Circuit for improving power loop efficiency of energy storage battery cluster

Abstract

The utility model discloses a circuit for improving the efficiency of a power loop of an energy storage battery cluster, which is applied to the field of energy storage batteries, and aims to solve the problems that a contactor is opened when current passes through a contactor in a conventional high-voltage box, so that the contact of the contactor causes electric arc, the service life of the contactor is seriously influenced, and a safety risk is brought to a battery system. According to the utility model, the design of the high-voltage box and the connection of the main loop are improved; contactors and fuses in the high-voltage box are omitted, so that the problems of contactor adhesion, fuse damage and the like are avoided; the main circuit of the battery cluster is optimized by adopting the switch with the arc extinguishing device, and the safety and reliability of the battery system are greatly improved by utilizing the reliable arc extinguishing device of the circuit breaker and the high breaking frequency.

Description

Technical Field

[0001] The utility model belongs to the field of energy storage batteries, and particularly relates to a BMS control device. Background Art

[0002] The existing high-voltage box inside the battery cluster consists of parts such as BMS, contactors, fuses, circuit breakers, current acquisition devices, etc., and has problems such as complex circuits and cumbersome control.

[0003] As shown in the appendix Figure 1 , K1, K2, and K3 are contactors, LA is a Hall sensor or a shunt, FU is a fuse, Q1 is a circuit breaker, R is a pre-charge resistor, 1#BMU and N#BMU are 1# battery control manager and N# battery control manager respectively. The existing battery cluster is connected in series by battery modules and then connected to the cluster management high-voltage box for control. Its voltage can be serially connected to several hundred volts - 1500 volts, or even higher. Therefore, the withstand voltage of the internal components of the high-voltage box must be higher than the total voltage of the battery cluster. When designing the high-voltage box, it is particularly important to select components with appropriate withstand voltage. The withstand voltage level of the devices becomes a constraint in the selection of electrical components, resulting in problems such as difficult selection, few available selections, and high prices.

[0004] Figure 1 In the high-voltage box, the control logic is to first close the circuit breaker Q1, detect the voltage between BAT+ and BAT-, then close K2, and then close K3. After the pre-charge voltage reaches a certain value, close K2 again and open K3. Its control logic is complex and it is difficult to find problem points. At the same time, when the battery system fails or needs to protect the battery system, the BMS (Battery Management System, battery cluster manager) disconnects the K1 and K2 contactors to disconnect the battery system from the PCS or the DC bus to protect the battery system of this cluster. However, because the PCS is running, it may cause the K1 and K2 contactors to trip when there is current passing through, resulting in arcs at the contactor contacts, seriously affecting the service life of the contactors and bringing safety risks to the battery system. Summary of the Utility Model

[0005] In order to solve the above technical problems, the utility model proposes a circuit for improving the power loop efficiency of an energy storage battery cluster. By canceling the contactors and fuses in the high-voltage box and using a switch with an arc extinguishing device to optimize the main circuit of the battery cluster, the effects of cost reduction and efficiency improvement can be achieved.

[0006] The technical solution adopted by the utility model is: A circuit for improving the power loop efficiency of an energy storage battery cluster, comprising:

[0007] Battery cluster, battery cluster manager (BMS), power conversion system (PCS); the battery cluster includes multiple serially connected battery modules, and the battery cluster is connected to the power conversion system (PCS) through a circuit breaker (Q1); each battery module is connected to a battery management unit (BMU); the battery cluster manager (BMS) is connected between each battery management unit (BMU) and the power conversion system (PCS); a fuse (FU) is also included, and the fuse (FU) is connected in series between two certain battery modules.

[0008] The battery cluster manager (BMS) is connected between each battery management unit (BMU) and the power conversion system (PCS) through a CAN bus.

[0009] A Hall sensor or a shunt (LA) is also included, and the Hall sensor or the shunt (LA) is connected to the battery cluster manager (BMS).

