Magnetic Flux Leakage Self-Excited Drive Virtual Parallel Battery Equalization Circuit, System and Control Method

Abstract

The present invention discloses a magnetic leakage self-excited drive virtual parallel battery equalization circuit, system and control method, which relates to the technical field of battery equalization. The magnetic leakage self-excited drive virtual parallel battery equalization circuit is provided with a magnetic reset unit, a plurality of magnetic leakage equalization units and a plurality of self-excited drive units, and has the characteristics of simple circuit, small volume and low cost. Moreover, in the present invention, after an initial drive signal of a switching tube in the first magnetic leakage equalization unit is provided by an external circuit, a positive feedback drive signal is generated by the self-excited drive unit to drive the conduction and cut-off of the switching tubes in other magnetic leakage equalization units, so as to realize self-excited drive, and further realize the automatic equalization of virtual parallel batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of battery equalization, and particularly to a magnetic leakage self-excited drive virtual parallel battery equalization circuit, system and control method. Background Art

[0002] With the wide application of various green energy technologies, the energy storage link becomes increasingly important. At present and for some time in the future, using chemical batteries is still an important way of energy storage. In practical applications, multiple single cells are often connected in series to form a battery pack for use.

[0003] Due to the consistency differences of each single cell, there are also differences in temperature, charge and discharge current, etc. during use. And after long-term use, the wear degrees of each series-connected battery will have large differences, resulting in different performances and voltages of each single cell. In practical use, connecting single cells with inconsistent performances in series will lead to inconsistent charge and discharge degrees of each single cell, resulting in overcharge and over-discharge, which will seriously affect the service life and performance of the entire battery pack, and even cause damage to the battery pack.

[0004] To solve the problem of voltage imbalance caused by inconsistent losses of each single cell in the battery pack after long-term use, the existing solution is to adopt a Battery Management System (BMS). This system uses a large number of voltage, current and temperature sensors to monitor each battery in real time. The control unit will formulate a battery equalization scheme according to the loss situation of each battery, and perform voltage equalization on each battery during charging and discharging to make the wear speeds of each group of batteries tend to be the same, so as to achieve the purpose of voltage equalization. However, the battery equalization system uses a large number of sensors, the circuit is complex, the voltage algorithms for managing and equalizing each single cell are complex, the system calculation and operation costs are high, and a large number of control parameters will also reduce the reliability.

[0005] The virtual parallel battery equalization circuit utilizes a multi-winding transformer to achieve the virtual parallel connection of each single battery. Each single battery corresponds to a winding and a switching tube. The coil parameters and turns of the windings are the same and are coupled together through a high-frequency magnetic core to achieve the function of automatic voltage equalization. Although the ordinary virtual parallel battery equalization circuit has the following advantages: ① Since each single battery is virtually paralleled, automatic voltage equalization can be achieved without a large number of sensors and complex equalization algorithms; ② For the virtually paralleled single batteries, voltage equalization with large current can be achieved; ③ Voltage equalization can be achieved in all states of the battery pack, including static, charging, and discharging. However, the ordinary virtual parallel battery equalization circuit includes a large number of switching tubes, which requires a corresponding large number of mutually isolated drive signals to be set, resulting in a complex structure of the isolation drive circuit, and thus making the circuit bulky and costly. Moreover, due to the relatively complex structure of the virtual parallel equalization circuit, it is also difficult to perform quantitative analysis and calculation of parameters such as its equalization current. Summary of the Invention

[0006] To solve the above problems existing in the prior art, the present invention provides a magnetic leakage self-excited drive virtual parallel battery equalization circuit, system, and control method that can achieve self-excited drive and has the characteristics of simple structure, small size, and low cost.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A magnetic leakage self-excited drive virtual parallel battery equalization circuit includes: a magnetic reset unit, a plurality of magnetic leakage equalization units, and a plurality of self-excited drive units; the number of the magnetic leakage equalization units is 1 more than the number of the self-excited drive units;

[0009] Each of the self-excited drive units includes: a self-excited winding;

