Polarity reversal connection prevention system for parallel battery clusters and control method

Abstract

The invention discloses a system for preventing polarity reversal connection of parallel battery clusters and a control method, and aims to solve the problem of battery polarity reversal connection of the battery clusters when a plurality of battery clusters are connected to a direct current bus in parallel, and the problems of poor detection efficiency, low reliability and insufficient adaptability of the polarity reversal connection of the battery clusters. The system comprises a plurality of battery clusters which are connected in parallel, a switch unit, a battery control unit and a voltage detection unit, wherein each battery cluster is connected to a direct current bus through the switch unit; the voltage detection unit is used for collecting battery end voltage and load end voltage of the battery cluster; the battery control unit is used for controlling opening and closing operation of the switch unit according to polarities and values of the battery end voltage and the load end voltage. By arranging the voltage detection unit, a judgment basis is provided for the battery control unit, and the battery control unit controls the switch unit to open and close based on the voltage signals, so that automatic battery cluster access control is realized, the debugging efficiency is greatly improved, and the human input is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage systems, and in particular to a parallel battery cluster polarity reverse connection prevention system and a control method. Background Art

[0002] Energy storage systems, as a key supporting technology for energy transition and sustainable development, have experienced rapid development. With the large-scale integration of renewable energy sources (such as solar and wind power), energy storage systems have played a key role in balancing power supply and demand, improving grid stability, and enhancing energy efficiency. Energy storage systems are increasingly being used in power systems, particularly in distributed energy, microgrids, and large-scale energy storage power plants. Parallel operation of multiple battery clusters has become a common configuration.

[0003] In practical engineering applications, to meet the demands of high capacity and high power, multiple battery cells are typically connected in series to form a battery cluster, which is then connected in parallel to the DC bus. In this multi-cluster parallel battery system, reverse polarity connection presents a potential safety hazard and technical difficulty. The risk of reverse polarity connection exists during installation, maintenance, and operation. Reverse polarity connection can cause internal short circuits in the battery, resulting in thermal runaway, damage to the battery and other electrical equipment, and potentially lead to safety incidents and severe economic losses.

[0004] Existing solutions, such as manual inspection and simple voltage detection, suffer from low reliability, poor efficiency and insufficient adaptability when faced with a large number of battery clusters. Summary of the Invention

[0005] (1) Purpose of the invention

[0006] The purpose of the present invention is to provide a parallel battery cluster polarity reverse connection prevention system and control method, aiming to solve the problem of battery polarity reverse connection in battery clusters when multiple battery clusters are connected in parallel to a DC bus, as well as the problems of poor efficiency, low reliability and insufficient adaptability in detecting battery cluster polarity reverse connection.

[0007] (2) Technical solution

[0008] To solve the above problems, a first aspect of the present invention provides a parallel battery cluster anti-polarity reverse connection system, comprising a plurality of parallel battery clusters, a switch unit, a battery control unit, and a voltage detection unit, wherein each of the battery clusters is connected to a DC bus via the switch unit;

[0009] The voltage detection unit is used to collect the battery terminal voltage and the load terminal voltage of the battery cluster;

[0010] The battery control unit is used to control the opening and closing operations of the switch unit according to the polarities and values of the battery terminal voltage and the load terminal voltage.

[0011] Preferably, the switch unit includes a total positive contactor, a total negative contactor and a pre-charge contactor;

[0012] The main positive contactor is used to control the connection between the positive electrode of the battery cluster and the DC bus;

[0013] The main negative contactor is used to control the connection between the negative electrode of the battery cluster and the DC bus;

[0014] The pre-charge contactor is connected in series with a pre-charge resistor and is connected in parallel with the main positive contactor to limit the inrush current when the battery cluster is connected to the busbar.

[0015] Preferably, the switch unit further includes an isolating switch, which is provided between the battery cluster and the DC bus. When the isolating switch is closed, the battery control unit is triggered.

[0016] Preferably, the switch unit further includes a bus switch, which is arranged at the output end of the DC bus and is used to control the on and off of the DC bus with the outside. The battery control unit controls the closing or opening of the bus switch according to the system status.

[0017] Preferably, the system further comprises an alarm unit, and the alarm unit is connected to the battery control unit;

[0018] When the polarities of the battery terminal voltage and the load terminal voltage are opposite, or the voltage difference between the parallel battery clusters exceeds a preset value, the battery control unit stops the power-on operation and the alarm unit triggers an alarm.

