Energy storage system auxiliary power supply circuit and control method thereof

Abstract

The application discloses a kind of energy storage system auxiliary power supply circuit and its control method, it includes battery, for output high voltage direct current;Physical high voltage break subcircuit, for executing high voltage on-off control based on external instruction response;Energy storage buffer subcircuit, including wide input DCDC module and buffer module;Wide input DCDC module is used to convert low voltage direct current and output basic power supply current;Buffer module is used to monitor real-time voltage value in real time and carry out comparison, less than when then release stored electric energy and output compensation power supply current;When greater than or equal to, then execute charging;Low voltage control subcircuit is used to receive basic power supply current or total power supply current formed by compensation power supply current confluence to obtain power supply and maintain normal work, while monitoring the voltage state of physical high voltage break subcircuit, and judge whether to meet undervoltage tripping condition, when meeting, generate control instruction control execution mechanical tripping action.The application can realize the anti-adhesion safety cut-off of main loop.

Description

Technical Field

[0001] This invention relates to the field of power supply control technology, and more specifically, to an auxiliary power supply circuit for an energy storage system and its control method. Background Technology

[0002] High-voltage energy storage systems are widely used in grid energy storage, industrial and commercial energy storage, and new energy grid-connected energy storage. Currently, mainstream high-voltage energy storage systems have DC bus voltages reaching 1000Vdc and 1500Vdc levels, possessing the technical characteristics of large capacity, high voltage, and high power output. The normal operation, grid connection, and start-up / shutdown of high-voltage energy storage systems all rely on stable power supply from control units such as BMS and EMS, as well as auxiliary power systems. The main circuit contactor is closed by the control unit to complete the system's power-on, grid connection, and energy exchange.

[0003] To address the challenges of self-reactivation and black-start power-on after a complete power outage in high-voltage energy storage systems, the industry has developed two mainstream auxiliary power-on and black-start technologies: high-voltage black-start board power-on and simple molded case circuit breaker direct power-on. These have become the core technologies for auxiliary power supply in high-voltage energy storage systems. The high-voltage black-start board solution integrates high-voltage fuses, high-voltage relays, SiC MOSFETs, and other high-voltage power-resistant devices on an independent PCB board, drawing power directly from the high-voltage DC bus. Auxiliary power supply is achieved through an onboard step-down circuit, completing the system's black-start activation before disconnecting the high-voltage switching devices to exit the starting circuit. However, this solution is highly susceptible to safety hazards such as high-voltage creepage, arcing, and short circuits under harsh industrial conditions like condensation, high humidity, and dust in the energy storage cabinet. Furthermore, the black-start board has extremely low transient impact resistance, supporting only 300-400 watts of instantaneous output power. During system startup, when multiple high-power main circuit contactors need to be driven simultaneously, insufficient instantaneous load power can easily lead to the starting power being cut off. In contrast, the simple molded case circuit breaker direct power-on... The current solution directly connects to high-voltage DC power via an industrial molded case circuit breaker (MCCB) and uses a wide-input step-down module for auxiliary power supply, simplifying the hardware structure and reducing insulation design and production costs. However, during normal system operation under load, if the MCCB unexpectedly trips or is manually misoperated, the auxiliary power supply circuit will instantly lose power, causing the BMS, EMS, and other control units to shut down first. In this case, the control units will lose power before the main contactor, losing control over the main contactor and making it impossible for the main contactor to disconnect under control. This can easily lead to severe arcing and burn-out, resulting in fatal contact arcing and physical adhesion. In addition, both of the above-mentioned existing auxiliary power supply solutions suffer from the defect of long-term standby battery over-discharge. In scenarios where the high-voltage energy storage system is shut down for a long time and is unattended, if the front-end physical switch is not manually disconnected, the auxiliary power supply step-down module will continuously generate static power consumption, continuously consuming the remaining power of the battery cluster. This can easily cause deep battery depletion and over-discharge damage, significantly shortening the battery life. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an auxiliary power supply circuit for an energy storage system, comprising: A battery, used to output high-voltage direct current; The physical high-voltage switching sub-circuit, which is electrically connected to the battery, is used to output on / off signals based on external commands and to perform high-voltage on / off control based on the on / off signals. The energy storage buffer sub-circuit includes a wide-input DC-DC module and a buffer module. One end of the wide-input DC-DC module is electrically connected to the physical high-voltage interruption sub-circuit, and the other end is connected to the low-voltage output bus. It is used to receive high-voltage DC and convert it into low-voltage DC, and then output the basic supply current through the low-voltage output bus. The buffer module is connected in parallel with the low-voltage output bus and is used to monitor the real-time voltage value of the low-voltage output bus and compare it with a preset discharge activation threshold. When the real-time voltage value is less than the discharge activation threshold, the stored energy is released and a compensation supply current is output. When the real-time voltage value is greater than or equal to the discharge activation threshold, charging is performed according to the low-voltage DC. The low-voltage control sub-circuit is electrically connected to the low-voltage output bus and the physical high-voltage interruption sub-circuit, respectively. It is used to receive the basic power supply current or the total power supply current formed by the combination of the basic power supply current and the compensation power supply current on the low-voltage output bus to obtain power and maintain normal operation. At the same time, it monitors the voltage status of the physical high-voltage interruption sub-circuit and determines whether the undervoltage tripping condition is met based on the voltage status. When the undervoltage tripping condition is met, it generates a control command to control the physical high-voltage interruption sub-circuit to perform a mechanical tripping action.

[0005] Furthermore, the physical high-voltage interruption sub-circuit includes a high-voltage rotary switch, a molded case shunt trip, and a fuse. The high-voltage rotary switch is connected between the battery and the wide-input DC-DC module, used to control the on / off state based on external commands and output on / off signals. The molded case shunt trip is connected between the battery and the high-voltage rotary switch, used to receive on / off signals to connect or disconnect the high-voltage power supply path connected to the battery, and also used to receive control commands and execute mechanical tripping actions to cut off the high-voltage power supply path according to the control commands. The fuse is connected between the high-voltage rotary switch and the molded case shunt trip, used to melt and disconnect the high-voltage power supply path first in the event of overcurrent or short-circuit faults.

[0006] Furthermore, the molded case shunt trip includes the molded case circuit breaker body and the shunt trip coil; the molded case circuit breaker body is electrically connected to the battery and the high-voltage rotary switch respectively, and is used to receive on / off signals to connect or disconnect the high-voltage power supply path; the shunt trip coil is electrically connected to the molded case circuit breaker body and the low-voltage control sub-circuit respectively, and is used to receive control commands and generate electromagnetic force to drive the molded case circuit breaker body to perform mechanical tripping action to cut off the high-voltage power supply path.

[0007] Furthermore, the buffer module includes a voltage detection unit and an electrolytic capacitor array. The voltage detection unit is electrically connected to the low-voltage output bus and the electrolytic capacitor array, respectively. The voltage detection unit monitors the real-time voltage value of the low-voltage output bus and compares it with the discharge activation threshold. When the real-time voltage value is less than the discharge activation threshold, the voltage detection unit connects the low-voltage output bus and the electrolytic capacitor array, causing the electrolytic capacitor array to release the stored electrical energy, thereby outputting a compensation supply current. When the real-time voltage value is greater than or equal to the discharge activation threshold, the electrolytic capacitor array is charged according to the low-voltage DC power.

[0008] Furthermore, the low-voltage control sub-circuit includes a BMS and a contactor drive coil. The BMS is electrically connected to the low-voltage output bus and the shunt trip coil, respectively. It is used to receive the base supply current to obtain power supply and control the main power circuit to conduct. Or, when a transient impact load is generated after the main power circuit is conducted, it receives the total supply current to maintain power supply and continuously control the main power circuit to conduct. At the same time, it monitors the voltage status of the shunt trip coil in real time and determines whether the molded case circuit breaker body meets the undervoltage trip condition based on the voltage status. When the undervoltage trip condition is met, a control command is generated and output to the shunt trip coil, so that the shunt trip coil generates electromagnetic force to drive the molded case circuit breaker body to perform a mechanical trip action to cut off the high-voltage power supply path. The contactor drive coil is electrically connected to the BMS and is used to receive the real-time voltage value of the low-voltage output bus and determine whether it is sufficient to support the engagement. If so, a transient impact load is generated to make the real-time voltage value drop below the discharge activation threshold. Otherwise, the real-time voltage value is monitored.

[0009] Furthermore, the present invention also provides a control method for an auxiliary power supply circuit of an energy storage system, the method being applied to the auxiliary power supply circuit of the energy storage system as described above, comprising the following steps: Step S01: The physical high-voltage switching sub-circuit responds to external commands to control the on / off state and outputs an on / off signal. Based on the on / off signal, it connects the battery and the wide-input DC-DC module, so that the high-voltage DC power output from the battery is transmitted to the wide-input DC-DC module. Step S02: The wide-input DC-DC module receives high-voltage DC power and converts it into low-voltage DC power. It outputs the basic power supply current through the low-voltage output bus and monitors the real-time voltage value of the low-voltage output bus through the buffer module. Step S03: After receiving the base supply current, the low-voltage control subcircuit starts to work. After the low-voltage control subcircuit starts working, it generates a transient impact load, causing the real-time voltage value to drop below the discharge activation threshold. When this occurs, the buffer module releases the stored electrical energy to output a compensation supply current, which merges with the base supply current on the low-voltage output bus to form a total supply current to maintain the normal operation of the low-voltage control subcircuit. When the real-time voltage value is greater than or equal to the discharge activation threshold, the buffer module is charged by low-voltage DC power. The low-voltage control subcircuit also monitors the voltage status of the physical high-voltage disconnection subcircuit in real time. Step S04: The low-voltage control sub-circuit determines whether the undervoltage tripping condition is met based on the monitored voltage status. When the undervoltage tripping condition is met, a control command is generated and output to the physical high-voltage interruption sub-circuit to drive the physical high-voltage interruption sub-circuit to perform a mechanical tripping action.

[0010] Furthermore, the low-voltage control sub-circuit begins operation after receiving the base supply current, specifically including the following steps: After the BMS receives the base power supply current and powers on, it initializes its internal parameters and reads the on / off signal output by the physical high voltage interruption sub-circuit to confirm that the high voltage power supply path between the battery and the wide input DC-DC module is in a conducting state. After the BMS receives power and maintains it for a period of time, the buffer module is in a fully charged standby state and receives the output mode enable command provided by the user. Based on the output mode enable command, it determines whether the real-time voltage value is stably maintained above the discharge activation threshold. When the real-time voltage value is stably maintained above the discharge activation threshold, the BMS determines that the output power of the wide-input DC-DC module is sufficient to support the contactor drive coil to engage. The BMS sends a pull-in command to the contactor drive coil, causing the excitation current of the contactor drive coil to rise rapidly from zero to the pull-in current value, driving the contactor drive coil to pull in and generate a transient impact load. When the real-time voltage value drops below the discharge activation threshold, the buffer module releases the stored electrical energy to output a compensation supply current, which merges with the base supply current on the low-voltage output bus to form a total supply current to maintain the main power circuit of the contactor drive coil control BMS on. The BMS confirms whether the current contactor drive coil is successfully engaged by detecting the recovery of the real-time voltage value after compensation or reading the status of the auxiliary contacts of the contactor drive coil. If the engagement is successful, the contactor drive coil is kept engaged. If the engagement fails, the fault information is recorded and the subsequent engagement process is stopped.

