Forward and flyback full-flow path high-capacity efficient equalization topology and control method

Abstract

The invention provides a forward-flyback full-circulation path high-capacity efficient equalization topology and a control method, and relates to the technical field of battery equalization management, and the method comprises the steps that only one multi-winding transformer is needed, and each battery pack corresponds to one transformer winding; the number of primary windings of the transformers is not increased along with the increase of the number of the batteries, and the number of the transformers is not increased along with the increase of the number of the battery packs; adjacent batteries share one pair of MOSFETs, so that nearly 50% of MOSFETs can be reduced; in addition, the equalizer provided by the invention can realize total energy flow paths between any batteries, between any battery monomer and a battery pack, between any battery packs and between any battery pack and the whole energy storage system, and can be flexibly applied to various conditions. Compared with an existing equalization topology, the equalizer provided by the invention is smaller in size and lower in cost, can select and match an equalization mode, and can be applied to a large-scale energy storage system.

Description

Technical Field

[0001] This disclosure relates to the field of battery equalization management technology, specifically to a high-capacity, high-efficiency equalization topology and control method for a full-flow path for both forward and reverse excitation. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] To meet the high voltage and large capacity requirements of electric vehicles, battery packs consist of hundreds of battery cells connected in series. While this series connection increases the total voltage and capacity of the battery pack, it also introduces inconsistencies. Consequently, these inconsistencies severely degrade the performance of the battery pack, ultimately leading to a decrease in the driving range of the electric vehicle and the lifespan of the battery pack. Therefore, implementing certain balancing controls for the battery pack is essential.

[0004] In battery balancing circuits, passive balancing is suitable for large-scale battery packs due to its simple structure and low cost, but it suffers from problems such as heat dissipation and slow balancing speed. Active balancing overcomes the shortcomings of passive balancing by transferring energy from higher-energy battery cells to lower-energy battery cells through an external balancing circuit. Based on different topologies, active balancing circuits can be classified into the following types: transformer-type balancing, inductive-capacitive balancing, and DC-DC converter-type balancing.

[0005] Among existing methods, one balancing topology is based on a dual-multi-winding flyback transformer. However, this scheme requires two transformer windings for each battery cell, resulting in high cost, complex structure, and limited energy flow paths, failing to achieve cell-to-cell balancing. Another balancing topology is based on a single-winding flyback transformer, but this scheme cannot achieve cell-to-cell energy flow, and all cells are connected in series in the primary winding, which can easily lead to excessive current and safety hazards.

[0006] In summary, most existing equilibrium topologies employ a single equilibrium path, hindering flexible energy flow. Furthermore, in flyback transformer-based equilibrium topologies, each individual cell corresponds to a single primary side, resulting in high costs and limiting their application in large-scale battery packs. Summary of the Invention

[0007] To address the aforementioned issues, this disclosure proposes a high-capacity, high-efficiency equalization topology and control method with a full-flow path, utilizing both forward and flyback converters. Individual cells within the battery pack share a switch array, enabling energy flow between any individual cells within the pack, between different battery packs, and between any individual cell and a battery pack, all while reducing MOSFETs by nearly 50%. The transformer forward converter allows for energy flow between the battery pack and the entire system, while the transformer flyback converter enables energy flow between the battery pack and the entire system, thus achieving a full energy flow path and improving the flexibility and efficiency of equalization. Furthermore, each battery pack corresponds to a primary winding of a transformer, and the entire energy system corresponds to a single transformer, reducing the number of transformers from n to 1. Moreover, the number of primary windings does not increase with the number of individual cells within the battery pack, and the number of transformers does not increase with the number of battery packs, significantly reducing the cost and size of the equalization system.

[0008] According to some embodiments, the present disclosure adopts the following technical solutions: The high-capacity, high-efficiency, balanced topology with full-flow path for both forward and reverse flyback includes a lithium battery pack, a switch array, a multi-winding transformer, and a data processing module. The lithium battery pack includes multiple battery packs, each containing multiple individual cells. All individual cells are numbered and distinguished as odd or even. Odd-numbered individual cells are connected to each other, and even-numbered individual cells are connected to each other. Each primary side of the multi-winding transformer is sequentially connected to each battery pack and battery cell via a switch array, and the secondary side is connected to the entire lithium battery pack via a switch tube. The switch array includes multiple sets of switch transistor assemblies, and adjacent individual cells share a set of switch transistor assemblies. All odd and even cells in the entire battery pack are connected to the primary side of the same multi-winding transformer using a pair of odd and even switch transistor assemblies. The data processing module is used to collect and process analog signals of lithium battery pack voltage, temperature and winding current, and control the switching transistor assembly to turn on and off based on the analog signals of lithium battery pack voltage, temperature and winding current, thereby forming different energy flow paths to achieve battery balancing.

[0009] Furthermore, the switch array includes four sets of switch transistor assemblies, two of which are connected to the positive and negative terminals of the primary winding and the positive terminal of the odd-numbered individual cells and the negative terminal of the even-numbered individual cells, respectively. The other two sets of switch transistor assemblies are connected to the positive and negative terminals of the primary winding and the positive terminal of the even-numbered individual cells and the negative terminal of the odd-numbered individual cells, respectively.