[0010] The power conversion system (PCS) includes: a first contactor (1K), a second contactor (2K), a third contactor (3K), a fourth contactor (4K), a first pre-charge resistor (1R), a first pre-charge resistor (1R), and a DC-AC converter;

[0011] The first end of the first contactor (1K) is connected to the positive pole of the battery cluster, the second end of the first contactor (1K) is connected to the first end of the DC-AC converter, the first end of the first pre-charge resistor (1R) is connected to the first end of the first contactor (1K), the second end of the first pre-charge resistor (1R) is connected to the first end of the third contactor (3K), and the second end of the third contactor (3K) is connected to the second end of the first contactor (1K);

[0012] The first end of the second contactor (2K) is connected to the negative pole of the battery cluster, the second end of the second contactor (2K) is connected to the second end of the DC-AC converter, the first end of the second pre-charge resistor (2R) is connected to the first end of the second contactor (2K), the second end of the second pre-charge resistor (2R) is connected to the first end of the fourth contactor (4K), and the second end of the fourth contactor (4K) is connected to the second end of the second contactor (2K).

[0013] The circuit breaker (Q1) specifically uses a switch with an arc extinguishing device.

[0014] The beneficial effects of the present utility model: By canceling the contactors in the original high-voltage box, problems such as contactor adhesion and fuse damage are avoided; by using a switch with an arc extinguishing device to optimize the main circuit of the battery cluster, the safety and reliability of the battery system are greatly improved by the reliable arc extinguishing device and high breaking capacity of the circuit breaker; the present utility model has the following advantages:

[0015] 1. By reducing the connection points of components such as connecting contactors, the connection point loss during energy transmission of the battery cluster is reduced, which helps to improve the DC efficiency of the entire battery cluster;

[0016] 2. The number of contactors is reduced, eliminating the safety hazards caused by the arcs generated by the DC contactors during load-breaking within the battery cluster. Meanwhile, the disconnection of the battery cluster is changed from a contactor to a circuit breaker, enhancing the service life and stability of the system (the number of load-breaking operations of a contactor is only dozens or over a hundred times, while the load-breaking capacity of a circuit breaker can reach thousands of times, and its service life is much longer than that of a contactor).

[0017] 3. By reducing electrical components, the cost of the battery cluster is lowered. The design of the high-voltage box can be eliminated in small industrial and commercial energy storage systems, further reducing the system cost. Meanwhile, the existing components of the energy storage inverter are fully utilized, improving the main circuit connection from the battery to the battery management to the energy storage inverter.

[0018] 4. By changing the installation position of the fuse, the voltage of the fuse can be effectively reduced, avoiding difficulties in fuse selection. Meanwhile, the problems of high voltage withstand and large volume of the fuse are solved, and the problems of troublesome installation and maintenance of the fuse within the high-voltage box are synchronously solved.

[0019] 5. By reducing the voltage of the fuse, the fuse is changed from a special high-voltage device to an ordinary low-voltage device, and the universality of the device plays a positive role in reducing the system cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the circuit connection diagram within the high-voltage box of the battery cluster in the prior art;

[0021] Figure 2 is the circuit connection diagram of the industrial and commercial energy storage system with a two-stage architecture;

[0022] Figure 3 is the circuit connection schematic diagram after the high-voltage box design of the present utility model is removed;

[0023] Figure 4 is the circuit connection schematic diagram for reducing the protection voltage of the present utility model;

[0024] Figure 5 is the system connection diagram after the system improvement of the present utility model;

[0025] Figure 6 is the circuit working process for improving the power loop efficiency of the energy storage battery cluster of the present utility model;

[0026] Figure 7 is the system connection diagram after optimizing the pre-charge, contactor, and high-voltage box of the present utility model;

[0027] Figure 8 is the battery system connection diagram for improving the fuse position of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To facilitate the understanding of the technical content of the present utility model by those skilled in the art, the content of the present utility model will be further explained below with reference to the accompanying drawings.

[0029] Through a full understanding of the battery system and an understanding of the energy storage converter, the present utility model discovers that the phenomenon of over-design in the energy storage system is very serious. At this time, it is necessary to optimize the main circuit structure of the energy storage system by combining the battery system and the energy storage converter system and streamline unnecessary components, so as to improve the overall stability and reliability of the system. Especially in the industrial and commercial energy storage system, its BMS control adopts a two-level architecture. After the high-voltage box outputs, it directly enters the main circuit of the energy storage converter. Its connection circuit is as Figure 2 shown. Figure 2 In the figure, K1, K2, and K3 in the high-voltage box are contactors, LA is a Hall sensor or a shunt, FU is a fuse, Q1 is a circuit breaker, and R is a pre-charge resistor; in the energy storage converter, PCS (Power Conversion System) is an energy storage current converter, and 1K, 2K, 3K, and 4K in the PCS are contactors, 1R is the first pre-charge resistor, and 2R is the second pre-charge resistor.