[0011] Furthermore, the process by which the buffer module releases stored electrical energy to compensate for the supply current includes different consecutive time periods from t0 to t4, specifically including the following steps: During the period from t0 to t1, the output power of the wide-input DC-DC module is insufficient to support the contactor drive coil to engage. The low-voltage output bus is not subjected to a large load impact. The wide-input DC-DC module operates in constant voltage mode, outputs the rated voltage value, and the buffer module is in a fully charged standby state. At time t1, the contactor drive coil instantly engages, generating a transient impact load. The output power of the wide-input DC-DC module instantly surges to the overload protection limit, while the real-time voltage value of the low-voltage output bus remains unchanged at the rated voltage value. During the period from t1 to t2, the transient impact load continued to exceed the overload protection limit of the wide input DC-DC module. The wide input DC-DC module was forced to switch from constant voltage mode to constant current limiting mode. The real-time voltage value was quickly pulled down from the rated voltage value to above the discharge activation threshold to prevent the buffer module from being falsely awakened. During the period from t2 to t3, the real-time voltage value drops below the discharge activation threshold, and the buffer module is activated. The buffer module is equivalent to a constant voltage source that clamps the real-time voltage value at the discharge activation threshold, using discharge output to compensate for the supply current. This discharge output, combined with the base supply current, causes the output power of the wide-input DC-DC module to surge, thereby preventing the wide-input DC-DC module from entering the hiccup protection dead zone. The specific steps for activating the buffer module include: When the voltage detection unit detects that the real-time voltage value is less than the discharge activation threshold, it outputs a conduction signal to connect the electrolytic capacitor array to the low-voltage output bus. The electrolytic capacitor array releases the stored electrical energy through the connection path. The buffer module is equivalent to a constant voltage source that clamps the real-time voltage value at the discharge activation threshold so that the discharge output can compensate for the supply current. The compensation supply current and the base supply current output by the wide input DC-DC module in constant current limiting mode converge on the low-voltage output bus, causing the output power of the wide input DC-DC module to jump and instantly reach the peak power. During the period from t3 to t4, the peak power is maintained until the transient impact load ends. The wide input DC-DC module automatically returns to constant voltage mode, steadily pulling the real-time voltage value back to above the discharge activation threshold. The voltage detection unit disconnects the connection path between the electrolytic capacitor array and the low-voltage output bus and performs charging.

[0012] Furthermore, the specific steps for the wide-input DC-DC module to be forced to switch from constant voltage mode to constant current limiting mode include: The wide-input DC-DC module continuously outputs the rated voltage value in constant voltage mode, while monitoring the output current value in real time and comparing the output current value with the internally preset current limiting protection threshold. When the transient impact load generated by the contactor drive coil energizing causes the output current value to exceed the current limiting protection threshold for the first time, the wide input DC-DC module activates the overcurrent response mechanism to maintain the constant voltage mode. The output current value continues to increase and exceeds the current limiting protection threshold. The wide input DC-DC module detects that the output power can no longer keep up with the load demand. The wide input DC-DC module determines that the load has exceeded the maximum output capacity of the constant voltage mode, and begins to release the constant voltage control of the real-time voltage value, and instead forcibly limits the output current value to not exceed the current limiting protection threshold. The wide-input DC-DC module is forced to switch from constant voltage mode to constant current limiting mode. The real-time voltage value is no longer constrained by the constant voltage mode, and the real-time voltage value is rapidly pulled down from the rated voltage value as the load increases.

[0013] Furthermore, the specific steps of the low-voltage control sub-circuit in determining whether the undervoltage tripping condition is met based on the monitored voltage state include: The BMS continuously monitors the on / off signal output by the high-voltage rotary switch to obtain the current on / off status of the high-voltage power supply path; If the current on / off state is on, the BMS will collect the voltage status value of the shunt trip coil in real time and compare the voltage status value with the preset undervoltage protection threshold. When the voltage status value is lower than the undervoltage protection threshold, an undervoltage trigger pulse is output. The BMS synchronously starts an anti-jitter delay timer to receive the undervoltage trigger pulse and start timing. During the timing process, the anti-jitter delay timer continuously monitors whether the undervoltage trigger pulse disappears. If the undervoltage trigger pulse disappears before the timing is completed, the anti-jitter delay timer is reset. If the undervoltage trigger pulse continues to exist and the voltage status value continues to be lower than the undervoltage protection threshold for a duration that reaches the preset anti-jitter delay time, the BMS determines that the undervoltage trip condition is met and outputs an undervoltage trip signal. The BMS generates a control command based on the undervoltage trip signal and outputs the control command to the shunt trip coil, which energizes the coil to generate electromagnetic force to drive the molded case circuit breaker body to perform a mechanical trip action to cut off the high-voltage power supply path.

[0014] The beneficial effects of this application are as follows: When the auxiliary power supply circuit of the energy storage system is working, it first receives external commands through a physical high-voltage switching sub-circuit to control its own on / off state and outputs an on / off signal. Based on the on / off signal, reliable conduction between the battery and the wide-input DC-DC module is achieved, so that the high-voltage DC power output from the battery is stably output to the wide-input DC-DC module, realizing the controllable opening of the high-voltage power input path and providing a stable power input foundation for subsequent voltage conversion and auxiliary power supply. The wide-input DC-DC module receives the high-voltage DC power transmitted from the battery and completes voltage conversion processing to obtain low-voltage DC power suitable for the subsequent low-voltage circuit operation. The basic power supply current is continuously output through the low-voltage output bus. At the same time, the buffer module monitors the real-time voltage value of the low-voltage output bus in real time, and grasps the dynamic changes of the voltage of the low-voltage output bus in real time. This provides an accurate basis for judging the operating conditions for subsequent buffer power replenishment and energy storage charging switching, ensuring that the power supply status of the low-voltage output bus can be sensed in real time. The low-voltage control subcircuit receives the base supply current to start operation. To address the bus voltage drop caused by transient load surges during the operation of the low-voltage control subcircuit, when the real-time voltage value is lower than the discharge activation threshold, the buffer module discharges and outputs a compensation supply current in a timely manner. This compensation supply current is combined with the base supply current to form the total supply current, ensuring the continuous and stable operation of the low-voltage control subcircuit and preventing it from shutting down due to power failure. When the real-time voltage value recovers to above the discharge activation threshold, the buffer module is automatically charged to store energy, achieving adaptive voltage regulation of the low-voltage output bus voltage. Meanwhile, the low-voltage control subcircuit continuously monitors the voltage status of the physical high-voltage disconnection subcircuit and determines whether the undervoltage tripping condition is met based on the monitored voltage status. When the undervoltage tripping condition is met, it actively outputs a control command to drive the physical high-voltage disconnection subcircuit to perform a mechanical tripping action. This allows the physical high-voltage disconnection subcircuit to be disconnected in advance in the event of erroneous tripping or circuit abnormalities, thus avoiding fatal faults such as contactor arcing and contact adhesion caused by power failure and loss of control of the low-voltage control subcircuit. This comprehensively solves the defects of traditional high-voltage energy storage auxiliary power supply schemes, such as low operational safety and large battery life loss, and meets the reliable power supply requirements for long-term standby. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the topology of the auxiliary power supply circuit of the energy storage system in Example 1; Figure 2 This is a detailed flowchart illustrating the control method for the auxiliary power supply circuit of the energy storage system in Example 2. Figure 3This is a waveform diagram showing the voltage and total power interaction between the output power and real-time voltage values ​​during different continuous time periods from t0 to t4 in Example 2. Figure 4 This is a flowchart illustrating the system power-on and abnormal power-off process of the control method for the auxiliary power supply circuit of the energy storage system in Example 2. Detailed Implementation

[0016] The following drawings disclose several embodiments of the present invention. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not essential. Furthermore, for the sake of simplicity, some conventional structures and components will be shown in the drawings in a simple schematic manner.

[0017] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings: Example 1 Reference Figure 1 , Figure 1 This is a schematic diagram of the topology of the auxiliary power supply circuit of the energy storage system in this embodiment. This embodiment provides an auxiliary power supply circuit for an energy storage system, including a battery, a physical high-voltage interruption subcircuit, an energy storage buffer subcircuit, and a low-voltage control subcircuit. The battery is a high-voltage power supply head, used to continuously output high-voltage DC power to provide basic high-voltage electrical energy input for subsequent circuits. The physical high-voltage interruption subcircuit is electrically connected to the battery, that is, the physical high-voltage interruption subcircuit is connected in series to the high-voltage power supply path of the battery. It is used to respond to external manual or system-issued external commands, outputting corresponding on / off signals, and completing the on / off control of the high-voltage power supply path based on the on / off signals. Simultaneously, in the event of undervoltage, it can receive control commands from the low-voltage control subcircuit and execute a mechanical trip action, thereby achieving a complete physical disconnection of the high-voltage power supply path. The energy storage buffer subcircuit is electrically connected to the physical high-voltage interruption subcircuit, used to achieve a stable conversion from high-voltage DC to low-voltage DC, to complete charging and energy storage when no transient impact load occurs, and to discharge and compensate for power supply when a transient impact load occurs after the low-voltage control subcircuit is operating normally. The low-voltage control subcircuit is electrically connected to the energy storage buffer subcircuit. It draws power from the energy storage buffer subcircuit and maintains its own operation according to its voltage conditions. It also monitors the voltage status of the physical high-voltage interruption subcircuit in real time and outputs control commands after determining that the undervoltage tripping conditions are met, thereby realizing the safety protection control of the high-voltage power supply path.

[0018] The physical high-voltage switching subcircuit is electrically connected to the battery, used to respond to external commands and output on / off signals, and to perform high-voltage on / off control based on these signals. The energy storage buffer subcircuit includes a wide-input DC-DC module and a buffer module. One end of the wide-input DC-DC module is electrically connected to the physical high-voltage switching subcircuit, and the other end is connected to the low-voltage output bus, used to receive high-voltage DC and convert it to low-voltage DC, and then output the basic supply current through the low-voltage output bus. The buffer module is connected in parallel with the low-voltage output bus, used to monitor the real-time voltage value of the low-voltage output bus and compare it with a preset discharge activation threshold. When the real-time voltage value is less than the discharge activation threshold, the buffer module will activate the discharge activation threshold. When the threshold is reached, the stored electrical energy is released and a compensation supply current is output; when the real-time voltage value is greater than or equal to the discharge activation threshold, charging is performed according to the low-voltage DC power; the low-voltage control sub-circuit is electrically connected to the low-voltage output bus and the physical high-voltage interruption sub-circuit respectively, and is used to receive the basic supply current or the total supply current formed by the combination of the basic supply current and the compensation supply current on the low-voltage output bus to obtain power and maintain normal operation. At the same time, it monitors the voltage status of the physical high-voltage interruption sub-circuit and determines whether the undervoltage tripping condition is met according to the voltage status. When the undervoltage tripping condition is met, a control command is generated to control the physical high-voltage interruption sub-circuit to perform mechanical tripping action.

