A battery system with equalization management function

Abstract

The application discloses a battery system with equalization management function, comprising a plurality of parallel battery clusters, and the battery clusters are connected to an energy storage converter through a battery bus. Any battery cluster comprises a plurality of serial battery packs and a high-voltage box connected in series with the battery packs, wherein any battery pack comprises a battery, a capacitor connected in series with the battery, and an equalizer, a first end of the equalizer being connected to a connection point of the battery and the capacitor, a second end of the equalizer being connected to an end of the battery away from the capacitor, and a third end of the equalizer being connected to an end of the capacitor away from the battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy, in particular to a battery system with equalization management function. BACKGROUND

[0002] Due to the low nominal voltage of the battery monomer, in actual application, for example, in the fields of photovoltaic, energy storage, new energy electric vehicles, etc., multiple battery packs in series are usually needed to form a battery cluster to meet different voltage requirements. In some fields, multiple battery clusters are further connected in parallel to form a battery system.

[0003] However, due to the inconsistency of the performance of the monomers of each battery pack, the state of charge or terminal voltage between each battery pack may be inconsistent during use. In the charging process, as long as one battery pack is fully charged or reaches the charging cutoff voltage, the charging must be stopped. In the discharging process, as long as one battery pack is discharged or reaches the discharging cutoff voltage, the discharging must be stopped. With the increase of the number of charge and discharge cycles, the degree of imbalance of each battery pack will gradually increase, thereby gradually reducing the charge and discharge capacity of the battery cluster, and ultimately causing the battery system to be prematurely scrapped, greatly affecting the service life of the battery pack. Therefore, battery equalization technology is crucial.

[0004] At present, most of the commonly used battery equalization schemes in the battery system are only for inter-cluster equalization or pack equalization. For example, a parallel full-power cluster DCDC scheme can be used to realize inter-cluster equalization, but it must use high-voltage semiconductor devices, so the cost is high, the weight is large, and the volume is large. While using a small-power pack DCDC scheme to form a cluster equalization bus, although the equalization of the battery pack can be met, inter-cluster equalization cannot be realized.

[0005] If both inter-cluster equalization and pack equalization need to be realized, full-power cluster DCDC and small-power pack DCDC need to be configured at the same time, which is costly. SUMMARY

[0006] In view of some or all of the problems in the prior art, the present application provides a battery system with equalization management function, comprising a plurality of parallel battery clusters, the battery clusters are connected to an energy storage converter through a battery bus, and any of the battery clusters comprises:

[0007] a plurality of series-connected battery packs, wherein any of the battery packs comprises:

[0008] a battery;

[0009] a capacitor connected in series with the battery; and

[0010] a balancer having a first end connected to the connection point of the battery and the capacitor, a second end connected to the end of the battery away from the capacitor, and a third end connected to the end of the capacitor away from the battery; and

[0011] a high-voltage box connected in series with the battery pack.

[0012] Further, the balancer comprises:

[0013] a first transistor having a collector connected to the end of the battery away from the capacitor, and an emitter connected to the first end of the inductor;

[0014] a first diode connected in parallel between the collector and the emitter of the first transistor;

[0015] a second transistor having a collector connected to the first end of the inductor, and an emitter connected to the end of the capacitor away from the battery;

[0016] a second diode connected in parallel between the collector and the emitter of the second transistor; and

[0017] a first inductor having a second end connected to the connection point of the battery and the capacitor.

[0018] Further, the balancer comprises:

[0019] a first transistor having a collector connected to the first end of the first inductor, and an emitter connected to the connection point of the battery and the capacitor;

[0020] a first diode connected in parallel between the collector and the emitter of the first transistor;

[0021] a second transistor having a collector connected to the connection point of the battery and the capacitor, and an emitter connected to the first end of the second inductor;

[0022] a second diode connected in parallel between the collector and the emitter of the second transistor;

[0023] a first inductor having a second end connected to the end of the battery away from the capacitor;

[0024] a second inductor having a second end connected to the end of the capacitor away from the battery; and

[0025] a first capacitor having two ends connected to the collector of the first transistor and the emitter of the second transistor, respectively.

