Battery cubicle converter and electrochemical energy storage conversion system

Abstract

The application provides a battery plug-in box converter and an electrochemical energy storage conversion system, and belongs to the field of electrochemical energy storage. The battery plug-in box converter comprises a main control unit, a DC / DC conversion circuit and a high-speed communication interface connected to the main control unit respectively; the positive and negative poles of one end of the DC / DC conversion circuit are connected to the output positive and negative poles of a battery plug-in box respectively; and the positive and negative poles of the other end of the DC / DC conversion circuit are connected to the positive and negative poles of a cascade circuit respectively. The short board effect caused by the fact that a certain battery or battery plug-in box in the electric pile reaches the cut-off voltage or fails can be eliminated by using the application, and the charge and discharge capacity and the charge and discharge efficiency are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electrochemical energy storage, and particularly relates to a battery plug-in box converter and an electrochemical energy storage conversion system. BACKGROUND

[0002] At present, the capacity demand of energy storage system on energy storage battery is increasing, and a large number of battery plug-in boxes in series and parallel in the battery become the main means for capacity expansion of the energy storage system. In actual projects, 1-10 batteries in parallel are generally used as a battery module, and 12 or 24 battery modules are connected in series to form a battery plug-in box, which is the smallest operation unit during the maintenance of the battery. Generally, a plurality of battery plug-in boxes are connected in series to form a battery cluster, and the voltage of the battery cluster is generally matched with the direct current voltage range of the energy storage converter. Figure 1 As shown in the figure, it is the composition mode of the battery and the energy storage converter in the common energy storage system.

[0003] However, the inconsistency of each battery after series and parallel connection becomes a restricting factor of the overall performance of the battery. When a single battery in the battery reaches the charge and discharge cutoff voltage, the entire battery has to stop charging and discharging, otherwise it will cause battery failure, and even cause fire accidents.

[0004] The current solution is to use a battery management system, which not only monitors the operating conditions such as voltage and temperature of each battery, but also uses active balancing or passive balancing to make the battery with higher voltage less charged and the battery with lower voltage less discharged in a single battery plug-in box. However, the balancing capacity is limited, and only the balancing between the batteries in a single battery plug-in box can be managed, and the short board effect of the battery often still occurs in actual projects. Figure 2 As shown in the figure, the battery management system in a single battery plug-in box includes acquisition and balancing circuits.

[0005] On the basis of using the battery management system, some manufacturers propose to use a group string type energy storage converter, that is, each battery cluster is connected to a storage converter, and the battery clusters are not connected in parallel. The function of short board battery or battery plug-in box can be realized at any time. The battery cluster continues to charge and discharge. However, when a single battery or battery plug-in box reaches the charge and discharge cutoff voltage, the entire cluster stops running, and the capacity utilization of other batteries is limited. Figure 3 As shown in the figure, it is the system composition mode of the group string type energy storage converter and the battery. SUMMARY

[0006] The purpose of the present application is to solve the problems existing in the prior art, and to provide a battery plug-in box converter and an electrochemical energy storage conversion system, which can eliminate the short board effect caused by the cutoff voltage or failure of a certain battery or plug-in box in the battery.

[0007] The application is realized by the following technical scheme:

[0008] In the first aspect of the application, a battery plug-in box converter is provided, which comprises a master control unit, a DC / DC conversion circuit and a high-speed communication interface connected to the master control unit respectively.

[0009] The positive and negative poles of one end of the DC / DC conversion circuit are connected to the output positive and negative poles of the battery plug-in box respectively.

[0010] The positive and negative poles of the other end of the DC / DC conversion circuit are connected to the positive and negative poles of the cascade circuit respectively.

[0011] The application is further improved in that a plurality of the battery plug-in box converters can be connected in series through the cascade circuit.

[0012] The application is further improved in that the battery plug-in box converter comprises a bypass circuit.

[0013] One end of the bypass circuit is connected to the output positive and negative poles of the battery plug-in box, and the other end is connected to the positive and negative poles of the cascade circuit.

[0014] The application is further improved in that during the platform period of battery charging and discharging, the bypass circuit is connected, and at the same time, the DC / DC conversion circuit is closed, so that the charging and discharging is carried out through the bypass circuit.

[0015] At the end of battery charging and the end of discharging, the bypass circuit is disconnected, and at the same time, the DC / DC conversion circuit is turned on, so that the DC / DC conversion circuit is put into operation.

[0016] The application is further improved in that the battery plug-in box converter further comprises a collection circuit connected to the master control unit.