[0010] Each of the magnetic leakage equalization units includes: an equalization winding, a freewheeling diode, and a switching tube;

[0011] The positive electrode of the freewheeling diode is connected to the drain of the switching tube; the negative electrode of the freewheeling diode is connected to the positive electrode of a single battery in the parallel battery pack; the source of the switching tube and the negative electrode of the single battery in the parallel battery pack are both grounded; the equalization winding is connected in parallel with the freewheeling diode; the terminals of the self-excited winding and the terminals of the equalization winding are of the same name; the self-excited winding is used to generate a positive feedback drive signal; the switching tube is used to open and close based on the drive signal;

[0012] The initial drive signal of the first magnetic leakage equalization unit is provided by an external circuit;

[0013] The magnetic reset unit is arranged in matching with one of the magnetic leakage type equalizing units; one end of the magnetic reset unit is connected to the positive electrode of the battery pack; the other end of the magnetic reset unit is grounded.

[0014] Optionally, the inductance of the equalizing winding includes: a magnetically coupled inductance and a magnetic leakage inductance; the magnetically coupled inductance is the main inductance, and the magnetic leakage inductance is the associated inductance;

[0015] One end of the equalizing winding is connected to the drain of the switching transistor; the other end of the equalizing winding is connected to the positive electrode of the single cell;

[0016] The magnetic leakage inductance is Le: Le <= L / (n - 1), where L is the inductance of the equalizing winding and n is the total number of magnetic leakage type equalizing units.

[0017] Optionally, the terminals of the magnetically coupled inductance and the terminals of the self-excited winding are of the same name.

[0018] Optionally, the magnetic reset unit includes: a magnetic reset winding and a diode;

[0019] One end of the magnetic reset winding is connected to the positive electrode of the diode; the negative electrode of the diode is connected to the positive electrode of the battery pack; the other end of the magnetic reset winding is grounded.

[0020] Optionally, the terminals of the magnetically coupled inductance in the magnetic leakage type equalizing unit that is arranged in matching with the magnetic reset unit and the terminals of the magnetic reset winding are of opposite names.

[0021] Optionally, the m-th self-excited driving unit further includes: an isolation resistor and an anti-interference resistor;

[0022] One end of the isolation resistor is connected to one end of the self-excited winding; the other end of the isolation resistor and one end of the anti-interference resistor are both connected to the gate of the switching transistor in the (m + 1)-th magnetic leakage type equalizing unit; the other end of the anti-interference resistor and the other end of the self-excited winding are both connected to the source of the switching transistor in the (m + 1)-th magnetic leakage type equalizing unit; m = 1, 2,..., n, where n is the total number of magnetic leakage type equalizing units.

[0023] Optionally, the number of turns of both the magnetically coupled inductance and the magnetic leakage inductance is n 1 ; the number of turns of the self-excited winding is n 3 ; where U G is the conduction voltage of the switching transistor, and E is the rated working voltage of the single cell.

[0024] Optionally, the number of turns of the magnetic reset winding is n 2 ; where

[0025] A multi-winding drive system includes the circuit provided above.

[0026] A magnetic leakage self-excited drive virtual parallel battery equalization control method includes:

[0027] Judging whether the battery pack is static according to the battery pack and the design parameters of the equalization circuit; the equalization circuit is the magnetic leakage self-excited drive virtual parallel battery equalization circuit provided above;

[0028] When the battery pack is static, controlling the duty cycle of the equalization current in the equalization circuit to remain unchanged;

[0029] When the battery pack discharges, increasing the duty cycle of the equalization current in the equalization circuit;

[0030] When the battery pack discharges, decreasing the duty cycle of the equalization current in the equalization circuit.