[0019] According to another aspect of the present invention, a control method for a battery control unit is provided, the control method comprising:

[0020] Close the isolation switch of any battery cluster to trigger the battery control unit to start the power-on process;

[0021] Control the opening and closing operations of the switch unit based on the polarity and value of the battery terminal voltage and the load terminal voltage;

[0022] The polarities and values of the battery terminal voltage and the load terminal voltage are collected by the voltage detection unit.

[0023] Preferably, the controlling the opening and closing operations of the switch unit based on the polarity and value of the battery terminal voltage and the load terminal voltage includes:

[0024] Control the opening and closing operation of the total negative contactor according to the polarity of the battery terminal voltage;

[0025] According to the value of the load terminal voltage, control the opening and closing operations of the total negative contactor, total positive contactor and pre-charge contactor;

[0026] When both the total negative contactor and the total positive contactor are closed, the polarity of the load terminal voltage is determined. When the load terminal voltage is positive, the current battery cluster is output to be powered on successfully. When the load terminal voltage is negative, an alarm is issued that there is a fault in the current battery cluster, and the current battery cluster power-on failure is output.

[0027] Preferably, controlling the opening and closing operations of the main negative contactor according to the polarity of the battery terminal voltage includes:

[0028] When the polarity of the battery terminal voltage is positive, close the total negative contactor;

[0029] When the polarity of the battery terminal voltage is negative, the closing of the total negative contactor is stopped, an alarm is given that the current battery cluster has a fault, and the power-on failure of the current battery cluster is output.

[0030] Preferably, the controlling the opening and closing operations of the total negative contactor, the total positive contactor and the pre-charge contactor according to the value of the load terminal voltage includes:

[0031] When the load terminal voltage is equal to zero, the main positive contactor is closed to connect the current battery cluster;

[0032] When the load terminal voltage is less than zero, the total negative contactor is disconnected, an alarm is given that the current battery cluster has a fault, and the power-on failure of the current battery cluster is output;

[0033] When the load terminal voltage is greater than zero, the opening and closing operations of the total negative contactor, the total positive contactor and the pre-charge contactor are controlled according to the voltage difference between the parallel battery clusters.

[0034] Preferably, the controlling the opening and closing operations of the total negative contactor, the total positive contactor, and the pre-charge contactor according to the voltage difference between the parallel battery clusters includes:

[0035] When the voltage difference between the parallel battery clusters is less than a first preset value, the pre-charge contactor is closed, the main positive contactor is closed after a first preset time, and the pre-charge contactor is opened after a second preset time;

[0036] When the voltage difference between the parallel battery clusters is greater than or equal to the first preset value and less than the second preset value, the pre-charge contactor is closed. After a third preset time, it is determined whether the voltage difference between the parallel battery clusters is less than the first preset value. If the voltage difference between the parallel battery clusters is less than the first preset value, the main positive contactor is closed after the first preset time, and the pre-charge contactor is disconnected after the second preset time. If the voltage difference between the parallel battery clusters is greater than or equal to the first preset value, the main negative contactor and the pre-charge contactor are disconnected, an alarm is issued that the voltage difference between the current parallel battery clusters is too large, and an output indicates that the current battery cluster power-on failure has occurred.

[0037] When the voltage difference between the parallel battery clusters is greater than or equal to the second preset value, the main negative contactor is disconnected, an alarm is given that the voltage difference between the current parallel battery clusters is too large, and an output is output that the current battery cluster fails to power on.

[0038] (3) Beneficial effects

[0039] The above technical solution of the present invention has the following beneficial technical effects:

[0040] 1. The voltage detection unit is set to collect the battery terminal voltage and load terminal voltage of the battery cluster in real time, providing a judgment basis for the battery control unit. The battery control unit controls the opening and closing of the switch unit based on these voltage signals, realizing automated battery cluster access control, greatly improving debugging efficiency and reducing manpower input;

[0041] 2. Real-time polarity monitoring prevents short circuits or thermal runaway caused by wiring errors, avoids the risk of battery short circuits caused by reverse polarity, ensures system safety from the source, reduces errors caused by human negligence, and improves overall reliability;

[0042] 3. Through the control method applied to the battery control unit, closing the isolation switch is used as the clear starting point for triggering the power-on process. This establishes clear operation starting conditions for the entire control process, ensuring that each power-on operation follows a unified and standardized sequence, avoiding arbitrary and chaotic operations.

