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

Abstract

The invention 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. According to the invention, the switched capacitor equalizer and the DC-DC partial power converter are integrated together, so that integration of battery pack voltage equalization and voltage regulation functions is realized. The capacitor network is connected with the center points of the first half-bridge circuit and all the second half-bridge circuits, and voltage balance among all the battery modules is achieved by controlling charging and discharging of the capacitor network. The DC-side output voltage is adjusted by controlling the output voltage of the DC-DC partial power converter, and compared with all power converters, the DC-DC partial power converter only needs to process part of power of the proportion of the output voltage to the DC-side output voltage, so that the conversion efficiency is improved, and the volume and the capacity of the converter are reduced. The invention 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] As energy consumption and environmental pollution become increasingly serious, the electric vehicle and new energy power generation industries based on battery energy storage are experiencing unprecedented development opportunities. To ensure the safe and reliable operation of the battery pack and extend its service life, it is particularly important to achieve voltage balancing between battery modules in the battery pack through a voltage balancing circuit. At the same time, the output voltage of the battery pack varies over a wide range, and the DC-DC converter plays an important role in regulating the output voltage range on the DC side.

[0003] At present, voltage balancing circuits are mainly divided into two categories: passive balancing and active balancing. Passive balancing achieves voltage balancing between battery modules by energy dissipation, but this method will cause energy loss and is not conducive to improving the overall efficiency of the system. Active balancing achieves voltage balancing between battery modules by energy exchange. Among them, the balancing circuit based on switched capacitors has become a solution that has attracted much attention due to its advantages such as simple control, high power density, good electromagnetic compatibility and suitability for on-chip integration.

[0004] According to the amount of power they bear during the voltage regulation process, DC-DC converters are divided into full power converters and partial power converters. Although the full power converter has a simple and reliable structure, all power must pass through the converter during the voltage regulation process, resulting in low efficiency, large size and high cost of the converter. In contrast, the partial power converter only needs to process a portion of the power that its output voltage accounts for in proportion to the DC side output voltage during the voltage regulation process, so it can significantly reduce the volume and capacity of the converter and improve the efficiency and power density of the converter.

[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 low-cost and miniaturized design of a battery management system while achieving the functions of voltage equalization and voltage regulation has become a technical challenge that needs to be overcome urgently by current technical personnel in this field. Summary of the invention

[0007] The object 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 of a battery management system caused by the independent configuration of an equalization circuit and a DC-DC converter in the prior art.

[0008] The present invention solves the above technical problems through the following technical solutions: 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; 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 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 correspond to the second half-bridge circuit 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 center points of the first half-bridge circuit and all the second half-bridge circuits to achieve voltage balance among all the battery modules in the battery pack; 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, the non-polar capacitor on the output side of the DC-DC partial power converter is connected in series with the battery pack, and 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.

[0009] 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.

[0010] 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 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.

[0011] 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; 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; 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.

[0012] 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.

[0013] 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.

[0014] The present invention also provides a control method of a voltage equalizer and a partial power converter integrated topology, which adopts the above-mentioned voltage equalizer and a partial power converter integrated topology, and comprises the following steps: The same control signal is used for the first half-bridge circuit and all the 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, 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 the battery modules is achieved by controlling the capacitor network to continuously charge and discharge. 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.

[0015] A further improvement of the present invention is that when the DC-DC partial power converter 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 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; 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, 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.

[0016] 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 a voltage and current dual closed-loop control, specifically: The control signal of the full bridge on the primary side of the CLLC converter 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. Then the CLLC converter always works in a quasi-resonant state, and the gain of the CLLC converter is always 1. 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.

[0017] 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.

[0018] Compared with the prior art, the positive and progressive effects of the present invention are: The voltage equalizer and partial power converter integrated topology provided by the present invention integrates the switch capacitor equalizer and the DC-DC partial power converter together, realizing the integration of the battery pack voltage equalization and voltage regulation functions; the capacitor network connects the center point of the first half-bridge circuit and all the second half-bridge circuits, realizes the voltage equalization between all the battery modules by controlling the charging and discharging of the capacitor network, and adjusts the DC side output voltage by controlling the output voltage of the DC-DC partial power converter. At the same time, compared with the whole power converter, the DC-DC partial power converter only needs to process a part of the power whose output voltage accounts for the proportion of the DC side output voltage, while meeting the voltage regulation performance, reducing the volume and capacity requirements of the converter, reducing the hardware resources and cost requirements, which is of great significance to the low-cost and miniaturized design of the battery management system.

[0019] 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.

[0020] Furthermore, the DC-DC partial power converter may be a single-stage or two-stage structure, and the most suitable structure may be selected according to actual needs, thereby improving the flexibility of the design.

[0021] The present invention also provides a control method for an integrated topology of a voltage equalizer and a partial power converter, wherein 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.

[0022] Furthermore, when the DC-DC partial power converter is a dual active full-bridge topology or a dual active half-bridge topology, a conventional single phase shift control method is adopted, which has the advantages of high efficiency, high reliability and easy control.

