Voltage equalizer integrated with partial power converter topology and control method thereof

Abstract

The application discloses a voltage equalizer and partial power converter integrated topology and a control method thereof, and belongs to the technical field of electrochemical energy storage. The application integrates a switched capacitor equalizer and a DC-DC partial power converter together, realizes the integration of battery pack voltage equalization and voltage regulation functions. The capacitor network is connected with the center points of the first half-bridge circuit and all the second half-bridge circuits, the voltage equalization between all the battery modules is realized by controlling the charging and discharging of the capacitor network. The output voltage of the DC-DC partial power converter is controlled to regulate the output voltage on the DC side, compared with the full power converter, the DC-DC partial power converter only needs to process a part of power in proportion to the output voltage on the DC side, the conversion efficiency is improved, and the size and capacity of the converter are reduced. The application has important significance for realizing the low-cost and miniaturized design of the battery management system.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical energy storage, and in particular to an integrated topology of a voltage equalizer and a partial power converter and a control method thereof. Background Art

[0002] With energy consumption and environmental pollution becoming increasingly severe, the electric vehicle and new energy power generation industries based on battery energy storage are experiencing unprecedented development opportunities. To ensure safe and reliable battery operation and extend its service life, it is crucial to achieve voltage balancing between battery modules within the battery pack using a voltage balancing circuit. Furthermore, the output voltage of a battery pack varies widely, and DC-DC converters play a crucial role in regulating the DC side output voltage range.

[0003] Currently, voltage balancing circuits are primarily categorized as passive balancing and active balancing. Passive balancing achieves voltage balancing between battery modules through energy dissipation, but this method results in energy loss and is detrimental to improving overall system efficiency. Active balancing, on the other hand, achieves voltage balancing between battery modules through energy exchange. Switched capacitor-based balancing circuits have become a popular solution due to their simple control, high power density, good electromagnetic compatibility, and suitability for on-chip integration.

[0004] DC-DC converters are categorized as full-power converters and partial-power converters based on the amount of power they handle during voltage regulation. While full-power converters offer a simple and reliable structure, they require all power to pass through the converter during voltage regulation, resulting in low efficiency, large size, and high cost. In contrast, partial-power converters only need to process a portion of the power proportional to the DC-side output voltage during voltage regulation. This significantly reduces the converter's size and capacity, improving its efficiency and power density.

[0005] However, the balancing circuit and DC-DC converter of existing battery energy storage systems are often configured independently, which increases the size and cost of the battery management system.

[0006] Therefore, providing an integrated topology of a voltage equalizer and a partial power converter to achieve the functions of voltage balancing and voltage regulation while realizing a low-cost and miniaturized design of a battery management system has become a technical challenge that currently needs to be overcome by those skilled in the art. Summary of the Invention

[0007] The purpose of the present invention is to provide an integrated topology of a voltage equalizer and a partial power converter and a control method thereof, so as to overcome the problem of bulky and high-cost battery management systems caused by the independent configuration of equalization circuits and DC-DC converters in the prior art.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] A voltage equalizer and partial power converter integrated topology includes a battery pack, a switched capacitor equalizer, and a DC-DC partial power converter; the battery pack is a plurality of battery modules connected in series, and the switched capacitor equalizer includes a switch array and a capacitor network;

[0010] The switch array is composed of a first half-bridge circuit and several second half-bridge circuits connected in series. The first battery module in the battery pack corresponds to the first half-bridge circuit, the positive electrode of the first battery module is connected to the drain of the upper tube of the first half-bridge circuit, and the negative electrode of the first battery module is connected to the source of the lower tube of the first half-bridge circuit. The remaining battery modules in the battery pack correspond one-to-one to the second half-bridge circuits, and the positive electrode of each battery module in the remaining battery modules is connected to the drain of the upper tube of the corresponding second half-bridge circuit, and the negative electrode of each battery module in the remaining battery modules is connected to the source of the lower tube of the corresponding second half-bridge circuit.

[0011] The capacitor network is connected to the center points of the first half-bridge circuit and all the second half-bridge circuits to achieve voltage balancing among all the battery modules in the battery pack;

[0012] The input side of the DC-DC partial power converter is connected with the same polarity as the first battery module in the battery pack, and the non-polar capacitor on the output side of the DC-DC partial power converter is connected in series with the battery pack. The DC-DC partial power converter is used to realize DC side output voltage regulation, and the DC side output voltage is the sum of the voltage of the non-polar capacitor and the battery pack.

[0013] A further improvement of the present invention is that the first half-bridge circuit and all the second half-bridge circuits use N-channel MOSFETs of the same model and parameters.

[0014] A further improvement of the present invention is that the capacitor network is composed of a plurality of non-polar capacitors, the structure of the capacitor network is one of a triangle structure, a star structure, a chain structure or a double-layer structure, and the models and parameters of all capacitors used in the capacitor network are the same.