[0010] Furthermore, the four sets of switching transistor assemblies are the first set of switching transistor assemblies, the second set of switching transistor assemblies, the third set of switching transistor assemblies, and the fourth set of switching transistor assemblies. The first set of switching transistor assemblies is composed of two switching transistors connected in reverse series. The first set of switching transistor assemblies is connected to the positive terminal of the odd-numbered individual cells and the positive terminal of the primary winding, and the fourth set of switching transistor assemblies is connected to the positive terminal of the odd-numbered individual cells and the negative terminal of the primary winding. The second set of switching transistor assemblies is connected to the positive terminal of the even-numbered individual cells and the positive terminal of the primary winding, and the third set of switching transistor assemblies is connected to the positive terminal of the even-numbered individual cells and the negative terminal of the primary winding.

[0011] Furthermore, all the switching transistors in the switch array are MOSFET switching transistors, and the switch array is used to select the battery cells connected to the transformer and the connection direction.

[0012] Furthermore, the data processing module includes a signal acquisition and processing module and a control module. The signal acquisition and processing module acquires and processes analog signals of lithium battery pack voltage, temperature, and winding current, and converts them into digital signals that the microcontroller can process. The control module includes a microcontroller that controls the operation of the switching transistor assembly. The microcontroller integrates an equalization strategy and a PWM control unit. The PWM control unit controls the switching transistor assembly to turn on and off, thereby forming different energy flow paths to achieve battery equalization.

[0013] According to some embodiments, the present disclosure adopts the following technical solutions: The high-capacity, high-efficiency equalization topology control method with full-flow path for both forward and reverse excitation has three working states for equalization within the battery pack: cell to cell, cell to pack, and pack to cell. Each working state has three modes, and the control method for each mode is as follows: In Cell to cell equalization mode I, the switching transistor assembly connecting the individual cell to the primary side of the multi-winding transformer is controlled to turn on, while the other switching transistor assemblies are turned off. The individual cell discharges, charging the primary coil, and the magnetic flux increases negatively. The primary coil generates a negative induced electromotive force, and the discharge current of the individual cell gradually increases from zero. In Cell to cell equalization mode II, the control requires the switching transistor assembly that connects the charging cell to the primary side of the multi-winding transformer to be turned on, while all other switching transistor assemblies are turned off. At this time, the primary coil generates a positive induced electromotive force to charge the cell, and the charging current gradually decreases until it is zero. Under Cell to cell equalization mode III, the state of the switching transistor assembly is the same as that under Cell to cell equalization mode II, ensuring that the circuit operates in DCM discontinuous mode and ensuring that the primary winding of the multi-winding transformer is completely demagnetized within one equalization cycle.

[0014] Furthermore, in Cell to pack equalization mode I, the control requires the switching transistor assembly that connects the discharged single cell to the primary side of the multi-winding transformer to turn on, while all other switching transistor assemblies are turned off. At this time, the primary coil generates a negative induced electromotive force, the magnetic flux increases negatively, and the coil charging current gradually increases from zero. In Cell to pack equalization mode II, the switching transistor assembly that controls the entire battery pack and the primary side of the multi-winding transformer is turned on, while the other switching transistor assemblies are turned off. At this time, the primary coil generates a positive induced electromotive force, the magnetic flux decreases in the positive direction, and the coil discharge current gradually decreases until it is zero. In Cell to pack equalization mode III, the state of the switching transistor assembly is the same as in Cell to pack equalization mode II, ensuring that the primary winding of the multi-winding transformer is completely demagnetized within one equalization cycle.

[0015] Furthermore, Pack to cell includes three equalization modes: Pack to cell equalization mode I, Pack to cell equalization mode II, and Pack to cell equalization mode III. The control process is the opposite of the state of the switching transistor in the cell to pack equalization mode.

[0016] Furthermore, the equalization between battery packs also has three working states: pack to pack, pack to string, and string to pack, and each working state includes three equalization modes; In Pack-to-pack balancing mode I, the switching transistor assembly connecting the battery pack to be discharged to the primary winding of the multi-winding transformer is turned on, while the other switching transistor assemblies are turned off. At this time, the primary winding generates an induced electromotive force with positive upper side and negative lower side, the magnetic flux increases positively, and the coil charging current gradually increases from zero. In Pack-to-pack balancing mode II, the switching transistor assembly connecting the battery pack to be charged to the primary winding is turned on, while the other switching transistor assemblies are turned off. At this time, the primary winding generates an induced electromotive force with positive lower side and negative upper side, the magnetic flux decreases positively, and the coil discharge current gradually decreases to zero. In Pack-to-pack balancing mode III, the state of the switching transistor assembly is the same as in Pack-to-pack balancing mode II, ensuring that the secondary winding of the multi-winding transformer is completely demagnetized within one balancing cycle.