[0031] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0032] The magnetic leakage self-excited drive virtual parallel battery equalization circuit provided by the present invention is provided with a magnetic reset unit, a plurality of magnetic leakage equalization units and a plurality of self-excited drive units, and has the characteristics of simple circuit, small volume and low cost. Moreover, in the present invention, after the initial drive signal of the switch tube in the first magnetic leakage equalization unit is provided by the external circuit, the self-excited drive unit generates a positive feedback drive signal to drive the conduction and cut-off of the switch tubes in other magnetic leakage equalization units, realizing self-excited drive, and further realizing the automatic equalization of virtual parallel batteries. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 It is the structural schematic diagram of the magnetic leakage self-excited drive virtual parallel battery equalization circuit provided by the present invention;

[0035] Figure 2 It is the schematic diagram of the series battery pack equivalent to a virtual parallel circuit provided by the present invention;

[0036] Figure 3 It is the implementation flowchart of the magnetic leakage self-excited drive virtual parallel battery equalization control method provided by the present invention. Detailed Embodiments

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] The object of the present invention is to provide a magnetic leakage self-excited drive virtual parallel battery equalization circuit, system and control method with the characteristics of simple structure, small volume and low cost, which can realize self-excited drive.

[0039] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0040] Embodiment 1

[0041] This embodiment provides a magnetic leakage self-excited drive virtual parallel battery equalization circuit, including: a magnetic reset unit, a plurality of magnetic leakage equalization units and a plurality of self-excited drive units. The number of magnetic leakage equalization units is 1 more than the number of self-excited drive units.

[0042] Each self-excited drive unit includes: a self-excited winding.

[0043] Each magnetic leakage equalization unit includes: an equalization winding, a freewheeling diode and a switching tube.

[0044] The positive pole of the freewheeling diode is connected to the drain of the switching tube. The negative pole of the freewheeling diode is connected to the positive pole of the single battery in the parallel battery pack. The source of the switching tube and the negative pole of the single battery in the parallel battery pack are both grounded. The equalization winding is connected in parallel with the freewheeling diode. The terminals of the self-excited winding and the equalization winding are the same name terminals. The self-excited winding is used to generate a positive feedback drive signal. The switching tube is used to open and close based on the drive signal.

[0045] The initial drive signal of the first magnetic leakage equalization unit is provided by an external circuit.

[0046] The magnetic reset unit is arranged in a matching manner with a magnetic leakage equalization unit. One end of the magnetic reset unit is connected to the positive pole of the battery pack. The other end of the magnetic reset unit is grounded.

[0047] For example, when the magnetic leakage self-excited drive virtual parallel battery equalization circuit is applied to a battery pack composed of n series-connected single battery units, as Figure 1As shown in the figure, it includes: n equalizing units, n - 1 self-exciting windings, 1 magnetic reset winding, and an external drive signal. Among them, each single-cell unit includes a single cell connected in series and the internal resistance of the single cell. Each single-cell unit is connected in parallel with an equalizing unit. Each equalizing unit includes an equalizing winding and a switching tube connected in series. The first n - 1 equalizing windings starting from the negative electrode of the battery pack are respectively provided with self-exciting windings with the same name ends. The nth equalizing winding is provided with a magnetic reset winding with opposite name ends. The magnetic reset winding is connected to the positive electrode of the battery pack through a diode. The external drive signal is used to drive the switching tube in the first equalizing unit starting from the negative electrode of the battery pack. For the switching tubes in the second equalizing unit to the nth equalizing unit, the gate of the switching tube in the mth equalizing unit is connected to the positive pole of the self-exciting winding corresponding to the (n + 2 - m)th equalizing unit, and the source of the switching tube in the mth equalizing unit is connected to the negative pole of the self-exciting winding corresponding to the (n + 2 - m)th equalizing unit.

[0048] Furthermore, the inductance of the equalizing winding includes: a magnetically coupled inductance and a leakage inductance. The magnetically coupled inductance is the main inductance, and the leakage inductance is the associated inductance.

[0049] One end of the equalizing winding is connected to the drain of the switching tube. The other end of the equalizing winding is connected to the positive electrode of the single cell. Among them, the terminals of the magnetically coupled inductance and the terminals of the self-exciting winding are the same name ends.

[0050] The leakage inductance is Le: Le <= L / (n - 1), where L is the inductance of the equalizing winding and n is the total number of leakage-type equalizing units.