[0015] A further improvement of the present invention is that: the first half-bridge circuit is configured separately or shared with the primary side of the DC-DC partial power converter;

[0016] When the primary side of the DC-DC partial power converter is a half-bridge circuit, if the first half-bridge circuit is configured separately, the first half-bridge circuit is connected in parallel with the half-bridge circuit on the primary side; if the first half-bridge circuit is shared with the primary side of the DC-DC partial power converter, the first half-bridge circuit is the half-bridge circuit on the primary side;

[0017] When the primary side of the DC-DC partial power converter is a full-bridge circuit, if the first half-bridge circuit is configured separately, the first half-bridge circuit is connected in parallel with the previous half-bridge circuit of the full-bridge circuit on the primary side; if the first half-bridge circuit is shared with the primary side of the DC-DC partial power converter, the first half-bridge circuit is the previous half-bridge circuit of the full-bridge circuit on the primary side.

[0018] A further improvement of the present invention is that the structure of the DC-DC partial power converter is a single-stage structure or a two-stage structure.

[0019] A further improvement of the present invention is that: the single-stage structure is a dual-active full-bridge topology or a dual-active half-bridge topology; the two-stage structure is a CLLC converter + bipolar Buck circuit topology, wherein the CLLC converter is used to achieve electrical isolation, and the bipolar Buck circuit is used to achieve wide-range regulation of the DC side output voltage.

[0020] The present invention also provides a control method for an integrated topology of a voltage equalizer and a portion of a power converter, which adopts the above-mentioned integrated topology of a voltage equalizer and a portion of a power converter, and includes the following steps:

[0021] The same control signal is used for the first half-bridge circuit and all second half-bridge circuits of the switch array. The control signal is a pair of complementary square wave signals with fixed periods and duty cycles. The upper and lower tubes of the first and second half-bridge circuits are turned on in a complementary manner. The voltage balance among all battery modules is achieved by controlling the continuous charging and discharging of the capacitor network. Specifically,

[0022] If the voltage of a battery module in the remaining battery modules is higher than the voltage of the first battery module, when the control signal turns off the upper tube of the second half-bridge circuit corresponding to the higher-voltage battery module and the first half-bridge circuit corresponding to the first battery module and turns on the lower tube, the higher-voltage battery module charges the capacitor network; when the control signal turns off the lower tube of the second half-bridge circuit corresponding to the higher-voltage battery module and the first half-bridge circuit corresponding to the first battery module and turns on the upper tube, the capacitor network discharges to the first battery module;

[0023] If the voltage of a battery module in the remaining battery modules is lower than the voltage of the first battery module, when the control signal turns off the lower tube and turns on the upper tube of the second half-bridge circuit corresponding to the lower voltage battery module and the first half-bridge circuit corresponding to the first battery module, the first battery module charges the capacitor network; when the control signal turns off the upper tube and turns on the lower tube of the second half-bridge circuit corresponding to the lower voltage battery module and the first half-bridge circuit corresponding to the first battery module, the capacitor network discharges to the lower voltage battery module.

[0024] A further improvement of the present invention is that when the DC-DC partial power converter is a dual active full-bridge topology, a traditional single phase shift control method is adopted, specifically:

[0025] When the power flow direction of the DC-DC partial power converter is forward, the control signal of the primary side full bridge of the dual active full bridge topology is set to be the same as the control signal of the switch array. The primary side full bridge control signal is delayed by a corresponding phase according to the voltage of the output side capacitor to obtain the control signal of the secondary side full bridge of the dual active full bridge topology;

[0026] When the power flow direction of the DC-DC partial power converter is reverse, the control signal of the primary side full bridge of the dual active full-bridge topology is set to be the same as the control signal of the switch array. The primary side full bridge control signal is advanced by a corresponding phase according to the voltage of the output side capacitor to obtain the control signal of the secondary side full bridge of the dual active full-bridge topology.

[0027] A further improvement of the present invention is that when the DC-DC partial power converter is a CLLC converter + bipolar Buck circuit topology, the CLLC converter adopts a fixed switching frequency open-loop control, and the bipolar Buck circuit adopts voltage and current dual closed-loop control, specifically:

[0028] Set the control signal of the primary-side full-bridge of the CLLC converter to be the same as the control signal of the switch array, and make the switching frequency equal to the resonant frequency of the resonant cavity of the CLLC converter. Then the CLLC converter always operates in a quasi-resonant state, and the gain of the CLLC converter is always 1.

[0029] The outer loop of the bipolar Buck circuit adopts voltage closed-loop control, and the inner loop of the bipolar Buck circuit adopts current closed-loop control.

[0030] A further improvement of the present invention is that the driving signal of the switch tube in the bipolar Buck circuit is generated by unipolar frequency multiplication modulation, so that the output voltage of the bipolar Buck circuit is either positive or negative.