[0026] Further, the balancer comprises:

[0027] an inductor;

[0028] a first transistor having a collector connected to the battery at a terminal distal from the capacitor and an emitter connected to a first terminal of the inductor;

[0029] a first diode connected in parallel between the collector and the emitter of the first transistor;

[0030] a second transistor having a collector connected to the first terminal of the inductor and an emitter connected to the terminal of the capacitor distal from the battery;

[0031] a second diode connected in parallel between the collector and the emitter of the second transistor;

[0032] a third transistor having a collector connected to a junction of the battery and the capacitor and an emitter connected to a second terminal of the inductor;

[0033] a third diode connected in parallel between the collector and the emitter of the third transistor;

[0034] a fourth transistor having a collector connected to the second terminal of the inductor and an emitter connected to the terminal of the capacitor distal from the battery;

[0035] a fourth diode connected in parallel between the collector and the emitter of the fourth transistor; and

[0036] a capacitor having two terminals connected to the terminal of the capacitor distal from the battery and the terminal of the battery distal from the capacitor, respectively.

[0037] The battery system with equalization management function provided by the application is composed of a low-cost low-voltage device such as a capacitor, a transistor and a diode, and the equalizer and the battery pack are integrated together. On one hand, the equalization of the battery pack in the cluster is controlled by the capacitor, and on the other hand, the high and low adjustment of the voltage of the whole cluster can be realized by adjusting the voltage of the capacitor, and the cluster current can be controlled, so that the whole system has the functions of cluster equalization and battery pack equalization, and the bus voltage of the power conversion system (PCS) can be raised by raising the voltage of the capacitor in the equalizer, and then the grid-connected voltage of the PCS can be raised. The equalizer adopts low-cost low-voltage devices, so the overall power is small, the cost is low, and the loss is small. BRIEF DESCRIPTION OF DRAWINGS

[0038] To further clarify the above and other advantages and features of the present application, a more particular description of embodiments thereof will be rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the application and are therefore not to be considered limiting of its scope. In the drawings, like or similar components are denoted by the same or similar reference signs.

[0039] Figure 1 FIG. 1 shows a structural diagram of a battery system with equalization management function according to an embodiment of the present application;

[0040] Figure 2 FIG. 2 shows a circuit structural diagram of an equalizer according to an embodiment of the present application;

[0041] Figure 3 FIG. 3 shows a circuit structural diagram of an equalizer according to another embodiment of the present application;

[0042] Figure 4 FIG. 4 shows a circuit structural diagram of an equalizer according to still another embodiment of the present application;

[0043] Figures 5a-5d FIG. 5 shows a current flow diagram of an equalizer in charging and discharging modes according to an embodiment of the present application;

[0044] Figures 6a-6d FIG. 6 shows a current flow diagram of an equalizer in charging and discharging modes according to another embodiment of the present application; and

[0045] Figures 7a-7d FIG. 7 shows a current flow diagram of an equalizer in charging and discharging modes according to still another embodiment of the present application. DETAILED DESCRIPTION

[0046] In the following description, reference is made to specific embodiments of the application. Those skilled in the art will recognize that the application can be practiced with

[0047] In this specification, reference can be made to "one embodiment" or "the embodiment" meaning that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0048] It should be noted that the embodiments of the present application are described in a particular order of process steps, however this is only for the purpose of illustrating the specific embodiment and does not limit the order of the steps. Instead, the order of the steps can be adjusted according to the adjustment of the process in different embodiments of the present application.

[0049] In the existing battery equalization scheme, high-voltage DCDC is usually used to realize cluster equalization, which is connected in parallel with the battery cluster, and after full-power conversion, the output is given to the battery bus. The full-power DCDC has large power, so the selected semiconductor device has high pressure, large volume, large weight, and large loss. In addition, if package equalization needs to be realized, a small-power package DCDC needs to be additionally configured, which further increases the overall cost of the battery system. In view of the above problems, the inventors have found that the key to equalization control of the battery system is to control the voltage of the battery package and the battery cluster, and the capacitor, as a kind of chargeable and dischargeable component, can adjust the voltage of the battery package if it is connected with the battery package, thereby adjusting the voltage of the battery cluster formed by the series connection of the battery package, and achieving the purpose of equalization control. Therefore, the problem of how to realize equalization control can be converted into how to control the charging and discharging of the capacitor. Based on this, the present application provides a battery system with equalization management function, which realizes the equalizer by using low-voltage semiconductor devices, so that the whole system has cluster equalization and package equalization at the same time. The scheme of the present application will be further described below in combination with the embodiment drawings.

[0050] In the present application, m represents any natural number in 1-M, and n represents any natural number in 1-N, M is the number of battery clusters, and N is the number of battery packages contained in one battery cluster.