[0051] The number of turns of both the magnetically coupled inductance and the leakage inductance is n 1 . The number of turns of the self-exciting winding is n 3 . Among them, U G is the conduction voltage of the switching tube, and E is the rated working voltage of the single cell, approximately equal to U / n (the virtual parallel voltage divided by n).

[0052] Furthermore, the magnetic reset unit includes: a magnetic reset winding and a diode.

[0053] One end of the magnetic reset winding is connected to the positive electrode of the diode. The negative electrode of the diode is connected to the positive electrode of the battery pack. The other end of the magnetic reset winding is grounded.

[0054] Among them, the terminals of the magnetically coupled inductance in the leakage-type equalizing unit matching the magnetic reset unit and the terminals of the magnetic reset winding are opposite name ends. The number of turns of the magnetic reset winding is n 2 . Among them,

[0055] Furthermore, the mth self-exciting drive unit further includes: an isolation resistor and an anti-interference resistor.

[0056] One end of the isolation resistor is connected to one end of the self-excited winding. The other end of the isolation resistor and one end of the anti-interference resistor are both connected to the gate of the switching transistor in the (m + 1)-th magnetic leakage type equalizing unit. The other end of the anti-interference resistor and the other end of the self-excited winding are both connected to the source of the switching transistor in the next magnetic leakage type equalizing unit. m = 1, 2,..., n, where n is the total number of magnetic leakage type equalizing units.

[0057] Embodiment 2

[0058] In this embodiment, taking into account the internal resistance of the single cell and the accompanying magnetic leakage inductance as an example, the specific structure and working principle of the magnetic leakage type self-excited drive virtual parallel battery equalizing circuit provided in Embodiment 1 above will be described.

[0059] As Figure 1 shown, n single cells V B1 , V B2 ,..., V Bn are connected in series, and the internal resistances of the single cells are R 1 , R 2 ,..., R n .

[0060] Each single cell V B1 , V B2 ,..., V Bn is respectively connected to an equalizing winding, a freewheeling diode D 1 , D 2 ,..., D n and a switching transistor S 1 , S 2 ,..., S n . The equalizing windings are all designed with a magnetically coupled inductance L 1 , L 2 ,..., L n and a magnetic leakage inductance L k1 , L k2 ,..., L kn . The magnetically coupled inductance amount L 1 = L 2 = L n = L c , and the number of turns of the magnetically coupled inductance and the magnetic leakage inductance in the equalizing winding is n 1 , and the magnetic leakage inductance amount L k1 = L k2 = L kn = L k . The equalizing winding inductance L = L c + L k .

[0061] G 1 、G2 ,..., G n are respectively the drive signals of switching transistors S 1 , S 2 ,..., S n . The drive signal G1 is provided by an external circuit, and the drive signals G 2 ,..., G n are driven by positive feedback through the self-excitation windings. The number of turns of each self-excitation winding is n 3 .

[0062] The number of turns of the magnetic reset winding is n 2 , and it is connected to the positive pole V of the battery pack through the diode D bat .

[0063] The same-named ends of each equalization winding, self-excitation winding, and magnetic reset winding are as Figure 1 shown

[0064] Based on the structure of the magnetic leakage self-excitation drive virtual parallel battery equalization circuit provided in this embodiment, its self-excitation drive principle is as follows:

[0065] The drive signal G 1 is provided with a conduction signal by an external circuit to drive the switching transistor S 1 to conduct. The magnetic core magnetic flux increases, and each self-excitation winding induces a voltage to generate drive signals G 2 ,..., G n to drive the switching transistors S 2 ,..., S n to conduct. At this time, the magnetic leakage self-excitation drive virtual parallel battery equalization circuit enters the virtual parallel automatic equalization state.