[0019] In this example, the battery is a high-voltage battery cluster in the energy storage system, with an output voltage typically of DC high voltage (e.g., 200Vdc to 800Vdc or higher), serving as the input power for the entire auxiliary power supply circuit. A physical high-voltage interruption sub-circuit is connected in series between the battery and the energy storage buffer sub-circuit. It can be manually switched on and off via external commands (such as rotating a high-voltage rotary switch), or it can mechanically trip upon receiving a control command from the low-voltage control sub-circuit, forcibly cutting off the high-voltage power supply path and achieving system-level safety protection. The wide-input DC-DC module in the energy storage buffer sub-circuit converts the high-voltage DC output from the battery into a stable low-voltage DC (24Vdc in this embodiment), which supplies power to the subsequent low-voltage control sub-circuit through the low-voltage output bus. The buffer module is connected in parallel to the low-voltage output bus. Under normal conditions, it is charged by the wide-input DC-DC module and kept in full-charge standby mode. When the low-voltage output bus voltage drops below the discharge activation threshold (22Vdc in this embodiment) due to the transient pull-in of a large load after the low-voltage control sub-circuit is working normally, the buffer module quickly switches to the discharge state, releases the stored energy to output a compensation supply current, and superimposes it with the basic supply current output by the wide-input DC-DC module to jointly bear the transient large load power demand. This prevents the wide-input DC-DC module from entering constant current limiting due to output overcurrent, which would cause the bus voltage to continuously drop to the undervoltage lockout or hiccup protection dead zone. The low-voltage control sub-circuit receives electrical energy (basic supply current or total supply current) from the low-voltage output bus to maintain normal operation of the low-voltage control sub-circuit. At the same time, it monitors the voltage status of the physical high-voltage disconnection sub-circuit in real time. When it determines that the high-voltage battery cluster is undervoltage or meets other preset tripping conditions, it sends a control command to the physical high-voltage disconnection sub-circuit to drive the physical high-voltage disconnection sub-circuit to perform mechanical tripping, completely cutting off the high-voltage power supply path and preventing battery over-discharge.

[0020] For further details, please review. Figure 1 The physical high-voltage interruption sub-circuit includes a high-voltage rotary switch, a molded case shunt trip, and a fuse. The high-voltage rotary switch is connected between the battery and the wide-input DC-DC module, used to control the on / off state based on external commands and output on / off signals. The molded case shunt trip is connected between the battery and the high-voltage rotary switch, used to receive on / off signals to connect or disconnect the high-voltage power supply path connected to the battery, and also used to receive control commands and execute mechanical tripping actions to cut off the high-voltage power supply path according to the control commands. The fuse is connected between the high-voltage rotary switch and the molded case shunt trip, used to melt and disconnect the high-voltage power supply path first in the event of overcurrent or short-circuit faults.

[0021] In this example, the high-voltage rotary switch is a rotary disconnector that can receive external commands (i.e., manual mechanical operation) and output corresponding on / off signals to achieve manual on / off control of the high-voltage power supply path. That is, when the operator rotates it forward, the high-voltage power supply path is closed, allowing the high-voltage DC power output from the battery to be introduced into the subsequent circuit. When rotating it in the reverse direction, the high-voltage power supply path is disconnected, achieving physical power cut-off. The molded case shunt trip can receive the on / off signals output by the high-voltage rotary switch and synchronously connect or disconnect the high-voltage power supply path connected to the battery. In addition to responding to the on / off signals to maintain connection or disconnection, the molded case shunt trip can also receive control commands issued by the low-voltage control sub-circuit when it detects undervoltage. When the control command is received, an electromagnetic force is generated to push the molded case shunt trip, causing the molded case shunt trip to instantly perform a mechanical trip action to disconnect, completely cutting off the high-voltage power supply path and achieving hard fault protection. The fuse is connected in series between the high-voltage rotary switch and the molded case shunt trip. Its two ends are electrically connected to the output terminal of the high-voltage rotary switch and the input terminal of the molded case shunt trip, respectively. The fuse contains a fusible element whose rated current matches the maximum operating current of the system. When a serious overcurrent or short-circuit fault occurs in the downstream circuit, the fault current causes the fusible element to heat up and melt. The fuse melts first, disconnecting the high-voltage power supply path, thus achieving passive overcurrent protection. During normal operation, the operator rotates the high-voltage rotary switch to the closed position, outputting the corresponding on / off signal. The molded case shunt trip receives the on / off signal and synchronously maintains the closed state. The high-voltage DC power is transmitted to the wide-input DC-DC module via the molded case shunt trip, fuse, and high-voltage rotary switch. When emergency disconnection is required or the low-voltage control subcircuit detects an undervoltage fault, the low-voltage control subcircuit sends a control command to the molded case shunt trip. The molded case shunt trip performs a mechanical trip, instantly disconnecting the high-voltage power supply path. If a serious overcurrent or short-circuit fault occurs in the high-voltage power supply path and the molded case shunt trip fails to act in time, the fuse blows first to achieve protection, forming a multi-redundant high-voltage interruption protection mechanism.

[0022] For further details, please review. Figure 1 The molded case shunt trip includes the molded case circuit breaker body and the shunt trip coil; the molded case circuit breaker body is electrically connected to the battery and the high-voltage rotary switch respectively, and is used to receive on / off signals to connect or disconnect the high-voltage power supply path; the shunt trip coil is electrically connected to the molded case circuit breaker body and the low-voltage control sub-circuit respectively, and is used to receive control commands and generate electromagnetic force to drive the molded case circuit breaker body to perform mechanical tripping action to cut off the high-voltage power supply path.

[0023] In this example, the molded case circuit breaker (MCCB) body is a low-voltage MCCB with a thermal-magnetic trip mechanism. Its main circuit is connected in series to the high-voltage power supply path between the battery and the high-voltage rotary switch. After receiving the on / off signal output by the high-voltage rotary switch, the MCCB body remains closed, allowing high-voltage DC power to be transmitted from the battery to the downstream high-voltage rotary switch and the wide-input DC-DC module. When the operator rotates the high-voltage rotary switch to the off position, the on / off signal is canceled, the MCCB body resets and opens, cutting off the high-voltage power supply path. The shunt trip coil is electrically connected to the MCCB body, and the two leads of the shunt trip coil are connected to the drive output terminal of the low-voltage control sub-circuit. When the low-voltage control sub-circuit determines that the undervoltage trip condition is met, it outputs a control command to the shunt trip coil, energizing the shunt trip coil to generate electromagnetic force to drive the MCCB body to perform a mechanical trip action, causing the MCCB body to quickly disconnect, thereby realizing remote or automatic emergency power outage protection. During normal operation, the molded case circuit breaker body remains closed after receiving the on / off signal from the high-voltage rotary switch, keeping the high-voltage power supply path in a conducting state. When the low-voltage control sub-circuit determines that the undervoltage trip condition is met, it outputs a control command to the shunt trip coil. The shunt trip coil is energized to generate electromagnetic force, driving the molded case circuit breaker body to perform a mechanical trip action. The molded case circuit breaker body instantly disconnects, completely cutting off the high-voltage power supply path from a physical perspective, and realizing remote automatic trip protection.

[0024] For further details, please review. Figure 1 The buffer module includes a voltage detection unit and an electrolytic capacitor array. The voltage detection unit is electrically connected to the low-voltage output bus and the electrolytic capacitor array respectively. The voltage detection unit monitors the real-time voltage value of the low-voltage output bus and compares it with the discharge activation threshold. When the real-time voltage value is less than the discharge activation threshold, the voltage detection unit conducts the low-voltage output bus and the electrolytic capacitor array, causing the electrolytic capacitor array to release the stored electrical energy, thereby outputting the compensation supply current. When the real-time voltage value is greater than or equal to the discharge activation threshold, the electrolytic capacitor array is charged according to the low-voltage DC power.

[0025] In this example, the voltage detection unit is used to collect the real-time voltage value of the low-voltage output bus and compare it with an internally preset discharge activation threshold. Based on the comparison result, it controls the on / off state between the electrolytic capacitor array and the low-voltage output bus. The electrolytic capacitor array consists of multiple electrolytic capacitors connected in parallel. It stores electrical energy in standby mode and quickly releases the stored electrical energy to provide compensation supply current during discharge activation. When the voltage detection unit determines that the real-time voltage value is less than the discharge activation threshold, the internal switch of the voltage detection unit is turned on, connecting the electrolytic capacitor array to the low-voltage output bus. The electrolytic capacitor array releases the stored electrical energy and outputs compensation supply current to the low-voltage output bus, which merges with the basic supply current output by the wide-input DC-DC module to form the total supply current. When the voltage detection unit determines that the real-time voltage value is greater than or equal to the discharge activation threshold, the internal switch of the voltage detection unit is turned off, the discharge path between the electrolytic capacitor array and the low-voltage output bus is broken, and the electrolytic capacitor array is in a charging state. The basic supply current output by the wide-input DC-DC module charges the electrolytic capacitor array until the voltage across the electrolytic capacitor array approaches the voltage value of the low-voltage output bus. The discharge activation threshold is set to 22Vdc, which is lower than the rated output voltage of the wide-input DC-DC module (24Vdc). This ensures that the electrolytic capacitor array remains in a charging standby state and does not participate in discharging during normal steady-state operation of the system. When the low-voltage control subcircuit operates normally, a transient impact load caused by the contactor group engaging causes the low-voltage output bus voltage to drop below 22Vdc. The voltage detection unit immediately activates the discharge path of the electrolytic capacitor array, releasing its stored energy to compensate for the transient power shortfall and support the normal operation of the downstream load. The capacity of the electrolytic capacitor array is determined comprehensively based on the compensation energy required by the transient impact load and the allowable voltage drop, ensuring sufficient compensation current is provided during the discharge of the buffer module to maintain the low-voltage output bus voltage at or above the minimum operating voltage of the downstream circuit.

[0026] Furthermore, the low-voltage control sub-circuit includes a BMS and a contactor drive coil. The BMS is electrically connected to the low-voltage output bus and the shunt trip coil, respectively. It is used to receive the base supply current to obtain power supply and control the main power circuit to conduct. Or, when a transient impact load is generated after the main power circuit is conducted, it receives the total supply current to maintain power supply and continuously control the main power circuit to conduct. At the same time, it monitors the voltage status of the shunt trip coil in real time and determines whether the molded case circuit breaker body meets the undervoltage trip condition based on the voltage status. When the undervoltage trip condition is met, a control command is generated and output to the shunt trip coil, so that the shunt trip coil generates electromagnetic force to drive the molded case circuit breaker body to perform a mechanical trip action to cut off the high-voltage power supply path. The contactor drive coil is electrically connected to the BMS and is used to receive the real-time voltage value of the low-voltage output bus and determine whether it is sufficient to support the engagement. If so, a transient impact load is generated to make the real-time voltage value drop below the discharge activation threshold. Otherwise, the real-time voltage value is monitored.