[0030] As Figure 2 shown, there are contactors and pre-charge circuits in the high-voltage box, and there are also contactors and pre-charge circuits inside the PCS. When the two are connected and used, there are two sets of contactor controls and pre-charge circuits in the loop, which belong to over-design and repeated design in the system, increasing the connection points of the contactors, increasing the line loss, and increasing the fault points. Therefore, the present utility model optimizes the main circuit of the system as follows:

[0031] Cancel the K1, K2, and K3 contactors in the high-voltage box of the main circuit;

[0032] Cancel the R pre-charge resistor in the high-voltage box of the main circuit;

[0033] Since the components in the high-voltage box are reduced, the high-voltage box can be directly optimized and does not need to be designed. The circuit connection after removing the high-voltage box is as Figure 3 shown. Figure 3 In the figure, LA is a Hall sensor or a shunt, FU is a fuse, Q1 is a circuit breaker, and R is a pre-charge resistor; in the energy storage converter, PCS is an energy storage current converter, 1K, 2K, 3K, and 4K are contactors, 1R is the first pre-charge resistor, and 2R is the second pre-charge resistor.

[0034] In the battery cluster system, the high voltage required by the energy storage converter is composed of each battery module in series. Connecting multiple battery modules in series can achieve a battery system with a voltage of thousands of volts. In the current high-voltage box, a fuse with a higher voltage rating is selected for protection. The present utility model moves the fuse in the high-voltage box between two battery modules, which can achieve the effect of reducing the protection voltage; the specific circuit diagram and implementation method are asFigure 4 as shown

[0035] In the present utility model, ①. The installation position of the fuse is optimized. The fuse originally at the high-voltage box or the cluster end is moved to be installed between two certain modules, which can reduce the withstand voltage level of the fuse, thereby improving the difficult selection due to high voltage and reducing the cost of the fuse;

[0036] ②. The fusing voltage of the fuse originally at the high-voltage box or the cluster end needs to be greater than the series voltage of all modules in the cluster (the rated voltage of a standard single module is 51.2V, and the highest voltage is 58.4V). If 15 battery modules are connected in series, the fuse voltage needs to be greater than 876V; if 25 battery modules are connected in series, the fuse voltage needs to be greater than 1460V;

[0037] ③. If the position of the fuse is moved between the modules, its withstand voltage only needs to be: module voltage * n modules or module voltage * m - n modules, taking the highest voltage. When the fuse melts, the voltage of the upper modules to the ground is at most module voltage * n modules (the number of upper modules), and the voltage of the lower modules to the ground is at most module voltage * m - n modules (the number of lower modules); for example: when 25 modules are connected in series, a fuse with a withstand voltage level of 1500V should originally be selected. At this time, if the fuse is moved between the 12th module and the 13th module, its withstand voltage is 58.4V * 13 modules = 759.2V, and at this time, a fuse with a withstand voltage of 800V or 1000V can be selected;

[0038] ④. The selection position of the fuse for the lowest voltage of the system is at the middle position of the module, and it can be moved forward or backward according to the actual situation;

[0039] After the above improvements, its system connection diagram is as Figure 5 shown Figure 5 In the figure, LA is a Hall sensor or a shunt, used to measure the current in the circuit, FU is a fuse, and Q1 is a circuit breaker; in the energy storage converter, PCS is an energy storage current converter, 1K, 2K, 3K, and 4K are contactors, 1R is the first pre-charge resistor, and 2R is the second pre-charge resistor.

