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CN-122026568-A - Intelligent control method and system for multi-pack parallel power battery system

CN122026568ACN 122026568 ACN122026568 ACN 122026568ACN-122026568-A

Abstract

The invention discloses an intelligent control method and system of a multi-pack parallel power battery system, which relate to the field of battery management, and the method comprises the following steps: after receiving the instruction, the system main controller comprehensively evaluates the total voltage, the SOC and the temperature of each battery pack, calculates a system balance index, and adaptively selects a control strategy based on the index. When the intelligent power-on is performed, the flexible power-on flow comprising closed-loop PID control is adopted according to the judgment of the voltage difference and the balance index, the battery packs are sequentially connected, and the closing impact is eliminated. And when the intelligent charging and discharging is performed, the convergence trend of each package of SOC is predicted based on an equivalent circuit model and a Kalman filtering algorithm, the charging mode is dynamically switched, and the current is actively distributed through the DC/DC converter, so that the balance is improved. When intelligent power-down, normal and fault scenes are distinguished, an orderly grading power-down flow is executed, and the voltage drop slope is monitored to ensure safety. According to the invention, through cooperation of software and hardware, the system safety, the balance and the service life are obviously improved.

Inventors

  • FENG ZHIQIANG
  • WU HAO
  • ZHANG YONG

Assignees

  • 中电科创智联(武汉)有限责任公司

Dates

Publication Date
20260512
Application Date
20251212

Claims (10)

  1. 1. The intelligent control method of the multi-pack parallel power battery system comprises a main controller and at least two battery packs which can be independently switched, and is characterized by comprising the following steps: a state parameter obtaining step of obtaining a plurality of state parameters of each battery pack in response to a control instruction, wherein the state parameters at least comprise total voltage, state of charge (SOC) and temperature; Calculating a comprehensive system balance index based on the state parameters; And the self-adaptive control step is to self-adaptively select and execute a corresponding control strategy from a plurality of preset control strategies according to the comparison result of the system equilibrium index and at least one preset threshold value so as to finish the power-on, charge-discharge or power-off operation of the system.
  2. 2. The method of claim 1, wherein the system equalization index is a weighted function of voltage difference, SOC difference, and temperature difference between the battery packs.
  3. 3. The method according to claim 1 or 2, wherein the control command is a power-on command, and the adaptive control step specifically comprises an intelligent power-on control sub-step: Calculating the voltage range delta V of all battery pack voltages; Based on the voltage range and the system equalization index e_index, one of the following modes is selected and executed: When DeltaV is less than or equal to V_th1 and E_index is less than or equal to E_th1, controlling the contactors of all the battery packs to be closed simultaneously; when DeltaV is larger than V_th1 or E_index is larger than E_th1, but DeltaV is smaller than or equal to V_th2, starting a flexible power-on flow; when DeltaV > V_th2, power-up is disabled and an alarm is given.
  4. 4. A method according to claim 3, wherein the flexible up-current path comprises: preferentially closing the contactor of the battery pack with the lowest voltage and the pre-charging contactor of the pre-charging loop; A closed-loop control algorithm is adopted, a target voltage value is taken as a set value, a pre-charging current is dynamically adjusted, and the battery pack with the lowest voltage is pre-charged; and monitoring a pre-charging process in real time, if the pre-charging is successful, opening the pre-charging contactor after the voltage of the battery pack with the lowest voltage reaches the target voltage value, and sequentially closing the contactors of the rest battery packs according to the determined access priority order.
  5. 5. The method of claim 4, wherein the access priority is determined based on dynamic calculation of the SOC and internal resistance of the battery pack, the lower the SOC and the greater the internal resistance of the battery pack, the higher the access priority thereof.
  6. 6. The method according to claim 1 or 2, wherein the control instruction is a charge-discharge instruction, and the adaptive control step specifically comprises an intelligent charge-discharge control sub-step: Monitoring charge and discharge current and SOC of each battery pack in real time; based on historical data and real-time state, predicting convergence trend of each battery pack SOC in future set time by adopting an equivalent circuit model and Kalman filtering; according to the predicted convergence trend of the SOC, the charging strategy is dynamically switched, wherein the strategy at least comprises: A fast charge mode of charging with constant power when the predicted final SOC is less than the first SOC threshold; And in the equalizing charge mode, when the predicted final SOC is greater than or equal to the first SOC threshold value, constant-current charge is adopted, and different charge current values are dynamically distributed for different battery packs.
  7. 7. The method of claim 6, wherein the method further comprises dynamically adjusting the load current ratio of the output of each battery pack in a Pulse Width Modulation (PWM) manner by rapidly switching the contactors of the different battery packs when the discharge imbalance is detected to exceed the preset limit during the discharge.
  8. 8. The method according to claim 1 or 2, wherein the control command is a power-down command, and the adaptive control step specifically comprises an intelligent power-down control sub-step: firstly, judging the power-down type, wherein the power-down type comprises normal power-down and fault power-down; according to different power-down types, different hierarchical power-down current procedures are executed: For normal power-down, firstly cutting off external connection, then firstly cutting off the battery pack with the largest current contribution rate, and after delaying for a first preset time, cutting off the rest battery packs according to the sequence of the SOC from high to low; for a power down failure, the failed battery pack is immediately isolated, and then the contactors of all the non-failed battery packs are opened within a second preset time shorter than the first preset time.
  9. 9. The method of claim 8, wherein in the normal power down process, after disconnecting the first battery pack, the system monitors a falling slope of the bus voltage, and if the falling slope exceeds a safety threshold, pauses a subsequent power down operation and reports an abnormality.
  10. 10. An intelligent control system for implementing the method of any one of claims 1 to 9, comprising: A plurality of battery packs, each battery pack being equipped with an independently controllable contactor; The sensor network is used for collecting the state parameters of each battery pack; A precharge circuit including a precharge resistor and a precharge contactor; the main controller is in communication connection with the sensor network, the contactors of each battery pack and the pre-charging contactor; The system also comprises a DC/DC converter arranged on each battery pack output passage, and the main controller dynamically distributes charging current for different battery packs by controlling the duty ratio of each DC/DC converter; the master controller is configured to perform the steps of the method of any of claims 1-9.