[0017] The application is further improved in that the high-speed communication interface adopts a high-speed industrial Ethernet interface.

[0018] In the second aspect of the application, an electrochemical energy storage conversion system is provided, which comprises a plurality of battery clusters, each battery cluster comprising an energy storage converter, a plurality of battery plug-in boxes and a plurality of battery plug-in box converters.

[0019] In each battery cluster, a battery plug-in box converter is connected to each battery plug-in box; the cascade circuit of the uppermost battery plug-in box converter is connected to the direct current side of the energy storage converter, and the cascade circuits of the other battery plug-in box converters and the cascade circuits of the battery plug-in box converters adjacent thereto are connected.

[0020] The application is further improved in that the electrochemical energy storage conversion system further comprises a centralized control device, a cluster management system and a battery management system.

[0021] A cluster management system is arranged in each battery cluster, and the cluster management system in each battery cluster controls the energy storage converter and the battery cubicle converter in the battery cluster;

[0022] The battery cubicle converter is connected to the battery management system one by one;

[0023] The cluster management system and the energy storage converter in each battery cluster can respectively communicate with the centralized control device.

[0024] The cluster management system in each battery cluster is connected to the energy storage converter through a communication cable;

[0025] The high-speed communication interface of the battery cubicle converter can be connected to the battery management system and the cluster management system through a communication cable;

[0026] The cluster management system and the energy storage converter in each battery cluster are respectively connected to the centralized control device through a communication cable.

[0027] Compared with the prior art, the beneficial effects of the present application are that the short board effect caused by the fact that a certain battery or battery cubicle in the stack reaches the cutoff voltage or fails can be eliminated by using the present application, and the charge and discharge capacity and the charge and discharge efficiency are improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a conventional DC side system primary topology diagram.

[0029] Figure 2 is a battery management system equalization topology diagram.

[0030] Figure 3 is a conventional group string type DC side system primary topology diagram.

[0031] Figure 4 is a primary topology diagram of the electrochemical energy storage converter system of the present application.

[0032] Figure 5 is a secondary topology diagram of the electrochemical energy storage converter system of the present application.

[0033] Figure 6 is a composition structure diagram of the battery cubicle converter of the present application. DETAILED DESCRIPTION

[0034] The present application will be described in further detail below with reference to the accompanying drawings:

[0035] The primary topology diagram of the electrochemical energy storage converter system of the present application is shown in Figure 4 , that is, a schematic diagram of a battery system connection, Figure 4 The connecting lines in the figure represent electrical connecting lines, and the secondary topology diagram of the system of the present application is shown inFigure 5 Figure 2 shows a connection diagram of the control system, Figure 5 The connection line in Figure 1 represents a communication cable. The structural composition of the battery plug-in box converter is shown in Figure 2. Figure 6

[0036] As shown in Figure 1, the electrochemical energy storage converter system of the present application comprises a plurality of battery clusters, each battery cluster comprising an energy storage converter, a plurality of battery plug-in boxes and a plurality of battery plug-in box converters. For clarity, Figure 4 only one energy storage converter is shown in Figure 1. Figure 4

[0037] Specifically, in each battery cluster, the battery plug-in box and the battery plug-in box converter are connected one-to-one, that is, one battery plug-in box converter is connected to each battery plug-in box, and the plurality of battery plug-in box converters are connected in series, and the battery plug-in box converter located at the top of each battery cluster is connected to the DC side of the energy storage converter.

[0038] As shown in Figure 1, the electrochemical energy storage converter system of the present application further comprises a centralized control device, a cluster management system and a battery management system. The battery plug-in box converter is connected one-to-one with the battery management system; each battery cluster is provided with a cluster management system, and the cluster management system in each battery cluster controls the energy storage converter and the battery plug-in box converter in the battery cluster. Each cluster management system communicates with the centralized control device, and each energy storage converter also communicates with the centralized control device, forming an electric pile. Figure 5 Specifically, the battery plug-in box converter located at the top of each battery cluster is connected to the cluster management system through a communication cable, and the cluster management system is also connected to the energy storage converter through a communication cable. The cluster management system and the energy storage converter in each battery cluster are further connected to the centralized control device through a communication cable, forming an electric pile. At the same time, in each battery cluster, each battery plug-in box converter is connected to a battery management system through a communication cable.