[0040] In the present utility model, with the rapid development of energy storage technology, more and more optimized control logics and control methods are applied to energy storage systems. The DC-side efficiency and AC-side efficiency of energy storage systems are particularly concerned. The stable operation of the battery system has become a key indicator for evaluating the reliability of energy storage systems. Therefore, the present utility model proposes a circuit connection for improving the power circuit of an energy storage battery cluster, and the main technical problems to be solved include:

[0041] The utility model optimizes the internal components of the high-voltage box of the battery cluster, reduces the contactors and pre-charge resistors in the circuit, and can cancel the high-voltage box (install the components separately when necessary), greatly reducing the component cost;

[0042] The utility model reduces the contactors, thus reducing the potential safety hazards of the system caused by the possible generation of electric arcs when the contactors are switched off under load;

[0043] The utility model reduces the components and the connection points of the main circuit of the battery cluster, thereby reducing the failure rate and improving the battery efficiency on the DC side (the connection points have relatively large power losses);

[0044] Through the design optimization of the main circuit, the utility model simplifies the control circuit and reduces the bulkiness and over-design of the battery system.

[0045] Refer to Figure 6 、 Figure 7 、 Figure 8 As shown in the figure, the circuit of the utility model for improving the power circuit efficiency of the energy storage battery cluster has the following working principle:

[0046] When the direct current is powered on, the DC-side circuit breaker Q1 is closed, and the battery outputs direct current to supply power to the BMS and EMS devices in the system. The DC port of the PCS is powered by the battery. After the device is started, the internal pre-charge circuits 3K and 4K of the PCS are closed, and the direct current is limited by the first pre-charge resistor 1R and the second pre-charge resistor 2R to charge the internal support capacitor of the PCS. When the voltages at both ends of the internal contactors 1K and 2K of the PCS are the same, the internal contactors 1K and 2K of the PCS are closed, and then 3K and 4K are disconnected to complete the startup process, and DC-AC inversion / rectification (charging / discharging) (rectification) is performed;

[0047] When the direct current is powered off, after the device is shut down, the DC-AC inversion / rectification (charging / discharging) is stopped, the internal contactors 1K and 2K of the PCS are disconnected, and then the circuit breaker Q1 is disconnected, thereby completing the device power-off process;

[0048] For the common fault protection of the battery system, when the device is working normally, when the BMS detects that the battery system has a fault or an abnormal condition, and after the BMS judges that the connection between the battery and the inverter system needs to be cut off, the BMS sends a fault shutdown signal (DO output) to the trip coil of the circuit breaker Q1 to disconnect and trip the circuit breaker Q1, realizing the disconnection of the connection between the battery and the inverter system to protect the battery system; for the severe fault protection of the battery system, when the battery system has a short circuit or the instantaneous current exceeds the limit current, and the BMS has no time to react and the circuit breaker Q1 has no time to trip, the fuse FU connected in series in the circuit is heated by the sudden increase in current and the conductor in the FU is melted, realizing the disconnection of the main circuit of the battery.

[0049] The working process of the battery system fault protection is as follows:

[0050] The BMS secondary control system first detects the battery-side voltage. If the battery-side voltage reaches the qualified value, the circuit breaker Q1 is allowed to close. Otherwise, the controller keeps the circuit breaker tripped and does not allow the circuit breaker to close.

[0051] After the circuit breaker Q1 closes normally, the battery system will normally supply power to the PCS or the DC bus. The BMS controller judges the state of the battery system through current acquisition, voltage acquisition, and primary cell data acquisition; and protects the battery system at all times. When primary and secondary faults occur in the battery system, an alarm signal is output to the PCS or the EMS (this control protection scheme is the same as the original BMS control logic).

[0052] If the battery reaches the standard of the BMS level-3 fault point during charging, discharging, or self-loss, the BMS disconnects the circuit breaker by outputting a circuit breaker tripping signal to protect the battery system.

[0053] After the BMS level-3 protection, the circuit breaker needs to be closed manually. After closing the circuit breaker, the BMS determines whether the circuit breaker needs to be disconnected again by detecting the battery system and the charging and discharging process.

[0054] Among them, when the battery system is in level-3 low-voltage protection, the circuit breaker disconnects. After the circuit breaker closes again, the BMS detects that the battery system is still in level-3 low-voltage fault and judges whether it is charging. If it is charging the battery within 5 minutes, the circuit breaker remains closed until the low-voltage fault of the battery disappears; if it is not detected that the battery is being charged within 5 minutes, the circuit breaker is disconnected again to protect the battery system.