[0017] Furthermore, in Pack to string equalization mode I: the switch assembly connected to the primary side of the multi-winding transformer is turned on, while the other switch assemblies are turned off. At this time, the primary coil generates a positive induced electromotive force, the magnetic flux increases in the positive direction, and the coil charging current gradually increases from zero. Pack to string equalization mode II: The entire battery pack is connected to the secondary side of the multi-winding transformer by the switching transistor assembly, and all other switching transistor assemblies are turned off. At this time, the secondary transformer generates a positive induced electromotive force, the magnetic flux decreases in the positive direction, and the coil discharge current gradually decreases to zero. Pack to string equalization mode III: At this time, the state of the switching transistor assembly is the same as that of mode II, ensuring that the secondary winding of the multi-winding transformer is completely demagnetized within one equalization cycle; And String to pack equalization mode I: The entire battery pack is connected to the secondary side of the multi-winding transformer by the switching transistor assembly, and the other switching transistor assemblies are turned off. At this time, the secondary coil generates an induced electromotive force with positive at the top and negative at the bottom, the magnetic flux increases in the positive direction, and the coil charging current gradually increases from zero. String to pack equalization mode II: The switching transistor assembly that needs to be connected to the primary side of the multi-winding transformer is turned on, and all other switching transistor assemblies are turned off. At this time, the primary transformer generates an induced electromotive force with positive at the top and negative at the bottom. The magnetic flux decreases in the positive direction, and the coil discharge current gradually decreases to zero. String to pack Equalization Mode III: At this time, the state of the switching transistor assembly is the same as that of Mode II, ensuring that the secondary winding of the multi-winding transformer is completely demagnetized within one equalization cycle.

[0018] Compared with the prior art, the beneficial effects of this disclosure are as follows: This disclosure presents a high-capacity, high-efficiency equalization topology with a full-flow path for both forward and reverse excitation. The battery cells are directly connected to the primary winding of the transformer through a shared switch array, which makes the equalization energy flow highly flexible and the equalization energy scale highly scalable.

[0019] This disclosure presents a high-capacity, high-efficiency equalization topology with a full-flow path for both forward and reverse excitation. Through the forward converter mode, it realizes energy equalization paths within the battery pack (cell to cell, cell to pack, pack to cell) and within the battery group (pack to pack), improving the flexibility and speed of equalization within the battery pack. Through the flyback converter mode, it realizes the energy flow path between the battery pack and the entire battery group, greatly improving the flexibility and efficiency of equalization.

[0020] This disclosure presents a high-capacity, high-efficiency equalization topology with a full-flow path for both forward and reverse flyback configurations. By dividing the individual cells within a battery pack into odd and even numbers, they share a switch array, reducing the number of switching transistors by nearly half. For a battery pack with n individual cells, this equalization topology requires only (2n+14) MOSFETs and one transformer primary winding. When the number of individual cells in the same battery pack increases, no additional transformer primary winding is needed; similarly, when the number of battery packs increases, no additional transformer is required. This makes it more suitable for large-scale energy equalization systems and significantly reduces the number of components, lowering the size and cost of the equalization topology. Attached Figure Description

[0021] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure.

[0022] Figure 1 This is a schematic diagram of the battery pack equalization topology according to an embodiment of the present disclosure; Figure 2 This is a schematic diagram of the balanced energy flow within the battery pack according to an embodiment of the present disclosure; Figure 3 This is a schematic diagram of the balanced energy flow within the battery pack according to an embodiment of this disclosure; Figure 4 This is a diagram showing the voltage waveform balancing result within the battery pack according to an embodiment of this disclosure; Figure 5 This is a diagram showing the equalization result of the current waveform within the battery pack according to an embodiment of this disclosure; Figure 6 This is a diagram showing the overall voltage waveform balancing result within the battery pack according to an embodiment of this disclosure; Figure 7 This is a diagram showing the overall current waveform balancing result within the battery pack according to an embodiment of this disclosure. Detailed Implementation

[0023] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0024] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this disclosure. Unless otherwise specified, 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 disclosure pertains.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] Example 1 One embodiment of this disclosure provides a high-capacity, high-efficiency balanced topology with a full-flow path for both forward and reverse flyback circuits, including: a lithium battery pack, a switch array, a multi-winding transformer, and a data processing module. The lithium battery pack includes multiple battery packs, each containing multiple individual cells. All individual cells are numbered and distinguished as odd or even. Odd-numbered individual cells are connected to each other, and even-numbered individual cells are connected to each other. Each primary side of the multi-winding transformer is sequentially connected to each battery pack and individual battery cell via a switch array, while the secondary side is connected to the entire lithium battery pack via a switch transistor. The switching array includes multiple sets of switching transistor assemblies, and adjacent individual cells share a set of switching transistor assemblies. All odd and even cells in the entire battery pack are connected to the primary side of the same multi-winding transformer using a pair of odd and even switching transistor assemblies. The data processing module is used to collect and process analog signals of lithium battery pack voltage, temperature and winding current, and control the switching transistor assembly to turn on and off based on the analog signals of lithium battery pack voltage, temperature and winding current, thereby forming different energy flow paths to achieve battery balancing.

[0027] As one embodiment, the lithium battery pack comprises n battery packs, each battery pack containing m individual cells, for a total of nm individual cells, numbered as follows:

[0028] Individual cells within a battery pack are distinguished by parity, while battery packs within a battery assembly are not distinguished by parity. Furthermore, the primary side of the multi-winding transformer is connected to each individual cell in sequence through a switch array, and the secondary side is connected to the entire battery pack and each battery pack through a switch array. The switch array includes (2m+14)n switching transistors, and adjacent battery cells share a set of switching transistor assemblies. All odd and even batteries in the entire battery pack share a pair of odd and even switching assemblies connected to the same primary winding.

