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CN-121984195-A - Off-grid inverter battery protection and charging control method and system based on impedance detection

CN121984195ACN 121984195 ACN121984195 ACN 121984195ACN-121984195-A

Abstract

The invention belongs to the technical field of off-grid inverters and battery management, and particularly relates to an off-grid inverter battery protection and charging control method and system based on impedance detection, wherein battery input parameters under two different load working conditions of no-load or light-load and on-load are collected, a corresponding relation model of lithium battery residual capacity SOC and battery internal resistance is preset by adopting an ohm law analysis algorithm to obtain the current actual internal resistance of a battery, a preset SOC-internal resistance corresponding relation model is input to be reversely pushed to obtain the current SOC value of the battery, an inverter charging current regulation threshold value is set in a grading manner, a multi-dimensional risk early warning threshold value is set in a grading manner, and when a monitoring value exceeds the corresponding set risk early warning threshold value, a corresponding grade risk early warning signal and matched treatment action are triggered to perform full-flow management and control of battery state real-time monitoring, charging current self-adaption regulation and risk early warning. Therefore, the problems of short service life, poor charging safety and the like of the battery in the prior art are solved.

Inventors

  • NIE QIBIAO
  • JIANG HUA
  • JIANG SHUNHU

Assignees

  • 南京欧陆电气股份有限公司

Dates

Publication Date
20260505
Application Date
20260331

Claims (10)