[0055] When the battery system is in level-3 high-voltage protection, the circuit breaker disconnects. After the circuit breaker closes again, the BMS detects that the battery system is still in level-3 high-voltage fault and judges whether it is charging. If it is charging the battery within 5 minutes, the circuit breaker is disconnected to protect the battery system; if it is not detected that the battery is being charged within 5 minutes, the circuit breaker remains closed.

[0056] The utility model optimizes the main circuit through the BMS management of the battery cluster in the energy storage system, improves the control logic of the BMS, and is conducive to the simplicity, efficiency, and reliability improvement of the energy storage system BMS design; especially, the control of the contactor, the judgment of the pre-charge voltage, and the control of the pre-charge circuit are less required in the BMS control; the battery system is protected by controlling the circuit breaker, and the reliable arc extinguishing device and high breaking capacity of the circuit breaker greatly improve the safety and reliability of the battery system.

[0057] In the management of the energy storage battery cluster of the present utility model, the BMS realizes the protection of the battery system by controlling the circuit breaker, reducing the use of contactors and pre-charge circuits; and realizes the optimization of the BMS for the battery system through a similar BMS management control strategy, using any circuit breaker, fuse switch or switch with an arc extinguishing device to optimize the main circuit of the battery cluster. Through the above-mentioned optimization design of the battery main circuit and the cancellation of the contactor, the purpose of cost reduction and efficiency improvement is achieved.

[0058] Those of ordinary skill in the art will realize that the embodiments described herein are for helping the reader understand the principles of the present utility model, and it should be understood that the protection scope of the present utility model is not limited to such specific statements and embodiments. For those skilled in the art, various changes and modifications can be made to the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the scope of the claims of the present utility model.

Claims

1. A circuit for improving the efficiency of a power circuit of an energy storage battery cluster, characterized in that: include: A battery cluster, a battery cluster manager (BMS), and a power storage device (PCS); the battery cluster includes a plurality of battery modules connected in series, and the battery cluster is connected to the power storage device (PCS) through a circuit breaker (Q1); each battery module is connected to a battery control manager (BMU); the battery cluster manager (BMS) is connected between each battery control manager (BMU) and the power storage device (PCS); and also includes a fuse (FU), which is connected in series between two battery modules.

2. A circuit for improving the efficiency of a power circuit of an energy storage battery cluster according to claim 1, characterized in that: The battery management system (BMS) is connected between the battery control unit (BMU) and the power storage system (PCS) through the CAN bus.

3. A circuit for improving the efficiency of a power circuit of an energy storage battery cluster according to claim 2, characterized in that: The device further comprises a Hall sensor or a shunt (LA), which is connected to a battery cluster manager (BMS).

4. A circuit for improving the efficiency of a power circuit of an energy storage battery cluster according to claim 3, characterized in that: The energy storage current device (PCS) comprises: a first contactor (1K), a second contactor (2K), a third contactor (3K), a fourth contactor (4K), a first pre-charging resistor (1R), a first pre-charging resistor (1R) and a DC-AC converter; A first end of the first contactor (1K) is connected to the positive electrode of the battery cluster, a second end of the first contactor (1K) is connected to the first end of the DC-AC converter, a first end of the first pre-charging resistor (1R) is connected to the first end of the first contactor (1K), a second end of the first pre-charging resistor (1R) is connected to the first end of the third contactor (3K), and a second end of the third contactor (3K) is connected to the second end of the first contactor (1K); The first end of the second contactor (2K) is connected to the negative electrode of the battery cluster, the second end of the second contactor (2K) is connected to the second end of the DC-AC converter, the first end of the second pre-charging resistor (2R) is connected to the first end of the second contactor (2K), the second end of the second pre-charging resistor (2R) is connected to the first end of the fourth contactor (4K), and the second end of the fourth contactor (4K) is connected to the second end of the second contactor (2K).

5. A circuit for improving the efficiency of a power circuit of an energy storage battery cluster according to claim 4, characterized in that: The circuit breaker (Q1) is specifically a switch with an arc extinguishing device.

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