[0029] As an alternative implementation, the switch array connected to the primary side of the multi-winding transformer includes four sets of switch components, wherein two sets of switch components are respectively connected to the positive and negative terminals of the primary winding and the positive terminal of the odd-numbered individual cells and the negative terminal of the even-numbered individual cells, and the other two sets of switch components are respectively connected to the positive and negative terminals of the primary winding and the positive terminal of the even-numbered individual cells and the negative terminal of the odd-numbered individual cells.

[0030] The four sets of switching transistor assemblies are designated as the first set, the second set, the third set, and the fourth set. Both the first and fourth sets consist of two switching transistors connected in reverse series. The first set is connected to the positive terminal of the odd-numbered individual cells and the positive terminal of the primary winding, while the fourth set is connected to the positive terminal of the odd-numbered individual cells and the negative terminal of the primary winding. The second set is connected to the positive terminal of the even-numbered individual cells and the positive terminal of the primary winding, while the third set is connected to the positive terminal of the even-numbered individual cells and the negative terminal of the primary winding.

[0031] Specifically, each switching transistor assembly includes two source-connected switching transistors, such as... Figure 1 As shown, the switching transistor and switching transistor The first set of switching transistors is connected in reverse series, and is connected to the positive terminal of the odd-numbered individual cells and the positive terminal of the primary winding; the switching transistors This includes two reverse-connected switching transistors, forming a second switching transistor assembly, connected to the positive terminal of the even-numbered individual cells and the positive terminal of the primary winding; the switching transistors It still includes two reverse-connected switching transistors, forming a third switching transistor assembly, connected to the positive terminal of the even-numbered individual cells and the negative terminal of the primary winding; the switching transistors and switching transistor The reverse series connection forms the fourth group of switching transistors, which are connected to the positive terminal of the odd-numbered individual cells and the negative terminal of the primary winding.

[0032] In one embodiment, the switching transistors in the switching array are all MOSFET switching transistors, and the switching array is used to select the battery cells connected to the transformer and the connection direction.

[0033] Furthermore, the data processing module includes a signal acquisition and processing module and a control module. The signal acquisition and processing module acquires and processes analog signals of lithium battery pack voltage, temperature, and winding current, and converts them into digital signals that the microcontroller can process. The control module includes a microcontroller that controls the operation of the switching transistor assembly. The microcontroller integrates an equalization strategy and a PWM control unit. The PWM control unit controls the switching transistor assembly to turn on and off, thereby forming different energy flow paths to achieve battery equalization.

[0034] As an alternative implementation, a microcontroller is typically used to control the operation of the switching transistor components. The microcontroller integrates an equalization strategy and a PWM control unit, using PWM control signals to control the switching transistor components to turn on and off, thereby creating different energy flow paths to achieve battery equalization. Individual battery information is collected by an AFE chip and sent to the control module. A multi-winding flyback transformer is used.

[0035] As an example, to better illustrate the working process, the following assumptions are made regarding the working process of the high-capacity, high-efficiency balanced topology with full-flow path of the flyback and flip-flops disclosed herein: (1) The side of the transformer connected to the battery pack is the primary side, and the side connected to the entire battery pack is the secondary side.

[0036] (2) On the primary side of the transformer, the current flows out of the individual battery cells in the positive direction; on the secondary side of the transformer, the current flows into the battery pack in the positive direction.

[0037] (3) In the primary and secondary windings of a transformer, the induced electromotive force is positive when the upper side is positive and the lower side is negative.

[0038] In the primary and secondary windings of a transformer, when the current flows from top to bottom, the magnetic flux is positive.

[0039] As one embodiment, the battery pack equalization has three operating states: cell-to-cell, cell-to-pack, and pack-to-cell. Each operating state has three modes, specifically: In Cell to cell equalization mode I, the switching transistor assembly that controls the conduction of the single cell battery and the primary side of the multi-winding transformer is turned on, while the other switching transistor assemblies are turned off. The single cell battery discharges and charges the primary coil, the magnetic flux increases negatively, the primary coil generates a negative induced electromotive force, and the discharge current of the single cell battery gradually increases from zero. In Cell to cell equalization mode II, the control requires the switching transistor assembly that connects the charging cell to the primary side of the multi-winding transformer to be turned on, while all other switching transistor assemblies are turned off. At this time, the primary coil generates a positive induced electromotive force to charge the cell, and the charging current gradually decreases until it is zero. Under Cell to cell equalization mode III, the state of the switching transistor assembly is the same as that under Cell to cell equalization mode II, ensuring that the circuit operates in DCM discontinuous mode and ensuring that the primary winding of the multi-winding transformer is completely demagnetized within one equalization cycle.