[0027] In this example, the BMS is the battery management unit of the energy storage system. Its power input is connected to the low-voltage output bus to draw power from the low-voltage output bus to maintain its normal operation. During the initial power-on phase, the BMS receives the basic supply current from the wide-input DC-DC module. After completing self-test and initialization, it controls the main positive contactor, main negative contactor, and pre-charge contactor in the main power circuit to perform the energizing action, thus turning on the main power circuit. At the instant the main power circuit turns on, the contactor drive coil is energized, generating a transient impact load. At this time, the real-time voltage value on the low-voltage output bus drops below the discharge activation threshold due to the transient impact load. The buffer module intervenes to discharge and output compensation supply current. The BMS then receives the total supply current formed by the combination of the basic supply current and the compensation supply current, ensuring that it does not lose power and reset during the transient impact, and continuously controlling the main power circuit to remain in the conducting state. The BMS also monitors the voltage status of the shunt trip coil (i.e., the high voltage on the incoming side of the molded case circuit breaker) in real time through its sampling interface. It compares the monitored voltage value with the internally preset undervoltage trip threshold. When it is determined that the undervoltage trip condition is met, the BMS outputs a control command (such as a 24Vdc drive voltage) to the shunt trip coil through its drive output terminal, so that the shunt trip coil is energized to generate electromagnetic force, which drives the molded case circuit breaker to perform a mechanical trip action and cut off the high voltage power supply path. The contactor drive coil is an electromagnetic coil that controls the engagement of each contactor in the main power circuit. Its power supply is provided by the drive circuit inside the BMS. Before issuing the contactor engagement command, the BMS first reads the real-time voltage value of the low-voltage output bus through its sampling interface to determine whether the current real-time voltage value is sufficient to support the reliable engagement of the contactor drive coil (i.e., whether it is higher than the minimum engagement voltage of the contactor). If so, it outputs a drive signal to energize the contactor drive coil and generate a transient impact load. Otherwise, it continues to monitor the real-time voltage value and performs the engagement operation only after the real-time voltage value of the low-voltage output bus recovers to a level sufficient to support engagement. The BMS also incorporates anti-jitter delay logic. When determining undervoltage trip conditions, it first performs a preset delay confirmation (e.g., 10ms to 20ms) to eliminate sampling interference and transient interference. Only after confirming a continuous undervoltage state can it output control commands to the shunt trip coil to prevent false tripping. At the same time, the BMS itself is powered by the total power supply current of the low-voltage output bus reinforced by the buffer module. Even if the real-time voltage value of the low-voltage output bus drops briefly at the moment the contactor group is energized, it can be maintained without power loss by the compensation current of the buffer module, ensuring the reliability of undervoltage detection and trip command issuance.

[0028] In summary, when the auxiliary power supply circuit of the energy storage system is started, the operator controls the high-voltage rotary switch to close via external commands. After receiving the on / off signal, the plastic case shunt trip remains in the closed state. The high-voltage DC power output from the battery is sent to the wide-input DC-DC module via the plastic case shunt trip, fuse, and high-voltage rotary switch. The wide-input DC-DC module converts the high-voltage DC power into low-voltage DC power and outputs the basic power supply current, which is transmitted to the subsequent circuit via the low-voltage output bus. The electrolytic capacitor array is charged to a fully charged standby state by the basic power supply current output by the wide-input DC-DC module. After the BMS receives the basic power supply current and powers on, it maintains normal operation. After the BMS is powered on and maintained for a period of time, the main power circuit is turned on, the contactor drive coil is energized to generate a transient impact load, the output current of the wide-input DC-DC module rapidly rises to the constant current limiting threshold, and the real-time voltage value of the low-voltage output bus begins to drop; when the real-time voltage value drops to less than the discharge activation threshold (i.e., 22Vdc), the voltage detection unit turns on the discharge path between the electrolytic capacitor array and the low-voltage output bus, the electrolytic capacitor array releases the stored electrical energy to output compensation supply current, which merges with the basic supply current output by the wide-input DC-DC module on the low-voltage output bus to form the total supply current, the BMS receives the total supply current to maintain power supply and continuously controls the main power circuit to turn on; after the transient impact load ends, the real-time voltage value of the low-voltage output bus rises back to greater than or equal to the discharge activation threshold, the voltage detection unit turns off the discharge path, and the electrolytic capacitor array switches to the wide-input DC-DC module to recharge to a fully charged standby state. During BMS operation, the BMS monitors the voltage status of the shunt trip coil in real time. When it determines that the undervoltage trip condition is met, it generates a control command and outputs it to the shunt trip coil. The shunt trip coil is energized and generates electromagnetic force to drive the molded case circuit breaker to perform a mechanical trip, physically cutting off the high-voltage power supply path and achieving over-discharge protection. Before each closing operation, the contactor drive coil receives the real-time voltage value of the low-voltage output bus and determines whether it is sufficient to support closing. If it is sufficient, a transient impact load is generated to make the real-time voltage value drop below the discharge activation threshold. Otherwise, it continues to monitor the real-time voltage value until the condition is met before performing closing.

[0029] Example 2 Please see Figure 1 Please refer to them together. Figures 2-4 , Figure 2 This is a detailed flowchart illustrating the control method for the auxiliary power supply circuit of the energy storage system in Example 2. Figure 3 This is a waveform diagram showing the voltage and total power interaction between the output power and real-time voltage values ​​during different continuous time periods from t0 to t4 in Example 2. Figure 4This is a flowchart illustrating the system power-on and abnormal power-off process of the control method for the auxiliary power supply circuit of the energy storage system in Embodiment 2. The present invention also provides a control method for the auxiliary power supply circuit of an energy storage system, which is applied to the auxiliary power supply circuit of the energy storage system as described in Embodiment 1, and includes the following steps: Step S01: The physical high-voltage switching sub-circuit responds to external commands to control the on / off state and outputs an on / off signal. Based on the on / off signal, it connects the battery and the wide-input DC-DC module, so that the high-voltage DC power output from the battery is transmitted to the wide-input DC-DC module. In this embodiment, the operator applies an external command to rotate the high-voltage rotary switch, causing the internal contacts of the high-voltage rotary switch to close. After the high-voltage rotary switch closes, it outputs an on / off signal, which is transmitted to the molded case circuit breaker body in the molded case shunt trip. After receiving the on / off signal, the main contacts of the molded case circuit breaker body remain closed to connect the high-voltage power supply path between the battery and the wide-input DC-DC module. The high-voltage DC power output from the battery is then transmitted sequentially through the molded case shunt trip, the fuse, and the high-voltage rotary switch to the input terminal of the wide-input DC-DC module. The shunt trip coil in the molded case shunt trip is de-energized until it receives a control command, thus not interfering with the normal conduction of the high-voltage power supply path. The fuse is connected in series between the high-voltage rotary switch and the molded case shunt trip, keeping the fuse intact within the normal circuit current range and not obstructing the transmission of high-voltage DC power. At this point, the high-voltage power supply path between the battery and the wide-input DC-DC module is fully established, and high-voltage DC power is continuously supplied to the wide-input DC-DC module.

[0030] Step S02: The wide-input DC-DC module receives high-voltage DC power and converts it into low-voltage DC power. It outputs the basic power supply current through the low-voltage output bus and monitors the real-time voltage value of the low-voltage output bus through the buffer module. In this embodiment, the wide-input DC-DC module receives high-voltage DC power from the battery and converts it into low-voltage DC power with a rated voltage of 24Vdc. Simultaneously, it outputs basic supply current to the subsequent circuitry through the low-voltage output bus. The wide-input DC-DC module operates in constant-voltage mode when the output current does not reach its internally set constant-current limiting threshold, maintaining the low-voltage output bus voltage at a stable 24Vdc. The voltage detection unit in the buffer module continuously samples the real-time voltage value of the low-voltage output bus and compares the sampled voltage signal with the internally preset discharge activation threshold of 22Vdc. At this time, the system experiences no large load impact, and the low-voltage output bus voltage stabilizes at 24Vdc, exceeding the discharge activation threshold of 22Vdc. The voltage detection unit outputs a shutdown signal, disconnecting the discharge path between the electrolytic capacitor array and the low-voltage output bus. The electrolytic capacitor array is slowly charged to near 24Vdc by the low-voltage DC power output from the wide-input DC-DC module through the charging circuit, entering a fully charged standby state.

[0031] Step S03: After receiving the base supply current, the low-voltage control subcircuit starts to work. After the low-voltage control subcircuit starts working, it generates a transient impact load, causing the real-time voltage value to drop below the discharge activation threshold. When this occurs, the buffer module releases the stored electrical energy to output a compensation supply current, which merges with the base supply current on the low-voltage output bus to form a total supply current to maintain the normal operation of the low-voltage control subcircuit. When the real-time voltage value is greater than or equal to the discharge activation threshold, the buffer module is charged by low-voltage DC power. The low-voltage control subcircuit also monitors the voltage status of the physical high-voltage disconnection subcircuit in real time. In this embodiment, the BMS in the low-voltage control sub-circuit receives the basic power supply current from the low-voltage output bus and starts up. After completing self-testing and initialization, it outputs a drive signal to the contactor drive coil, controlling the contactor in the main power circuit to perform a closing action. The moment the contactor drive coil is energized, a transient impact load is generated. This load power far exceeds the rated output power of the wide-input DC-DC module. The output current of the wide-input DC-DC module rapidly rises to its internally set constant current limiting threshold, forcing it to switch from constant voltage mode to constant current limiting mode. The output current is clamped between 105% and 135% of the rated current, and the output voltage linearly decreases from 24Vdc as the load increases. The real-time voltage value of the low-voltage output bus drops from 24Vdc. In the range before dropping to 22Vdc, the voltage detection unit continuously determines that the real-time voltage value is greater than or equal to the discharge activation threshold of 22Vdc. The discharge path of the electrolytic capacitor array remains off, the buffer module does not participate in the discharge, and only the wide-input DC-DC module supplies power to the load. When the real-time voltage value of the low-voltage output bus continues to drop below 22Vdc, the voltage detection unit outputs a conduction signal, connecting the discharge path between the electrolytic capacitor array and the low-voltage output bus. The electrolytic capacitor array releases its stored energy, outputting a compensation supply current to the low-voltage output bus. The compensation supply current and the base supply current output by the wide-input DC-DC module converge on the low-voltage output bus to form the total supply current. The total output power corresponding to the total supply current instantly jumps to a peak power of approximately 1000W. The low-voltage output bus voltage is clamped near 22Vdc, preventing the wide-input DC-DC module from entering the hiccup protection dead zone due to the continuous drop in output voltage, which could cause power loss in the subsequent circuits. The BMS receives the total supply current and maintains normal operation, continuously controlling the main power circuit to remain in the conducting state. After the contactor completes engagement and the transient load impact ends, the total load drops, and the wide-input DC-DC module automatically returns to constant voltage mode, gradually pulling the low-voltage output bus voltage back from 22Vdc to 24Vdc. Once the voltage detection unit detects that the real-time voltage value has risen to greater than or equal to 22Vdc, it shuts off the discharge path of the electrolytic capacitor array. The electrolytic capacitor array then switches to low-voltage DC power output from the wide-input DC-DC module to recharge to a fully charged standby state. During normal system operation, the BMS continuously monitors the voltage status value of the physical high-voltage interruption sub-circuit in real time and compares this voltage status value with the internally preset undervoltage trip threshold.

[0032] Step S04: The low-voltage control sub-circuit determines whether the undervoltage tripping condition is met based on the monitored voltage status. When the undervoltage tripping condition is met, a control command is generated and output to the physical high-voltage interruption sub-circuit to drive the physical high-voltage interruption sub-circuit to perform a mechanical tripping action.