[0051] Figure 1 The structure of a battery system with equalization management function according to an embodiment of the present application is shown in the figure. As shown in the figure, Figure 1 A battery system with equalization management function includes a plurality of parallel battery clusters 101,..., 10M, the two ends of the battery cluster are connected to the positive and negative electrodes of the power conversion system (PCS) Vbus end through the battery bus + and the battery bus -, and then connected to the grid Grid.

[0052] As shown in the figure, Figure 1 Any of the battery clusters 10m includes a plurality of series-connected battery packages 10m1, 10m2,..., 10mN, and a high-voltage box 20m, and the high-voltage box 20m is connected in series with the battery package.

[0053] As shown in the figure, any of the battery packs 10mn comprises a battery 10mn1, a capacitor 10mn2 and an equalizer 10mn3. The capacitor is connected in series with the battery, and the positions of the capacitor and the battery can be interchanged, that is, the positive electrode of the capacitor can be connected to the negative electrode of the battery, or the positive electrode of the battery can be connected to the negative electrode of the capacitor. The equalizer comprises three ports, wherein the first port is connected to the connection point of the battery and the capacitor, the second port is connected to the end of the battery away from the capacitor, and the third port is connected to the end of the capacitor away from the battery. The equalizer is mainly used to control the charging and discharging of the capacitor, thereby realizing cluster equalization and pack equalization.

[0054] In the embodiments of the present application, the triode in the equalizer is preferably an IGBT or a MOSFET, unless otherwise specified.

[0055] Figure 2 The circuit structure schematic diagram of the equalizer in one embodiment of the present application is shown. As shown in the figure, Figure 2 in one embodiment of the present application, the equalizer comprises two triodes, two diodes and an inductor. Among them:

[0056] The collector of the first triode T1 is connected to the end of the battery away from the capacitor, and the emitter is connected to the first end of the inductor L;

[0057] The first diode D1 is connected in parallel between the collector and the emitter of the first triode T1;

[0058] The collector of the second triode T2 is connected to the first end of the inductor L, and the emitter is connected to the end of the capacitor away from the battery;

[0059] The second diode D2 is connected in parallel between the collector and the emitter of the second triode; and

[0060] The second end of the inductor L is connected to the connection point of the battery and the capacitor.

[0061] According to the embodiment shown in the figure, Figure 2 , Figures 5a-5b , Figures 5c-5d the current flow direction schematic diagrams in the charging mode and the discharging mode are shown respectively. During the charging process of the battery system, in the Ton time, as shown in the figure, the first triode T1 is turned on, and the second triode T2 is in the off state, the D1 tube is forward biased and turned on, at this time, the cluster current Ir flows through the battery and the capacitor, charging the battery and the capacitor, and at the same time, the inductor L flows through the first diode D1, charging the battery; in the Toff time, as shown in the figure, Figure 5a the second triode T2 is turned on, and the first triode T1 is in the off state, the D2 tube is forward biased and turned on, at this time, the cluster current Ir flows through the capacitor and the battery, discharging the capacitor and the battery, and at the same time, the inductor L flows through the second diode D2, discharging the capacitor. Figure 5bAs shown, the first triode T1 is off, and the second triode T2 is on, and the cluster current Ir flows through the battery and the capacitor, and the battery and the capacitor are in the discharging state, and the battery charges the inductor L via the first triode T1; in the Toff time, as shown, Figure 5c As shown, the first triode T1 is off, and the second triode T2 is on, and the cluster current Ir flows through the battery and the capacitor, and the battery and the capacitor are in the discharging state, and the battery charges the inductor L via the first triode T1; in the Toff time, as shown, Figure 5d As shown, the first triode T1 is off, and the second triode T2 is on, and the cluster current Ir flows through the battery and the capacitor, and the battery and the capacitor are in the discharging state, and the battery charges the inductor L via the first triode T1; in the Toff time, as shown,

[0062] Figure 3 A circuit structure schematic diagram of the equalizer of another embodiment of the present application is shown. As shown, Figure 3 As shown, in another embodiment of the present application, in the Ton time, as shown, Figure 2 The embodiment shown is improved, and an inductor is connected in series with the battery and the capacitor, respectively. Specifically, the equalizer comprises:

[0063] A first triode T1, whose collector is connected to the first end of a first inductor L1, and whose emitter is connected to the connection point of the battery and the capacitor;

[0064] A first diode D1, which is connected in parallel between the collector and the emitter of the first triode L1;

[0065] A second triode T2, whose collector is connected to the connection point of the battery and the capacitor, and whose emitter is connected to the first end of a second inductor L2;

[0066] A second diode D2, which is connected in parallel between the collector and the emitter of the second triode T2;

[0067] A first inductor L1, whose second end is connected to the end of the battery away from the capacitor;

[0068] A second inductor L2, whose second end is connected to the end of the capacitor away from the battery; and

[0069] A first capacitor C2, whose two ends are connected to the collector of the first transistor and the emitter of the second transistor respectively.