[0031] Compared with the prior art, the present invention has the following positive effects:

[0032] The voltage equalizer and partial power converter integrated topology provided by the present invention integrates a switched capacitor equalizer and a DC-DC partial power converter, achieving integrated battery pack voltage equalization and voltage regulation functions. A capacitor network connects the center point of the first half-bridge circuit and all second half-bridge circuits, achieving voltage equalization between all battery modules by controlling the charge and discharge of the capacitor network, and regulating the DC-side output voltage by controlling the output voltage of the DC-DC partial power converter. Furthermore, compared with a full power converter, the DC-DC partial power converter only needs to process a portion of the power whose output voltage accounts for the proportion of the DC-side output voltage. While meeting voltage regulation performance, this reduces the converter's volume and capacity requirements, reduces hardware resources and costs, and is of great significance for achieving a low-cost, miniaturized design of a battery management system.

[0033] Furthermore, when the first half-bridge circuit is shared with the primary-side half-bridge or full-bridge circuit of the DC-DC partial power converter, the system structure is simplified and the cost can be further reduced.

[0034] Furthermore, the DC-DC partial power converter can be a single-stage or two-stage structure, and the most suitable structure can be selected according to actual needs, thereby improving the flexibility of design.

[0035] The present invention also provides a control method for an integrated topology of a voltage equalizer and a partial power converter. The first half-bridge circuit and all second half-bridge circuits of the switch array use the same pair of complementary square wave signals with fixed periods and duty cycles, which not only reduces the complexity of control but also avoids the additional hardware resources required for closed-loop control.

[0036] Furthermore, when the DC-DC partial power converter is a dual active full-bridge topology or a dual active half-bridge topology, a traditional single phase shift control method is adopted, which has the advantages of high efficiency, high reliability and easy control.

[0037] Furthermore, when the DC-DC partial power converter is a CLLC converter + bipolar Buck circuit topology, since the CLLC converter always operates in a quasi-resonant state, this makes the design of the high-frequency transformer and the resonant cavity simpler, reducing the complexity of the circuit topology design; the CLLC converter gain is always 1, which can achieve ZVS turn-on of the primary side switch tube and ZCS turn-off of the secondary side switch tube, thereby improving the efficiency of the CLLC converter.

[0038] Furthermore, the bipolar Buck circuit uses unipolar frequency multiplication modulation, and its output voltage is either positive or negative, thereby achieving a wide range of regulation of the DC side output voltage, which is crucial to improving the operating performance of the battery energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0040] Figure 1 A schematic diagram of the integrated topology of the voltage equalizer and part of the power converter of the present invention;

[0041] Figure 2 This is a schematic diagram of the structure of a partial power converter of the present invention when it adopts a CLLC converter + bipolar Buck circuit topology;

[0042] Figure 3 Schematic diagram of the dual active full-bridge topology structure of the present invention;

[0043] Figure 4 Schematic diagram of complementary square wave signals of the present invention;

[0044] Figure 5 Schematic diagram of the equalization principle when the voltage of a battery module of the present invention is higher than the voltage of the first battery module; Figure (a) shows the higher voltage battery module charging the capacitor network, and Figure (b) shows the capacitor network discharging the first battery module;

[0045] Figure 6 Schematic diagram of the equalization principle when the voltage of a battery module of the present invention is lower than the voltage of the first battery module; Figure (a) shows the first battery module charging the capacitor network, and Figure (b) shows the capacitor network discharging the lower voltage battery module;

[0046] Figure 7 This is a block diagram of the voltage and current dual closed-loop control of the bipolar Buck circuit of the present invention;

[0047] Figure 8 This is a schematic diagram of the unipolar frequency multiplication modulation principle of the present invention.

[0048] Among them, 1 is the battery pack; 2 is the switched capacitor equalizer; 3 is the DC-DC partial power converter; 4 is the CLLC converter; 5 is the bipolar Buck circuit;

[0049] C f is the output side capacitor of the DC-DC power converter 3, V DC is the DC side output voltage, V B is the battery pack voltage, V f is the output side capacitor voltage of the DC-DC partial power converter 3;

[0050] G 2m and G 2m+1 Two complementary square wave control signals;

[0051] B h For high-voltage battery modules (battery modules with a voltage higher than the voltage of the first battery module), B k For low-voltage battery modules (battery modules with a voltage lower than the voltage of the first battery module), R SC is the total parasitic resistance of the switched capacitor unit;

[0052] V DCref is the output side capacitor voltage reference value of the DC-DC power converter 3, Vf is the actual value of the output side capacitor voltage of the DC-DC power converter 3, I Lref is the inductor current reference value, I L is the actual value of the inductor current;

[0053] V r and- V r is a triangular carrier, V m For the modulated wave. DETAILED DESCRIPTION

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0056] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0057] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0058] Furthermore, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be interpreted broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0059] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, which are intended to explain the present invention rather than to limit it.