[0033] In this embodiment, the BMS continuously compares the voltage state value corresponding to the physical high-voltage interruption sub-circuit monitored in real time with the internally preset undervoltage trip threshold. The BMS is internally configured with anti-jitter delay logic. When the voltage state value is continuously sampled below the undervoltage trip threshold for a duration reaching the preset delay time, the BMS determines that the undervoltage trip condition is met and generates a control command through its drive output terminal. This control command is a 24Vdc drive voltage, output to the shunt trip coil in the molded case shunt trip unit via the drive circuit. Upon receiving the control command, the shunt trip coil is energized, generating electromagnetic force to drive the mechanical tripping mechanism inside the molded case circuit breaker body to move instantaneously, causing the main contacts of the molded case circuit breaker body to quickly disconnect, completely severing the high-voltage power supply path between the battery and the wide-input DC-DC module from a physical perspective. After the high-voltage power supply path is cut off, the input terminal of the wide-input DC-DC module loses high-voltage DC power and stops outputting low-voltage DC power. The low-voltage output bus voltage gradually drops to zero, and the BMS and other downstream circuits are subsequently de-energized. The entire auxiliary power supply circuit stops working, achieving over-discharge protection.

[0034] like Figure 4As shown, in the initial state of the system, all relay bodies are in the open position. After the operator manually closes the physical switch on the high-voltage side (including the high-voltage rotary switch and the molded case shunt trip), the wide-input DC-DC module is energized and converts the high-voltage DC to 24Vdc low-voltage DC, which is then output to the low-voltage output bus. The BMS is powered on and starts up, completing system initialization, and the system enters normal load operation. During normal load operation, the voltage detection unit continuously monitors the real-time voltage value of the low-voltage output bus and compares it with the discharge activation threshold of 22Vdc. When the contactor drive coil is energized, generating a transient impact load that causes the real-time voltage value to drop below 22Vdc, the voltage detection unit outputs a conduction signal to connect the electrolytic capacitor array to the low-voltage output bus. The electrolytic capacitor array releases its stored energy to output a compensation supply current, which merges with the base supply current output by the wide-input DC-DC module to form a total supply current. This clamps the real-time voltage value of the low-voltage output bus near 22Vdc, preventing the wide-input DC-DC module from entering the hiccup protection dead zone. After the transient load event ends, the wide-input DC-DC module automatically resumes constant voltage mode, pulling the real-time voltage value of the low-voltage output bus back to 24Vdc. The voltage detection unit shuts off the discharge path, and the electrolytic capacitor array is recharged to a fully charged standby state. During system operation, the BMS continuously monitors the on / off signal output by the high-voltage rotary switch to obtain the current on / off status of the high-voltage power supply path. When the on / off status is on, the BMS collects the voltage status value of the shunt trip coil in real time and compares it with the preset undervoltage protection threshold. When the voltage status value is lower than the undervoltage protection threshold, the BMS outputs an undervoltage trigger pulse and starts an anti-jitter delay timer. During the timing process, it continuously monitors whether the undervoltage trigger pulse disappears. If the pulse disappears before the timing is completed, the timer is reset and it is determined to be an instantaneous interference. If the pulse continues to exist and the voltage remains below the threshold for a duration that reaches the anti-jitter delay time (e.g., 10ms~20ms), the BMS determines that the undervoltage trip condition is met and outputs an undervoltage trip signal. It generates a control command and outputs it to the shunt trip coil to energize it and generate electromagnetic force to drive the molded case circuit breaker body to perform a mechanical trip action, physically cutting off the high-voltage power supply path. The system enters a safe sleep state, realizing over-discharge protection.

[0035] Furthermore, the low-voltage control sub-circuit begins operation after receiving the base supply current, specifically including the following steps: After the BMS receives the base power supply current and powers on, it initializes its internal parameters and reads the on / off signal output by the physical high voltage interruption sub-circuit to confirm that the high voltage power supply path between the battery and the wide input DC-DC module is in a conducting state. After the BMS receives power and maintains it for a period of time, the buffer module is in a fully charged standby state and receives the output mode enable command provided by the user. Based on the output mode enable command, it determines whether the real-time voltage value is stably maintained above the discharge activation threshold. In this embodiment, the BMS receives the basic power supply current from the wide-input DC-DC module from the low-voltage output bus and then powers on. The internal microcontroller of the BMS executes a power-on reset program, completing internal parameter initialization operations such as register initialization, clock configuration, ADC sampling module calibration, and I / O port status settings. After initialization, the BMS reads the on / off signal output by the auxiliary contact of the high-voltage rotary switch in the physical high-voltage switching sub-circuit through its digital input port. This on / off signal is a high-level signal; a high level indicates that the high-voltage rotary switch is in the closed position and the high-voltage power supply path is in a conducting state, while a low level indicates that the high-voltage rotary switch is in the open position and the high-voltage power supply path is in a disconnected state. When the BMS reads a high-level on / off signal, it confirms that the high-voltage power supply path between the battery and the wide-input DC-DC module is in a conducting state, and the high-voltage DC power from the battery is continuously supplied to the wide-input DC-DC module. After the BMS receives power and maintains stable operation for a period of time, the electrolytic capacitor array in the buffer module has been charged to approximately 24Vdc by the low-voltage DC power output from the wide-input DC-DC module. The voltage detection unit continuously monitors the real-time voltage value of the low-voltage output bus and determines that it is stably maintained above the discharge activation threshold of 22Vdc, and the electrolytic capacitor array is in a fully charged standby state. At this time, the user issues an output mode activation command through the host computer or human-machine interface. After receiving the command, the BMS reads the real-time voltage value of the low-voltage output bus through its ADC sampling channel, continuously sampling for multiple cycles (e.g., 10 consecutive samplings, each with a 1ms interval), and determines whether the real-time voltage value is consistently maintained above 22Vdc and the fluctuation range does not exceed the set range (e.g., the fluctuation range does not exceed 0.5Vdc). If the real-time voltage value remains consistently above 22Vdc, the BMS determines that the current low-voltage output bus power supply status is normal and meets the conditions for performing subsequent contactor engagement operations.

[0036] When the real-time voltage value is stably maintained above the discharge activation threshold, the BMS determines that the output power of the wide-input DC-DC module is sufficient to support the contactor drive coil to engage. In this embodiment, the BMS continuously reads the real-time voltage value of the low-voltage output bus through the ADC sampling channel and compares the read real-time voltage value with the discharge activation threshold of 22Vdc one by one. When multiple consecutive sampled values ​​are greater than 22Vdc and the deviation between two adjacent sampled values ​​is less than a set threshold, the BMS determines that the real-time voltage value is stably maintained above the discharge activation threshold. Based on this, the BMS determines that the output power of the current wide-input DC-DC module is sufficient to support the transient power requirements for contactor drive coil engagement. That is, the 24Vdc voltage and basic supply current output by the wide-input DC-DC module in constant voltage mode can provide sufficient energy in the initial stage of contactor drive coil engagement. Even if the voltage drops below 22Vdc due to transient impact, the buffer module can still maintain the total supply current to meet the engagement requirements of the contactor drive coil after intervention, and the contactor drive coil will not fail to engage or the BMS will power down and reset due to insufficient power supply. After the internal logic of the BMS passes the determination, it proceeds to the next contactor engagement operation process.

[0037] The BMS sends a pull-in command to the contactor drive coil, causing the excitation current of the contactor drive coil to rise rapidly from zero to the pull-in current value, driving the contactor drive coil to pull in and generate a transient impact load. When the real-time voltage value drops below the discharge activation threshold, the buffer module releases the stored electrical energy to output a compensation supply current, which merges with the base supply current on the low-voltage output bus to form a total supply current to maintain the main power circuit of the contactor drive coil control BMS on. In this embodiment, the BMS sends a pull-in command to the contactor drive coil through its digital output port. This pull-in command is a high-level drive signal, which is amplified by the drive circuit and applied to both ends of the contactor drive coil. The voltage across the contactor drive coil jumps from zero to 24Vdc, and the excitation current in the coil rises rapidly from zero according to an exponential law. When the excitation current rises to the pull-in current value of the contactor drive coil, the electromagnetic force generated by the contactor drive coil overcomes the spring force of the reset spring, causing the armature to pull in and driving the main contacts of the contactor in the main power circuit to close. At the moment the contactor drive coil pulls in, its equivalent impedance drops sharply, and the excitation current further increases, forming a transient impact load lasting from several milliseconds to tens of milliseconds. The peak power of this transient impact load far exceeds the rated output power of the wide-input DC-DC module. The output current of the wide-input DC-DC module rapidly climbs to its internally set constant current limiting threshold, and the output voltage drops linearly from 24Vdc, causing the real-time voltage value of the low-voltage output bus to drop accordingly. When the real-time voltage value drops below 22Vdc, the voltage detection unit in the buffer module outputs a conduction signal, connecting the discharge path between the electrolytic capacitor array and the low-voltage output bus. The electrolytic capacitor array releases its stored energy to output a compensation supply current. The compensation supply current and the base supply current output by the wide-input DC-DC module converge on the low-voltage output bus to form the total supply current. The total output power corresponding to the total supply current instantly jumps to a peak power of approximately 1000W. The voltage of the low-voltage output bus is clamped near 22Vdc, maintaining the power supply required for the contactor drive coil to remain engaged, while ensuring the BMS itself does not lose power and reset due to voltage drops, thus ensuring the main power circuit remains conductive.

[0038] The BMS confirms whether the current contactor drive coil is successfully engaged by detecting the recovery of the real-time voltage value after compensation or reading the status of the auxiliary contacts of the contactor drive coil. If the engagement is successful, the contactor drive coil is kept engaged. If the engagement fails, the fault information is recorded and the subsequent engagement process is stopped.

[0039] In this embodiment, after issuing the engagement command, the BMS continuously monitors the real-time voltage value of the low-voltage output bus and the status of the auxiliary contacts of the contactor drive coil. The BMS reads the real-time voltage value through the ADC sampling channel and observes the recovery of the real-time voltage value after the buffer module discharges and compensates: if the contactor drive coil engages successfully, the transient impact load drops rapidly after the contactor engages, the wide-input DC-DC module automatically returns to constant voltage mode, and the low-voltage output bus voltage gradually rises from 22Vdc to 24Vdc. The real-time voltage value exhibits a typical waveform characteristic of first dropping and then rising. At the same time, the BMS reads the status signal of the auxiliary contacts of the contactor drive coil through its digital input port. The auxiliary contacts synchronously switch states after the main contacts of the contactor drive coil close, outputting a level signal corresponding to the state of the main contacts (e.g., the auxiliary contacts output a high level when the main contacts are closed). When the BMS reads a high-level auxiliary contact status signal, it confirms that the contactor drive coil has successfully engaged and the main power circuit has reliably conducted. The BMS continues to maintain the contactor drive coil engagement command output, keeping the contactor drive coil engaged and the main power circuit continuously conducting. If the BMS does not detect a real-time voltage rise above 22Vdc within a preset timeout period (e.g., 10ms~20ms), or reads a persistent low-level auxiliary contact status signal for the contactor drive coil, it determines that the contactor drive coil engagement has failed. The BMS immediately stops sending engagement commands to the contactor drive coil, cuts off the drive signal output, de-energizes the contactor drive coil, and restores the main power circuit to the open state. Simultaneously, the BMS records the fault information of this engagement failure in its internal non-volatile memory, including the fault occurrence time, the current low-voltage output bus voltage value, and the on / off signal status, and stops subsequent engagement processes, waiting for the user to troubleshoot the fault and reissue the output mode activation command.

