Energy storage device and preparation method and control method thereof

Abstract

This application provides an energy storage device and its manufacturing and control methods. The energy storage device includes an energy storage inverter, a battery module, a high-voltage box assembly, and an energy storage battery management system. The battery module and high-voltage box assembly are derived from retired battery packs. The high-voltage box assembly is electrically connected to the energy storage inverter and the battery module, forming a high-voltage power circuit. The energy storage battery management system is electrically connected to the high-voltage box assembly, the battery module, and the energy storage inverter, forming a control circuit. By fully reusing the original battery module and high-voltage box assembly from retired battery packs, the energy storage device significantly reduces the cost of energy storage retrofitting and avoids the cost and compliance risks associated with hacking the original vehicle system and disassembling and replacing hardware. With the energy storage battery management system as the control core, the complete transfer of high-voltage system control is achieved through independent high-voltage power circuits and control circuits, solving the problem of mismatch between the original vehicle control logic and the energy storage scenario.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, specifically to an energy storage device and its preparation and control methods. Background Technology

[0002] With the development of the new energy vehicle industry, a large number of power batteries are entering the retirement stage. Related technologies typically achieve secondary utilization by removing the original high-voltage system, hacking the original vehicle's BMS, or retaining the original system entirely. However, this approach faces challenges such as high modification costs, control logic incompatibility, and safety risks. Summary of the Invention

[0003] The purpose of this application is to provide an energy storage device and its preparation and control methods. The energy storage device completely reuses the original battery modules and high-voltage box components of the retired battery pack, avoiding the need to crack the original vehicle system and solving problems such as the mismatch between the original vehicle control logic and the energy storage scenario, and the high cost of modification.

[0004] In a first aspect, this application provides an energy storage device, which is formed by modifying a retired battery pack, and the energy storage device includes: Energy storage converter; The battery module is derived from the retired battery pack; The high-voltage box assembly is derived from the retired battery pack. The high-voltage box assembly is electrically connected to the energy storage converter and the battery module respectively, forming a high-voltage power circuit. An energy storage battery management system is electrically connected to the high-voltage box assembly, the battery module, and the energy storage converter, forming a control loop.

[0005] This application provides an energy storage device formed by modifying a retired battery pack. The energy storage device includes an energy storage inverter, battery modules, a high-voltage box assembly, and an energy storage battery management system. The battery modules and the high-voltage box assembly are derived from the retired battery pack. The high-voltage box assembly is electrically connected to both the energy storage inverter and the battery modules, forming a high-voltage power circuit. The energy storage battery management system is electrically connected to the high-voltage box assembly, battery modules, and energy storage inverter, forming a control circuit. By fully reusing the original battery modules and high-voltage box assembly from the retired battery pack, the energy storage device significantly reduces the cost of energy storage modification from the source, avoiding the cost and compliance risks associated with hacking the original vehicle system and disassembling and replacing hardware. Using the newly added energy storage battery management system as the control core, and through independent high-voltage power and control circuits, complete migration of high-voltage system control is achieved, solving the problem of mismatch between the original vehicle control logic and the energy storage scenario. Simultaneously, an active safety closed loop at the energy storage level is constructed, achieving all-time safety management from the cell level to the system level, balancing the dual goals of low-cost modification and high-safety operation.

[0006] The high-voltage box assembly includes a main positive contactor, a main negative contactor, and a pre-charge contactor; the energy storage battery management system includes a drive unit, which is electrically connected to the main positive contactor, the main negative contactor, and the pre-charge contactor.

[0007] The energy storage battery management system includes a multi-state machine control model, which includes: In the initialization state, the energy storage battery management system is used for initialization detection of the energy storage device; In the self-test state, the energy storage battery management system is used to perform safety assessment and testing on the energy storage device; In the pre-charge state, the energy storage battery management system is used to pre-charge the energy storage converter through the battery module; With the main circuit closed, the energy storage battery management system is used to control the closure of the high-voltage power circuit. Under normal operating conditions, the energy storage battery management system is used to monitor the status parameters of the high-voltage power circuit and control the charging and discharging power. In fault protection mode, the energy storage battery management system is used to control the high-voltage power circuit to disconnect.

[0008] The high-voltage box assembly further includes an insulation monitoring instrument and a high-voltage interlock circuit. The energy storage battery management system includes a main control unit, which is electrically connected to the insulation monitoring instrument and the high-voltage interlock circuit. The main control unit can be used to collect the insulation resistance signal of the insulation monitoring instrument and the circuit on / off signal of the high-voltage interlock circuit in real time, and determine whether to perform power limiting operation or fault protection based on the insulation resistance signal and the circuit on / off signal.

[0009] The energy storage battery management system includes a sampling unit, which can be used to collect the voltage, temperature and current of the battery module. The energy storage battery management system also includes a main control unit, which can be used to calculate the battery charging state and internal resistance based on the voltage, temperature and current of the battery module, and determine the maximum allowable power and generate a power limit command in combination with the actual operating power fed back by the energy storage converter.

[0010] The high-voltage box assembly further includes a pre-charge resistor, the energy storage converter includes a DC bus, the pre-charge resistor is electrically connected to the pre-charge contactor and the DC bus, the battery module is electrically connected to the pre-charge contactor, and the current of the battery module enters the DC bus through the pre-charge contactor and the pre-charge resistor.

[0011] The energy storage battery management system further includes a communication unit electrically connected to the energy storage converter. The communication unit is capable of receiving actual operating power feedback from the energy storage converter and sending power limiting commands. The main control unit is capable of verifying power execution deviations and dynamically correcting power limits to form a complete dynamic power closed-loop control.

[0012] Secondly, this application provides a method for preparing an energy storage device, the method comprising: Provide the battery module and high-voltage box assembly within the retired battery pack; Physically disconnect the electrical connection between the original vehicle battery management system and the high-voltage box assembly within the retired battery pack, causing the original vehicle battery management system to exit the control chain; An energy storage converter and an energy storage battery management system are provided. The high-voltage box assembly is electrically connected to the energy storage converter and the battery module respectively. The energy storage battery management system is electrically connected to the high-voltage box assembly, the battery module and the energy storage converter, so that the energy storage battery management system is added to the control chain.