[0060] See also Figure 1 A voltage equalizer and partial power converter integrated topology includes a battery pack 1, a switched capacitor equalizer 2, and a DC-DC partial power converter 3; the battery pack 1 is a plurality of battery modules connected in series, and the switched capacitor equalizer 2 includes a switch array and a capacitor network;

[0061] The switch array is composed of a first half-bridge circuit and several second half-bridge circuits connected in series. The first battery module in battery pack 1 corresponds to the first half-bridge circuit, the positive electrode of the first battery module is connected to the drain of the upper tube of the first half-bridge circuit, and the negative electrode of the first battery module is connected to the source of the lower tube of the first half-bridge circuit. The remaining battery modules in battery pack 1 correspond one-to-one to the second half-bridge circuit, and the positive electrode of each battery module in the remaining battery modules is connected to the drain of the upper tube of the corresponding second half-bridge circuit, and the negative electrode of each battery module in the remaining battery modules is connected to the source of the lower tube of the corresponding second half-bridge circuit.

[0062] The capacitor network connects the center points of the first half-bridge circuit and all the second half-bridge circuits to achieve voltage balancing among all the battery modules in the battery pack 1;

[0063] The input side of the DC-DC partial power converter 3 is connected to the same polarity as the first battery module in the battery pack 1, and the non-polar capacitor on the output side of the DC-DC partial power converter 3 is connected in series with the battery pack 1. The DC-DC partial power converter 3 is used to realize DC side output voltage regulation, and the DC side output voltage is the sum of the voltage of the non-polar capacitor and the battery pack 1.

[0064] The voltage equalizer and partial power converter integrated topology provided by the present invention integrates a switched capacitor equalizer and a DC-DC partial power converter, achieving integrated battery pack voltage equalization and voltage regulation functions. A capacitor network connects the center point of the first half-bridge circuit and all second half-bridge circuits, achieving voltage equalization between all battery modules by controlling the charge and discharge of the capacitor network, and regulating the DC-side output voltage by controlling the output voltage of the DC-DC partial power converter. Furthermore, compared with a full power converter, the DC-DC partial power converter only needs to process a portion of the power whose output voltage accounts for the proportion of the DC-side output voltage. While meeting voltage regulation performance, this reduces the converter's volume and capacity requirements, reduces hardware resources and costs, and is of great significance for achieving a low-cost, miniaturized design of a battery management system.

[0065] Specifically, the first half-bridge circuit and all the second half-bridge circuits use N-channel MOSFETs of the same model and parameters.

[0066] Specifically, the capacitor network is composed of a plurality of non-polar capacitors. The structure of the capacitor network is a triangle structure, a star structure, a chain structure or a double-layer structure. All capacitors used in the capacitor network have the same model and parameters.

[0067] Specifically, the first half-bridge circuit is configured separately or shared with the primary side of the DC-DC partial power converter 3;

[0068] When the primary side of the DC-DC partial power converter 3 is a half-bridge circuit, if the first half-bridge circuit is configured separately, the first half-bridge circuit is connected in parallel with the half-bridge circuit on the primary side; if the first half-bridge circuit is shared with the primary side of the DC-DC partial power converter 3, the first half-bridge circuit is the half-bridge circuit on the primary side;

[0069] When the primary side of the DC-DC partial power converter 3 is a full-bridge circuit, if the first half-bridge circuit is configured separately, the first half-bridge circuit is connected in parallel with the previous half-bridge circuit of the full-bridge circuit on the primary side; if the first half-bridge circuit is shared with the primary side of the DC-DC partial power converter 3, the first half-bridge circuit is the previous half-bridge circuit of the full-bridge circuit on the primary side.

[0070] When the first half-bridge circuit is shared with the primary-side half-bridge or full-bridge circuit of the DC-DC partial power converter, the system structure is simplified and the cost can be further reduced.

[0071] Specifically, the structure of the DC-DC partial power converter 3 is a single-stage structure or a two-stage structure.

[0072] The DC-DC partial power converter can be a single-stage or two-stage structure, and the most suitable structure can be selected according to actual needs, thereby improving the flexibility of design.

[0073] Specifically, the single-stage structure is a dual active bridge (DAB) or a dual-active half-bridge (DAHB) topology, wherein the dual active bridge topology structure is as shown in Figure 3 The two-stage structure is a CLLC converter 4+ dual-polarity Buck circuit 5 topology, wherein the CLLC converter 4 works in an open-loop mode and only serves as an input-output electrical isolation function; the output voltage of the dual-polarity Buck circuit 5 is positive or negative, thereby realizing wide-range regulation of the output voltage on the DC side.