[0040] Furthermore, such as Figure 3 As shown, the process by which the buffer module releases stored electrical energy to compensate for the supply current includes different consecutive time periods from t0 to t4, specifically including the following steps: During the period from t0 to t1, the output power of the wide-input DC-DC module is insufficient to support the contactor drive coil to engage. The low-voltage output bus is not subjected to a large load impact. The wide-input DC-DC module operates in constant voltage mode, outputs the rated voltage value, and the buffer module is in a fully charged standby state. In this embodiment, during the time period from t0 to t1, the BMS has not yet sent a energizing command to the contactor drive coil, the contactor drive coil is in a de-energized state, and all contactors in the main power circuit are in the open position, so there is no large load impact on the low-voltage output bus. The wide-input DC-DC module receives high-voltage DC power from the battery, and its internal power conversion circuit operates in constant voltage mode. Through closed-loop feedback control, it stabilizes the low-voltage output bus voltage at the rated voltage of 24Vdc, while simultaneously outputting a basic supply current to the low-voltage output bus. This basic supply current is used to supply other standby loads in the BMS and low-voltage control sub-circuit, and the total load power is much lower than the rated output power of the wide-input DC-DC module. The voltage detection unit in the buffer module continuously monitors the real-time voltage value of the low-voltage output bus. This real-time voltage value is stable at 24Vdc, always greater than the discharge activation threshold of 22Vdc. The voltage detection unit outputs a turn-off signal, and the discharge path between the electrolytic capacitor array and the low-voltage output bus remains disconnected. The electrolytic capacitor array is continuously charged by the low-voltage DC power output from the wide-input DC-DC module through the charging circuit. The voltage across the electrolytic capacitor array gradually rises to close to 24Vdc, storing sufficient electrical energy and being in a fully charged standby state, ready to intervene in discharging when the real-time voltage value drops below the discharge activation threshold.

[0041] At time t1, the contactor drive coil instantly engages, generating a transient impact load. The output power of the wide-input DC-DC module instantly surges to the overload protection limit, while the real-time voltage value of the low-voltage output bus remains unchanged at the rated voltage value. In this embodiment, at time t1, the BMS sends a pull-in command to the contactor drive coil through its digital output port. The pull-in command is a high-level drive signal, which is amplified by the drive circuit and applied to both ends of the contactor drive coil. The voltage across the contactor drive coil jumps from zero to 24Vdc, and the excitation current in the coil rises rapidly from zero. When the excitation current rises to the pull-in current value, the electromagnetic force generated by the contactor drive coil drives its internal mechanism to operate, causing the main contacts of the contactor in the main power circuit to close. At the instant the contactor drive coil pulls in, its equivalent impedance drops sharply, and the excitation current further increases, forming a transient impact load. The peak power of this transient impact load instantly reaches several times the rated output power of the wide-input DC-DC module. The output power of the wide-input DC-DC module instantly surges from its lower value in standby mode to its internally set overload protection limit, i.e., 105% to 135% of the rated output power. However, since the energy stored in the electrolytic capacitor array and output filter capacitor connected in parallel at the output of the wide-input DC-DC module can still maintain the stability of the output voltage, and the transient impact load has just been established at time t1 and has not yet continued to pull down the voltage, the real-time voltage value of the low-voltage output bus remains unchanged at 24Vdc at time t1, without any significant drop.

[0042] During the period from t1 to t2, the transient impact load continued to exceed the overload protection limit of the wide input DC-DC module. The wide input DC-DC module was forced to switch from constant voltage mode to constant current limiting mode. The real-time voltage value was quickly pulled down from the rated voltage value to above the discharge activation threshold to prevent the buffer module from being falsely awakened. In this embodiment, during the time period t1 to t2, the transient impact load generated by the continuous engagement of the contactor drive coil persists, and the power of this load continuously exceeds the overload protection limit of the wide-input DC-DC module. The current detection circuit inside the wide-input DC-DC module detects that the output current has reached its internally set constant current limiting threshold. The closed-loop control loop switches from the voltage loop to the current loop, and the wide-input DC-DC module is forced to switch from constant voltage mode to constant current limiting mode. The output current is clamped between 105% and 135% of the rated current and no longer increases. Due to the forced limitation of the output current, as the transient impact load continues to lower the equivalent load impedance, the real-time voltage value of the low-voltage output bus drops rapidly from 24Vdc. Within the range where the real-time voltage value drops from 24Vdc to 22Vdc, the voltage detection unit continuously compares the real-time voltage value with the discharge activation threshold of 22Vdc. Since the real-time voltage value is still greater than 22Vdc, the voltage detection unit outputs a shutdown signal that remains unchanged, the discharge path of the electrolytic capacitor array remains open, and the buffer module is not woken up, thus avoiding accidental discharge of the buffer module due to minor fluctuations or brief drops. In constant current limiting mode, the wide-input DC-DC module alone supplies power to the entire transient load, and its output power decreases linearly as the output voltage decreases.

[0043] During the period from t2 to t3, the real-time voltage value drops below the discharge activation threshold, and the buffer module is activated. The buffer module is equivalent to a constant voltage source that clamps the real-time voltage value at the discharge activation threshold, using discharge output to compensate for the supply current. This discharge output, combined with the base supply current, causes the output power of the wide-input DC-DC module to surge, thereby preventing the wide-input DC-DC module from entering the hiccup protection dead zone. The specific steps for activating the buffer module include: In this embodiment, at time t2, the real-time voltage value of the low-voltage output bus continues to drop below the discharge activation threshold of 22Vdc. The voltage detection unit detects that the real-time voltage value is below the discharge activation threshold and outputs a conduction signal, connecting the discharge path between the electrolytic capacitor array and the low-voltage output bus. The electrical energy stored in the electrolytic capacitor array is released to the low-voltage output bus through the discharge path, outputting a compensation supply current. After the buffer module is activated, the electrolytic capacitor array continues to discharge, clamping the real-time voltage value of the low-voltage output bus at around 22Vdc, preventing the real-time voltage value from continuing to drop. The compensation supply current and the basic supply current output by the wide-input DC-DC module in constant current limiting mode converge on the low-voltage output bus to form the total supply current. The total output power corresponding to the total supply current instantly jumps from the lower value when the wide-input DC-DC module is powered alone to a peak power of approximately 1000W. This peak power is sufficient to support all transient power requirements for contactor drive coil engagement, while preventing the wide-input DC-DC module from entering the hiccup protection dead zone due to the output voltage continuously dropping below its undervoltage lockout threshold, ensuring that the downstream BMS and low-voltage control sub-circuit do not lose power and reset during transient impacts.

[0044] When the voltage detection unit detects that the real-time voltage value is less than the discharge activation threshold, it outputs a conduction signal to connect the electrolytic capacitor array to the low-voltage output bus. In this embodiment, the voltage detection unit continuously acquires the real-time voltage value of the low-voltage output bus and compares it with the internally preset discharge activation threshold of 22Vdc. When the real-time voltage value of the low-voltage output bus continuously drops from 24Vdc and first falls below 22Vdc, the voltage detection unit determines that the real-time voltage value is less than the discharge activation threshold, and its output state switches from a shutdown signal to a conduction signal. This conduction signal is transmitted to the on / off control terminal between the electrolytic capacitor array and the low-voltage output bus, causing the on / off control terminal, which was originally in a disconnected state, to switch to a conduction state. A discharge path is established between the electrolytic capacitor array and the low-voltage output bus, and the electrical energy stored in the electrolytic capacitor array has the physical conditions to be released to the low-voltage output bus.

[0045] The electrolytic capacitor array releases the stored electrical energy through the connection path. The buffer module is equivalent to a constant voltage source that clamps the real-time voltage value at the discharge activation threshold so that the discharge output can compensate for the supply current. In this embodiment, the electrolytic capacitor array is connected to the low-voltage output bus through a conductive discharge path. The voltage across the electrolytic capacitor array is higher than that of the low-voltage output bus, and the forward voltage difference drives the electrolytic capacitor array to release stored electrical energy to the low-voltage output bus. The electrolytic capacitor array consists of multiple large-capacity electrolytic capacitors connected in parallel, with a total capacity of tens of thousands of microfarads. During the discharge process, the electrolytic capacitor array continuously releases electrical energy, causing its voltage to gradually decrease. However, due to the large capacity of the electrolytic capacitor array, the voltage drop is limited within the discharge time of several milliseconds to tens of milliseconds. Simultaneously, the wide-input DC-DC module continuously outputs a base supply current to the low-voltage output bus in constant current limiting mode. This base supply current, together with the compensation supply current released by the electrolytic capacitor array, acts on the low-voltage output bus, stabilizing the real-time voltage value of the low-voltage output bus at around 22Vdc. During this stage, the buffer module continuously injects compensation supply current into the low-voltage output bus to prevent the real-time voltage value from falling further below the undervoltage lockout threshold of the wide-input DC-DC module, ensuring that the subsequent circuits obtain a stable supply voltage during transient impacts.

[0046] The compensation supply current and the base supply current output by the wide input DC-DC module in constant current limiting mode converge on the low-voltage output bus, causing the output power of the wide input DC-DC module to jump and instantly reach the peak power. In this embodiment, the compensation supply current released by the electrolytic capacitor array flows into the low-voltage output bus through the discharge path, and the basic supply current output by the wide-input DC-DC module in constant current limiting mode flows into the low-voltage output bus through its output terminal. The two currents naturally merge at the common node of the low-voltage output bus to form the total supply current. The merged total supply current flows to the downstream load, including the contactor drive coil in the energized state and low-voltage control sub-circuits such as the BMS. The total output power corresponding to the total supply current is the sum of the output power of the wide-input DC-DC module in constant current limiting mode and the discharge power of the electrolytic capacitor array. The output power of the wide-input DC-DC module in constant current limiting mode decreases linearly with the decrease of output voltage, while the discharge power of the electrolytic capacitor array is close to the product of the voltage across the electrolytic capacitor array and the discharge current in the early stage of its discharge. The superposition of the two causes the total output power on the low-voltage output bus to jump instantaneously from the lower value when the wide-input DC-DC module is powered alone, reaching a peak power of approximately 1000W. This peak power far exceeds the output capacity of the wide-input DC-DC module when powered alone, and is sufficient to support all transient power requirements required for the entire contactor drive coil energizing process. This ensures reliable energizing of the contactor drive coil and reliable conduction of the main power circuit, while maintaining the BMS and other control circuits from losing power and resetting during transient impacts, thus achieving kilowatt-level power superposition between the wide-input DC-DC module and the buffer module.

[0047] During the period from t3 to t4, the peak power is maintained until the transient impact load ends. The wide input DC-DC module automatically returns to constant voltage mode, steadily pulling the real-time voltage value back to above the discharge activation threshold. The voltage detection unit disconnects the connection path between the electrolytic capacitor array and the low-voltage output bus and performs charging.