[0043] 4. The battery control unit automatically controls the opening and closing of the switch unit based on the polarity and value of the battery terminal voltage and load terminal voltage collected by the voltage detection unit. There is no need for manual intervention in the operation of the contactors one by one, which greatly saves time and manpower, significantly improves the efficiency of debugging and power-on, and adapts to the efficient operation requirements of large-scale energy storage systems. It avoids negligence, misjudgment or omission of operating steps that may occur in manual operation, improves the reliability of system operation, and ensures the accuracy and consistency of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the connection between a battery cluster and a DC bus in a parallel battery cluster anti-reverse polarity connection system provided by the present invention;

[0045] Figure 2 is a circuit diagram of two or more battery clusters connected in parallel according to one embodiment of the present invention;

[0046] Figure 3 is a circuit diagram of two battery clusters connected in parallel according to another embodiment of the present invention;

[0047] Figure 4 This is a flow chart of a control method applied to a battery control unit provided by the present invention. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0049] The accompanying drawings illustrate schematic diagrams of layer structures according to embodiments of the present invention. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes, relative sizes, and positional relationships of the various regions and layers shown in the figures are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions based on actual needs.

[0050] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0051] In the description of the present invention, it should be noted that the terms “first”, “second” and “third” are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0052] Combine Figure 1 The first aspect of the present invention provides a parallel battery cluster anti-reverse polarity connection system, comprising a plurality of parallel battery clusters, a switch unit, a battery control unit BCU, and a voltage detection unit, wherein each battery cluster is connected to a DC busbar via a switch unit; the voltage detection unit is used to collect the battery terminal voltage and the load terminal voltage of the battery cluster; the battery control unit BCU is used to control the opening and closing operations of the switch unit according to the polarity and value of the battery terminal voltage and the load terminal voltage. Specifically, the voltage detection unit collects the battery terminal voltage and the load terminal voltage (PCS terminal voltage) of the battery cluster, and the battery control unit BCU receives these voltage signals, determines the battery cluster status according to their polarity and value, and then controls the opening and closing of the switch unit. Multiple battery clusters are connected in parallel and connected to the DC busbar via the switch unit to achieve power transmission.

[0053] The specific method for the voltage detection unit to collect the battery terminal voltage and the load terminal voltage is not limited here. The voltage detection unit can be connected to the total positive line and the total negative line of the battery cluster to obtain the positive and negative voltages of the battery terminal, and the voltage detection unit can be connected to the total positive line of the DC bus to collect the positive voltage of the load terminal. At this time, after the battery cluster is connected to the load terminal, the battery control unit BCU needs to identify the voltage polarity of the load terminal as positive when judging the polarity of the load terminal voltage, judge that the current battery cluster power-on meets the requirements, and control the switch unit to remain in a closed state.

[0054] By setting up a voltage detection unit to collect the battery terminal voltage and load terminal voltage of the battery cluster in real time, it provides a judgment basis for the battery control unit BCU. The battery control unit BCU controls the opening and closing of the switch unit based on these voltage signals, realizing automated battery cluster access control. Compared with manual cluster-by-cluster verification, this greatly improves debugging efficiency and reduces manpower input. For example, in the multi-cluster battery debugging scenario within the factory, the system can quickly identify the voltage status of the battery cluster when it is connected. If the battery terminal voltage polarity is detected to be abnormal, the battery control unit BCU directly controls the switch unit not to close the switch, avoiding the risk of battery short circuit caused by reverse polarity, ensuring system safety from the source, and reducing errors caused by human negligence, thereby improving overall reliability.

[0055] Example 1

[0056] Combine Figure 2 In this embodiment, two or more battery clusters are connected in parallel, and a high-voltage box is set between each battery cluster and the DC bus. The switch unit, battery control unit BCU and voltage detection unit are integrated in the high-voltage box.

[0057] In a preferred embodiment, the switch unit includes a main positive contactor KM1, a main negative contactor KM2, and a pre-charge contactor KM3. The main positive contactor KM1 controls the connection between the positive terminal of the battery cluster and the DC bus; the main negative contactor KM2 controls the connection between the negative terminal of the battery cluster and the DC bus. The pre-charge contactor KM3 is connected in series with a pre-charge resistor R and is connected in parallel with the main positive contactor KM1 to limit the inrush current when the battery cluster is connected to the bus. Specifically, the main positive contactor KM1 controls the connection between the positive terminal of the battery cluster and the DC bus, while the main negative contactor KM2 controls the connection between the negative terminal. The pre-charge contactor KM3 is connected in series with a pre-charge resistor R and is connected in parallel with the main positive contactor KM1.