[0023] 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, the design of the high-frequency transformer and the resonant cavity is simpler, reducing 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.

[0024] Furthermore, the bipolar Buck circuit adopts 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

[0025] 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.

[0026] Figure 1 It is a schematic diagram of the integrated topology of the voltage equalizer and part of the power converter of the present invention; Figure 2 It is a structural schematic diagram of a partial power converter of the present invention when a CLLC converter + bipolar Buck circuit topology is adopted; Figure 3 It is a schematic diagram of the dual active full-bridge topology structure of the present invention; Figure 4 A schematic diagram of a complementary square wave signal of the present invention; Figure 5 The equalization principle diagram of the present invention when the voltage of a certain battery module is higher than the voltage of the first battery module; Figure (a) shows that the higher voltage battery module charges the capacitor network, and Figure (b) shows that the capacitor network discharges the first battery module; Figure 6 The equalization principle diagram of the present invention when the voltage of a battery module 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 battery module with lower voltage; Figure 7 The figure is a voltage and current double closed-loop control block diagram of the bipolar Buck circuit of the present invention; Figure 8 This is a schematic diagram of the unipolar frequency multiplication modulation principle of the present invention.

[0027] Among them, 1 is a battery pack; 2 is a switched capacitor equalizer; 3 is a DC-DC partial power converter; 4 is a CLLC converter; 5 is a bipolar Buck circuit; C f is the output side capacitor of the DC-DC partial 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; G 2m and G 2m+1 Two complementary square wave control signals; 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; V DCref is the output side capacitor voltage reference value of the DC-DC partial power converter 3, V f is the actual value of the output side capacitor voltage of the DC-DC partial power converter 3, I Lref is the inductor current reference value, I L is the actual value of the inductor current; V r and- V r is a triangular carrier wave, V m For the modulated wave. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 here can be arranged and designed in various different configurations.

[0029] 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 claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] 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, further definition and explanation thereof is not required in subsequent drawings.

[0031] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0032] In addition, it should be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments, which are intended to explain the present invention rather than to limit it.

[0034] See also Figure 1 , a voltage equalizer and partial power converter integrated topology, including 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; 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, 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 1 correspond to the second half-bridge circuits one by one, 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. The capacitor network connects the center points of the first half-bridge circuit and all the second half-bridge circuits to achieve voltage balance among all the battery modules in the battery pack 1; The input side of the DC-DC partial power converter 3 is connected with 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.

[0035] The voltage equalizer and partial power converter integrated topology provided by the present invention integrates the switch capacitor equalizer and the DC-DC partial power converter together, realizing the integration of the battery pack voltage equalization and voltage regulation functions; the capacitor network connects the center point of the first half-bridge circuit and all the second half-bridge circuits, realizes the voltage equalization between all the battery modules by controlling the charging and discharging of the capacitor network, and adjusts the DC side output voltage by controlling the output voltage of the DC-DC partial power converter. At the same time, compared with the whole power converter, the DC-DC partial power converter only needs to process a part of the power whose output voltage accounts for the proportion of the DC side output voltage, while meeting the voltage regulation performance, reducing the volume and capacity requirements of the converter, reducing the hardware resources and cost requirements, which is of great significance to the low-cost and miniaturized design of the battery management system.

[0036] Specifically, the first half-bridge circuit and all the second half-bridge circuits use N-channel MOSFETs of the same model and parameters.

[0037] 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, and the models and parameters of all capacitors used in the capacitor network are the same.

[0038] Specifically, 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.

[0039] 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.

[0040] Specifically, the structure of the DC-DC partial power converter 3 is a single-stage structure or a two-stage structure.

[0041] 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.

[0042] Specifically, the single-stage structure is a dual active full-bridge topology (Dual Active Bridge, DAB) or a dual active half-bridge topology (Dual-Active Half-Bridge, DAHB), where the dual active bridge topology is as follows: Figure 3 As shown; the two-stage structure is a CLLC converter 4 + bipolar Buck circuit 5 topology, wherein the CLLC converter 4 operates in an open-loop mode and only serves to electrically isolate the input and output; the output voltage of the bipolar Buck circuit 5 is either positive or negative, thereby achieving a wide range of regulation of the DC side output voltage.

[0043] Based on the same inventive concept, the present invention also provides a control method of a voltage equalizer and a partial power converter integrated topology, which adopts the above-mentioned voltage equalizer and a partial power converter integrated topology, and comprises the following steps: See also Figure 4 , the same control signal is used for the first half-bridge circuit and all the second half-bridge circuits of the switch array, and the control signal is a pair of complementary square wave signals with fixed periods and duty cycles, 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 the battery modules is achieved by controlling the capacitor network to continuously charge and discharge, 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.

[0044] In the control method provided by the present invention, the first half-bridge circuit and all the second half-bridge circuits of the switch array use the same pair of complementary square wave signals with fixed period and duty cycle, which not only reduces the complexity of control but also avoids the additional hardware resources required for closed-loop control.