[0013] Thirdly, this application provides a control method for an energy storage device, applied to the energy storage device, the control method comprising: Perform initialization testing on the energy storage device; The energy storage device was subjected to safety assessment and testing. The energy storage converter is pre-charged by the battery module; Control the closure of the high-voltage power circuit; Monitor the status parameters of the high-voltage power circuit and control the charging and discharging power. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a block diagram of the internal structure of an energy storage device provided in an embodiment of this application; Figure 2 This is a block diagram of the internal structure of a high-voltage box assembly provided in an embodiment of this application; Figure 3 This is an internal structural block diagram of an energy storage battery management system provided in an embodiment of this application; Figure 4This is a flowchart of a method for preparing an energy storage device according to an embodiment of this application; Figure 5 This is a flowchart of a control method for an energy storage device provided in an embodiment of this application; Figure 6 This is a flowchart of step S600 in a control method for an energy storage device provided in an embodiment of this application.

[0016] Label Explanation: Energy storage device 100, energy storage converter 10, battery module 20, high voltage box assembly 30, main positive contactor 31, main negative contactor 32, precharge contactor 33, insulation monitor 34, high voltage interlock circuit 35, precharge resistor 36, energy storage battery management system 40, drive unit 41, sampling unit 42, main control unit 43, communication unit 44. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0018] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0019] In this specification, for convenience, terms such as "middle," "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer" are used to indicate orientation or positional relationships in conjunction with the accompanying drawings. This is solely for the purpose of facilitating the description and simplification, and does not imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this disclosure. The positional relationships of the constituent elements may be appropriately varied depending on the orientation of the constituent elements being described. Therefore, the use of terms not limited to those described in the specification may be appropriately replaced as needed.

[0020] In this specification, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joint" shall be interpreted broadly. For example, they may refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection via an intermediate component, or a connection within two components. Those skilled in the art will understand the meaning of these terms in this disclosure as appropriate.

[0021] With the development of the new energy vehicle industry, a large number of power batteries are entering the retirement stage. Related technologies typically achieve secondary utilization by removing the original high-voltage system, hacking the original vehicle's BMS, or retaining the original system entirely. However, this approach faces challenges such as high modification costs, control logic incompatibility, and safety risks.

[0022] Please refer to Figures 1 to 3 , Figure 1 This is a block diagram of the internal structure of an energy storage device provided in an embodiment of this application. Figure 2 This is a block diagram of the internal structure of a high-voltage box assembly provided in an embodiment of this application. Figure 3 This is an internal structural block diagram of an energy storage battery management system provided in an embodiment of this application.

[0023] This application provides an energy storage device 100, which is formed by modifying a retired battery pack. The energy storage device 100 completely reuses the original battery module 20 and high-voltage box assembly 30 of the retired battery pack, avoiding the need to crack the original vehicle system and solving problems such as mismatch between the original vehicle control logic and the energy storage scenario, and high modification costs.

[0024] The energy storage device 100 includes an energy storage converter 10 (PCS), a battery module 20, a high-voltage box assembly 30, and an energy storage battery management system 40 (BMS). The battery module 20 is derived from the retired battery pack, and the high-voltage box assembly 30 is derived from the retired battery pack. The high-voltage box assembly 30 is electrically connected to the energy storage converter 10 and the battery module 20, forming a high-voltage power circuit. The energy storage battery management system 40 is electrically connected to the high-voltage box assembly 30, the battery module 20, and the energy storage converter 10, forming a control circuit.

[0025] The battery module 20 is derived from a retired battery pack used for retrofitting. It is the core energy storage carrier of the energy storage device 100 and the core reuse component for the cascade utilization of retired battery packs. It is responsible for the storage and release of electrical energy and is the energy core of the entire energy storage device 100.

[0026] The high-voltage box assembly 30 also originates from the retired battery pack used for the renovation. Together with the battery module 20, it serves as a native reuse component of the retired battery pack. It is the core hub for high-voltage power transmission in the entire energy storage device 100, and plays the role of switching on and off the high-voltage circuit and controlling power transmission. It is also the necessary high-voltage connection node between the battery module 20 and the energy storage converter 10.

[0027] The energy storage converter 10 is the core functional component of the energy storage device 100 that realizes the conversion of electrical energy form. It is responsible for the bidirectional conversion of AC and DC power, and realizes the bidirectional interaction of electrical energy between the battery module 20 and the external power grid and electrical load.

[0028] The energy storage battery management system 40 is the sole control center of the energy storage device 100. It is the control component for converting retired battery packs into dedicated energy storage devices. It undertakes the functions of operation management, status monitoring and control command issuance for the entire system, and is the core of the safe, stable and controllable operation of the energy storage device 100.

[0029] The high-voltage box assembly 30 is electrically connected to the energy storage converter 10 and the battery module 20, respectively, forming a complete closed high-voltage power circuit in series. This high-voltage power circuit is the physical channel for high-voltage power transmission during the charging and discharging process of the energy storage device 100, serving as the carrier for energy storage and release. During charging, external electrical energy is converted by the energy converter and then transmitted to the battery module 20 through the high-voltage box assembly 30 to complete energy storage. During discharging, the electrical energy stored in the battery module 20 is transmitted to the energy storage converter 10 through the high-voltage box assembly 30, converted, and then output to complete energy release.

[0030] The energy storage battery management system 40 establishes independent electrical connections with the high-voltage box assembly 30, the battery module 20, and the energy storage converter 10, forming a control loop covering the energy storage device 100. This control loop serves as the transmission channel for control signals and operational monitoring data of the energy storage device 100, and is the physical carrier for the energy storage battery management system 40 to achieve full system control. Through this control loop, the energy storage battery management system 40 collects real-time operational status data from the battery module 20, the high-voltage box assembly 30, and the energy storage converter 10. Simultaneously, based on the operational status, it issues corresponding control commands to manage the on / off state of the high-voltage power circuit, the power conversion efficiency, and the operating mode, ensuring the safe and stable operation of the entire energy storage device 100.

[0031] The battery module 20 and the high-voltage box assembly 30 of the energy storage device 100 are both derived from the retired battery pack to be modified. In other words, the original high-voltage power devices and energy storage core carrier of the retired battery pack are completely preserved. There is no need to disassemble, replace or reconstruct the original high-voltage hardware, nor is there a need to crack and adapt the original closed battery management system. This significantly reduces the material cost, labor cost and technical adaptation cost of the retired battery energy storage modification from the hardware source.