[0039]

[0040] As shown in the embodiment of Figure 1, a cluster management system and an energy storage converter are provided on each battery cluster, and the battery cluster, the cluster management system and the energy storage converter are one-to-one, that is, N battery clusters correspond to N cluster management systems and N energy storage converters. Each energy storage converter and each cluster management system communicates with the centralized control device. At the same time, each battery plug-in box converter is connected to a battery management system. Figure 5 Specifically, the functions of the cluster management system are as follows:

[0041]

[0042] ​​​1. Receive the battery data uploaded by each battery management system (BMU) in the battery cluster (voltage, temperature, etc. of each battery in the battery cluster) and the data uploaded by the battery cassette converter (PACK voltage and battery cassette converter working status, etc. data) ;

[0043] 2. According to the above data, calculate the SOC and SOH values of each battery, calculate the SOC and SOH values of each battery cassette, calculate the SOC and SOH values of the entire battery cluster, and according to the analysis results of these data and the instructions received from the centralized control device, control the operation mode of the battery cassette converter, including one of the three modes of voltage reduction, bypass and straight-through of the battery cassette converter;

[0044] 3. Upload these data to the centralized control system, and also receive the instructions of the centralized control system, and the centralized control device is responsible for receiving external instructions and informing the upper control system of the chargeable and dischargeable capacity of the entire stack, and charging and discharging the entire battery cluster.

[0045] In addition, the cluster management system and the energy storage converter also have mutual interaction control logic (for example, power reduction operation, etc. to protect the charging and discharging current of the battery within a reasonable range.

[0046] The above functions are realized by using existing algorithms, which will not be described here.

[0047] The electrochemical energy storage converter system of the present application, Figure 3 The experimental data of two battery clusters of the traditional system shown in the table are as follows:

[0048] The experimental data of battery cluster 1 are shown in Table 1:

[0049]

[0050] The experimental data of battery cluster 2 are shown in Table 2:

[0051]

[0052] Table 2

[0053] The "enable" in Table 1 and Table 2 refers to the system of the present application, and the "disable" refers to Figure 3 The traditional system (i.e. the system without battery cassette converter) shown in the table, and the "cycle result" refers to the data of full charging and full discharging of the two battery clusters; and the "dispersion degree" refers to the inconsistency of the SOC in the entire battery cluster, that is, the higher the inconsistency of the SOC, the greater the loss of the system charging and discharging.

[0054] The dispersion rate is determined by the system itself, that is, the dispersion rate of the system is determined when the battery plug-in box forms the electric pile, but the dispersion rate will change with the change of the charging and discharging system. The dispersion rate is used to measure the inconsistency of the SOC. In Tables 1 and 2, the difference between the dispersion degrees of the PACK during charging and discharging is the dispersion rate. From the difference between the dispersion degrees of the PACK, it can be seen that the dispersion rate of the system of the application is lower than that of the traditional system (in Table 1, the dispersion rate of the battery cluster 1 in the system of the application is 0.013-0.009=0.004, the dispersion rate of the battery cluster 1 in the traditional system is 0.009-0.001=0.008, in Table 2, the dispersion rate of the battery cluster 2 in the system of the application is 0.030-0.019=0.011, the dispersion rate of the battery cluster 2 in the traditional system is 0.017-0.001=0.016), and the lower the dispersion rate, the higher the full charging and discharging capacity, that is, the larger the charging and discharging capacity. Therefore, compared with the traditional system, the charging and discharging capacity of the system of the application is improved.

[0055] As can be seen from Tables 1 and 2, in the case of a very low dispersion rate of the battery plug-in box (that is, the case where the electric quantity of the whole cluster of battery cells is very consistent), the effect of the application can also be achieved, and the discharging capacity of the battery cluster 1 and the battery cluster 2 is increased by about 2.5%.

[0056] Since the cluster management system of the application is used to control the operating state of each battery plug-in box converter, the short board effect of the system of the application is reduced, thereby improving the charging and discharging capacity of the whole system.

[0057] Moreover, the charging and discharging efficiency is further improved by the battery plug-in box converter. As shown in Figure 6 The battery plug-in box converter includes a master control unit and a DC / DC conversion circuit and a high-speed communication interface connected thereto. One end of the DC / DC conversion circuit is connected to the positive and negative poles of the battery plug-in box, and the other end of the DC / DC conversion circuit is connected to the positive and negative poles of the cascade circuit. The battery plug-in box converter and other battery plug-in box converters can be connected in series through the cascade circuit, that is, the cascade side end (cascade circuit) of the battery plug-in box converter is connected to the cascade side end (cascade circuit) of the adjacent battery plug-in box converter, to realize the series connection of multiple battery plug-in box converters. The high-speed communication interface can be connected to the cluster management system and the battery management system.