Description

Intelligent control method and system for multi-pack parallel power battery system Technical Field The invention belongs to the field of battery management, and particularly relates to an intelligent control method of a multi-pack parallel power battery system. Background In order to meet the requirements of long endurance and high power, multi-pack parallel connection becomes a main stream technical scheme of a power battery system. However, direct parallel connection of multiple battery packs introduces a series of technical challenges: When the vehicle is started, if voltage difference exists among a plurality of battery packs connected in parallel, huge circulation (impact current) can be generated at the moment of closing the contactor. This not only ablates the contactor contacts, creates a safety hazard, but also causes damage to the battery. And in the process of charging and discharging, current can preferentially flow to battery packs with smaller internal resistance or higher voltage, so that the energy states of the battery packs are different, the available capacity of the system is reduced, and the overall aging of the battery packs is accelerated. And the power-down risk is that if all the battery packs are disconnected at the same time during abnormal power-down, the high-voltage platform can disappear instantaneously, and unpredictable circuit transient processes can be possibly caused to impact high-voltage components. Existing solutions have focused on hardware loop current suppression (e.g., adding diodes) or simple fault isolation and timing control. For example, there is a common sense thinking of "first closing the lowest voltage battery pack", but there is a lack of comprehensive judgment on the system state (e.g., SOC, temperature), and there is no involvement of fine closed-loop control of the precharge process, predictive equalization of charge and discharge states, and classification strategies for different power-down scenarios. The schemes lack the capability of intelligent collaborative optimization of the whole processes of power-on, power-off, charge-discharge from the control strategy level. Therefore, an intelligent cooperative control scheme capable of performing multi-parameter fusion judgment, self-adaptive adjustment and fault tolerance is urgently needed in the field, so that the reliability, safety and efficiency of the system are fundamentally improved. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a method and a system which can effectively inhibit the power-on and power-off impact current of a multi-packet parallel system and have the self-processing capability of precharge faults. Another object of the present invention is to provide a charge-discharge control strategy based on dynamic adjustment of real-time and predictive equalization to actively improve system equalization and capacity utilization. It is still another object of the present invention to provide a system that can distinguish between normal and fault scenarios, and achieve smooth, safe, and controllable current flow in system classification. In order to achieve the aim of the invention, the intelligent control method of the multi-pack parallel power battery system adopts the following technical scheme that the system comprises a main controller and at least two battery packs which can be independently switched. The method has the core concept of constructing an adaptive control framework taking a system balance index as a core decision parameter, and comprises the following steps: a state parameter obtaining step of obtaining a plurality of state parameters of each battery pack in response to a control instruction, wherein the state parameters at least comprise total voltage, state of charge (SOC) and temperature; Calculating a comprehensive system balance index based on the state parameters; And the self-adaptive control step is to self-adaptively select and execute a corresponding control strategy from a plurality of preset control strategies according to the comparison result of the system equilibrium index and at least one preset threshold value so as to finish the power-on, charge-discharge or power-off operation of the system. An intelligent control system, applied to the method, comprising: A plurality of battery packs, each battery pack being equipped with an independently controllable contactor; The sensor network is used for collecting the state parameters of each battery pack; A precharge circuit including a precharge resistor and a precharge contactor; the main controller is in communication connection with the sensor network, the contactors of each battery pack and the pre-charging contactor; The system also comprises a DC/DC converter arranged on each battery pack output passage, and the main controller dynamically distributes charging current for different battery packs by controlling the duty ratio of each DC/DC converter; the mas