[0040] In Cell to pack equalization mode I, the switching transistor assembly that needs to be connected to the primary side of the multi-winding transformer to control the conduction of the single cell that needs to be discharged is turned on, while the other switching transistor assemblies are turned off. At this time, the primary coil generates a negative induced electromotive force, the magnetic flux increases in the negative direction, and the coil charging current gradually increases from zero. In Cell to pack equalization mode II, the switching transistor assembly that controls the entire battery pack and the primary side of the multi-winding transformer is turned on, while the other switching transistor assemblies are turned off. At this time, the primary coil generates a positive induced electromotive force, the magnetic flux decreases in the positive direction, and the coil discharge current gradually decreases until it is zero. In Cell to pack equalization mode III, the state of the switching transistor assembly is the same as in Cell to pack equalization mode II, ensuring that the primary winding of the multi-winding transformer is completely demagnetized within one equalization cycle.

[0041] Pack to cell includes three equalization modes: Pack to cell equalization mode I, Pack to cell equalization mode II, and Pack to cell equalization mode III. The control process is the opposite of the state of the switching transistor in the cell to pack equalization mode.

[0042] As one example, the equalization between battery packs also has three working states: pack to pack, pack to string, and string to pack, and each working state includes three equalization modes; In Pack to pack equalization mode I, the switch tube assembly connected to the primary side of the multi-winding transformer is controlled to turn on the battery pack that needs to be discharged, while the other switch tube assemblies are turned off. At this time, the primary winding generates an induced electromotive force with positive upper and negative lower, the magnetic flux increases in the positive direction, and the coil charging current gradually increases from zero. In Pack-to-pack equalization mode II, the switching transistor assembly connected to the primary winding of the battery pack that needs to be charged is turned on, and the other switching transistor assemblies are turned off. At this time, the primary winding generates a positive lower and negative upper induced electromotive force, the magnetic flux decreases in the positive direction, and the coil discharge current gradually decreases to zero. In Pack to Pack Equalization Mode III, the state of the switching transistor assembly is the same as in Pack to Pack Equalization Mode II, ensuring that the secondary winding of the multi-winding transformer is completely demagnetized within one equalization cycle.

[0043] Pack to string equalization mode I: The switching transistor assembly connected to the primary side of the transformer is turned on, while the other switching transistor assemblies are turned off. At this time, the primary coil generates a positive induced electromotive force, the magnetic flux increases in the positive direction, and the coil charging current gradually increases from zero. Pack to string equalization mode II: The entire battery pack is connected to the secondary side of the transformer by the switching transistor assembly, and all other switching transistor assemblies are turned off. At this time, the secondary transformer generates a positive induced electromotive force, the magnetic flux decreases in the positive direction, and the coil discharge current gradually decreases to zero. Pack to string equalization mode III: At this time, the state of the switching transistor assembly is the same as that of mode II, ensuring that the secondary winding of the multi-winding transformer is completely demagnetized within one equalization cycle; String to pack equalization mode I: The entire battery pack is connected to the secondary side of the multi-winding transformer by the switching transistor assembly, and all other switching transistor assemblies are turned off. At this time, the secondary coil generates an induced electromotive force with positive at the top and negative at the bottom, the magnetic flux increases in the positive direction, and the coil charging current gradually increases from zero. String to pack equalization mode II: The switching transistor assembly that requires the charging battery pack to be connected to the primary side of the transformer is turned on, and all other switching transistor assemblies are turned off. At this time, the primary side transformer generates an induced electromotive force with positive at the top and negative at the bottom. The magnetic flux decreases in the positive direction, and the coil discharge current gradually decreases to zero. String to pack Equalization Mode III: At this time, the state of the switching transistor assembly is the same as that of Mode II, ensuring that the secondary winding of the multi-winding transformer is completely demagnetized within one equalization cycle.

[0044] Example 2 One embodiment of this disclosure provides a control method for a high-capacity, high-efficiency balanced topology with a full-flow path for both forward and reverse flyback paths, comprising: The battery pack equalization has three operating states: cell-to-cell, cell-to-pack, and pack-to-cell. Each operating state has three modes, specifically: Cell to cell equalization mode I: The switching transistor assembly connecting the battery cell to the primary side of the transformer is turned on, while the other switching transistor assemblies are turned off. The battery cell discharges, charging the primary coil. The magnetic flux increases negatively, and the primary coil generates a negative induced electromotive force. The discharge current of the battery cell gradually increases from zero. Cell to cell equalization mode II: The switching transistor assembly that needs to be connected to the primary side of the transformer is turned on, and all other switching transistor assemblies are turned off. At this time, the primary coil generates a positive induced electromotive force to charge the individual battery cell. The charging current gradually decreases until it is zero. Cell to cell equalization mode III: The state of the switching transistor components is the same as that of Cell to cell equalization mode II, ensuring that the circuit operates in DCM discontinuous mode and that the primary winding of the transformer can be completely demagnetized within one equalization cycle.