[0048] In this embodiment, at time t3, the contactor drive coil has completed the engagement process, the main contacts of the contactor in the main power circuit are reliably closed, the excitation current of the contactor drive coil drops from its peak to the holding current, the transient load impact ends, and the total load power rapidly decreases to within the rated output power of the wide-input DC-DC module. The output current of the wide-input DC-DC module then drops below the constant current limiting threshold. The current detection circuit determines that the output current has exited the current limiting region, and the closed-loop control loop switches from the current loop back to the voltage loop. The wide-input DC-DC module automatically returns to constant voltage mode. In constant voltage mode, the wide-input DC-DC module gradually increases the output voltage through closed-loop feedback control, steadily pulling the real-time voltage value of the low-voltage output bus back from 22Vdc to 24Vdc. During the period from t3 to t4, the voltage detection unit continuously monitors the real-time voltage value. When the real-time voltage value rises to above or equal to the discharge activation threshold of 22Vdc, the voltage detection unit outputs a shutdown signal, disconnecting the discharge path between the electrolytic capacitor array and the low-voltage output bus. The electrolytic capacitor array stops discharging to compensate for the supply current. Instead, the low-voltage DC power output from the wide-input DC-DC module is used to recharge the capacitors via the charging circuit. The voltage across the electrolytic capacitor array gradually rises from 22Vdc to nearly 24Vdc, restoring it to a fully charged standby state and preparing it for the next transient load impact. The system then enters a stable cyclic operation state.

[0049] Furthermore, the specific steps for the wide-input DC-DC module to be forced to switch from constant voltage mode to constant current limiting mode include: The wide-input DC-DC module continuously outputs the rated voltage value in constant voltage mode, while monitoring the output current value in real time and comparing the output current value with the internally preset current limiting protection threshold. In this embodiment, the wide-input DC-DC module continuously maintains the low-voltage output bus voltage at the rated value of 24Vdc in constant voltage mode. Simultaneously, the module internally monitors the output current in real time and continuously compares the monitored output current value with a preset current-limiting protection threshold. This current-limiting protection threshold corresponds to 105% to 135% of the rated output current of the wide-input DC-DC module. During the initial period from t1 to t2, the transient impact load generated by the contactor drive coil has not yet caused the output current value to reach the current-limiting protection threshold, and the wide-input DC-DC module continues to operate in constant voltage mode.

[0050] When the transient impact load generated by the contactor drive coil energizing causes the output current value to exceed the current limiting protection threshold for the first time, the wide input DC-DC module activates the overcurrent response mechanism to maintain the constant voltage mode. In this embodiment, as the contactor drive coil continues to engage, the transient impact load further increases, and the output current value at the output terminal of the wide-input DC-DC module continues to rise. When the output current value first exceeds the internally preset current limiting protection threshold, the overcurrent response mechanism inside the wide-input DC-DC module is activated. After the overcurrent response mechanism is activated, the wide-input DC-DC module does not immediately switch its operating mode, but maintains a constant voltage mode, and the low-voltage output bus voltage is still stably controlled at 24Vdc. The wide-input DC-DC module relies on the energy stored in the electrolytic capacitor array connected in parallel at the output terminal to replenish the transient current gap and maintain the stability of the output voltage.

[0051] The output current value continues to increase and exceeds the current limiting protection threshold. The wide input DC-DC module detects that the output power can no longer keep up with the load demand. The wide input DC-DC module determines that the load has exceeded the maximum output capacity of the constant voltage mode, and begins to release the constant voltage control of the real-time voltage value, and instead forcibly limits the output current value to not exceed the current limiting protection threshold. In this embodiment, as the output current continues to increase and exceeds the current-limiting protection threshold, the wide-input DC-DC module detects that its output power can no longer keep up with the increasing load demand and determines that the current load has exceeded the maximum output capacity of the constant-voltage mode. The wide-input DC-DC module then begins to release the constant-voltage control over the real-time voltage of the low-voltage output bus, the voltage regulation loop is gradually exited, and the current-limiting loop is activated. The wide-input DC-DC module then forcibly limits the output current to not exceeding the current-limiting protection threshold. The output current is clamped at the current value corresponding to the current-limiting protection threshold and no longer increases.

[0052] The wide-input DC-DC module is forced to switch from constant voltage mode to constant current limiting mode. The real-time voltage value is no longer constrained by the constant voltage mode, and the real-time voltage value is rapidly pulled down from the rated voltage value as the load increases.

[0053] In this embodiment, the wide-input DC-DC module switches from constant voltage mode to constant current limiting mode, and the output current is stably limited to the current value corresponding to the current limiting protection threshold, preventing further increase. Because the output current is forcibly limited while the transient load impact continues, the real-time voltage value of the low-voltage output bus is no longer constrained by the constant voltage mode. The real-time voltage value drops rapidly from 24Vdc as the load increases. The rate of drop in the real-time voltage value depends on the rate of load increase. During the contactor drive coil engagement, the real-time voltage value continues to decrease until it falls below the discharge activation threshold of 22Vdc, triggering the buffer module to intervene in the discharge.

[0054] Furthermore, the specific steps of the low-voltage control sub-circuit in determining whether the undervoltage tripping condition is met based on the monitored voltage state include: The BMS continuously monitors the on / off signal output by the high-voltage rotary switch to obtain the current on / off status of the high-voltage power supply path; In this embodiment, the BMS is electrically connected to the auxiliary contact output of the high-voltage rotary switch via its digital input port, continuously reading the on / off signal output by the high-voltage rotary switch. This on / off signal is a high-level signal; when the high-voltage rotary switch is in the closed position, the auxiliary contact is closed, and the on / off signal is high, indicating that the high-voltage power supply path is conducting; when the high-voltage rotary switch is in the open position, the auxiliary contact is open, and the on / off signal is low, indicating that the high-voltage power supply path is disconnected. The BMS reads the level state of the on / off signal once in each sampling period, with the sampling period set to 1ms to ensure rapid response to changes in the state of the high-voltage rotary switch. The BMS's internal registers continuously update and store the current on / off signal level value for subsequent logic judgment.

[0055] If the current on / off state is on, the BMS will collect the voltage status value of the shunt trip coil in real time and compare the voltage status value with the preset undervoltage protection threshold. In this embodiment, the BMS reads a high-level on / off signal, determines that the current high-voltage power supply path is in a conducting state, and then initiates real-time acquisition of the shunt trip coil voltage state value. The BMS is electrically connected to the input terminal of the shunt trip coil through its ADC sampling channel. The input terminal voltage of the shunt trip coil is the high-voltage voltage on the input side of the molded case circuit breaker body, and this voltage value reflects the current output voltage level of the battery. The ADC converter inside the BMS continuously acquires the voltage state value of the shunt trip coil at a sampling rate of 1kHz, converts the analog voltage signal into a digital quantity, and stores it in an internal register. The BMS has a preset undervoltage protection threshold, which corresponds to 80% of the battery's rated voltage. The BMS compares each acquired voltage state value with the undervoltage protection threshold. The comparison result is divided into two cases: if the voltage state value is higher than or equal to the undervoltage protection threshold, it is determined to be in a normal state; if the voltage state value is lower than the undervoltage protection threshold, it is determined to be in an undervoltage state.

[0056] When the voltage status value is lower than the undervoltage protection threshold, an undervoltage trigger pulse is output. The BMS synchronously starts an anti-jitter delay timer to receive the undervoltage trigger pulse and start timing. During the timing process, the anti-jitter delay timer continuously monitors whether the undervoltage trigger pulse disappears. If the undervoltage trigger pulse disappears before the timing is completed, the anti-jitter delay timer is reset. If the undervoltage trigger pulse continues to exist and the voltage status value continues to be lower than the undervoltage protection threshold for a duration that reaches the preset anti-jitter delay time, the BMS determines that the undervoltage trip condition is met and outputs an undervoltage trip signal. In this embodiment, when the BMS determines that the voltage state value is lower than the undervoltage protection threshold, the internal logic circuit of the BMS outputs an undervoltage trigger pulse, which is a high-level signal. The BMS simultaneously starts its integrated anti-jitter delay timer, which begins timing upon receiving the undervoltage trigger pulse, with a preset timing duration of 10ms. During the anti-jitter delay timer's timing, the BMS continuously reads the voltage state value of the shunt trip coil in each sampling cycle and compares it with the undervoltage protection threshold, continuously monitoring whether the undervoltage trigger pulse disappears. If, within any sampling cycle before the 10ms timing is completed, the voltage state value rises to above or equal to the undervoltage protection threshold, the undervoltage trigger pulse disappears. The BMS determines that this voltage drop is a transient interference rather than a persistent undervoltage fault, immediately resets the anti-jitter delay timer, clears its timing value to zero, and returns to standby mode, waiting for the next undervoltage trigger pulse. If the undervoltage trigger pulse continues to exist and the voltage status value remains below the undervoltage protection threshold without ever rising when the 10ms timer completes, the BMS determines that the undervoltage trip condition is met, and its internal logic circuit outputs an undervoltage trip signal. This undervoltage trip signal is a high-level pulse signal with a duration of 20ms.

[0057] The BMS generates a control command based on the undervoltage trip signal and outputs the control command to the shunt trip coil, which energizes the coil to generate electromagnetic force to drive the molded case circuit breaker body to perform a mechanical trip action to cut off the high-voltage power supply path.

[0058] In this embodiment, after receiving an undervoltage trip signal, the BMS generates a corresponding control command through its digital output port, which is a 24Vdc drive voltage. The BMS's digital output port is electrically connected to the two ends of the shunt trip coil via a drive circuit. The control command is applied to the two ends of the shunt trip coil in the form of a 24Vdc drive voltage. After receiving the 24Vdc drive voltage, the shunt trip coil is energized, generating an electromagnetic force inside the coil. This electromagnetic force acts on the molded case circuit breaker body, driving the molded case circuit breaker body to operate instantaneously, causing the main contacts of the molded case circuit breaker body to quickly disconnect. After the main contacts disconnect, the high-voltage power supply path between the battery and the wide-input DC-DC module is completely cut off at the physical level, and the battery stops supplying high-voltage DC power to the wide-input DC-DC module. After losing high-voltage DC power, the wide-input DC-DC module stops working, and the low-voltage output bus voltage gradually drops to zero. The BMS and other downstream circuits are then de-energized, and the entire auxiliary power supply circuit stops operating, achieving over-discharge protection.

[0059] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. An auxiliary power supply circuit for an energy storage system, characterized in that, include: A battery, used to output high-voltage direct current; A physical high-voltage interruption subcircuit, electrically connected to the battery, is used to output on / off signals based on external commands and to perform high-voltage on / off control based on the on / off signals. The physical high-voltage interruption subcircuit includes a high-voltage rotary switch, a molded case shunt trip, and a fuse. The high-voltage rotary switch is connected between the battery and the wide-input DC-DC module, used to control on / off operation based on external commands and output on / off signals. The molded case shunt trip is connected between the battery and the high-voltage rotary switch, used to receive on / off signals to connect or disconnect the high-voltage power supply path connected to the battery, and also used to receive control commands and execute mechanical tripping actions to cut off the high-voltage power supply path according to the control commands. The fuse is connected between the high-voltage rotary switch and the molded case shunt trip, used to first melt and disconnect the high-voltage power supply path in the event of overcurrent or short-circuit faults. The energy storage buffer sub-circuit includes a wide-input DC-DC module and a buffer module. One end of the wide-input DC-DC module is electrically connected to the physical high-voltage interruption sub-circuit, and the other end is connected to the low-voltage output bus. It is used to receive high-voltage DC and convert it into low-voltage DC, and then output the basic supply current through the low-voltage output bus. The buffer module is connected in parallel with the low-voltage output bus and is used to monitor the real-time voltage value of the low-voltage output bus and compare it with a preset discharge activation threshold. When the real-time voltage value is less than the discharge activation threshold, the stored energy is released and a compensation supply current is output. When the real-time voltage value is greater than or equal to the discharge activation threshold, charging is performed according to the low-voltage DC. The low-voltage control sub-circuit is electrically connected to the low-voltage output bus and the physical high-voltage interruption sub-circuit, respectively. It is used to receive the basic power supply current or the total power supply current formed by the combination of the basic power supply current and the compensation power supply current on the low-voltage output bus to obtain power and maintain normal operation. At the same time, it monitors the voltage status of the physical high-voltage interruption sub-circuit and determines whether the undervoltage tripping condition is met based on the voltage status. When the undervoltage tripping condition is met, it generates a control command to control the physical high-voltage interruption sub-circuit to perform a mechanical tripping action.