[0066] The drive signal G1 is provided with a cut-off signal by an external circuit to drive the switching transistor S 1 to cut off. Due to the freewheeling effect of the magnetic leakage inductor L k1 , the excitation current i e1 rapidly decreases. It is designed that the decrease amount of i e1 is greater than or equal to the increase amount of the sum of the remaining excitation currents i e2 ,..., i en . Then the induced voltage of each self-excitation winding is negative or 0, so as to drive the switching transistors S 2 ,..., S n to cut off. At this time, the magnetic leakage self-excitation drive virtual parallel battery equalization circuit exits the virtual parallel automatic equalization state.

[0067] Based on the above structure, the equalization current calculation formula is:

[0068]

[0069] In the formula, E 1 , E2 , E n represents the voltage of the single battery V B1 , V B2 ,..., V Bn . U is the virtual parallel voltage, and g 1 , g 2 ,..., g n represent the conductances of each equalizing circuit, which is the reciprocal of the equalizing circuit resistance. The equalizing circuit resistance is composed of the internal resistance of the single battery, the internal resistance of the equalizing winding, and the internal resistance of the connecting wire in series. i e1 , i e2 ,..., i en is the exciting current of each equalizing winding. I 1 , I 2 ,..., I n is the equalizing current of each equalizing winding, and t is the time. Figure 1 The i 1 ~i n are respectively the sum currents of each exciting current and each equalizing current.

[0070] Since the sum of the equalizing currents of each equalizing winding is zero, that is:

[0071]

[0072] So there is:

[0073]

[0074] Among them, i e is the total exciting current.

[0075] Since the virtual parallel voltage U is basically constant and the change range is small, the exciting current can increase approximately linearly. The exciting current starts from zero in each cycle, that is:

[0076]

[0077] From formula (1), it can be obtained that:

[0078]

[0079] The virtual parallel voltage U is:

[0080]

[0081] Each exciting current is:

[0082]

[0083]

[0084] Each equalizing current is:

[0085]

[0086]

[0087]

[0088] Furthermore, in order to achieve more precise control, in this embodiment, the design requirements for the leakage inductance are as follows:

[0089] Switching transistor S 1 When it is turned off instantaneously by an external control signal, each exciting current is i e / n.

[0090] At this time, for the switching transistor S 1 the exciting current of the corresponding externally controlled exciting winding starts to decrease, with a change rate of -U / Le, and the change amount is: -U / Le × i e / n.

[0091] The exciting currents of the other n - 1 self-excited drive windings still increase at the original change rate, with a change rate of U / L, and the change amount is: (n - 1)U / L × i e / n.

[0092] Therefore, -U / Le × i e / n + (n - 1)U / L × i e / n ≤ 0.

[0093] That is, the design requirement for the leakage inductance is obtained: Le ≤ L / (n - 1). Where Le is the leakage inductance.

[0094] Since the normal leakage magnetic flux of a general transformer winding is about 1%, it can meet the requirements of leakage magnetic self-excited drive for battery packs with the number of battery series less than or equal to 100.

[0095] For battery packs with the number of battery series greater than 100, for the switching transistor S 1 the leakage magnetic flux of the corresponding externally controlled drive winding requires special design to meet the design requirements of the leakage inductance. For example, the winding coil is wound on the innermost layer, and PQ series magnetic cores, magnetic cans or magnetic rings with small leakage magnetic flux are used.

[0096] For battery packs with the number of battery series greater than 100, they can also be split into multiple battery packs with the number of battery series less than 100 for balancing.

[0097] Furthermore, in this embodiment, the design requirements for the self-excited drive winding are:

[0098] The self-excited drive winding is connected to the gate of the switching transistor directly through a series isolation resistor and a parallel anti-interference resistor, and its negative pole is connected to the source of the switching transistor directly. Without other circuits such as diodes, the circuit structure can be simplified.

[0099] The number of turns n of the self-excited drive winding 3 Satisfies: Wherein, U G Is the conduction voltage of the switching transistor, usually taken as 12V. E is the rated working voltage of the single cell.

[0100] Furthermore, in this embodiment, the design requirements of the magnetic reset winding are:

[0101] The magnetic reset winding is also called the degaussing winding. The function of magnetic reset (degaussing) is: after n switching transistors are turned off, the excitation energy of the equalizing winding is fed to the battery pack to make the magnetic field strength of the equalizing winding zero. Therefore, after the switching transistor is turned off, it must wait for a time not less than the magnetic reset time t f Before it can be turned on again.