[0058] Through this configuration, the main positive contactor KM1 and the main negative contactor KM2 in the switch unit respectively control the connection between the positive and negative poles of the battery cluster and the DC bus, ensuring precise control of the circuit on and off. The pre-charge contactor KM3 is connected in series with the pre-charge resistor R and in parallel with the main positive contactor KM1. When the battery cluster is connected to the bus, the pre-charge contactor KM3 can be closed first, and the current flows through the pre-charge resistor R, effectively limiting the inrush current. For example, when a new battery cluster is first connected to the bus, if the main positive contactor KM1 is closed directly, a large current shock may be generated due to the instantaneous charging of components such as capacitors, damaging the contactor contacts or battery modules. The coordination of the pre-charge contactor KM3 and the pre-charge resistor R allows the current to rise steadily, protecting key equipment such as contactors and batteries, extending the service life of the equipment, and ensuring stable connection of the battery cluster to the system.

[0059] In a preferred embodiment, the switch unit further includes an isolating switch QF, which is disposed between the battery cluster and the DC bus. When the isolating switch QF is closed, the battery control unit BCU is triggered. With this configuration, the isolating switch QF is disposed between the battery cluster and the DC bus, and its closing action triggers the battery control unit BCU to initiate relevant processes, thereby establishing a clear operating sequence. Only after the isolating switch QF is closed and the physical connection is confirmed to be correct does the system begin subsequent power-on detection and other operations. For example, during on-site debugging, if the operation and maintenance personnel mistakenly trigger the control unit startup process first, erroneous operation may result. However, the configuration of the isolating switch QF mandates that the physical connection be completed before electrical control is performed, preventing false triggering when not ready, improving the stability of system operation, and avoiding potential problems caused by a disordered operating sequence.

[0060] In a preferred case, the switch unit further includes a bus switch QFO, which is arranged at the output end of the DC bus and is used to control the on / off connection between the DC bus and the outside. The battery control unit BCU controls the closing or opening of the bus switch QFO according to the system status. With such a setting, the bus switch QFO is located at the output end of the DC bus, and the battery control unit BCU controls it according to the system status (such as a fault, normal operation, etc.). When a battery cluster in the system fails (such as a short circuit, overcurrent), the battery control unit BCU can quickly disconnect the bus switch QFO, cut off the connection between the DC bus and the outside, and isolate the fault locally. For example, in a large energy storage system with multiple battery clusters connected in parallel, if a battery cluster has an abnormal current due to an internal fault, disconnecting the bus switch QFO at this time can prevent the fault current from affecting other battery clusters and external equipment, thereby enhancing the safety and controllability of the system and facilitating the subsequent inspection and maintenance of the faulty cluster.

[0061] In a preferred embodiment, the system further includes an alarm unit connected to the battery control unit BCU; when the polarity of the battery terminal voltage and the load terminal voltage are opposite, or the voltage difference between the parallel battery clusters exceeds a preset value, the battery control unit BCU stops the power-on operation and the alarm unit triggers an alarm.

[0062] Through this setup, the alarm unit is connected to the battery control unit (BCU) and responds to the BCU's judgment in real time. When the battery terminal voltage and the load terminal voltage have opposite polarity (i.e., reverse polarity occurs) or the voltage difference between parallel battery clusters exceeds a preset value, the BCU immediately stops powering on, and the alarm unit triggers an alarm (such as emitting an audible or visual signal). For example, during battery cluster connection, if polarity is reversed due to a wiring error, the alarm unit promptly alerts maintenance personnel to avoid serious consequences such as internal short circuits and thermal runaway caused by reverse polarity. If the voltage difference between parallel clusters is too large, the alarm unit prompts maintenance personnel to conduct an inspection to prevent excessive discharge or overcharging of a battery cluster due to the large voltage difference, thereby extending the overall life of the battery cluster and ensuring stable system operation.

[0063] It should be noted that the specific method of connecting the DC busbar to the external circuit is not limited here. In preferred embodiments, an overvoltage protection device FVB is provided between the DC busbar and the external circuit to limit overvoltage in the circuit, protect subsequent equipment from abnormally high voltage shocks, and provide overvoltage protection. A fuse FU3 can also be provided in the external circuit. The fuse is used for short-circuit or overload protection. When the current exceeds the rated value, the fuse melts to cut off the circuit and prevent equipment damage. Furthermore, a fuse FU2 can be provided in the battery cluster circuit within the high-voltage box to protect the battery cluster and the electrical safety within the high-voltage box.

[0064] Example 2

[0065] Combine Figure 3 In this embodiment, two battery clusters are connected in parallel. A high-voltage box is installed between each battery cluster and the DC bus. The high-voltage box integrates a switch unit, a battery control unit (BCU), and a voltage detection unit. The operating logic is the same as in the first embodiment and will not be repeated here.

