CN-121984197-A - Deep discharge control method and system for series battery modules

CN121984197ACN 121984197 ACN121984197 ACN 121984197ACN-121984197-A

Abstract

The invention discloses a deep discharge control method and system for series battery modules, which comprises the steps of detecting the residual voltage of each battery module in real time, generating a deep discharge permission signal when the residual voltage of at least one battery module is not lower than a first preset threshold value, judging whether preset deep discharge conditions are met currently according to the deep discharge permission signal, controlling all the battery modules with the residual voltages not lower than the first preset threshold value to be connected into a circuit at the same time to form a series discharge loop if the deep discharge conditions are met, and supplying the output voltage of the series discharge loop to an external load or a feed-in power grid after the output voltage of the series discharge loop is converted by a bidirectional DC/DC converter and subjected to inversion treatment by the bidirectional DC/AC inverter. The control method is applied to the scene of recycling batteries, effectively solves the problems of high risk, incomplete discharge and energy waste in the treatment process, and remarkably improves safety, economy and environmental protection.

Inventors

ZHANG XINGWANG
YI LI
LAI QIANCHENG
QIN MAO
Yang Kangjia
XU XIAOFANG
Tan tiannuo
SHI WEIPENG

Assignees

广州擎天实业有限公司
中国电器科学研究院股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260119

Claims (9)

1. The deep discharge control method of the series battery module is characterized by comprising the following steps of: Detecting the residual voltage of each battery module in real time; generating a deep discharge permission signal when the residual voltage of at least one battery module is not lower than a first preset threshold value; Judging whether a preset deep discharge condition is met or not currently according to the deep discharge permission signal; if the deep discharge condition is met, all the battery modules with the residual voltages not lower than a first preset threshold value are controlled to be connected into a circuit at the same time so as to form a series discharge loop; the output voltage of the series discharge loop is converted by a bidirectional DC/DC converter and subjected to inversion treatment by a bidirectional DC/AC inverter, and then is supplied to an external load or fed into a power grid; the first preset threshold corresponds to the lowest initial voltage of the battery module participating in deep discharge.
2. The deep discharge control method of a serial battery module according to claim 1, comprising: continuously monitoring the residual voltage of each battery module connected into the series discharge loop in the deep discharge process; When the residual voltage of any battery module is detected to reach a discharge cut-off condition, the battery module is controlled to exit the series discharge loop through the bypass switch, and the rest battery modules continue to discharge; When all the battery modules reach the discharge cut-off condition, an exit instruction is generated to control all the battery modules to exit the deep discharge state.
3. The deep discharge control method of a serial battery module according to claim 1, further comprising: Monitoring the input voltage of the bidirectional DC/DC converter in real time; Generating a compensation instruction when the input voltage of the bidirectional DC/DC converter is lower than a second preset threshold value; according to the compensation instruction, controlling a compensation circuit to perform voltage supplementing operation so as to raise the total voltage of the series discharge loop; Wherein the second preset threshold corresponds to a minimum input operating voltage required by the bi-directional DC/DC converter.
4. The method for controlling deep discharge of a serial battery module according to claim 1, wherein controlling the battery module to withdraw from or to be connected to a serial discharge circuit comprises: When the residual voltage of the battery module is not lower than a first preset threshold value, enabling the corresponding battery module to be connected into a series discharge loop; when the residual voltage of the battery modules reaches the discharge cut-off condition, the corresponding battery modules are led out of the series discharge loop.
5. The deep discharge control method of serial battery modules according to claim 1, wherein the preset deep discharge conditions are simultaneously satisfied: The external load demand power is not greater than the maximum output power of the series discharge loop; The surface temperature of the battery module does not exceed a safe temperature threshold; no insulation fault, communication interruption or voltage imbalance fault is detected.
6. The deep discharge control method of the series battery module according to claim 1, wherein: after the output voltage of the series discharge loop is boosted by the bidirectional DC/DC converter, the input voltage range of the output voltage is adapted to the input requirement of the bidirectional DC/AC inverter; the bi-directional DC/AC inverter inversion process includes converting direct current to alternating current and controlling the feed direction to achieve grid feed or load power.
7. A series battery module deep discharge control system for implementing the series battery module deep discharge control method of any one of claims 1 to 6, comprising: The battery management unit is used for detecting the residual voltage of each battery module in real time and generating a deep discharge permission signal when the residual voltage of at least one battery module is not lower than a first preset threshold value; The control system unit is in signal connection with the battery management unit and is used for judging whether a preset deep discharge condition is met or not currently according to the deep discharge permission signal; The switch control module group is used for meeting the deep discharge condition and controlling all the battery modules with the residual voltages not lower than a first preset threshold value to be connected into the circuit at the same time so as to form a series discharge loop; The power conversion unit comprises a bidirectional DC-DC converter and a bidirectional DC/AC inverter and is used for controlling the output voltage of the series discharge loop to be supplied to an external load or fed into a power grid after being converted by the bidirectional DC/DC converter and inverted by the bidirectional DC/AC inverter; the first preset threshold corresponds to the lowest initial voltage of the battery module participating in deep discharge.
8. The deep discharge control system of claim 6, wherein the switch control module group comprises: Each battery module is correspondingly provided with a bypass switch and a straight-way switch; When the residual voltage of the battery module is not lower than a first preset threshold value, executing the closing of a straight-way switch and the opening of a bypass switch, so that the corresponding battery module is connected into a series discharge loop; When the residual voltage of the battery module reaches a discharge cut-off condition, a straight-way switch is opened, and a bypass switch is closed, so that the corresponding battery module exits from the series discharge loop; The switch control module group realizes mutual exclusion operation of the bypass switch and the straight-way switch through the hardware interlocking circuit so as to ensure that the bypass switch and the straight-way switch are not closed at the same time.
9. The deep discharge control system of a series battery module of claim 7, further comprising: And the compensation circuit module is used for carrying out voltage compensation on the series discharge loop through the series compensation power supply when the input voltage of the DC/DC converter is lower than a second preset threshold value.