2. The auxiliary power supply circuit for the energy storage system according to claim 1, characterized in that, The molded case shunt trip includes a molded case circuit breaker body and a shunt trip coil; the molded case circuit breaker body is electrically connected to the battery and the high-voltage rotary switch respectively, and is used to receive on / off signals to connect or disconnect the high-voltage power supply path; the shunt trip coil is electrically connected to the molded case circuit breaker body and the low-voltage control sub-circuit respectively, and is used to receive control commands and generate electromagnetic force to drive the molded case circuit breaker body to perform mechanical tripping action to cut off the high-voltage power supply path.

3. The auxiliary power supply circuit for the energy storage system according to claim 1, characterized in that, The buffer module includes a voltage detection unit and an electrolytic capacitor array. The voltage detection unit is electrically connected to the low-voltage output bus and the electrolytic capacitor array respectively. The voltage detection unit monitors the real-time voltage value of the low-voltage output bus and compares it with the discharge activation threshold. When the real-time voltage value is less than the discharge activation threshold, the voltage detection unit connects the low-voltage output bus and the electrolytic capacitor array, causing the electrolytic capacitor array to release the stored electrical energy, thereby outputting the compensation supply current. When the real-time voltage value is greater than or equal to the discharge activation threshold, the electrolytic capacitor array is charged according to the low-voltage DC power.

4. The auxiliary power supply circuit for the energy storage system according to claim 2, characterized in that, The low-voltage control sub-circuit includes a BMS and a contactor drive coil. The BMS is electrically connected to the low-voltage output bus and the shunt trip coil, respectively. It is used to receive the base supply current to obtain power supply and control the main power circuit to conduct. Or, when a transient impact load is generated after the main power circuit is conducted, it receives the total supply current to maintain power supply and continuously control the main power circuit to conduct. At the same time, it monitors the voltage status of the shunt trip coil in real time and determines whether the molded case circuit breaker body meets the undervoltage trip condition based on the voltage status. When the undervoltage trip condition is met, a control command is generated and output to the shunt trip coil, so that the shunt trip coil generates electromagnetic force to drive the molded case circuit breaker body to perform a mechanical trip action to cut off the high-voltage power supply path. The contactor drive coil is electrically connected to the BMS. It is used to receive the real-time voltage value of the low-voltage output bus and determine whether it is sufficient to support the contactor's engagement. If so, a transient impact load is generated to make the real-time voltage value drop below the discharge activation threshold. Otherwise, the real-time voltage value is monitored.

5. A control method for an auxiliary power supply circuit of an energy storage system, characterized in that, The method, applied to the auxiliary power supply circuit of the energy storage system as described in any one of claims 1-4, includes the following steps: Step S01: The physical high-voltage switching sub-circuit responds to external commands to control the on / off state and outputs an on / off signal. Based on the on / off signal, it connects the battery and the wide-input DC-DC module, so that the high-voltage DC power output from the battery is transmitted to the wide-input DC-DC module. Step S02: The wide-input DC-DC module receives high-voltage DC power and converts it into low-voltage DC power. It outputs the basic power supply current through the low-voltage output bus and monitors the real-time voltage value of the low-voltage output bus through the buffer module. Step S03: After receiving the base supply current, the low-voltage control subcircuit starts to work. After the low-voltage control subcircuit starts working, it generates a transient impact load, causing the real-time voltage value to drop below the discharge activation threshold. When this occurs, the buffer module releases the stored electrical energy to output a compensation supply current, which merges with the base supply current on the low-voltage output bus to form a total supply current to maintain the normal operation of the low-voltage control subcircuit. When the real-time voltage value is greater than or equal to the discharge activation threshold, the buffer module is charged by low-voltage DC power. The low-voltage control subcircuit also monitors the voltage status of the physical high-voltage disconnection subcircuit in real time. Step S04: The low-voltage control sub-circuit determines whether the undervoltage tripping condition is met based on the monitored voltage status. When the undervoltage tripping condition is met, a control command is generated and output to the physical high-voltage interruption sub-circuit to drive the physical high-voltage interruption sub-circuit to perform a mechanical tripping action.

6. The control method for the auxiliary power supply circuit of the energy storage system according to claim 5, characterized in that, The low-voltage control sub-circuit starts working after receiving the base supply current, specifically including the following steps: After the BMS receives the base power supply current and powers on, it initializes its internal parameters and reads the on / off signal output by the physical high voltage interruption sub-circuit to confirm that the high voltage power supply path between the battery and the wide input DC-DC module is in a conducting state. After the BMS receives power and maintains it for a period of time, the buffer module is in a fully charged standby state and receives the output mode enable command provided by the user. Based on the output mode enable command, it determines whether the real-time voltage value is stably maintained above the discharge activation threshold. When the real-time voltage value is stably maintained above the discharge activation threshold, the BMS determines that the output power of the wide-input DC-DC module is sufficient to support the contactor drive coil to engage. The BMS sends a pull-in command to the contactor drive coil, causing the excitation current of the contactor drive coil to rise rapidly from zero to the pull-in current value, driving the contactor drive coil to pull in and generate a transient impact load. When the real-time voltage value drops below the discharge activation threshold, the buffer module releases the stored electrical energy to output a compensation supply current, which merges with the base supply current on the low-voltage output bus to form a total supply current to maintain the main power circuit of the contactor drive coil control BMS on. The BMS confirms whether the current contactor drive coil is successfully engaged by detecting the recovery of the real-time voltage value after compensation or reading the status of the auxiliary contacts of the contactor drive coil. If the engagement is successful, the contactor drive coil is kept engaged. If the engagement fails, the fault information is recorded and the subsequent engagement process is stopped.

7. The control method for the auxiliary power supply circuit of the energy storage system according to claim 6, characterized in that, The process by which the buffer module releases stored electrical energy to compensate for the supply current includes different consecutive time periods from t0 to t4, specifically including the following steps: During the period from t0 to t1, the output power of the wide-input DC-DC module is insufficient to support the contactor drive coil to engage. The low-voltage output bus is not subjected to a large load impact. The wide-input DC-DC module operates in constant voltage mode, outputs the rated voltage value, and the buffer module is in a fully charged standby state. At time t1, the contactor drive coil instantly engages, generating a transient impact load. The output power of the wide-input DC-DC module instantly surges to the overload protection limit, while the real-time voltage value of the low-voltage output bus remains unchanged at the rated voltage value. During the period from t1 to t2, the transient impact load continued to exceed the overload protection limit of the wide input DC-DC module. The wide input DC-DC module was forced to switch from constant voltage mode to constant current limiting mode. The real-time voltage value was quickly pulled down from the rated voltage value to above the discharge activation threshold to prevent the buffer module from being falsely awakened. During the period from t2 to t3, the real-time voltage value drops below the discharge activation threshold, and the buffer module is activated. The buffer module is equivalent to a constant voltage source that clamps the real-time voltage value at the discharge activation threshold, using discharge output to compensate for the supply current. This discharge output, combined with the base supply current, causes the output power of the wide-input DC-DC module to surge, thereby preventing the wide-input DC-DC module from entering the hiccup protection dead zone. The specific steps for activating the buffer module include: When the voltage detection unit detects that the real-time voltage value is less than the discharge activation threshold, it outputs a conduction signal to connect the electrolytic capacitor array to the low-voltage output bus. The electrolytic capacitor array releases the stored electrical energy through the connection path. The buffer module is equivalent to a constant voltage source that clamps the real-time voltage value at the discharge activation threshold so that the discharge output can compensate for the supply current. The compensation supply current and the base supply current output by the wide input DC-DC module in constant current limiting mode converge on the low-voltage output bus, causing the output power of the wide input DC-DC module to jump and instantly reach the peak power. During the period from t3 to t4, the peak power is maintained until the transient impact load ends. The wide input DC-DC module automatically returns to constant voltage mode, steadily pulling the real-time voltage value back to above the discharge activation threshold. The voltage detection unit disconnects the connection path between the electrolytic capacitor array and the low-voltage output bus and performs charging.

8. The control method for the auxiliary power supply circuit of the energy storage system according to claim 7, characterized in that, The specific steps involved in forcing the wide-input DC-DC module to switch from constant voltage mode to constant current limiting mode include: The wide-input DC-DC module continuously outputs the rated voltage value in constant voltage mode, while monitoring the output current value in real time and comparing the output current value with the internally preset current limiting protection threshold. When the transient impact load generated by the contactor drive coil energizing causes the output current value to exceed the current limiting protection threshold for the first time, the wide input DC-DC module activates the overcurrent response mechanism to maintain the constant voltage mode. The output current value continues to increase and exceeds the current limiting protection threshold. The wide input DC-DC module detects that the output power can no longer keep up with the load demand. The wide input DC-DC module determines that the load has exceeded the maximum output capacity of the constant voltage mode, and begins to release the constant voltage control of the real-time voltage value, and instead forcibly limits the output current value to not exceed the current limiting protection threshold. The wide-input DC-DC module is forced to switch from constant voltage mode to constant current limiting mode. The real-time voltage value is no longer constrained by the constant voltage mode, and the real-time voltage value is rapidly pulled down from the rated voltage value as the load increases.

9. The control method for the auxiliary power supply circuit of the energy storage system according to claim 5, characterized in that, The specific steps of the low-voltage control sub-circuit to determine whether the undervoltage tripping condition is met based on the monitored voltage status include: The BMS continuously monitors the on / off signal output by the high-voltage rotary switch to obtain the current on / off status of the high-voltage power supply path; If the current on / off state is on, the BMS will collect the voltage status value of the shunt trip coil in real time and compare the voltage status value with the preset undervoltage protection threshold. When the voltage status value is lower than the undervoltage protection threshold, an undervoltage trigger pulse is output. The BMS synchronously starts an anti-jitter delay timer to receive the undervoltage trigger pulse and start timing. During the timing process, the anti-jitter delay timer continuously monitors whether the undervoltage trigger pulse disappears. If the undervoltage trigger pulse disappears before the timing is completed, the anti-jitter delay timer is reset. If the undervoltage trigger pulse continues to exist and the voltage status value continues to be lower than the undervoltage protection threshold for a duration that reaches the preset anti-jitter delay time, the BMS determines that the undervoltage trip condition is met and outputs an undervoltage trip signal. The BMS generates a control command based on the undervoltage trip signal and outputs the control command to the shunt trip coil, which energizes the coil to generate electromagnetic force to drive the molded case circuit breaker body to perform a mechanical trip action to cut off the high-voltage power supply path.

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