[0102] When n switching transistors are turned off, the excitation currents of the n equalizing windings are all i e / n, and the magnetic reset current is:

[0103] The magnetic reset time t f And the number of turns n of the magnetic reset winding 2 Satisfies:

[0104] Also:

[0105] So t f And n 2 Satisfies: Wherein, t on Is the conduction time of the switching transistor.

[0106] Therefore, the maximum duty cycle of the external control signal is: When The maximum duty cycle is about 80%. During the magnetic reset time t f Until the time before the next cycle of conduction, the circuit stops equalizing, which is beneficial to depolarization and thus beneficial to extending the battery life.

[0107] Embodiment Three

[0108] This embodiment provides a multi-winding drive system, including the magnetic leakage type self-excited drive circuit provided in the above Embodiment One or Embodiment Two, so as to be applicable to the multi-winding drive situation in other circuits.

[0109] Embodiment Four

[0110] In this embodiment, the series battery pack is equivalent to a circuit with virtual parallel connection, as Figure 2 shown. V B1 ~V Bn are individual cells, R 1 ~R n are the internal resistances of individual cells, and i b1 ~i bn is the superposition of charge and discharge current and balancing current. Figure 2 The U T in represents the virtual parallel voltage after equivalence.

[0111] Due to various reasons, the performance aging degrees of individual cells are different, manifested as the obvious increase in the internal resistance of the cell with poor performance.

[0112] When the battery pack is in the charging state, the charging currents of individual cells are the same, but the terminal voltage of the cell with poor performance is significantly higher. At this time, the magnetic leakage self-excited drive virtual parallel battery balancing circuit provided in Embodiment 1 or Embodiment 2 starts to work, and the balancing current of the cell with a higher terminal voltage is larger and significantly cancels out the charging current, seriously affecting the charging effect. Therefore, when the battery pack is in the charging state, the duty ratio of the balancing current should be appropriately reduced, that is, appropriately reduced compared with the duty ratio of the balancing current when the battery pack is in the static state.

[0113] When the battery pack is in the discharging state, the discharge currents of individual cells are the same, the terminal voltage of the cell with poor performance is significantly lower, and the energy supply is significantly insufficient. At this time, the balancing circuit works, and the duty ratio of the balancing current needs to be appropriately increased, that is, appropriately increased compared with the duty ratio of the balancing current when the battery pack is in the static state, to supplement the insufficient energy supply of the cell with poor performance.

[0114] The implementation process of the specific control strategy is as Figure 3 shown.

[0115] Embodiment 5

[0116] Based on the control strategy of the duty ratio of the balancing current during charge and discharge provided in Embodiment 4, this embodiment provides a magnetic leakage self-excited drive virtual parallel battery balancing control method, which includes:

[0117] Step 100: Determine whether the battery pack is static according to the design parameters of the battery pack and the balancing circuit. Among them, the balancing circuit is the magnetic leakage self-excited drive virtual parallel battery balancing circuit provided in Embodiment 1 or Embodiment 2 above.

[0118] Step 101: When the battery pack is static, keep the duty ratio of the balancing current in the balancing circuit unchanged.

[0119] Step 102: When the battery pack discharges, moderately increase the duty cycle of the balancing current in the balancing circuit.

[0120] Step 103: When the battery pack discharges, moderately decrease the duty cycle of the balancing current in the balancing circuit.

[0121] In this embodiment, the range of increase or decrease of the duty cycle can be 10% - 20%. During actual use, the amount of increase or decrease of the duty cycle can be adaptively set, and no specific limitation is provided here.