[0074] Based on the same inventive concept, the application further provides a control method of a voltage equalizer and partial power converter integrated topology, which adopts the voltage equalizer and partial power converter integrated topology and comprises the following steps:

[0075] Referring to Figure 4 The same control signal is used for the first half-bridge circuit of the switch array and all the second half-bridge circuits, the control signal is a pair of complementary square wave signals with fixed periods and duty cycles, the upper and lower tubes of the first half-bridge circuit and the second half-bridge circuit are complementarily turned on, the capacitor network is continuously charged and discharged through control, and voltage equalization between all the battery modules is realized, specifically as follows:

[0076] If the voltage of a certain battery module in the remaining battery modules is higher than the voltage of the first battery module, when the control signal makes the upper tube of the second half-bridge circuit corresponding to the higher-voltage battery module and the first half-bridge circuit corresponding to the first battery module turn off and the lower tube turn on, the higher-voltage battery module charges the capacitor network, and when the control signal makes the lower tube of the second half-bridge circuit corresponding to the higher-voltage battery module and the first half-bridge circuit corresponding to the first battery module turn off and the upper tube turn on, the capacitor network discharges to the first battery module;

[0077] If the voltage of a certain battery module in the remaining battery modules is lower than the voltage of the first battery module, when the control signal makes the lower tube of the second half-bridge circuit corresponding to the lower-voltage battery module and the first half-bridge circuit corresponding to the first battery module turn off and the upper tube turn on, the first battery module charges the capacitor network, and when the control signal makes the upper tube of the second half-bridge circuit corresponding to the lower-voltage battery module and the first half-bridge circuit corresponding to the first battery module turn off and the lower tube turn on, the capacitor network discharges to the lower-voltage battery module.

[0078] The control method provided by the application uses the same pair of complementary square wave signals with fixed periods and duty cycles for the first half-bridge circuit of the switch array and all the second half-bridge circuits, which not only reduces the complexity of control but also avoids the additional hardware resources required by closed-loop control.

[0079] Specifically, when the DC-DC partial power converter 3 is a dual active full-bridge topology, a traditional single phase shift control method is adopted, specifically:

[0080] When the power flow direction of the DC-DC partial power converter 3 is forward, the control signal of the primary side full bridge of the dual active full bridge topology is set to be the same as the control signal of the switch array, and the primary side full bridge control signal is delayed by a corresponding phase according to the voltage of the output side capacitor to obtain the control signal of the secondary side full bridge of the dual active full bridge topology;

[0081] When the power flow direction of the DC-DC partial power converter 3 is reverse, the control signal of the primary side full bridge of the dual active full-bridge topology is set to be the same as the control signal of the switch array, and the primary side full bridge control signal is advanced by the corresponding phase according to the voltage of the output side capacitor to obtain the control signal of the secondary side full bridge of the dual active full-bridge topology.

[0082] When the DC-DC partial power converter is a dual active full-bridge topology or a dual active half-bridge topology, a traditional single phase-shift control method is adopted, which has the advantages of high efficiency, high reliability and easy control.

[0083] Specifically, when the DC-DC partial power converter 3 is a CLLC converter 4 + bipolar Buck circuit 5 topology, the CLLC converter 4 adopts a fixed switching frequency open-loop control, and the bipolar Buck circuit 5 adopts a voltage and current dual closed-loop control, specifically:

[0084] The control signal of the primary-side full-bridge of the CLLC converter 4 is set to be the same as the control signal of the switch array, and the switching frequency is equal to the resonant frequency of the resonant cavity of the CLLC converter 4. Then, the CLLC converter 4 always operates in a quasi-resonant state, and the gain of the CLLC converter 4 is always 1.

[0085] The outer loop of the bipolar Buck circuit 5 adopts voltage closed-loop control, and the inner loop of the bipolar Buck circuit 5 adopts current closed-loop control.

[0086] When the DC-DC power converter adopts the CLLC converter + bipolar Buck circuit topology, the CLLC converter always operates in a quasi-resonant state, which simplifies the design of the high-frequency transformer and the resonant cavity and reduces the complexity of the circuit topology design. The gain of the CLLC converter is always 1, which can achieve ZVS turn-on of the primary-side switch tube and ZCS turn-off of the secondary-side switch tube, thereby improving the efficiency of the CLLC converter.

[0087] Specifically, the driving signal of the switch tube in the bipolar Buck circuit 5 is generated by unipolar frequency multiplication modulation, so that the output voltage of the bipolar Buck circuit 5 is either positive or negative.

[0088] The bipolar Buck circuit uses unipolar frequency multiplication modulation, and its output voltage can be either positive or negative, thereby achieving a wide range of regulation of the DC side output voltage, which is crucial to improving the operating performance of the battery energy storage system.

[0089] Example 1

[0090] See also Figure 2 A voltage equalizer and partial power converter integrated topology includes a battery pack 1, a switched capacitor equalizer 2, and a DC-DC partial power converter 3; the battery pack 1 is n Battery modules B 1~ B n In series, the switched capacitor equalizer 2 comprises a switch array and a capacitor network;

[0091] The switch array consists of a first half-bridge circuit and n -1 second half-bridge circuit in series, the first battery module in battery pack 1 B 1 corresponds to the first half-bridge circuit, the first battery module B 1 is connected to the drain of the upper tube of the first half-bridge circuit, the first battery module B The negative electrode of 1 is connected to the source of the lower tube of the first half-bridge circuit, and the remaining n - 1 battery module B 1~ B n One-to-one correspondence with the second half-bridge circuit, the remaining n -1 The positive electrode of each battery module in the battery module is connected to the drain of the upper tube of the corresponding second half-bridge circuit, and the remaining n The negative electrode of each battery module in one battery module is connected to the source electrode of the lower tube of the corresponding second half-bridge circuit;

[0092] The capacitor network connects the center points of the first half-bridge circuit and all the second half-bridge circuits. The capacitor network is composed of a plurality of non-polarized capacitors and is used to achieve voltage balancing among all the battery modules in the battery pack 1.