[0045] As an alternative implementation method, Cell to cell equalization mode I ( In the primary side inductor, the voltage across the inductor coil is... for:

[0046] in, The current in the discharge circuit during mode I. This is the magnetizing inductance for the primary side coil; From Kirchhoff's laws:

[0047] in, , This is the equivalent resistance in the primary side circuit. For a discharging battery, by solving the differential equation, we get:

[0048] Substitute the formula Zhongde:

[0049] As an alternative implementation method, Cell to cell equalization mode II ( In the circuit, the voltage across the primary winding is:

[0050] in, For the current in the charging circuit in Mode II, according to Kirchhoff's laws:

[0051] in, For rechargeable single-cell batteries, among which... By solving the differential equation, we obtain:

[0052] in, From the maximum value It begins to gradually decrease, after The formula for reducing it to 0 is as follows:

[0053]

[0054] As an alternative implementation method, Cell to cell equalization mode III ( In this context, the following conditions must be met:

[0055] Ensure the circuit operates in DCM mode so that the transformer can be completely demagnetized after one switching cycle.

[0056] As one example, such as Figure 2 As shown, since the cell-to-cell balancing process is basically the same, differing only in the on and off states of the switch array, the following explanation uses the discharge and charging of a single battery as an example. Within one PWM cycle, there are three operating modes. The balancing process within the battery pack will be explained in detail below: Cell-to-cell equilibrium mode I ): Switching transistor The circuit is turned on, and all other switching transistors are turned off. The primary winding is kept off at all times to prevent energy from flowing back into the primary winding. At this time, the individual cell... When the primary winding of a transformer is charged, the magnetic flux increases negatively, generating a negative induced electromotive force on the primary side. Since the secondary side is short-circuited, no current flows through it.

[0057] Cell-to-cell equilibrium mode II ): Switching transistor The circuit is on, and all other switching transistors are off, including the switching transistor. Always being turned off effectively prevents energy backflow from the primary winding. At this time, a positive induced electromotive force is generated on the primary side, supplying power to the individual battery cells. During charging, the secondary side is short-circuited, and no current flows.

[0058] Cell-to-cell equilibrium mode III ): During this stage, the state of the switching transistor is basically the same as that of cell-to-cell equalization mode II. During the equalization cycle, the conduction time of different modes needs to be reasonably allocated to ensure that the circuit works in DCM discontinuous mode, so that the primary winding of the transformer can be completely demagnetized after one equalization cycle.

[0059] As one example, cell-to-pack and pack-to-cell equalization also have three working modes, which are described below. Figure 2 Taking cell to pack as an example, that is Explanation of individual battery discharge and overall battery pack charging: cell to pack mode I ( ): Switching transistor When the circuit is turned on, all other switching transistors are turned off. Keeping the primary coil off at all times effectively prevents energy backflow from the primary coil. At this time, the individual cell... Charging the primary coil of the transformer generates a negative induced electromotive force, and there is no energy flow path on the secondary side.

[0060] cell to pack mode II ): Switching transistor When the circuit is turned on, all other switching transistors are turned off. Keeping it off at all times effectively prevents energy backflow from the primary coil. At this time, the primary coil charges the battery pack, generating a positive induced electromotive force, and there is no energy flow path on the secondary side.

[0061] cell to pack mode III ): During this stage, the switching state is basically the same as in cell to pack mode II. During the equalization cycle, the conduction time of different modes needs to be reasonably allocated to ensure that the circuit works in DCM discontinuous mode, so that the primary winding of the transformer can be completely demagnetized after one equalization cycle.

[0062] The Pack to Cell working mode is similar to the Cell to Pack mode, which also changes the state of the switching transistors to change the energy flow path.

[0063] As one example, such as Figure 3 The following is a detailed explanation of the balancing process between battery packs, i.e., within the battery group: The following analysis examines the energy transfer between battery packs, using battery pack 1 discharging and battery pack 2 charging as an example. There are three operating modes: Pack to cell mode I ( ): Battery Pack 1 Internal Switching Transistor When the circuit is turned on, all other switching transistors are turned off. Keeping it off can effectively prevent energy backflow in the circuit. At this time, battery pack 1 charges the primary coil, generating a negative induced electromotive force, and there is no energy flow path on the secondary side.

[0064] Pack to cell mode II ): Battery Pack 2 Internal Switching Transistor When the circuit is turned on, all other switching transistors are turned off. By keeping the circuit off at all times, energy backflow is effectively prevented. At this time, the primary coil charges battery pack 2, generating a positive induced electromotive force, and there is no energy flow path on the secondary side.

[0065] Pack to cell mode III ): During this stage, the switching transistor is in the same state as in Mode II. The conduction time of different modes is reasonably allocated within the equalization cycle to ensure that the circuit works in DCM discontinuous mode, so that the primary winding of the transformer can be completely demagnetized after one equalization cycle.

[0066] As one example, pack to string and string to pack equalization operate in transformer flyback mode, with three operating modes, combined with... Figure 3 Taking "pack to string" as an example, that is, discharging battery pack 1 and charging the entire battery pack, the following explanation is provided: pack to string mode I ( ): Battery Pack 1 Internal Switching Transistor When the circuit is turned on, all other switching transistors are turned off. Keeping it off can effectively prevent energy backflow in the circuit. At this time, battery pack 1 charges the primary coil, generating a positive induced electromotive force, and there is no energy flow path in the other primary windings and secondary side.

[0067] pack to string mode II ( ): During this stage, the switching transistor Conductive, When the switch is turned off, energy backflow can be effectively prevented. All other switches are turned off, and at this time, the secondary coil generates a negative induced electromotive force to charge the entire battery pack.