[0058] Figure 4 And Figure 5 In the embodiment shown in the figure, the cascade circuit of the uppermost battery plug-in box converter in each battery cluster is connected to the direct current side of the energy storage converter, and the cascade circuit of the other battery plug-in box converter is connected to the cascade circuit of the adjacent battery plug-in box converter, Figure 5In the illustrated architecture, the high-speed communication interface of the topmost battery rack converter of each battery cluster is connected to the cluster management system.

[0059] Further, a bypass circuit is arranged inside the battery rack converter, one end of the bypass circuit is connected to the positive and negative output terminals of the battery rack, and the other end is connected to the positive and negative terminals of the cascade circuit. In the platform period of battery charging and discharging, the bypass circuit is connected by the cluster management system control, and the DC / DC conversion circuit is closed at the same time, so that the current flows through the bypass circuit for charging and discharging, and the DC / DC conversion circuit does not work. Only at the end of battery charging or discharging, the bypass circuit is disconnected by the cluster management system control, and the DC / DC conversion circuit is turned on, so that the DC / DC conversion circuit is put into operation (the function can be realized by controlling the on-off of the bypass circuit and the DC / DC conversion circuit through PLC programming in the existing circuit control method, which is not described here again.). In this way, the bypass circuit eliminates the short board between each battery rack in the battery cluster. Under normal circumstances, the bypass circuit will not be affected by the loss of charging and discharging efficiency during the entire charging and discharging process. Only at the end of charging and discharging, the DC / DC conversion circuit is put into operation, which greatly improves the charging and discharging efficiency.

[0060] Further, the collection circuit (such as battery voltage and temperature collection circuit, battery equalization circuit) of the battery management system can also be combined into the battery rack converter (here, only the physical location is changed, and the function of the battery management system is not changed, which is not described here again). The collection circuit is connected to the main control unit.

[0061] The main control unit of the battery rack converter receives the output voltage instruction value sent by the centralized control device, and drives the DC / DC conversion circuit according to the output voltage instruction value, so that the battery rack converter naturally inputs or outputs current to the port of the battery side according to the output current (this is the control logic inside the DC / DC conversion circuit, which controls the duty cycle, and is not described here again). At this time, the battery side is clamped by the battery voltage, the cascade side voltage is controlled by the battery rack converter, and the output current is controlled by the energy storage converter as a whole (that is, the output and input power of the converter is controlled to charge and discharge), according to the power balance principle, the battery side current naturally changes with the other three variables (that is, the battery voltage, the cascade side voltage and the output current).

[0062] At the same time, the main control unit of the battery rack converter feeds back the battery voltage temperature and other state information and equipment running state information of the battery rack to the cluster management system through the high-speed communication interface. These state information are collected by the collection circuit in the existing battery rack and sent to the main control unit, which is not described here again.

[0063] The communication interface of the battery plug-in box converter adopts a high-speed industrial Ethernet interface to realize millisecond-level information interaction and high-speed control of the overall system.

[0064] When a battery in the battery plug-in box fails, the entire battery cluster in which the battery plug-in box is located is taken out of operation. Specifically, the energy storage converter corresponding to the battery cluster is turned off, so that the entire battery cluster is taken out of operation. At this time, the bypass circuit corresponding to the battery plug-in box is controlled to be disconnected by the centralized control device, and the DC / DC conversion circuit corresponding to the battery plug-in box is controlled to be disconnected, so that the battery plug-in box is separated from the battery cluster, facilitating subsequent maintenance or replacement.

[0065] Figure 4 and Figure 5 In the embodiment shown, the centralized control device collects information of all the batteries in the battery stack, judges the operating state of each battery and whether the charge / discharge current needs to be reduced, and the like. These functions can be realized by PLC programming according to actual needs, and will not be described herein again. Only a brief introduction is given as follows.

[0066] The control of the battery plug-in box converter by the centralized control device is divided into three parts, namely, battery cluster internal control, battery stack control and total current limiting control, which are specifically as follows.

[0067] Battery cluster internal control: Since the cascade side of all the battery plug-in box converters in the battery cluster is in series, the current is consistent, and only the input / output power of the battery plug-in box can be controlled by the difference in the cascade side voltage of each battery plug-in box converter. Therefore, the centralized control device judges whether the battery needs to be current-limited according to the operating state of the battery in each battery plug-in box, and issues a cascade side voltage instruction value to each battery plug-in box converter, so as to adjust the input / output power of each battery plug-in box in real time by controlling the difference in the cascade side voltage of each battery plug-in box, to ensure the continuous maximum operation of the entire battery cluster and eliminate the short board. At the same time, the sum of the cascade side voltages of all the battery plug-in box converters should be equal to the rated voltage of the DC side of the energy storage converter.