[0093] The input side of the DC-DC partial power converter 3 is connected to the first battery module in the battery pack 1. B 1 Same polarity connection, DC-DC part power converter 3 Non-polarized capacitor on the output side C f Connected in series with the battery pack 1, the DC-DC partial power converter 3 is used to achieve the DC side output voltage V DC Regulation, the DC side output voltage V DC is the non-polarized capacitor voltage V f and battery pack 1 voltage VB sum.

[0094] The capacitor network adopts a star structure, the DC-DC partial power converter 3 adopts a two-stage CLLC converter 4 + bipolar Buck circuit 5 topology, and the first half-bridge circuit and the primary side half-bridge of the CLLC converter 4 are shared.

[0095] Example 2

[0096] Based on the same inventive concept, the present invention also provides a control method for an integrated topology of a voltage equalizer and a portion of a power converter, comprising the following steps:

[0097] See also Figure 4 , the switch array of the switched capacitor equalizer 2 and the primary side half bridge of the CLLC converter 4 use the same control signal, which is a pair of complementary square wave signals with fixed period and duty cycle G 2m and G 2m+1 , so that the upper tubes and lower tubes of the first half-bridge circuit and the second half-bridge circuit are complementary turned on, and the voltage balance among all battery modules is achieved by controlling the continuous charging and discharging of the capacitor network.

[0098] See also Figure 5 (a) and Figure 5 (b) If a battery module in battery pack 1 B h The voltage of the first battery module is higher than B 1 voltage, when the control signal enables the higher voltage battery module B h The corresponding second half-bridge circuit and the first battery module B 1 When the upper tube of the first half-bridge circuit is turned off and the lower tube is turned on, the higher voltage battery module B h To charge the capacitor network, when the control signal makes the higher voltage battery module B h The corresponding second half-bridge circuit and the first battery module B 1 When the lower tube of the first half-bridge circuit is turned off and the upper tube is turned on, the capacitor network supplies power to the first battery module. B 1 discharge;

[0099] See also Figure 6 (a) and Figure 6 (b) If a battery module in battery pack 1 B k The voltage of the first battery module is lower than B 1 voltage, when the control signal enables the lower voltage battery module B kThe first battery module when the corresponding first half-bridge circuit is in the state of the lower transistor being off and the upper transistor being on B 1 The first battery module when the corresponding first half-bridge circuit is in the state of the lower transistor being off and the upper transistor being on B 1 Charging the capacitor network when the control signal makes the lower voltage battery module B k The first battery module when the corresponding first half-bridge circuit is in the state of the lower transistor being off and the upper transistor being on B 1 The capacitor network to the lower voltage battery module when the corresponding first half-bridge circuit is in the state of the lower transistor being on and the upper transistor being off B k Discharging;

[0100] The switch works at a very high frequency, and the voltage balance between all battery modules can be achieved by the continuous charging and discharging of the capacitor network.

[0101] Embodiment three

[0102] When the DC-DC partial power converter 3 is a dual active full-bridge topology, the traditional single phase-shift control method is adopted, which is as follows:

[0103] Referring to Figure 3 When the power flow direction of the DC-DC partial power converter 3 is forward, the control signal of the primary side full-bridge of the dual active full-bridge topology is set to be the same as that of the switch array, and the control signal of the secondary side full-bridge of the dual active full-bridge topology is obtained according to the voltage of the output side capacitor C f . V DCref The control signal of the primary side full-bridge is delayed by a corresponding phase to obtain the control signal of the secondary side full-bridge of the dual active full-bridge topology;

[0104] Referring to Figure 3 When the power flow direction of the DC-DC partial power converter 3 is reverse, the control signal of the primary side full-bridge of the dual active full-bridge topology is set to be the same as that of the switch array, and the control signal of the secondary side full-bridge of the dual active full-bridge topology is obtained according to the voltage of the output side capacitor C f . V DCref The control signal of the primary side full-bridge is advanced by a corresponding phase to obtain the control signal of the secondary side full-bridge of the dual active full-bridge topology.

[0105] Embodiment four

[0106] When the DC-DC partial power converter 3 is a CLLC converter 4 + dual-polarity Buck circuit 5 topology, the CLLC converter 4 adopts fixed switching frequency open-loop control, which is as follows:

[0107] Referring to Figure 4, the switch array of the switched capacitor equalizer 2 and the primary side half bridge of the CLLC converter 4 use the same control signal, and the CLLC converter 4 adopts a fixed switching frequency open-loop control, and the switching frequency is equal to the resonant frequency of the resonant cavity, that is,

[0108]

[0109] in, f s is the switching frequency, f r is the resonant frequency, L r is the resonant inductor, C r is the resonant capacitor.