[0068] pack to string mode III ( ): During this stage, the switching transistor is in the same state as in Mode II. The conduction time of different modes is reasonably allocated within the equalization cycle to ensure that the circuit works in DCM discontinuous mode, so that the primary winding of the transformer can be completely demagnetized after one equalization cycle.

[0069] The working principle of String to pack and pack to string is similar, which also changes the state of the switch and changes the energy flow path. It will not be explained in detail here.

[0070] Simulation Experiment In this embodiment, a battery pack balancing simulation experiment was conducted. The battery pack consists of four battery packs connected in series, and each battery pack contains four individual cells connected in series. The maximum voltage difference within the battery pack is 58mV, and the maximum voltage difference between battery packs is 800mV. The initial voltage distribution of the battery pack is shown in Table 1.

[0071] Table 1 Initial voltage distribution of the battery pack;

[0072] Simulation results for cell-to-pack, pack-to-cell, and cell-to-cell equalization modes within battery pack 1 are as follows: Figure 4 and Figure 5 As shown, as balancing progresses, the voltage difference within the battery pack gradually decreases, with the maximum voltage difference decreasing from 58mV to 1mV. The voltage distribution within this battery pack exhibits a situation where both the maximum and minimum values ​​differ significantly from the mean; therefore, the cell-to-cell balancing mode is chosen for its shorter balancing time.

[0073] Simulation results for equalization modes within the battery pack (i.e., between battery cells) using pack-to-string, string-to-pack, and pack-to-pack modes are as follows: Figure 6 and Figure 7 As shown, the maximum voltage difference decreased from 800mV to 1mV. The voltage distribution within this battery pack exhibits a significant difference between the maximum and minimum values ​​and the mean; therefore, the pack-to-pack balancing mode is used, resulting in a shorter balancing time.

[0074] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0075] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0076] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. A high-capacity, high-efficiency balanced topology with full-flow path for both forward and reverse flyback connections, characterized in that: It includes a lithium battery pack, a switch array, a multi-winding transformer, and a data processing module. The lithium battery pack includes multiple battery packs, each containing multiple individual cells. All individual cells are numbered and distinguished as odd or even. Odd-numbered individual cells are connected to each other, and even-numbered individual cells are connected to each other. Each primary side of the multi-winding transformer is sequentially connected to each battery pack and battery cell via a switch array, and the secondary side is connected to the entire lithium battery pack via a switch tube. The switch array includes multiple sets of switch transistor assemblies, and adjacent individual cells share a set of switch transistor assemblies. All odd and even cells in the entire battery pack are connected to the primary side of the same multi-winding transformer using a pair of odd and even switch transistor assemblies. The data processing module is used to collect and process analog signals of lithium battery pack voltage, temperature and winding current, and control the switching transistor assembly to turn on and off based on the analog signals of lithium battery pack voltage, temperature and winding current, thereby forming different energy flow paths to achieve battery balancing.

2. The high-capacity, high-efficiency balanced topology with full-flow path for both forward and reverse flyback connections as described in claim 1, characterized in that, The switching array includes four sets of switching transistor assemblies. Two sets of switching transistor assemblies are connected to the positive and negative terminals of the primary winding and the positive terminal of the odd-numbered individual cells and the negative terminal of the even-numbered individual cells, respectively. The other two sets of switching transistor assemblies are connected to the positive and negative terminals of the primary winding and the positive terminal of the even-numbered individual cells and the negative terminal of the odd-numbered individual cells, respectively.

3. The high-capacity, high-efficiency balanced topology with full-flow path for both forward and reverse flyback connections as described in claim 2, characterized in that, The four sets of switching transistor assemblies are designated as the first set, the second set, the third set, and the fourth set. Both the first and fourth sets consist of two switching transistors connected in reverse series. The first set is connected to the positive terminal of the odd-numbered individual cells and the positive terminal of the primary winding, while the fourth set is connected to the positive terminal of the odd-numbered individual cells and the negative terminal of the primary winding. The second set is connected to the positive terminal of the even-numbered individual cells and the positive terminal of the primary winding, while the third set is connected to the positive terminal of the even-numbered individual cells and the negative terminal of the primary winding.

4. The high-capacity, high-efficiency balanced topology with full-flow path for both forward and reverse flyback connections as described in claim 1, characterized in that, The switching transistors in the switching array are all MOSFET switching transistors. The switching array is used to select the battery cells connected to the transformer and the connection direction.

5. The high-capacity, high-efficiency balanced topology with full-flow path for both forward and reverse flyback connections as described in claim 1, characterized in that, The data processing module includes a signal acquisition and processing module and a control module. The signal acquisition and processing module acquires and processes analog signals of lithium battery pack voltage, temperature and winding current, and converts them into digital signals that the microcontroller can process. The control module includes a microcontroller, which controls the operation of the switching transistor assembly. The microcontroller integrates an equalization strategy and a PWM control unit. The PWM control unit controls the switching transistor assembly to turn on and off, thereby forming different energy flow paths to achieve battery equalization.