[0045] 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: 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; 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.

[0046] When the DC-DC partial power converter is a dual active full-bridge topology or a dual active half-bridge topology, a conventional single phase shift control method is adopted, which has the advantages of high efficiency, high reliability and easy control.

[0047] 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: 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, so that the CLLC converter 4 always works 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.

[0048] 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, the design of the high-frequency transformer and the resonant cavity is simpler, reducing 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.

[0049] 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.

[0050] 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.

[0051] Embodiment 1 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; 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 - The positive electrode of each battery module in 1 battery module is connected to the drain of the upper tube of the corresponding second half-bridge circuit, and the remainingn 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; The capacitor network connects the center points of the first half-bridge circuit and all the second half-bridge circuits, and the capacitor network is composed of a plurality of non-polar capacitors, 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 B 1 Same polarity connection, non-polarized capacitor on the output side of the DC-DC power converter 3 C f Connected in series with the battery pack 1, the DC-DC partial power converter 3 is used to realize the DC side output voltage V DC regulation, the DC side output voltage V DC Non-polar capacitor voltage V f With battery pack 1 voltage V B sum.

[0052] 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.

[0053] Embodiment 2 Based on the same inventive concept, the present invention also provides a control method of a voltage equalizer and a partial power converter integrated topology, comprising the following steps: 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 capacitor network to continuously charge and discharge.

[0054] 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 B1 When the upper tube of the first half-bridge circuit corresponding to the 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 corresponding to 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; 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 k The corresponding second half-bridge circuit and the first battery module B 1 When the lower tube of the first half-bridge circuit corresponding to the first half-bridge circuit is turned off and the upper tube is turned on, the first battery module B 1 charges the capacitor network, and when the control signal makes the lower voltage battery module B k The corresponding second half-bridge circuit and the first battery module B 1 When the upper tube of the first half-bridge circuit corresponding to the circuit is turned off and the lower tube is turned on, the capacitor network supplies power to the lower voltage battery module. B k Discharge; The switching tube operates at a very high frequency, and the voltage balance between all battery modules can be achieved through continuous charging and discharging of the capacitor network.

[0055] Embodiment 3 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: See also 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 the control signal of the switch array, and the output side capacitor C f Voltage V DCref The primary side full bridge control signal is delayed by a corresponding phase to obtain the control signal of the secondary side full bridge of the dual active full bridge topology; See also 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 the control signal of the switch array, and the output side capacitor C f VoltageV DCref The primary side full bridge control signal is advanced by a corresponding phase to obtain the control signal of the secondary side full bridge of the dual active full bridge topology.

[0056] Embodiment 4 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, specifically: 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, 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,

[0057] 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.

[0058] The bipolar Buck circuit 5 adopts voltage and current dual closed-loop control, specifically: 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 With battery pack 1 voltage V B The difference between See also Figure 7 , the inner loop of the bipolar Buck circuit 5 uses current closed-loop control to control the inductor current I L is equal to the load current, so that the power transmitted by the DC-DC partial power converter 3 is its output voltage V f DC side output voltage V DC proportional part of the load power; See also Figure 8 The driving signal of the switch tube of the bipolar Buck circuit 5 is generated by unipolar frequency multiplication modulation, so that the output voltage of the bipolar Buck circuit 5 V fEither positive or negative, thereby expanding the voltage regulation range.

[0059] Finally, it should be noted that the above-listed embodiments exist only as one or more specific forms of expression of the technical solution of the present invention. Their purpose is to clearly explain the concept, principle and application of the present invention through specific examples, and it is by no means intended to limit the protection scope of the present invention to these specific embodiments. In fact, the real value of the present invention lies in the technical ideas and innovations it proposes, rather than its form of expression or means of implementation.

[0060] For ordinary technicians in the relevant technical field, after in-depth reading and understanding of the technical solution of the present invention, they are fully capable of making various forms of changes, modifications or equivalent substitutions 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 changed 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.

[0061] In addition, with the continuous progress and development of technology, new technical means and methods continue to emerge, which also provides broad space for further improvement and perfection of the present invention. Therefore, the protection scope of the present invention should also include those reasonably foreseeable improvements and extensions based on the existing technology. As long as these improvements and extensions do not deviate from the basic principles and core concepts of the present invention, they should be regarded as equivalents of the present invention and are also protected by patent rights.

Claims

1. A voltage equalizer and partial power converter integrated topology, characterized in that: It 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 adjust the DC side output voltage, wherein the DC side output voltage is the sum of the voltages 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 with the same model 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. The models and parameters of all capacitors used in the capacitor network are the same.

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 a voltage equalizer and a partial power converter integrated topology, characterized in that: The voltage equalizer and partial power converter integrated topology as claimed in 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 the 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, 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 the battery modules is achieved by controlling the capacitor network to continuously charge and discharge. 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 equal to the resonant frequency of the resonant cavity of the CLLC converter (4), so that 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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