[0110] The bipolar Buck circuit 5 uses voltage and current dual closed-loop control, specifically:

[0111] See also Figure 7 The outer loop of the bipolar Buck circuit 5 adopts voltage closed loop control to control the output side capacitor of the DC-DC power converter 3 C f Voltage V f Equal to the DC side output voltage V DC and battery pack 1 voltage V B The difference between

[0112] See also Figure 7 , the inner loop of the bipolar Buck circuit 5 adopts current closed loop control to control the inductor current I L Equal to the load current, so that the power transmitted by the DC-DC power converter 3 is its output voltage V f DC side output voltage V DC proportional part of the load power;

[0113] See also Figure 8 The driving signal of the bipolar Buck circuit 5 switch tube is generated by unipolar frequency multiplication modulation, so that the output voltage of the bipolar Buck circuit 5 is V f Either positive or negative, thereby expanding the voltage regulation range.

[0114] Finally, it should be noted that the embodiments listed above are merely one or more specific manifestations of the technical solution of the present invention. Their purpose is to clearly illustrate the concept, principles, and application of the present invention through specific examples, and is in no way intended to limit the scope of protection of the present invention to these specific embodiments. In fact, the true value of this invention lies in its technical ideas and innovations, not in its form of expression or implementation.

[0115] For ordinary technicians in the relevant technical field, after thoroughly reading and understanding the technical solutions of the present invention, they are fully capable of making various forms of changes, modifications or equivalent replacements to the specific implementation methods of the invention based on their own professional knowledge and skills. These changes may include but are not limited to: adjusting the value range of technical parameters, optimizing algorithm processes to improve efficiency, replacing some technical components to achieve better compatibility or reduce costs, etc. As long as these modified technical solutions still substantially maintain the technical features claimed for protection by the original invention, that is, they can still achieve the core functions and effects of the present invention, then these changes should be deemed to fall within the scope of protection of the pending claims of the present invention.

[0116] Furthermore, with the continuous advancement and development of technology, new technical means and methods continue to emerge, providing ample room for further improvement and perfection of the present invention. Therefore, the scope of protection of the present invention should also include reasonably foreseeable improvements and extensions based on existing technologies. As long as these improvements and extensions do not deviate from the basic principles and core concepts of the present invention, they should be considered equivalent to the present invention and equally protected by patent rights.

Claims

1. A voltage equalizer and partial power converter integrated topology, characterized in that: The invention comprises a battery pack (1), a switched capacitor equalizer (2), and a DC-DC partial power converter (3); the battery pack (1) is a plurality of battery modules connected in series, and the switched capacitor equalizer (2) comprises a switch array and a capacitor network; The switch array is composed of a first half-bridge circuit and a plurality of second half-bridge circuits connected in series, the first battery module in the battery pack (1) corresponds to the first half-bridge circuit, the positive electrode of the first battery module is connected to the drain of the upper tube of the first half-bridge circuit, the negative electrode of the first battery module is connected to the source of the lower tube of the first half-bridge circuit, the remaining battery modules in the battery pack (1) correspond to the second half-bridge circuits one by one, the positive electrode of each battery module in the remaining battery modules is connected to the drain of the upper tube of the corresponding second half-bridge circuit, and the negative electrode of each battery module in the remaining battery modules is connected to the source of the lower tube of the corresponding second half-bridge circuit; The capacitor network connects the first half-bridge circuit and the center points of all the second half-bridge circuits, and is used to achieve voltage balancing among all the battery modules in the battery pack (1); The input side of the DC-DC partial power converter (3) is connected to the first battery module in the battery pack (1) with the same polarity, the non-polar capacitor on the output side of the DC-DC partial power converter (3) is connected in series with the battery pack (1), and the DC-DC partial power converter (3) is used to achieve DC side output voltage regulation, and the DC side output voltage is the sum of the voltage of the non-polar capacitor and the battery pack (1).

2. The voltage equalizer and partial power converter integrated topology according to claim 1, characterized in that: The first half-bridge circuit and all the second half-bridge circuits use N-channel MOSFETs of the same type and parameters.

3. The voltage equalizer and partial power converter integrated topology according to claim 1, characterized in that: The capacitor network is composed of a plurality of non-polar capacitors. The structure of the capacitor network is a triangle structure, a star structure, a chain structure or a double-layer structure. All capacitors used in the capacitor network have the same model and parameters.