6. A control method based on the high-capacity, high-efficiency balanced topology with full-flow paths according to any one of claims 1-5, characterized in that, The battery pack balancing has three working states: cell to cell, cell to pack, and pack to cell. Each working state has three modes. The control method for each mode is as follows: In Cell to cell balancing mode I, the switching transistor assembly connecting the individual cell to the primary side of the multi-winding transformer is controlled to turn on, while the other switching transistor assemblies are turned off. The individual cell discharges and charges the primary coil. The magnetic flux increases negatively, and the primary coil generates a negative induced electromotive force. The discharge current of the individual cell gradually increases from zero. In Cell to cell equalization mode II, the control requires the switching transistor assembly that connects the charging cell to the primary side of the multi-winding transformer to be turned on, while all other switching transistor assemblies are turned off. At this time, the primary coil generates a positive induced electromotive force to charge the cell, and the charging current gradually decreases until it is zero. Under Cell to cell equalization mode III, the state of the switching transistor assembly is the same as that under Cell to cell equalization mode II, ensuring that the circuit operates in DCM discontinuous mode and ensuring that the primary winding of the multi-winding transformer is completely demagnetized within one equalization cycle.

7. The control method for a high-capacity, high-efficiency balanced topology with full-flow paths as described in claim 6, characterized in that, In Cell to pack balancing mode I, the switching transistor assembly connecting the individual battery cell to be discharged and the primary winding of the multi-winding transformer is turned on, while all other switching transistor assemblies are turned off. At this time, the primary winding coil generates a negative induced electromotive force, the magnetic flux increases negatively, and the coil charging current gradually increases from zero. In Cell to pack balancing mode II, the switching transistor assembly connecting the entire battery pack and the primary winding of the multi-winding transformer is turned on, while all other switching transistor assemblies are turned off. At this time, the primary winding coil generates a positive induced electromotive force, the magnetic flux decreases positively, and the coil discharge current gradually decreases until it reaches zero. In Cell to pack balancing mode III, the state of the switching transistor assembly is the same as in Cell to pack balancing mode II, ensuring that the primary winding of the multi-winding transformer is completely demagnetized within one balancing cycle.

8. The control method for a high-capacity, high-efficiency balanced topology with full-flow paths as described in claim 6, characterized in that, Pack to cell includes three equalization modes: Pack to cell equalization mode I, Pack to cell equalization mode II, and Pack to cell equalization mode III. The control process is the opposite of the state of the switching transistor in the cell to pack equalization mode.

9. The control method for a high-capacity, high-efficiency balanced topology with full-flow paths as described in claim 6, characterized in that, The equalization between battery packs also has three operating states: pack to pack, pack to string, and string to pack, and each operating state includes three equalization modes. In Pack to pack equalization mode I, the switching transistor assembly connecting the battery pack to be discharged to the primary winding of the multi-winding transformer is turned on, while the other switching transistor assemblies are turned off. At this time, the primary winding generates an induced electromotive force with the upper positive and lower negative, the magnetic flux increases positively, and the coil charging current gradually increases from zero. In Pack to pack equalization mode II, the switching transistor assembly connecting the battery pack to be charged to the primary winding is turned on, while the other switching transistor assemblies are turned off. At this time, the primary winding generates an induced electromotive force with the lower positive and upper negative, the magnetic flux decreases positively, and the coil discharge current gradually decreases to zero. In Pack to pack equalization mode III, the state of the switching transistor assembly is the same as in Pack to pack equalization mode II, ensuring that the secondary winding of the multi-winding transformer is completely demagnetized within one equalization cycle.

10. The control method for a high-capacity, high-efficiency balanced topology with full-flow paths as described in claim 9, characterized in that, Pack to string equalization mode I: The switching transistor assembly connected to the primary side of the multi-winding transformer and the battery pack that needs to be discharged is turned on, while the other switching transistor assemblies are turned off. At this time, the primary coil generates a positive induced electromotive force, the magnetic flux increases in the positive direction, and the coil charging current gradually increases from zero. Pack to string equalization mode II: The entire battery pack is connected to the secondary side of the multi-winding transformer by the switching transistor assembly, and all other switching transistor assemblies are turned off. At this time, the secondary transformer generates a positive induced electromotive force, the magnetic flux decreases in the positive direction, and the coil discharge current gradually decreases to zero. Pack to string equalization mode III: At this time, the state of the switching transistor assembly is the same as that of mode II, ensuring that the secondary winding of the multi-winding transformer is completely demagnetized within one equalization cycle; And String to pack equalization mode I: The entire battery pack is connected to the secondary side of the multi-winding transformer by the switching transistor assembly, and the other switching transistor assemblies are turned off. At this time, the secondary coil generates an induced electromotive force with positive at the top and negative at the bottom, the magnetic flux increases in the positive direction, and the coil charging current gradually increases from zero. String to pack equalization mode II: The switching transistor assembly that needs to be connected to the primary side of the multi-winding transformer is turned on, and all other switching transistor assemblies are turned off. At this time, the primary transformer generates an induced electromotive force with positive at the top and negative at the bottom. The magnetic flux decreases in the positive direction, and the coil discharge current gradually decreases to zero. String to pack Equalization Mode III: At this time, the state of the switching transistor assembly is the same as that of Mode II, ensuring that the secondary winding of the multi-winding transformer is completely demagnetized within one equalization cycle.

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