[0066] Example 3

[0067] like Figure 4 As shown, another aspect of the present invention provides a control method for a battery control unit (BCU), the control method comprising: closing the isolation switch QF of any battery cluster to trigger the battery control unit (BCU) to start a power-on process; and controlling the opening and closing operations of the switch unit based on the polarity and value of the battery terminal voltage and the load terminal voltage; wherein the polarity and value of the battery terminal voltage and the load terminal voltage are collected by a voltage detection unit.

[0068] This control method uses the closing of the disconnector QF as the clear starting point for triggering the power-on process. This establishes clear operational starting conditions for the entire control process, ensuring that each power-on operation follows a standardized sequence and avoiding arbitrary and chaotic operations. The electrical control process only begins after the physical connection confirms the closing of the disconnector QF, ensuring the correctness of the operational logic from the source. This effectively prevents potential problems caused by incorrect operation sequences, especially in complex systems with multiple battery clusters. The battery control unit (BCU) automatically controls the opening and closing of the switch units based on the polarity and values of the battery and load terminal voltages collected by the voltage detection unit, eliminating the need for manual contactor operation. In multi-battery cluster scenarios, such as large energy storage power plants, dozens of battery clusters can quickly initiate independent power-on processes by closing the disconnector QF. The system automatically completes detection and control. Compared to manual operation, this significantly saves time and manpower, significantly improves commissioning and power-on efficiency, and meets the requirements for efficient operation of large-scale energy storage systems. This avoids possible oversights, misjudgments, or missed steps in manual operation, improving system reliability and ensuring accurate and consistent operation. For any battery cluster, simply closing its disconnector QF initiates the corresponding power-up process. This process is independent of the number or size of battery clusters and is applicable to a wide range of energy storage systems, from small to large. Whether it's a modular system with two clusters in parallel or a large-scale power station with multiple clusters in parallel, this flexible control solution offers broad applicability, providing a versatile and reliable control solution for implementing diverse energy storage projects.

[0069] In a preferred case, based on the polarity and value of the battery terminal voltage and the load terminal voltage, controlling the opening and closing operations of the switch unit includes: controlling the opening and closing operations of the total negative contactor KM2 according to the polarity of the battery terminal voltage; controlling the opening and closing operations of the total negative contactor KM2, the total positive contactor KM1 and the pre-charging contactor KM3 according to the value of the load terminal voltage; when the total negative contactor KM2 and the total positive contactor KM1 are both closed, judging the polarity of the load terminal voltage, when the load terminal voltage is positive, outputting that the current battery cluster is powered on successfully, and when the load terminal voltage is negative, alarming that there is a fault in the current battery cluster, and outputting that the current battery cluster has failed to power on.

[0070] This control method refines the contactor control logic. The total negative contactor KM2 is controlled based on the battery terminal voltage polarity, ensuring that the total negative contactor KM2 is closed only when the battery terminal voltage polarity is correct. The total negative contactor KM2, total positive contactor KM1, and pre-charge contactor KM3 are controlled based on the load terminal voltage value. After both the total negative contactor KM2 and the total positive contactor KM1 are closed, the load terminal voltage polarity is further determined to determine whether power-on is successful. For example, if the battery terminal voltage polarity is incorrect, the total negative contactor KM2 will not close, directly avoiding subsequent erroneous operations. If the load terminal voltage is negative after both the total negative contactor KM2 and the total positive contactor KM1 are closed, this indicates a potential system fault (such as a wiring error or abnormal load). A timely alarm can prevent the battery from operating in an abnormal state, ensuring that each connection step is accurate and correct, guaranteeing the safety and correctness of the connection between the battery cluster and the system.

[0071] In a preferred case, according to the polarity of the battery terminal voltage, controlling the opening and closing operations of the total negative contactor KM2 includes: when the polarity of the battery terminal voltage is positive, closing the total negative contactor KM2; when the polarity of the battery terminal voltage is negative, stopping the closing operation of the total negative contactor KM2, alarming that there is a fault in the current battery cluster, and outputting the current battery cluster power-on failure.

[0072] This control method directly determines and controls the battery terminal voltage polarity. When the battery terminal voltage is positive, the main negative contactor KM2 is closed, which is the correct operation based on normal voltage polarity. When the battery terminal voltage is negative, the main negative contactor KM2 is immediately stopped and an alarm is triggered. This direct judgment logic immediately prevents incorrect operation upon detecting polarity anomalies. For example, when reconnecting a battery cluster to the system after installation or maintenance, if the battery terminal voltage polarity is reversed due to wiring errors, this control logic can quickly identify and prevent the main negative contactor KM2 from closing. This prevents internal battery circuit anomalies caused by reverse polarity, protects the battery cluster's electrical performance, and prevents more serious failures caused by polarity issues.