[0068] Battery stack control: Since the consistency of each battery cluster may still be insufficient, the balancing and current limiting among the battery clusters also need to be considered. Therefore, when the energy storage system uniformly charges and discharges the battery stack, the system should be able to control the amount of charge / discharge current that each battery cluster should share. Since there is internal resistance in the copper bars, wires and power devices connected by the system, the charge / discharge current of each cluster battery will react as a voltage drop on the internal resistance. Therefore, only a slight difference in the total voltage of each battery cluster needs to be controlled to control the different shunts among the battery clusters. The system of the present application has an energy storage converter arranged in each battery cluster, which separates the circulating current among the battery clusters at the hardware level, and controls the different shunts among the battery clusters.

[0069] Total current control: Because the centralized control device can collect the operating state of all batteries in the stack, adjust the power size of each battery box in the battery cluster according to the state of each battery box, and adjust the current size of each battery cluster in the stack according to the state of each battery cluster, the battery management system can balance the batteries in the battery box, and the current limiting and fault states of all batteries in the stack can be responded and adjusted in time. However, if the total stack is close to the saturation or empty state, or there are many battery boxes that are withdrawn after failure, the total stack needs to be limited in current and power. At this time, the centralized control device should communicate with the energy storage converter, report the total charging / discharging power or current that the stack can accommodate in real time, and realize the protection of the whole stack.

[0070] Finally, it should be noted that the above technical solutions are only one embodiment of the present application. For those skilled in the art, based on the application method and principle disclosed in the present application, various types of improvements or modifications can be easily made, and are not limited to the methods described in the above specific embodiments. Therefore, the above-described method is only preferred and has no limiting meaning.

Claims

1. A battery rack converter, characterized by: The battery plug-in box converter comprises a master control unit, a DC / DC conversion circuit, a high-speed communication interface and a bypass circuit connected thereto respectively; the positive and negative poles of one end of the DC / DC conversion circuit are connected with the output positive and negative poles of the battery plug-in box respectively; the positive and negative poles of the other end of the DC / DC conversion circuit are connected with the positive and negative poles of the cascade circuit respectively; one end of the bypass circuit is connected with the output positive and negative poles of the battery plug-in box, and the other end is connected with the positive and negative poles of the cascade circuit; in the platform period of battery charging and discharging, the bypass circuit is connected, and the DC / DC conversion circuit is closed, so that the charging and discharging is carried out through the bypass circuit; in the end of battery charging and the end of discharging, the bypass circuit is disconnected, and the DC / DC conversion circuit is turned on, so that the DC / DC conversion circuit is put into operation, and the master control unit receives the output voltage instruction value and drives the DC / DC conversion circuit according to the output voltage instruction value.

2. The battery rack converter of claim 1, wherein: A plurality of the battery plug-in box converters can be connected in series through the cascade circuit.

3. The battery rack converter of claim 1, wherein: The battery plug-in box converter further comprises a collection circuit connected with the master control unit.

4. The battery rack converter of claim 1, wherein: The high-speed communication interface adopts a high-speed industrial Ethernet interface.

5. An electrochemical energy storage inverter system, characterized by: The electrochemical energy storage conversion system comprises a plurality of battery clusters, each battery cluster comprising an energy storage converter, a plurality of battery plug-in boxes and a plurality of battery plug-in box converters according to any one of claims 1-4; In each battery cluster, a battery plug-in box converter is connected to each battery plug-in box; the cascade circuit of the uppermost battery plug-in box converter is connected with the direct current side of the energy storage converter, and the cascade circuits of the other battery plug-in box converters and the cascade circuits of the battery plug-in box converters adjacent thereto are connected.

6. The electrochemical energy storage power conversion system of claim 5, wherein: The electrochemical energy storage conversion system further comprises a centralized control device, a cluster management system and a battery management system; Each battery cluster is provided with a cluster management system, and the cluster management system in each battery cluster controls the energy storage converter and the battery plug-in box converter in the battery cluster; The battery plug-in box converter is connected with the battery management system one by one; The cluster management system in each battery cluster and the energy storage converter can respectively communicate with the centralized control device.

7. The electrochemical energy storage power conversion system of claim 6, wherein: The cluster management system in each battery cluster is connected with the energy storage converter through a communication cable; The high-speed communication interface of the battery plug-in box converter can be connected with the battery management system and the cluster management system through a communication cable; The cluster management system in each battery cluster and the energy storage converter are respectively connected with the centralized control device through a communication cable.

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