4. The voltage equalizer and partial power converter integrated topology according to claim 1, characterized in that: The first half-bridge circuit is configured separately or shared with the primary side of the DC-DC partial power converter (3); When the primary side of the DC-DC partial power converter (3) is a half-bridge circuit, if the first half-bridge circuit is configured separately, the first half-bridge circuit is connected in parallel with the half-bridge circuit on the primary side; if the first half-bridge circuit is shared with the primary side of the DC-DC partial power converter (3), the first half-bridge circuit is the half-bridge circuit on the primary side; When the primary side of the DC-DC partial power converter (3) is a full-bridge circuit, if the first half-bridge circuit is configured separately, the first half-bridge circuit is connected in parallel with the previous half-bridge circuit of the full-bridge circuit on the primary side; if the first half-bridge circuit is shared with the primary side of the DC-DC partial power converter (3), the first half-bridge circuit is the previous half-bridge circuit of the full-bridge circuit on the primary side.

5. The voltage equalizer and partial power converter integrated topology according to claim 1, characterized in that: The structure of the DC-DC partial power converter (3) is a single-stage structure or a two-stage structure.

6. The voltage equalizer and partial power converter integrated topology according to claim 5, characterized in that: The single-stage structure is a dual-active full-bridge topology or a dual-active half-bridge topology; the two-stage structure is a CLLC converter (4) + bipolar Buck circuit (5) topology, wherein the CLLC converter (4) is used to achieve electrical isolation, and the bipolar Buck circuit (5) is used to achieve wide-range regulation of the DC side output voltage.

7. A control method for an integrated topology of a voltage equalizer and a partial power converter, characterized in that: The voltage equalizer and partial power converter integrated topology according to any one of claims 1 to 6 is adopted, comprising the following steps: The same control signal is used for the first half-bridge circuit and all second half-bridge circuits of the switch array. The control signal is a pair of complementary square wave signals with fixed periods and duty cycles. The upper and lower tubes of the first and second half-bridge circuits are turned on in a complementary manner. The voltage balance among all battery modules is achieved by controlling the continuous charging and discharging of the capacitor network. Specifically, If the voltage of a battery module in the remaining battery modules is higher than the voltage of the first battery module, when the control signal turns off the upper tube of the second half-bridge circuit corresponding to the higher-voltage battery module and the first half-bridge circuit corresponding to the first battery module and turns on the lower tube, the higher-voltage battery module charges the capacitor network; when the control signal turns off the lower tube of the second half-bridge circuit corresponding to the higher-voltage battery module and the first half-bridge circuit corresponding to the first battery module and turns on the upper tube, the capacitor network discharges to the first battery module; If the voltage of a battery module in the remaining battery modules is lower than the voltage of the first battery module, when the control signal turns off the lower tube and turns on the upper tube of the second half-bridge circuit corresponding to the lower voltage battery module and the first half-bridge circuit corresponding to the first battery module, the first battery module charges the capacitor network; when the control signal turns off the upper tube and turns on the lower tube of the second half-bridge circuit corresponding to the lower voltage battery module and the first half-bridge circuit corresponding to the first battery module, the capacitor network discharges to the lower voltage battery module.

8. The control method of the voltage equalizer and partial power converter integrated topology according to claim 7, characterized in that: When the DC-DC partial power converter (3) is a dual active full-bridge topology, a conventional single phase shift control method is adopted, specifically: When the power flow direction of the DC-DC partial power converter (3) is forward, the control signal of the primary side full bridge of the dual active full bridge topology is set to be the same as the control signal of the switch array, and the control signal of the primary side full bridge is delayed by a corresponding phase according to the voltage of the output side capacitor to obtain the control signal of the secondary side full bridge of the dual active full bridge topology; When the power flow direction of the DC-DC partial power converter (3) is reverse, the control signal of the primary side full bridge of the dual active full bridge topology is set to be the same as the control signal of the switch array, and the primary side full bridge control signal is advanced by a corresponding phase according to the voltage of the output side capacitor to obtain the control signal of the secondary side full bridge of the dual active full bridge topology.

9. The control method of the voltage equalizer and partial power converter integrated topology according to claim 7, characterized in that: When the DC-DC partial power converter (3) is a CLLC converter (4) + bipolar Buck circuit (5) topology, the CLLC converter (4) adopts a fixed switching frequency open-loop control, and the bipolar Buck circuit (5) adopts a voltage and current dual closed-loop control, specifically: The control signal of the primary-side full bridge of the CLLC converter (4) is set to be the same as the control signal of the switch array, and the switching frequency is made equal to the resonant frequency of the resonant cavity of the CLLC converter (4). Then, the CLLC converter (4) always operates in a quasi-resonant state, and the gain of the CLLC converter (4) is always 1. The outer loop of the bipolar Buck circuit (5) adopts voltage closed-loop control, and the inner loop of the bipolar Buck circuit (5) adopts current closed-loop control.

10. The control method of the voltage equalizer and partial power converter integrated topology according to claim 9, characterized in that: The driving signal of the switch tube in the bipolar Buck circuit (5) is generated by unipolar frequency multiplication modulation, so that the output voltage of the bipolar Buck circuit (5) is either positive or negative.

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