[0032] The high-voltage power circuit uses the original high-voltage box assembly 30 as the high-voltage hub, connected in series between the energy storage inverter 10 and the battery module 20, and is the only physical channel for the charging and discharging power transmission of the entire energy storage device 100. The high-voltage box assembly 30 directly determines the on / off state and operating status of the high-voltage circuit. The control circuit uses the newly added energy storage battery management system 40 as the control core, and establishes independent electrical connections with the high-voltage box assembly 30, the battery module 20, and the energy storage inverter 10, forming a control link covering the energy storage device 100. Through the control circuit, the energy storage battery management system 40 completely replaces the original vehicle battery management system, directly taking over the core drive control authority of the high-voltage box assembly 30, becoming the sole control entity of the energy storage device 100, fully realizing the core design of control transfer, and solving problems such as the mismatch between control logic and energy storage scenario, and the inability of operating strategies to adapt to the degradation characteristics of tiered batteries caused by reusing the original vehicle battery management system in related technologies.

[0033] Furthermore, the energy storage battery management system 40 of this application, through a fully covered control loop, can collect the operating status of the battery module 20, the working status of the high-voltage box assembly 30, and the operating data of the energy storage converter 10 in real time, forming a complete safety closed loop of status acquisition, logical decision-making, command issuance, and execution feedback; at the same time, relying on the control authority of the high-voltage box assembly 30 directly under its control, it can quickly cut off the high-voltage power circuit in abnormal conditions, realize rapid safety protection of the entire system, and construct a full-link energy storage safety protection system from the cell level to the system level, solving problems such as the lack of safety closed loop, delayed protection response, and insufficient safety level for energy storage scenarios.

[0034] This application provides an energy storage device 100, which is formed by modifying a retired battery pack. The energy storage device 100 includes an energy storage inverter 10, a battery module 20, a high-voltage box assembly 30, and an energy storage battery management system 40. The battery module 20 and the high-voltage box assembly 30 are derived from the retired battery pack. The high-voltage box assembly 30 is electrically connected to the energy storage inverter 10 and the battery module 20, forming a high-voltage power circuit. The energy storage battery management system 40 is electrically connected to the high-voltage box assembly 30, the battery module 20, and the energy storage inverter 10, forming a control circuit. By fully reusing the original battery module 20 and the high-voltage box assembly 30 from the retired battery pack, the energy storage device 100 significantly reduces the cost of energy storage modification from the source, avoiding the cost and compliance risks associated with hacking the original vehicle system and disassembling and replacing hardware. With the newly added energy storage battery management system 40 as the control core, the complete transfer of high-voltage system control is achieved through the independent high-voltage power circuit and control circuit, solving the problem of mismatch between the original vehicle control logic and the energy storage scenario. At the same time, an active safety closed loop at the energy storage level is constructed to achieve all-time safety management from the cell level to the system level, taking into account both low-cost retrofitting and high-safety operation.

[0035] Please refer to Figures 1 to 3 In one embodiment, the high-voltage box assembly 30 includes a main positive contactor 31, a main negative contactor 32, and a pre-charge contactor 33; the energy storage battery management system 40 includes a drive unit 41, which is electrically connected to the main positive contactor 31, the main negative contactor 32, and the pre-charge contactor 33 respectively.

[0036] The main positive contactor 31, the main negative contactor 32, and the pre-charge contactor 33 are all high-voltage switching devices that are integrated into the high-voltage box assembly 30 of the original vehicle of the retired battery pack. The main positive contactor 31 and the main negative contactor 32 are the actuators for switching the high-voltage power circuit on and off, and the pre-charge contactor 33 is the actuator for the pre-charge process.

[0037] The drive unit 41 is a built-in functional unit of the energy storage battery management system 40. It is the output port of the high-voltage control command and is specifically used to convert the control logic of the energy storage battery management system 40 into the opening and closing action of the contactor. It is the execution unit for realizing high-voltage control.

[0038] In this embodiment, the drive unit 41 of the energy storage battery management system 40 establishes independent electrical connections with each of the three contactors, forming a dedicated drive control link. This design replaces the original drive connection between the original vehicle battery management system and the contactors, making the energy storage battery management system 40 the sole control entity capable of controlling the opening and closing actions of the contactors, thus fully realizing the transfer of control over the high-voltage system.

[0039] This implementation method does not require disassembling or replacing the contactor hardware in the original vehicle's high-voltage box. Control can be taken over simply by modifying the drive link, thus reducing modification costs from the source. At the same time, through point-to-point direct drive, it achieves precise and rapid control of pre-charging, main circuit switching, and emergency tripping in case of fault, thus achieving the dual goals of low cost and high safety.

[0040] Please refer to Figures 1 to 3 In one embodiment, the energy storage battery management system 40 includes a multi-state machine control model. Setting up a multi-state machine control model in the energy storage battery management system 40 can provide a standardized, controllable, and highly secure full-process operation mechanism for the energy storage system after the retirement battery pack is upgraded.

[0041] The multi-state machine control model includes initialization state, self-test state, pre-charge state, main circuit closed state, normal operation state, and fault protection state. Each state is switched in an orderly manner according to fixed logic to ensure that the system can only enter the next stage when the safety conditions are met, so as to achieve stable and reliable operation of the energy storage level.

[0042] In the initialization state, the energy storage battery management system 40 is used to perform initialization detection on the energy storage device 100.

[0043] This state is the first startup phase after the energy storage device 100 is powered on. The main body of execution is the energy storage battery management system 40. The core is to perform initialization detection on the entire system of the energy storage device 100, complete its own hardware and software reset, establish control communication links with the high-voltage box assembly 30, the battery module 20, and the energy storage converter 10, confirm that the new control link after the transfer of control is complete and usable, establish a basic control channel for subsequent full-process safety management, completely replace the power-on initialization function of the original vehicle battery management system, and adapt to the exclusive control logic of the energy storage scenario.

[0044] In the self-test state, the energy storage battery management system 40 is used to perform safety assessment and testing on the energy storage device 100.

[0045] This state is a mandatory safety verification step before high-voltage power-on. The main body for execution is the energy storage battery management system 40. Its core function is to perform safety judgment and detection on the entire system of the energy storage device 100, and to comprehensively verify the basic safety status of the battery module 20, the high-voltage box assembly 30, the energy storage converter 10 and the high-voltage power circuit. Only when all test items meet the safety requirements of the energy storage scenario are they allowed to enter the next state, thus avoiding the risk of powering on with faults from the source and building an energy storage-level safety barrier.