[0073] In a preferred case, according to the value of the load terminal voltage, the opening and closing operations of the total negative contactor KM2, the total positive contactor KM1 and the pre-charge contactor KM3 are controlled, including: when the load terminal voltage is equal to zero, the total positive contactor KM1 is closed and the current battery cluster is connected; when the load terminal voltage is less than zero, the total negative contactor KM2 is disconnected, an alarm is issued that there is a fault in the current battery cluster, and the current battery cluster fails to power on; when the load terminal voltage is greater than zero, the opening and closing operations of the total negative contactor KM2, the total positive contactor KM1 and the pre-charge contactor KM3 are controlled according to the voltage difference between the parallel battery clusters.

[0074] It should be noted that the voltage difference between parallel battery clusters here refers to the comparison of the voltage detection units within each high-voltage box. Excessive voltage differences can lead to voltage inconsistencies between battery clusters. If the inter-cluster voltage difference is large, the higher-voltage battery cluster will bear more current output, potentially causing over-discharge of that cluster, affecting its lifespan and performance. Furthermore, the load-side voltage is also affected by the combined effects of the battery cluster's output characteristics and the inter-cluster voltage difference. Excessive voltage differences can cause load-side voltage instability, impacting normal load operation.

[0075] Through this control method, differentiated contactor operation strategies are formulated for different load-end voltage values. When the load-end voltage is equal to zero, the total positive contactor KM1 is closed. This is applicable when there is no other voltage interference at the load end, ensuring normal access to the battery cluster. When the load-end voltage is less than zero, the total negative contactor KM2 is disconnected and an alarm is sounded. This can promptly handle abnormal load-end voltage (such as reverse voltage) and prevent current backflow from damaging the battery cluster. When the load-end voltage is greater than zero, further control is performed based on the voltage difference between parallel battery clusters, allowing the system to adapt to a variety of complex voltage conditions. For example, in a scenario where multiple battery clusters are connected in parallel and there is a certain voltage at the load end, this strategy can flexibly respond to different voltage conditions, ensuring that the system can operate safely under various operating conditions and avoiding contactor misoperation or battery cluster damage caused by abnormal load-end voltage.

[0076] In a preferred embodiment, the opening and closing operations of the total negative contactor KM2, the total positive contactor KM1 and the pre-charge contactor KM3 are controlled according to the voltage difference between the parallel battery clusters. The operation includes: when the voltage difference between the parallel battery clusters is less than a first preset value, closing the pre-charge contactor KM3, closing the total positive contactor KM1 after a first preset time, and disconnecting the pre-charge contactor KM3 after a second preset time; when the voltage difference between the parallel battery clusters is greater than or equal to the first preset value and less than the second preset value, closing the pre-charge contactor KM3, and judging whether the voltage difference between the parallel battery clusters is greater than or equal to the first preset value and less than the second preset value after a third preset time. Less than a first preset value, if the voltage difference between the parallel battery clusters is less than the first preset value, the total positive contactor KM1 is closed after the first preset time, and the pre-charge contactor KM3 is disconnected after the second preset time. If the voltage difference between the parallel battery clusters is greater than or equal to the first preset value, the total negative contactor KM2 and the pre-charge contactor KM3 are disconnected, an alarm is given that the voltage difference between the current parallel battery clusters is too large, and an output is output that the current battery cluster power-on fails; when the voltage difference between the parallel battery clusters is greater than or equal to the second preset value, the total negative contactor KM2 is disconnected, an alarm is given that the voltage difference between the current parallel battery clusters is too large, and an output is output that the current battery cluster power-on fails.

[0077] This control method implements hierarchical control based on the voltage difference between parallel battery clusters, fully accounting for the impact of voltage differences on the system. When the voltage difference is less than the first preset value, the pre-charge contactor KM3 and the main positive contactor KM1 are closed normally to ensure smooth integration of the battery clusters. When the voltage difference is greater than or equal to the first preset value and less than the second preset value, the pre-charge contactor KM3 is first closed for a certain period of adjustment, and then the pressure difference is used to determine whether to continue operation. This attempts to balance the pressure difference through the pre-charge process and avoids forced power-on when the pressure difference is too large. When the voltage difference is greater than or equal to the second preset value, the main negative contactor KM2 is directly disconnected and an alarm is sounded, preventing excessive discharge of the battery cluster or equipment damage caused by excessive pressure difference. For example, in a scenario where multiple battery clusters are connected in parallel and the voltages of the clusters are not completely consistent, precise control based on the pressure difference ensures the safety of the parallel process, extends the service life of the battery clusters, avoids system failures caused by improper pressure difference handling, and ensures the stable operation of the energy storage system.