[0070] According to Figure 3 the embodiment shown, Figures 6a-6b , Figures 6c-6d respectively show the current flow schematic diagram in the charging mode and the discharging mode. In the charging process, in the Toff stage, as shown in Figure 6a , T1 transistor is off, T2 transistor is on, at this time, the first inductor L1 charges through T2 transistor and the first capacitor C2, at the same time, the first inductor L1 charges, the capacitor discharges, and the L2 is charged through T2 transistor, in the Ton stage, as shown in Figure 6b , T2 transistor is off, T1 transistor is on, and the first diode D1 is forward biased and turned on, at this time, the first inductor L1 continues to flow, charges the battery through the first diode D1, at the same time, the cluster current is divided into two current branches, one of which charges the capacitor, and the other charges the first capacitor C2 through the first diode D1, the first capacitor C2 and the second inductor L2, at this time, the second inductor L2 continues to flow. In the discharging process, in the Ton stage, as shown in Figure 6c , T2 transistor is off, T1 transistor is on, the battery charges the first inductor L1, the current of the first inductor L1 increases, at the same time, the cluster current Ir discharges the battery through the second inductor L2, the first capacitor C2 and T1 transistor, in this process, the first capacitor C2 and the capacitor are discharged, and the L2 is charged; in the Toff stage, as shown in Figure 6d , T1 transistor is off, the second diode D2 is forward biased and turned on, at this time, the first inductor L1 continues to flow, discharges the battery through the first capacitor C2 and the second diode D2, the first capacitor C2 is charged, the second inductor L2 continues to flow, and the capacitor is charged through the second diode D2. In the whole charging and discharging process, according to the average model, the voltage across the capacitor Uc = Ub * D / (1-D), where D = Ton / (Ton + Toff), Ir is the cluster current, Ub is the battery voltage, and Uc is the capacitor voltage.

[0071] Figure 4 The circuit structure schematic diagram of the equalizer of another embodiment of the application is shown. As shown in Figure 4 , in another embodiment of the application, on the basis of the embodiment shown in Figure 2 , a set of transistors and diodes are added between the second end of the inductor and the battery and the capacitor respectively, specifically, the equalizer comprises:

[0072] an inductor L;

[0073] a first transistor T1, whose collector is connected to the connection point of the battery and the capacitor, and whose emitter is connected to the second end of the inductor L;

[0074] The first diode D1 is connected in parallel between the collector and emitter of the third transistor T1;

[0075] The collector of the second transistor T2 is connected to the second terminal of the inductor L, and the emitter is connected to the end of the capacitor away from the battery.

[0076] The second diode D2 is connected in parallel between the collector and emitter of the fourth transistor T2;

[0077] The collector of the third transistor T3 is connected to the first end of the inductor L, and the emitter is connected to the end of the capacitor away from the battery.

[0078] The third diode D3 is connected in parallel between the collector and emitter of the second transistor D3;

[0079] The fourth transistor T4 has its collector connected to the end of the battery furthest from the capacitor, and its emitter connected to the first end of the inductor L.

[0080] The fourth diode D4 is connected in parallel between the collector and emitter of the first transistor T4; and

[0081] The second capacitor C2 has its two ends connected to the end of the capacitor furthest from the battery and the end of the battery furthest from the capacitor, respectively.