[0046] In the pre-charge state, the energy storage battery management system 40 is used to pre-charge the energy storage inverter 10 through the battery module 20.

[0047] This state is the surge protection step before high-voltage power-on. The main body for execution is the energy storage battery management system 40. Its core function is to pre-charge the energy storage converter 10 through the battery module 20, eliminate the voltage difference between the battery module 20 and the DC side of the energy storage converter 10, and avoid the large current surge generated when the main circuit is closed, which could damage the high-voltage power devices retained by the original vehicle. This not only protects the reused original vehicle hardware and extends the service life of the retired battery, but also ensures the safety of high-voltage power-on.

[0048] In the main circuit closed state, the energy storage battery management system 40 is used to control the closure of the high-voltage power circuit.

[0049] This stage represents the implementation phase of the control transfer architecture. The executing entity is the energy storage battery management system 40. Its core function is to control the safe closure of the high-voltage power circuit, ensuring the energy storage device 100 is ready for charging and discharging operations, provided that pre-charging is complete and there are no safety risks. In this stage, the energy storage battery management system 40 completely replaces the high-voltage control authority of the original vehicle battery management system, becoming the sole entity capable of controlling the on / off state of the high-voltage power circuit, thus fully realizing the transfer of control over the high-voltage system.

[0050] In the normal operating state, the energy storage battery management system 40 is used to monitor the status parameters of the high-voltage power circuit and control the charging and discharging power.

[0051] This state represents the working state of the energy storage device 100. The executing entity is the energy storage battery management system 40. Its core function is to monitor all status parameters of the high-voltage power circuit in real time, and to manage the charging and discharging power of the energy storage device 100 based on the health characteristics of the retired battery. This enables core functions such as grid connection, peak-valley arbitrage, and backup power in energy storage scenarios. It solves the problem of mismatch between the original vehicle battery management system's on-board charging and discharging logic and the long-cycle, high-power cyclic operating conditions of energy storage scenarios, allowing retired power batteries to perfectly adapt to the operational needs of energy storage scenarios.

[0052] In the fault protection state, the energy storage battery management system 40 is used to control the high-voltage power circuit to disconnect.

[0053] This state is the safety protection link of the energy storage device 100. The main body for execution is the energy storage battery management system 40. Its core function is to immediately control the high-voltage power circuit to disconnect and terminate the charging and discharging operation when the system abnormality is detected or the safe operating conditions are not met. This achieves hardware-level safety protection, builds an energy storage-level fault safety closed loop, avoids the safety risks of the original vehicle battery management system's fault protection logic being incompatible with the energy storage grid connection scenario, and ensures the high safety operation of the retired power battery after energy storage modification.

[0054] In one implementation, the multi-state machine control model further includes a power-limited operating state.

[0055] The power-limited operation state is a transitional buffer state between the normal operation state and the fault protection state. The control and decision-making entity is still the energy storage battery management system 40. It is an extension of the control transfer architecture and does not rely on any function of the original vehicle battery management system throughout the process.

[0056] Retired batteries, after long-term use, suffer from capacity decay, decreased consistency, and narrowed safety margins. Direct fault tripping can easily cause overstress damage to the batteries, and frequent start-stop cycles can shorten their service life. Energy storage grid-connected scenarios have strict requirements for equipment operational continuity; direct shutdowns under non-emergency faults can affect grid stability and even violate grid-connection compliance requirements. Adding the aforementioned power-limited operating state enables tiered safety management under non-emergency anomalies, balancing equipment safety, battery life, and grid-connected operational continuity.

[0057] Specifically, in the initialization state, after the system is powered on, it performs basic tests, including: battery voltage detection, temperature detection, communication detection of the energy storage battery management system 40, communication detection of the energy storage converter 10, high voltage interlock circuit 35 (HVIL) detection, and insulation monitoring instrument 34 (IMD) detection. When all test results meet the safety conditions, the system enters the self-test state. In the self-test state, the energy storage battery management system 40 further performs safety judgments, including: determining whether the state of charge of the battery module 20 is within the safe range (10%–90%), determining whether the temperature of the battery module 20 is within the allowable range (-20℃~55℃), and determining whether the insulation resistance is greater than the safety threshold. If the detection is normal, it enters the pre-charge state.

[0058] Please refer to Figures 1 to 3In one embodiment, the high-voltage box assembly 30 further includes an insulation monitor 34 and a high-voltage interlock circuit 35. The energy storage battery management system 40 includes a main control unit 43, which is electrically connected to the insulation monitor 34 and the high-voltage interlock circuit 35 respectively. The main control unit 43 can be used to collect the insulation resistance signal of the insulation monitor 34 and the circuit on / off signal of the high-voltage interlock circuit 35 in real time, and determine whether to perform power limiting operation or fault protection based on the insulation resistance signal and the circuit on / off signal.

[0059] The insulation monitoring device 34 and the high-voltage interlock circuit 35 are both original safety devices of the high-voltage box assembly 30 of the retired battery pack. They eliminate the need for disassembly, replacement, or addition of safety monitoring hardware, reducing modification costs at the source and avoiding the process and compliance risks associated with hardware reconstruction. Specifically, the insulation monitoring device 34 monitors the insulation status of the high-voltage system to ground, preventing leakage and electric shock risks; the high-voltage interlock circuit 35 monitors the closure integrity of the high-voltage connectors throughout the system, preventing high-voltage exposure risks caused by connector detachment or opening of the box. Both are fundamental components for high-voltage system safety protection.

[0060] The main control unit 43 is the safety decision-making center of the energy storage battery management system 40. The main control unit 43 can replace the safety control function of the original vehicle battery management system and is specifically adapted to the safety requirements of energy storage scenarios.

[0061] The main control unit 43 establishes direct and independent electrical connections with the insulation monitoring instrument 34 and the high-voltage interlock circuit 35, respectively, physically replacing the original connection links between the original vehicle battery management system and the above two safety devices. This makes the main control unit 43 the only entity that can directly obtain safety monitoring signals and execute safety decisions, thus fully realizing the risk-free migration of high-voltage safety control authority from the original vehicle system to the newly added energy storage battery management system 40.