[0078] It should be noted that the specific parameters for the preset voltage and time are not limited here and are determined based on the actual parameters of the battery cluster and load end in the system. After a power-on failure, the alarm unit accurately reports the current fault information based on the actual scenario, promptly and accurately reporting the circuit status of the system, ensuring system stability and improving operation and maintenance efficiency.

[0079] like Figure 4 As shown, in this embodiment, the first preset value is set to 10V, the second preset value is set to 20V, the first preset time is 5s, the second preset time is 2s, and the third preset time can be adjusted according to actual conditions, which is represented by T. The specific control method in the embodiment of the present invention is as follows:

[0080] S1. The battery management system BMS auxiliary power is powered on, and the circuit breaker QF in the high-voltage box of any battery cluster is closed. At this time, the battery cluster power-on instruction is triggered, and the BCU starts and performs self-test.

[0081] S2. Determine whether the battery cluster has a fault, such as whether the mechanism is intact and whether the electrical performance is normal. If the battery cluster has a fault, the battery safety unit (BSU) will alarm the battery cluster fault (this can be a combination of the battery control unit (BCU) and the alarm unit). At this time, the fault content is reported to indicate that the BMS itself is faulty or the battery cluster is faulty. The corresponding battery cluster high-voltage box fault light will light up, and the current battery cluster has failed to power on.

[0082] S3. Determine whether the battery terminal voltage is greater than zero. If not, the BSU alarms that the current battery cluster is wired incorrectly. At this time, the fault content reported indicates a sampling line or polarity or BCU sampling fault. The corresponding battery cluster high-voltage box fault light is on, and the current battery cluster fails to power on.

[0083] S4. Close the high-voltage box KM2 and determine whether the PCS terminal voltage is equal to zero. If the PCS terminal voltage is less than zero, disconnect KM2. The BSU alarms that the current battery cluster and busbar wiring are incorrect. The fault light of the corresponding battery cluster high-voltage box lights up, and the current battery cluster fails to power on.

[0084] S5. If the voltage at the PCS terminal is zero, close the high-voltage box KM1 and connect the current battery cluster.

[0085] S6. Determine whether the PCS terminal voltage is greater than zero. If so, it indicates that the battery cluster is supplying power normally, and reports that the current battery cluster is powered on successfully. If not, the BSU alarms that the current battery cluster and busbar wiring are incorrect, disconnects KM1 and KM2, and the corresponding battery cluster high-voltage box fault light lights up, indicating that the current battery cluster has failed to power on.

[0086] S7. If the PCS terminal voltage is greater than zero, determine the range of the inter-cluster voltage difference;

[0087] S71. When the voltage difference between clusters is less than 10V, close KM3, close KM1 after 5s, and disconnect KM3 after 2s to ensure smooth integration of the battery clusters, and then proceed to S6.

[0088] S72. When the voltage difference between clusters is greater than or equal to 10V and less than or equal to 20V, close KM3 to balance the voltage difference between clusters, and determine whether the voltage difference between clusters is less than 10V after Ts. If so, proceed to S71 above; if not, cut off KM2 and KM3, the BSU alarm voltage difference is too large, the corresponding battery cluster high-voltage box fault light is on, and the current battery cluster fails to power on.

[0089] S73. When the voltage difference between clusters is greater than or equal to 20V, KM2 is disconnected, the BSU alarm voltage difference is too large, the fault light of the high-voltage box of the corresponding battery cluster lights up, and the current battery cluster fails to power on.

[0090] It should be understood that the above-described specific embodiments of the present invention are merely illustrative or illustrative of the principles of the present invention and do not constitute limitations of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included within the scope of protection of the present invention. In addition, the appended claims are intended to cover all variations and modifications that fall within the scope and metes and bounds of the appended claims, or equivalents thereof.

Claims

1. A parallel battery cluster anti-polarity reverse connection system, characterized in that: The system includes a plurality of parallel battery clusters, a switch unit, a battery control unit and a voltage detection unit, wherein each battery cluster is connected to a DC bus through the switch unit; The voltage detection unit is used to collect the battery terminal voltage and the load terminal voltage of the battery cluster; The battery control unit is used to control the opening and closing operations of the switch unit according to the polarities and values of the battery terminal voltage and the load terminal voltage.

