct a simulation test on a DC-DC multi-winding flyback ultra-high frequency DC converter. Figure 6 As shown in the figure, it is the simulation circuit diagram of the flyback ultra-high frequency DC converter device in this simulation test example. V 1 , V 2 Indicates a voltmeter, A 1 , A 2 , A 3and represents the ammeter. In this simulation test example, the voltage amplitude of the DC input of the four-battery group is 16-18V, and the switching frequency f s =10MHz, duty cycle a=0.5. Capacitor C 1 The value is 1583pF, the capacitance C 2 The capacitance value is 99pF and the inductance L 1 The output capacitor is 100nH. C o Value divided into 100μF.

[0047] Figure 7 for Figure 6 The first full-control switch in the simulation circuit diagram Q 1 The voltage and current waveform diagram, where curve V1 represents the first fully controlled switch Q 1 Voltage waveform at both ends, curve I 1 Indicates that the current flows through the first full-control switch Q 1 Current waveform. It can be seen that at the moment the switch is turned on and off, the voltage and current waveforms have no intersection, indicating that soft switching is achieved at a switching frequency of 10MHz.

[0048] Figure 8 for Figure 6 Diode in simulation circuit diagram D 2 The current waveform at both ends is shown in the figure. I 2 This means that the current flowing through the diode D 2 As can be seen from the figure, the current changes smoothly and the diode is naturally turned off, thus achieving zero current shutdown and reducing losses.

[0049] Fig. 9 for Figure 6 The simulation circuit diagram shows the output B 1 The balanced current waveform diagram. I 3 That means battery B 1 The balanced current waveform is shown in Figure 2. It can be seen that the current remains stable with small ripple, and the battery cell is charged with a constant current, ensuring the stability of the battery cell.

[0050] According to the above test results, the present invention has the advantages of simple and reliable structure, fast response capability, few passive components, small circuit loss, strong expandability and stable output DC current.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A DC-DC multi-winding flyback battery balancing topology unit balancing topology structure, characterized in that: It includes an inverter unit, a multi-winding transformer, and M groups of battery balancing topology units, where M≥2; The inverter unit is electrically connected to the primary side of the multi-winding transformer through a full-control switch; the inverter unit is used to convert the constant DC output of the battery balancing topology unit into an AC output; the switching frequency of the full-control switch is greater than or equal to 10 MHz; The secondary side of the multi-winding transformer is electrically connected to each of the battery balancing topology units respectively; Each group of the battery balancing topology units includes a rectifier unit, a gating switch and two balancing paths connected in sequence; the rectifier unit is used to convert the AC input voltage into a constant DC output; the gating switch is used to control the balancing path connected to the rectifier unit; the balancing path includes a single cell and a filter capacitor connected in parallel to the single cell; the single cells of different battery balancing topology units are connected in series in sequence.

2. A DC-DC multi-winding flyback battery balancing topology unit balancing topology structure according to claim 1, characterized in that: The secondary side of the multi-winding transformer includes M secondary windings, and each secondary winding is connected to a group of the battery balancing topology units.

3. A DC-DC multi-winding flyback battery balancing topology unit balancing topology structure according to claim 2, characterized in that: The balancing topology structure includes 2M single cells connected in series in sequence, and the positive electrode and the negative electrode of the series-connected battery group are respectively connected to the two ends of the inverter unit.

4. A DC-DC multi-winding flyback battery balancing topology unit balancing topology structure according to claim 3, characterized in that: The inverter unit comprises a first resonant capacitor, a first resonant inductor and a full-control switch connected in series in sequence; One end of the first resonant capacitor is connected to the negative electrode of the series battery pack; the other end of the first resonant capacitor is connected to the first end of the full-control switch as the negative electrode of the AC output; One end of the first resonant inductor is connected to the positive electrode of the series battery pack, and the other end is the positive electrode of the AC output; The second end of the full-control switch is connected to the negative electrode of the series-connected battery pack.

5. A DC-DC multi-winding flyback battery balancing topology unit balancing topology structure according to any one of claim 4, characterized in that: The fully-controlled switch adopts N-channel MOSFET, P-channel MOSFET or GaN FET, the first end of the fully-controlled switch is the drain, the second end is the source, and the third end is the gate.

6. A DC-DC multi-winding flyback battery balancing topology unit balancing topology structure according to claim 5, characterized in that: The multi-winding transformer includes a primary winding and M secondary windings; One end of the primary winding is connected to the positive electrode of the inverter unit; the other end of the primary winding is connected to the negative electrode of the inverter unit; and the primary winding of the multi-winding transformer also includes a leakage inductance, which is used to provide to the first resonant inductance; The first end of each secondary winding serves as the positive pole of the AC output, and the second end serves as the negative pole of the AC output.

7. A DC-DC multi-winding flyback battery balancing topology unit balancing topology structure according to any one of claims 3 to 6, characterized in that: The rectifying unit comprises a second capacitor, a first gate switch, a second gate switch, a first diode and a second diode; One end of the second capacitor, the first end of the first gate switch and the cathode of the second diode are commonly connected to the positive electrode of the secondary winding; the other end of the second capacitor is connected to the negative electrode of the secondary winding as the negative electrode of the first output; The anode of the second diode is connected to the second end of the second gate switch; the first end of the second gate switch serves as the negative electrode of the second output of the rectifier unit; The second end of the first selection switch is connected to the anode of the first diode; the cathode of the first diode serves as the positive electrode of the first output of the rectifier unit; the negative electrode of the first output and the positive electrode of the second output are the same end; The positive pole of the first output of the kth rectifier unit is connected to the positive pole of the 2k-1th single cell; the positive pole of the second output of the kth rectifier unit is connected to the positive pole of the 2kth single cell; the negative pole of the second output of the kth rectifier unit is connected to the negative pole of the 2kth single cell.

8. A DC-DC multi-winding flyback battery balancing topology unit balancing topology structure according to claim 7, characterized in that: The gate switch is an N-channel MOSFET or a P-channel MOSFET, the first end of the gate switch is a drain, the second end is a source, and the third end is a gate.

9. A DC-DC multi-winding flyback battery balancing topology unit balancing topology structure according to claim 8, characterized in that: The parasitic capacitance of the gate switch, the first diode and the second diode is absorbed by the second capacitor.

Images