[0062] The main control unit 43 is electrically connected to the insulation monitoring instrument 34 and the high-voltage interlock circuit 35 respectively. The direct point-to-point connection eliminates the risks of delay, distortion and failure caused by signal relay, ensures zero-delay transmission of safety signals, meets the requirement of emergency safety response within 20ms in energy storage scenarios, and solves the problem of mismatch between the safety logic of the original vehicle battery management system and the energy storage scenario, and the inability to adapt to battery degradation characteristics.

[0063] The main control unit 43 performs a two-dimensional comprehensive judgment on the safety status of the high-voltage system based on two independent safety signals, and constructs a dual safety closed loop of insulation monitoring and high-voltage interlocking to avoid safety protection failure caused by a single signal fault and greatly improve the system's safety redundancy.

[0064] Furthermore, the main control unit 43 can continuously collect the insulation resistance signal output by the insulation monitor 34 and the circuit on / off signal output by the high-voltage interlock circuit 35, realizing all-time safety monitoring and adapting to the scenario requirements of the energy storage device 100 for long-term grid-connected operation.

[0065] Specifically, in the pre-charge state, the energy storage battery management system 40 controls the pre-charge contactor 33 to close, charging the DC bus of the energy storage converter 10 through the pre-charge resistor 36. When the DC bus voltage of the energy storage converter 10 is detected to satisfy: Vdc ≥ 0.9 × Vbattery, the system enters the main circuit closed state.

[0066] Please refer to Figures 1 to 3 In one embodiment, the high-voltage box assembly 30 further includes a pre-charge resistor 36, the energy storage converter 10 includes a DC bus, the pre-charge resistor 36 is electrically connected to the pre-charge contactor 33 and the DC bus, the battery module 20 is electrically connected to the pre-charge contactor 33, and the current of the battery module 20 enters the DC bus through the pre-charge contactor 33 and the pre-charge resistor 36.

[0067] In the pre-charge state, the energy storage battery management system 40 directly controls the pre-charge contactor 33 in the original vehicle's high-voltage box assembly 30 to close via its built-in drive unit 41, connecting the pre-charge circuit and charging the DC bus of the energy storage converter 10 through the original vehicle's matching pre-charge resistor 36. This action does not require modification or disassembly of the hardware in the original vehicle's high-voltage box; it can be achieved simply by taking over the drive authority.

[0068] The energy storage converter 10 has a large-capacity bus capacitor on its DC side. Initially, the capacitor voltage is 0. If the high-voltage main circuit is directly closed, the battery module 20 will create a near-short-circuit impact on the 0-voltage capacitor, generating a surge of current tens of times the rated current. This can easily damage the original vehicle's reused contactors, fuses, and battery cells. The core function of the pre-charging process is to limit the charging current through the pre-charging resistor 36, pre-charging the DC bus capacitor to a voltage close to that of the battery module 20, eliminating voltage differences, mitigating the risk of a closing impact at the source, protecting the original vehicle's reused hardware, and extending the lifespan of the battery module 20.

[0069] This application clarifies the sole quantitative criterion for determining whether pre-charging is complete and the main circuit is in a closed state: the DC bus voltage Vdc of the energy storage converter 10 ≥ 0.9 × the total voltage Vbattery of the battery module 20. This threshold setting ensures that the voltage difference between the DC bus and the battery module 20 is sufficiently small, and that the closing inrush current is controlled within the rated tolerance range of the original vehicle components, thus guaranteeing high-voltage power-on safety.

[0070] Specifically, in the main circuit closed state, the energy storage battery management system 40 sequentially executes closing the main negative contactor 32, closing the main positive contactor 31, and opening the pre-charge contactor 33, and the system enters the normal operation state.

[0071] Specifically, in the normal operating state, the energy storage battery management system 40 monitors the voltage, current, temperature, state of charge, insulation resistance signal, and circuit on / off signal of the battery module 20 in real time, and controls the charging and discharging power according to the power limiting command.

[0072] The energy storage battery management system 40 monitors the battery status and system safety status in all dimensions. It precisely controls the charging and discharging power of the energy storage device 100 through power limiting commands. This not only realizes the core functions of energy storage scenarios such as peak-valley arbitrage, grid voltage regulation, and emergency backup power, but also ensures that retired batteries always operate within the safety boundary through dynamic power constraints, avoiding abnormal operating conditions such as overcharging, over-discharging, and over-temperature, and extending the cascade utilization life of retired batteries.

[0073] Please refer to Figures 1 to 3 In one embodiment, the energy storage battery management system 40 includes a sampling unit 42, which can be used to collect the voltage, temperature and current of the battery module 20. The energy storage battery management system 40 includes a main control unit 43, which can be used to calculate the battery charging state and internal resistance based on the voltage, temperature and current of the battery module 20, and determine the maximum allowable power and generate a power limit command in combination with the actual operating power fed back by the energy storage converter 10.

[0074] Please refer to Figures 1 to 3 In one embodiment, the energy storage battery management system 40 further includes a communication unit 44, which is electrically connected to the energy storage converter 10. The communication unit 44 can receive the actual operating power feedback of the energy storage converter 10 and send the power limiting command. The main control unit 43 can verify the power execution deviation and dynamically correct the power limit to form a complete dynamic power closed-loop control, ensuring the accuracy of power control and adapting to the grid compliance requirements of energy storage grid connection.

[0075] It should be noted that the energy storage battery management system 40 calculates the maximum allowable power of the system based on the following parameters: Pmax = min(Psoc, Ptemp, Pvolt, Pres), where Psoc is the SOC-limited power, Ptemp is the temperature-limited power, Pvolt is the voltage-limited power, and Pres is the battery internal resistance-limited power. The final output power of the system is: Pcmd = min(Pmax, Ppcs), where Ppcs is the allowable power of the energy storage converter 10. This algorithm can dynamically adjust the system power according to the health status of the battery module 20, ensuring the long-term safe operation of the system.

[0076] Specifically, in the fault protection state, when the following conditions occur: battery overvoltage, battery overcurrent, battery overtemperature, IMD insulation fault, HVIL disconnection, or PCS communication abnormality, the energy storage battery management system 40 immediately executes: disconnecting the main contactor, stopping power output, and the system entering a safe shutdown state.

[0077] Please refer to Figures 1 to 4 , Figure 4 This is a flowchart of a method for preparing an energy storage device according to an embodiment of this application.

[0078] This application also provides a method for manufacturing an energy storage device 100. The method for manufacturing the energy storage device 100 includes steps S10, S20 and S30. A detailed description of steps S10, S20 and S30 is as follows.