[0082] according to Figure 4 The embodiment shown, Figures 7a-7b , Figures 7c-7d The diagrams show the current flow in charging and discharging modes, respectively. During the charging process, in the Toff phase, as... Figure 7a As shown, transistors T1 and T3 are off, while transistors T2 and T4 are on. At this time, the cluster current Ir charges inductor L through transistors T2 and T4. Simultaneously, the battery and capacitor are both discharging, charging inductor L. During the Ton phase, as... Figure 7bAs shown, T2 and T4 are off, T1 and T3 are on, and the first diode D1 and the third diode D3 are forward biased and on, at this time, the inductor L charges the capacitor through the first diode D1 and the third diode D3, and at the same time, the cluster current Ir charges the battery and the capacitor. In the discharge process, in the Ton stage, T2 and T4 are off, T1 and T3 are on, the capacitor discharges, and charges the inductor L through T1 and T3, and at the same time, the cluster current realizes the discharge of the capacitor and the battery; in the Toff stage, T1 and T3 are off, T2 and T4 are on, and the second diode D2 and the fourth diode D4 are forward biased and on, at this time, the inductor L charges the capacitor through the second diode D2, the fourth diode D4, and the battery and the capacitor. In the whole charging and discharging process, according to the average model, the battery voltage Ub=Uc*(2*D-1) / (1-D), wherein Uc is the capacitor voltage, D=Ton / (Ton+Toff), and the second capacitor voltage Uo=Uc+Ub.

[0083] The application provides a battery system with equalization management function, which is composed of a capacitor, a triode, a diode and other low-cost low-voltage devices, and the equalizer is integrated with the battery pack. On the one hand, the equalization of the battery pack in the cluster is controlled by the capacitor, and on the other hand, the high and low adjustment of the whole cluster voltage can be realized by adjusting the capacitor voltage, and the cluster current can be controlled, so that the whole system has the functions of cluster equalization and battery pack equalization, and the bus voltage of the power conversion system (PCS) can be improved by improving the capacitor voltage in the equalizer, and the grid-connected voltage of the PCS can be improved. The equalizer adopts low-cost low-voltage devices, so the overall power is small, the cost is low, and the loss is small.

[0084] Although the embodiments of the application are described above, it should be understood that they are only presented as examples and not as limitations. It is obvious to those skilled in the related art that various combinations, modifications and changes can be made without departing from the spirit and scope of the application. Therefore, the width and scope of the application disclosed herein should not be limited by the above disclosed exemplary embodiments, but should only be defined according to the appended claims and their equivalent replacements.

Claims

1. A battery system having a function of equalizing management, characterized by comprising: The battery system comprises a plurality of parallel battery clusters connected to an energy storage converter via a battery bus, and any of the battery clusters comprises a plurality of series battery packs and a high voltage box connected in series with the battery packs, wherein any of the battery packs comprises a battery, a capacitor connected in series with the battery, and a balancer, wherein the balancer comprises: a first transistor having its collector connected to one end of the battery away from the capacitor, and its emitter connected to a first end of an inductor; a first diode having its anode connected to the emitter of the first transistor, and its cathode connected to the collector of the first transistor; a second transistor having its collector connected to a first end of an inductor, and its emitter connected to one end of the capacitor away from the battery; a second diode having its anode connected to the emitter of the second transistor, and its cathode connected to the collector of the second transistor; and an inductor having its second end connected to the junction of the battery and the capacitor; or the balancer comprises: a first transistor having its collector connected to a first end of a first inductor, and its emitter connected to the junction of the battery and the capacitor; a first diode having its anode connected to the emitter of the first transistor, and its cathode connected to the collector of the first transistor; a second transistor having its collector connected to the junction of the battery and the capacitor, and its emitter connected to a first end of a second inductor; a second diode having its anode connected to the emitter of the second transistor, and its cathode connected to the collector of the second transistor; a first inductor having its second end connected to one end of the battery away from the capacitor; a second inductor having its second end connected to one end of the capacitor away from the battery; and a first capacitor having its two ends connected to the collector of the first transistor and the emitter of the second transistor, respectively; or the balancer comprises: an inductor; a first transistor having its collector connected to the junction of the battery and the capacitor, and its emitter connected to a second end of the inductor; a first diode having its anode connected to the emitter of the first transistor, and its cathode connected to the collector of the first transistor; a second transistor having its collector connected to the second end of the inductor, and its emitter connected to one end of the capacitor away from the battery; a second diode having its anode connected to the emitter of the second transistor, and its cathode connected to the collector of the second transistor; a third transistor having its collector connected to a first end of the inductor L, and its emitter connected to one end of the capacitor away from the battery; a third diode having its anode connected to the emitter of the third transistor, and its cathode connected to the collector of the third transistor; a fourth transistor having its collector connected to one end of the battery away from the capacitor, and its emitter connected to a first end of the inductor L; a fourth diode having its anode connected to the emitter of the fourth transistor, and its cathode connected to the collector of the fourth transistor; and a second capacitor having its two ends connected to one end of the capacitor away from the battery, and one end of the battery away from the capacitor, respectively.

Images