2. The system according to claim 1, wherein: The switch unit includes a total positive contactor, a total negative contactor and a pre-charge contactor; The main positive contactor is used to control the connection between the positive electrode of the battery cluster and the DC bus; The main negative contactor is used to control the connection between the negative electrode of the battery cluster and the DC bus; The pre-charge contactor is connected in series with a pre-charge resistor and is connected in parallel with the main positive contactor to limit the inrush current when the battery cluster is connected to the busbar.

3. The system according to claim 2, characterized in that The switch unit further includes an isolating switch, which is disposed between the battery cluster and the DC bus. When the isolating switch is closed, the battery control unit is triggered.

4. The system according to claim 2, wherein: The switch unit further includes a bus switch, which is arranged at the output end of the DC bus and is used to control the connection and disconnection between the DC bus and the outside. The battery control unit controls the closing or opening of the bus switch according to the system status.

5. The system according to claim 1, wherein: The system further comprises an alarm unit connected to the battery control unit; When the polarities of the battery terminal voltage and the load terminal voltage are opposite, or the voltage difference between the parallel battery clusters exceeds a preset value, the battery control unit stops the power-on operation and the alarm unit triggers an alarm.

6. A control method using the system according to any one of claims 1 to 5, characterized in that: The control method is applied to a battery control unit, and the control method includes: Close the isolation switch of any battery cluster to trigger the battery control unit to start the power-on process; Control the opening and closing operations of the switch unit based on the polarity and value of the battery terminal voltage and the load terminal voltage; The polarities and values of the battery terminal voltage and the load terminal voltage are collected by the voltage detection unit.

7. The control method according to claim 6, characterized in that: The controlling of the opening and closing operations of the switch unit based on the polarity and value of the battery terminal voltage and the load terminal voltage includes: Control the opening and closing operation of the total negative contactor according to the polarity of the battery terminal voltage; According to the value of the load terminal voltage, control the opening and closing operations of the total negative contactor, total positive contactor and pre-charge contactor; When both the total negative contactor and the total positive contactor are closed, the polarity of the load terminal voltage is determined. When the load terminal voltage is positive, the current battery cluster is output to be powered on successfully. When the load terminal voltage is negative, an alarm is issued that there is a fault in the current battery cluster, and the current battery cluster power-on failure is output.

8. The control method according to claim 7, characterized in that: Controlling the opening and closing operations of the main negative contactor according to the polarity of the battery terminal voltage includes: When the polarity of the battery terminal voltage is positive, close the total negative contactor; When the polarity of the battery terminal voltage is negative, the closing of the total negative contactor is stopped, an alarm is given that the current battery cluster has a fault, and the power-on failure of the current battery cluster is output.

9. The control method according to claim 7, characterized in that: The control of the opening and closing operations of the total negative contactor, the total positive contactor, and the pre-charge contactor according to the value of the load terminal voltage includes: When the load terminal voltage is equal to zero, the main positive contactor is closed to connect the current battery cluster; When the load terminal voltage is less than zero, the total negative contactor is disconnected, an alarm is given that the current battery cluster has a fault, and the power-on failure of the current battery cluster is output; When the load terminal voltage is greater than zero, the opening and closing operations of the total negative contactor, the total positive contactor and the pre-charge contactor are controlled according to the voltage difference between the parallel battery clusters.

10. The control method according to claim 9, characterized in that: The control of the opening and closing operations of the total negative contactor, the total positive contactor, and the pre-charge contactor according to the voltage difference between the parallel battery clusters includes: When the voltage difference between the parallel battery clusters is less than a first preset value, the pre-charge contactor is closed, the main positive contactor is closed after a first preset time, and the pre-charge contactor is opened after a second preset time; When the voltage difference between the parallel battery clusters is greater than or equal to the first preset value and less than the second preset value, the pre-charge contactor is closed. After a third preset time, it is determined whether the voltage difference between the parallel battery clusters is less than the first preset value. If the voltage difference between the parallel battery clusters is less than the first preset value, the main positive contactor is closed after the first preset time, and the pre-charge contactor is disconnected after the second preset time. If the voltage difference between the parallel battery clusters is greater than or equal to the first preset value, the main negative contactor and the pre-charge contactor are disconnected, an alarm is issued that the voltage difference between the current parallel battery clusters is too large, and an output indicates that the current battery cluster power-on failure has occurred. When the voltage difference between the parallel battery clusters is greater than or equal to the second preset value, the main negative contactor is disconnected, an alarm is given that the voltage difference between the current parallel battery clusters is too large, and an output is output that the current battery cluster fails to power on.

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