[0079] S10: Provide the battery module 20 and high-voltage box assembly 30 within the retired battery pack.

[0080] The battery module 20 and the high-voltage box assembly 30, which are originally matched with the retired battery pack, are directly used. The original vehicle's complete high-voltage hardware structure is preserved. There is no need to disassemble or replace the high-voltage power devices. The existing mature hardware is used as the energy carrier and high-voltage transmission hub of the energy storage device 100, thereby reducing the transformation cost from the source.

[0081] S20: Physically disconnect the electrical connection between the original vehicle battery management system in the retired battery pack and the high-voltage box assembly 30, so that the original vehicle battery management system exits the control chain.

[0082] Step S20 is the control transfer step. By physically disconnecting the electrical connection between the original vehicle battery management system and the high-voltage box assembly 30, the original vehicle BMS directly releases the control authority of the contactors and safety monitoring devices in the high-voltage box assembly 30, so that the original vehicle battery management system completely withdraws from the overall control chain and no longer participates in the high-voltage circuit management, thus completely avoiding the defect of mismatch between the original vehicle on-board control logic and the energy storage operation scenario.

[0083] S30: Provide an energy storage converter 10 and an energy storage battery management system 40, electrically connect the high-voltage box assembly 30 to the energy storage converter 10 and the battery module 20 respectively, and electrically connect the energy storage battery management system 40 to the high-voltage box assembly 30, the battery module 20 and the energy storage converter 10, so that the energy storage battery management system 40 is added to the control chain.

[0084] Step S30 completes the adaptation of new components and the construction of a new control architecture, configuring the energy storage converter 10 and the energy storage battery management system 40; on the one hand, the high-voltage box assembly 30 is connected to the battery module 20 and the energy storage converter 10 respectively to build a complete high-voltage power circuit and realize bidirectional power transmission; on the other hand, the energy storage battery management system 40 is connected to the high-voltage box assembly 30, the battery module 20 and the energy storage converter 10 to construct an independent control circuit, so that the energy storage battery management system 40 fully takes over the authority of equipment monitoring, high-voltage control, power regulation and fault protection, newly joins and dominates the control chain, forming a safe closed-loop control system adapted to energy storage conditions, and completing the compliant transformation of retired battery packs to the energy storage device 100.

[0085] Please refer to Figures 1 to 5 , Figure 5 This is a flowchart of a control method for an energy storage device provided in an embodiment of this application.

[0086] This application also provides a control method for an energy storage device 100, which is applied to the energy storage device 100. The control method for the energy storage device 100 includes steps S100, S200, S300, S400 and S500. A detailed description of steps S100, S200, S300, S400 and S500 is as follows.

[0087] S100: Perform initialization testing on the energy storage device 100.

[0088] This step is the first startup stage after the energy storage device 100 is powered on at low voltage, corresponding to the initialization state of the multi-state machine control model.

[0089] The energy storage battery management system 40 first completes its own hardware and software reset, and the power-on initialization of the internal sampling unit 42, drive unit 41, communication unit 44, and main control unit 43; then it establishes communication with the high-voltage box assembly 30, battery module 20, and energy storage converter 10 one by one to verify the integrity and availability of the entire system control link; finally, it completes the energy storage scenario-specific parameter configuration of each component and establishes basic operating conditions.

[0090] Understandably, the energy storage battery management system 40 completely replaces the power-on initialization function of the original vehicle battery management system, confirming that the original vehicle battery management system has completely exited the control chain, and the newly added energy storage battery management system 40 becomes the only control entity in the entire system that can issue commands and receive feedback.

[0091] If all initialization tests pass, the process can proceed to step S200; if any test fails, the startup process will be terminated directly, triggering a fault message to prevent startup with a fault.

[0092] S200: Perform a safety assessment and test on the energy storage device 100.

[0093] This step is a mandatory safety verification process before high-voltage power-on, corresponding to the self-check state of the multi-state machine control model.

[0094] The energy storage battery management system 40 performs multi-dimensional safety judgment and detection on the entire system, including: collecting the cell voltage, temperature and current of the battery module 20 to determine whether the battery body is within the safe operating range; collecting the insulation resistance signal of the insulation monitoring instrument 34 in the high-voltage box assembly 30, the on / off signal of the high-voltage interlock circuit 35 and the status of the contactor auxiliary contacts to confirm that there are no abnormalities in the high-voltage safety circuit; and verifying the operating status of the energy storage converter 10 to confirm that the equipment is fault-free and in a standby and working state.

[0095] Understandably, the safety assessment and testing of the energy storage device 100 completely replaces the vehicle self-test logic of the original vehicle battery management system, solving the problem of mismatch between the original vehicle self-test rules and the safety requirements of the energy storage grid connection scenario; at the same time, the safety monitoring devices of the original vehicle high-voltage box are reused throughout the process, without the need for additional hardware.

[0096] If all safety criteria are met, the process can proceed to step S300; if any criterion is not met, the process will be prohibited from proceeding to the subsequent high-voltage power-on stage and will directly trigger the fault protection.

[0097] S300: The energy storage converter 10 is pre-charged by the battery module 20.

[0098] This step is an anti-impact protection step before high-voltage power-on, corresponding to the pre-charge state of the multi-state machine control model. It can protect the original vehicle's reusable hardware and extend the lifespan of retired batteries.

[0099] The energy storage battery management system 40 controls the pre-charge contactor 33 in the high-voltage box assembly 30 to close via the built-in drive unit 41, while the main positive contactor 31 and the main negative contactor 32 remain open, connecting the pre-charge circuit of the battery module 20, the pre-charge contactor 33, the pre-charge resistor 36, and the DC bus of the energy storage converter 10; it also collects the total voltage of the battery module 20 and the DC bus voltage of the energy storage converter 10 in real time, and determines that the pre-charge is complete when the DC bus voltage reaches 90% or more of the total voltage of the battery module 20.

[0100] Understandably, by pre-charging the energy storage converter 10 through the battery module 20, the risk of high current surge during main circuit closing can be eliminated at the source, protecting high-voltage components such as contactors and fuses reused in the original vehicle. The pre-charging contactor 33 and pre-charging resistor 36 in the original vehicle's high-voltage box are reused throughout the process, without the need for hardware disassembly and modification. The pre-charging process is achieved only through the control takeover of the energy storage battery management system 40, which aligns with the goal of low-cost retrofitting.