[0122] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0123] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention. At the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A magnetic flux leakage self-excited drive virtual parallel battery equalization circuit, Characterized in that, Comprising: A magnetic reset unit, a plurality of magnetic flux leakage equalization units and a plurality of self-excited drive units; The number of the magnetic flux leakage equalization units is 1 more than the number of the self-excited drive units; Each of the self-excited drive units includes: a self-excited winding; Each of the magnetic flux leakage equalization units includes: an equalization winding, a freewheeling diode and a switching tube; The positive pole of the freewheeling diode is connected to the drain of the switching tube; the negative pole of the freewheeling diode is connected to the positive pole of a single cell in the parallel battery pack; the source of the switching tube and the negative pole of the single cell in the parallel battery pack are both grounded; the equalization winding is connected in parallel with the freewheeling diode; the terminals of the self-excited winding and the terminals of the equalization winding are of the same name; the self-excited winding is used to generate a positive feedback drive signal; the switching tube is used to open and close based on the drive signal; The initial drive signal of the first magnetic flux leakage equalization unit is provided by an external circuit; The magnetic reset unit is arranged in matching with one of the magnetic flux leakage equalization units; one end of the magnetic reset unit is connected to the positive pole of the battery pack; the other end of the magnetic reset unit is grounded; The inductance of the equalization winding includes: a magnetically coupled inductance and a magnetic flux leakage inductance; the terminals of the magnetically coupled inductance and the terminals of the self-excited winding are of the same name; The m-th self-excited drive unit further includes: an isolation resistor and an anti-interference resistor; One end of the isolation resistor is connected to one end of the self-excited winding; the other end of the isolation resistor and one end of the anti-interference resistor are both connected to the gate of the switching tube in the (m + 1)-th magnetic flux leakage equalization unit; the other end of the anti-interference resistor and the other end of the self-excited winding are both connected to the source of the switching tube in the (m + 1)-th magnetic flux leakage equalization unit; m = 1, 2,..., n.

2. The magnetic flux leakage self-excited drive virtual parallel battery equalization circuit according to claim 1, Characterized in that, The magnetically coupled inductance is the main inductance, and the magnetic flux leakage inductance is the associated inductance; One end of the equalization winding is connected to the drain of the switching tube; the other end of the equalization winding is connected to the positive pole of the single cell; The magnetic flux leakage inductance is Le: Le <= L / (n - 1), where L is the inductance of the equalization winding and n is the total number of the magnetic flux leakage equalization units.

3. The magnetic flux leakage self-excited drive virtual parallel battery equalization circuit according to claim 2, Characterized in that, The magnetic reset unit includes: a magnetic reset winding and a diode; One end of the magnetic reset winding is connected to the positive pole of the diode; the negative pole of the diode is connected to the positive pole of the battery pack; the other end of the magnetic reset winding is grounded.

4. The magnetic flux leakage self-excited drive virtual parallel battery equalization circuit according to claim 3, Characterized in that, The terminals of the magnetically coupled inductance in the magnetic flux leakage equalization unit arranged in matching with the magnetic reset unit and the terminals of the magnetic reset winding are of opposite names.

5. The magnetic flux leakage self-excited drive virtual parallel battery equalization circuit according to claim 1, Characterized in that, The number of turns of both the magnetic coupling inductor and the leakage magnetic inductor is n 1 ; the number of turns of the self-excited winding is n 3 ; where U G is the conduction voltage of the switching tube, and E is the rated working voltage of the single cell 6. The magnetic flux leakage self-excited drive virtual parallel battery equalization circuit according to claim 5, Characterized in that, The number of turns of the magnetic reset winding is n 2 ; wherein, 7. A multi-winding drive system, characterized in that, it includes the circuit described in any one of claims 1-6.

8. A magnetic leakage self-excited drive virtual parallel battery equalization control method, characterized in that, the control method includes: judging whether the battery pack is static according to the battery pack and the design parameters of the equalization circuit; the equalization circuit is the magnetic leakage self-excited drive virtual parallel battery equalization circuit described in any one of claims 1-6; when the battery pack is static, controlling the duty cycle of the equalization current in the equalization circuit to remain unchanged; when the battery pack discharges, increasing the duty cycle of the equalization current in the equalization circuit; when the battery pack discharges, decreasing the duty cycle of the equalization current in the equalization circuit.

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