Description

Deep discharge control method and system for series battery modules Technical Field The invention relates to the technical field of deep discharge of batteries, in particular to a deep discharge control method and system for series battery modules. Background With the rapid development of new energy automobile industry, the recycling and processing problems of power batteries are increasingly prominent. The safe deep discharge of the retired battery is a key link of battery recovery processing, and the safety and effectiveness of subsequent disassembly and material recovery are directly related. At present, the deep discharge technology of the battery mainly comprises traditional methods such as deep discharge of resistance, deep discharge of seawater immersion and the like, but the methods have a plurality of problems in practical application. The traditional retired battery deep discharge method has obvious potential safety hazard and energy waste problems. The seawater soaking method can generate toxic gases such as hydrogen, hydrogen fluoride and the like in the deep discharge process, so that explosion and poisoning risks exist, heavy metal can pollute a marine ecosystem, and meanwhile, internal short circuit of a battery can be possibly caused, and local overheating and thermal runaway are caused. The resistance deep discharge rule directly converts energy in the battery into heat energy to be wasted, so that the energy utilization rate is low, additional heat dissipation management and factory cooling measures are needed, and the treatment cost is increased. The existing deep discharging technology of the battery lacks effective abnormality detection and processing mechanism when processing the series battery modules, can not realize safe deep discharging of the battery modules (deep discharging is below 0V), and can not monitor the battery state and perform intelligent regulation and control in real time in the deep discharging process. Meanwhile, the prior art has the defect of voltage compensation in the deep discharging process of the battery module, and the stability and the safety of the deep discharging process are difficult to ensure. Therefore, a method for safely and efficiently realizing deep discharge of the series battery modules is needed, so that the problems of potential safety hazards and energy waste existing in the traditional deep discharge method can be solved, the deep discharge and intelligent management of the battery modules can be realized, and the safety and efficiency of battery recycling treatment are improved. Disclosure of Invention The invention provides a method and a system for controlling deep discharge of a series battery module in order to solve the problems of potential safety hazard and energy waste existing in the traditional deep discharge method of retired batteries. In order to solve the problems, the invention is realized according to the following technical scheme: The invention provides a deep discharge control method of series battery modules, which comprises the following steps of detecting residual voltage of each battery module in real time, generating a deep discharge permission signal when the residual voltage of at least one battery module is not lower than a first preset threshold value, judging whether preset deep discharge conditions are met currently according to the deep discharge permission signal, controlling all the battery modules with the residual voltages not lower than the first preset threshold value to be connected into a circuit at the same time to form a series discharge loop if the deep discharge conditions are met, and supplying output voltage of the series discharge loop to an external load or a feed-in power grid after being converted by a bidirectional DC/DC converter and subjected to inversion treatment by the bidirectional DC/AC inverter, wherein the first preset threshold value corresponds to the lowest initial voltage of the battery modules participating in the deep discharge. In combination with the first aspect, the invention provides a first implementation of the first aspect, specifically, in the deep discharging process, the residual voltage of each battery module connected into the series discharging loop is continuously monitored, when the residual voltage of any battery module is detected to reach the discharging cut-off condition, the battery module is controlled to exit the series discharging loop through the bypass switch, the other battery modules continue discharging, and when all the battery modules reach the discharging cut-off condition, an exit command is generated to control all the battery modules to exit the deep discharging state. With reference to the first aspect, the invention provides a second implementation manner of the first aspect, specifically, monitoring the input voltage of the bidirectional DC/DC converter in real time, generating a compensation instruction when the input voltage of the bidi