[0101] Once pre-charging is complete, proceed to step S400; if pre-charging times out or voltage is abnormal, immediately disconnect the pre-charging contactor 33, terminate the process, and trigger fault protection.

[0102] S400: Controls the closure of the high-voltage power circuit.

[0103] This step corresponds to the main loop closure state of the multi-state machine control model, formally completing the safe high-voltage power-on of the energy storage device 100.

[0104] The energy storage battery management system 40, according to a safe sequence, first controls the main negative contactor 32 in the high-voltage box assembly 30 to close, and then controls the main positive contactor 31 to close, connecting the high-voltage power main circuit of the battery module 20, the high-voltage box assembly 30, and the energy storage converter 10; after confirming that the main circuit has been closed normally through the feedback of the contactor auxiliary contacts, it disconnects the pre-charge contactor 33 and exits the pre-charge circuit.

[0105] Understandably, the energy storage battery management system 40 completely replaces the original vehicle battery management system's control authority over the high-voltage main circuit. The energy storage battery management system 40 becomes the only entity capable of controlling the on / off state of the high-voltage circuit, thus achieving a risk-free migration of high-voltage system control from the original vehicle system to the newly added energy storage battery management system 40. The main circuit contactor of the original vehicle's high-voltage box is reused throughout the process, requiring no hardware modifications and achieving low-cost retrofitting.

[0106] If the main circuit closes normally without any abnormalities, proceed to step S500; if the contactor fails to close normally or an abnormality occurs in the circuit, immediately disconnect all high-voltage contactors, cut off the high-voltage circuit, and trigger fault protection.

[0107] S500: Monitors the status parameters of the high-voltage power circuit and controls the charging and discharging power.

[0108] This step represents the working stage of the energy storage device 100, corresponding to the normal operation state of the multi-state machine control model.

[0109] The energy storage battery management system 40 monitors the status parameters of the high-voltage power circuit in real time, including the voltage, current, temperature, state of charge, insulation resistance signal, and on / off signal of the high-voltage interlock circuit 35 of the battery module 20. Based on the real-time operating status of the battery module 20 and the hardware operating capabilities of the energy storage converter 10, it dynamically calculates the maximum allowable power and generates a power limit command, which is sent to the energy storage converter 10 for charge and discharge control. At the same time, it receives the actual operating power feedback of the energy storage converter 10, verifies the execution deviation, and dynamically corrects the power limit to form a complete dynamic power closed-loop control.

[0110] Understandably, monitoring the state parameters of the high-voltage power circuit and controlling the charging and discharging power can replace the vehicle charging and discharging control logic of the original vehicle battery management system, solving the problem of mismatch between the original vehicle control logic and the long-cycle, high-power cyclic operating conditions of energy storage scenarios; at the same time, it adapts to the safety boundary after the degradation of retired batteries, and ensures that the battery always operates within the safe range through dynamic power management, thus extending the cascade utilization life of the battery module 20.

[0111] Please refer to Figure 6 , Figure 6 This is a flowchart of step S600 in a control method for an energy storage device provided in an embodiment of this application.

[0112] The control method for the energy storage device 100 further includes step S600, which is described in detail below.

[0113] S600: When a preset signal is abnormal, power limiting operation or fault protection is performed, wherein the preset signal includes voltage signal, current signal, temperature signal, insulation resistance signal, and circuit on / off signal.

[0114] The voltage signal, collected by the sampling unit 42, covers the individual cell voltage and total voltage of the battery module 20, as well as the DC bus voltage of the energy storage converter 10. It serves as an indicator for determining battery overcharging, over-discharging, and abnormal circuit voltage. The current signal, collected by the current sensor within the high-voltage box assembly 30 and received by the main control unit 43 of the energy storage battery management system 40, covers the real-time charging and discharging current of the high-voltage circuit. It serves as an indicator for determining circuit overcurrent and short-circuit faults. The temperature signal, collected by the sampling unit 42, covers the cell temperature and module temperature of the battery module 20. It serves as an indicator for determining the risk of battery overheating and thermal runaway. The insulation resistance signal, collected by the insulation monitoring instrument 34, is directly transmitted to the main control unit 43 of the energy storage battery management system 40. It serves as an indicator for determining the risk of high-voltage system leakage and insulation failure. The circuit on / off signal is collected by the high-voltage interlock circuit 35 in the high-voltage box assembly 30 and directly transmitted to the main control unit 43 of the energy storage battery management system 40. It is an indicator for determining the risk of high-voltage connector loosening, box opening, and high-voltage exposure.

[0115] It should be noted that this step is not limited to the normal operation phase of S500, but rather extends throughout the entire lifecycle of the energy storage device 100 from S100 initialization to S500 normal operation, achieving all-weather, comprehensive safety management. The triggering rules are as follows: Initialization, self-test, pre-charge, and main circuit closing phase (S100-S400): If any preset signal is abnormal, the fault protection will be directly triggered to terminate the startup process and prevent high-voltage power-on with a fault. Normal operation phase (S500): Based on the severity of the abnormality of the preset signal, power limiting operation or fault protection is implemented in stages to take into account equipment safety, battery life and grid connection continuity.

[0116] This step involves differentiated and graded handling based on the severity of the anomaly, with the entire process being independently decided and executed by the energy storage battery management system 40.

[0117] The first level is power-limited operation handling. The triggering conditions are: the preset signal exceeds the normal operating range, but does not reach the emergency fault threshold, such as the battery temperature slightly exceeding the standard, the insulation resistance slightly decreasing, the voltage and current approaching the safety limit but not exceeding it, and the high-voltage interlock circuit 35 not being completely disconnected but only having poor contact, etc., which are non-emergency conditions.

[0118] The energy storage battery management system 40 dynamically lowers the upper limit of charging and discharging power, generates graded power limit commands and sends them to the energy storage converter 10, bringing the system operating conditions back to the safe boundary; at the same time, it continuously monitors the changing trend of abnormal signals at high frequency, keeps the high-voltage power circuit closed throughout, and does not interrupt the basic operation of the equipment. If the abnormal signal returns to the normal range and remains stable for a preset time, the system switches back to normal operation; if the abnormality continues to worsen and reaches the emergency fault threshold, it immediately switches to fault protection handling.

[0119] The second level is fault protection handling. Triggering conditions: A preset signal exceeds the safety critical threshold, reaching the emergency fault level, such as severe overcharging or over-discharging of the cell voltage, short circuit overcurrent in the circuit, severely excessive battery temperature, insulation resistance below the safety critical value, or complete disconnection of the high-voltage interlock circuit 35. Among these, the complete disconnection of the high-voltage interlock circuit 35 is the highest priority fault, with no buffer delay, and this handling is triggered immediately.

[0120] The energy storage battery management system 40 executes the highest priority emergency protection, simultaneously issuing a full disconnect command to the main positive contactor 31, main negative contactor 32, and pre-charge contactor 33 to the high-voltage box assembly 30, immediately cutting off the high-voltage power circuit; at the same time, it issues a shutdown lockout command to the energy storage converter 10, stopping all power output, realizing hardware-level safety backup, and preventing the expansion of safety risks.

[0121] By implementing graded management, we can prevent degraded batteries from being subjected to excessive stress and shocks, reduce unnecessary high-voltage start-stop cycles, and effectively extend the cascade utilization life of retired batteries.

[0122] This application provides illustrative examples of the operating parameters of some devices, which should not be construed as limiting the scope of this application.

[0123] The rated power range of the energy storage converter 10 is 100kW~500kW, the DC bus voltage range is 500V~1000V, and the maximum DC current of the energy storage converter 10 is ≤500A.

[0124] The insulation monitoring instrument 34 has a detection range of 0~10MΩ, a detection accuracy of ≤±5%, and a response time of ≤1s.

[0125] The rated voltage of the high-voltage interlock circuit 35 is ≤60V, the loop resistance of the high-voltage interlock circuit 35 is ≤1Ω, and the detection method of the high-voltage interlock circuit 35 is closed-loop continuous detection.

[0126] In this application, the terms "embodiment" and "implementation" mean that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of these phrases in various locations throughout the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this application can be combined with other embodiments. Furthermore, it should be understood that the features, structures, or characteristics described in the various embodiments of this application can be arbitrarily combined to form yet another embodiment that does not depart from the spirit and scope of the technical solution of this application, provided there is no contradiction between them.

[0127] The above description represents some embodiments of this application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

Claims

1. An energy storage device, characterized in that, The energy storage device is formed by modifying retired battery packs, and the energy storage device includes: Energy storage converter; The battery module is derived from the retired battery pack; The high-voltage box assembly is derived from the retired battery pack. The high-voltage box assembly is electrically connected to the energy storage converter and the battery module respectively, forming a high-voltage power circuit. An energy storage battery management system is electrically connected to the high-voltage box assembly, the battery module, and the energy storage converter, forming a control loop.

2. The energy storage device according to claim 1, characterized in that, The high-voltage box assembly includes a main positive contactor, a main negative contactor, and a pre-charge contactor; the energy storage battery management system includes a drive unit, which is electrically connected to the main positive contactor, the main negative contactor, and the pre-charge contactor respectively.

3. The energy storage device according to claim 1, characterized in that, The energy storage battery management system includes a multi-state machine control model, which includes: In the initialization state, the energy storage battery management system is used for initialization detection of the energy storage device; In the self-test state, the energy storage battery management system is used to perform safety assessment and testing on the energy storage device; In the pre-charge state, the energy storage battery management system is used to pre-charge the energy storage converter through the battery module; With the main circuit closed, the energy storage battery management system is used to control the closure of the high-voltage power circuit. Under normal operating conditions, the energy storage battery management system is used to monitor the status parameters of the high-voltage power circuit and control the charging and discharging power. In fault protection mode, the energy storage battery management system is used to control the high-voltage power circuit to disconnect.

4. The energy storage device according to claim 1, characterized in that, The high-voltage box assembly also includes an insulation monitor and a high-voltage interlock circuit. The energy storage battery management system includes a main control unit, which is electrically connected to the insulation monitor and the high-voltage interlock circuit respectively. The main control unit can be used to collect the insulation resistance signal of the insulation monitor and the circuit on / off signal of the high-voltage interlock circuit in real time, and determine whether to perform power limiting operation or fault protection based on the insulation resistance signal and the circuit on / off signal.

5. The energy storage device according to claim 1, characterized in that, The energy storage battery management system includes a sampling unit, which can be used to collect the voltage, temperature and current of the battery module. The energy storage battery management system also includes a main control unit, which can be used to calculate the battery charging state and internal resistance based on the voltage, temperature and current of the battery module, and determine the maximum allowable power and generate a power limit command by combining the actual operating power fed back by the energy storage converter.

6. The energy storage device according to claim 2, characterized in that, The high-voltage box assembly also includes a pre-charge resistor, the energy storage converter includes a DC bus, the pre-charge resistor is electrically connected to the pre-charge contactor and the DC bus respectively, the battery module is electrically connected to the pre-charge contactor, and the current of the battery module enters the DC bus through the pre-charge contactor and the pre-charge resistor.

7. The energy storage device according to claim 5, characterized in that, The energy storage battery management system also includes a communication unit, which is electrically connected to the energy storage converter. The communication unit can receive the actual operating power feedback of the energy storage converter and send the power limiting command. The main control unit can verify the power execution deviation and dynamically correct the power limit to form a complete dynamic power closed-loop control.

8. A method for preparing an energy storage device, characterized in that, The method for preparing the energy storage device according to any one of claims 1-7 comprises: Provide the battery module and high-voltage box assembly within the retired battery pack; Physically disconnect the electrical connection between the original vehicle battery management system and the high-voltage box assembly within the retired battery pack, causing the original vehicle battery management system to exit the control chain; An energy storage converter and an energy storage battery management system are provided. The high-voltage box assembly is electrically connected to the energy storage converter and the battery module respectively. The energy storage battery management system is electrically connected to the high-voltage box assembly, the battery module and the energy storage converter, so that the energy storage battery management system is added to the control chain.

9. A control method for an energy storage device, characterized in that, The control method for the energy storage device according to any one of claims 1-7 includes: Perform initialization testing on the energy storage device; The energy storage device was subjected to safety assessment and testing. The energy storage converter is pre-charged by the battery module; Control the closure of the high-voltage power circuit; Monitor the status parameters of the high-voltage power circuit and control the charging and discharging power.

10. The control method according to claim 9, characterized in that, The control method for the energy storage device also includes: When a preset signal is abnormal, power limiting operation or fault protection is executed. The preset signal includes voltage signal, current signal, temperature signal, insulation resistance signal, and circuit on / off signal.

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