  1. 1. The off-grid inverter battery protection and charging control method based on impedance detection is characterized by comprising the following steps of: collecting battery input parameters under two different load working conditions of no-load or light-load and load; Based on the battery input parameters under the two different load working conditions, according to a direct current voltage drop principle, an ohm law analysis algorithm is adopted to calculate and obtain total equivalent impedance of a battery, a connecting wire and a contact part, a corresponding relation model of lithium battery residual capacity SOC and battery internal resistance adapting to off-grid working conditions is preset, a preset connecting wire and a contact resistance reference value are subtracted from the total equivalent impedance to obtain the current actual internal resistance of the battery, a preset SOC-internal resistance corresponding relation model is input, and a current SOC value of the battery is obtained by back-pushing; Setting an inverter charging current adjusting threshold value in a grading manner based on the current SOC value and the actual internal resistance of the battery, adaptively adjusting the charging current of the inverter to enable the charging current to be matched with the current health state and the residual electric quantity of the battery, reducing the heating value in the battery charging process, simultaneously monitoring the change rate of the total equivalent impedance and the change trend of the actual internal resistance of the battery in real time, and setting a multi-dimensional risk early warning threshold value in a grading manner; when the monitoring value exceeds the corresponding set risk early warning threshold value, triggering a risk early warning signal of a corresponding grade and a matched treatment action, and performing battery state real-time monitoring, charging current self-adaptive adjustment and risk early warning full-flow management and control.
  2. 2. The method for protecting and charging an off-grid inverter battery based on impedance detection according to claim 1, wherein collecting battery input parameters under two different load conditions of no-load or light-load and load comprises: Constructing a double-working-condition steady-state data acquisition system; Setting a steady state judgment rule of an idle or light load working condition and a load working condition based on the dual-station steady state data acquisition system, synchronously acquiring battery end output voltage, battery output current, inverter direct current side input voltage and input current after the two working conditions reach steady state, and synchronously recording environmental temperature data before and after working condition switching to obtain original parameter data; And carrying out moving average filtering and outlier removing processing on the acquired original parameter data, and outputting a standardized parameter data set for calculating impedance.
  3. 3. The method for protecting and charging the off-grid inverter battery based on impedance detection according to claim 2, wherein the method is characterized in that based on battery input parameters under the two different load conditions, a total equivalent impedance of the battery, a connecting wire and a contact part is calculated by adopting an ohm law analysis algorithm according to a direct current voltage drop principle, and the method comprises the following steps: Constructing a duplex Kuang Zukang analysis model based on a direct current voltage drop principle; based on the duplex Kuang Zukang analysis model, inputting two standardized parameter data sets under different load working conditions, extracting core characteristic parameters of battery terminal voltage and output current under the two working conditions, and calculating to obtain a battery terminal voltage difference value and an output current difference value under the two working conditions; Based on the voltage difference value of the battery terminal and the output current difference value, the total equivalent impedance of a loop of the battery, a connecting wire and a contact part is obtained through an ohm law analysis algorithm according to a direct current voltage drop principle, and a confidence interval of a calculation result is synchronously output.
  4. 4. The method for protecting and charging an off-grid inverter battery based on impedance detection according to claim 1, wherein the method is characterized by presetting a corresponding relation model of lithium battery residual capacity SOC and battery internal resistance adapting to off-grid working conditions, and comprises the following steps: Constructing a basic model frame of the SOC-internal resistance corresponding relation adapting to off-grid working conditions; Based on the SOC-internal resistance corresponding relation basic model framework, combining nominal parameters and cycle life characteristics of a target lithium battery with test data at different temperatures and different charge and discharge multiplying powers, performing interval optimization through a piecewise linear fitting algorithm, dividing a plurality of SOC characteristic intervals, respectively fitting mapping functions of internal resistance and SOC of the battery in each interval, and completing model parameter calibration; based on the calibrated model parameters, model accuracy verification and deviation correction are carried out through measured data under the off-grid working condition, and a corresponding relation model of the lithium battery SOC and the battery internal resistance, which is adaptive to the off-grid working condition, is established.
  5. 5. The method for protecting and charging an off-grid inverter battery based on impedance detection according to claim 1, wherein the step-by-step setting of an inverter charging current adjustment threshold based on the current SOC value and the actual internal resistance of the battery, and the adaptive adjustment of the charging current of the inverter, comprises: constructing a battery state self-adaptive charging regulation model; Based on the battery state self-adaptive charging adjustment model, taking the current SOC value of the battery as a core dimension, dividing a multi-stage charging current adjustment interval by combining the battery health state represented by the actual internal resistance of the battery, and setting a charging current adjustment threshold value and a charging current upper limit value corresponding to each interval in a grading manner; And based on the multi-stage charging current regulation intervals, setting charging current regulation threshold values and charging current upper limit values corresponding to the intervals in a grading manner, dynamically correcting the charging current upper limit values by combining the environmental temperature data acquired in real time, regulating control parameters of a charging loop in real time through an inverter PWM (pulse width modulation) modulation algorithm, dynamically regulating the charging current to set values of the corresponding intervals, and carrying out self-adaptive matching of the charging current with the current health state and the residual electric quantity of the battery.
  6. 6. The method for protecting and charging an off-grid inverter battery based on impedance detection according to claim 1, wherein the method for monitoring the change rate of total equivalent impedance and the change trend of the actual internal resistance of the battery in real time, and setting the multi-dimensional risk early warning threshold in a grading manner comprises the following steps: constructing a battery full life cycle risk early warning index system; Based on the battery full life cycle risk early warning index system, a sliding time window algorithm is adopted to extract the short-time change rate of total equivalent impedance and the long-time change trend of the actual internal resistance of the battery in real time, and three multi-dimensional risk early warning thresholds of total equivalent impedance mutation threshold, battery internal resistance relative change rate threshold and internal resistance absolute value threshold are set in a grading mode by combining the safety performance parameters of the target lithium battery and the operation requirements of off-grid working conditions; Based on the multi-dimensional risk early warning threshold value, a corresponding judgment rule of the risk level and the monitoring threshold value is established, and the pre-preparation of risk early warning is completed.
  7. 7. An off-grid inverter battery protection and charge control system based on impedance detection, comprising: the double-working-condition acquisition module acquires battery input parameters under two different working conditions of no-load or light-load and on-load; the internal resistance SOC calculation module is used for calculating total equivalent impedance of the battery, a connecting wire and a contact part according to a direct current voltage drop principle and an ohm law analysis algorithm based on battery input parameters under the two different load working conditions, presetting a corresponding relation model of lithium battery residual capacity SOC and battery internal resistance which are adaptive to off-grid working conditions, deducting preset connecting wire and contact resistance reference values from the total equivalent impedance to obtain the current actual internal resistance of the battery, inputting a preset SOC-internal resistance corresponding relation model, and reversely pushing to obtain the current SOC value of the battery; The charging regulation and threshold setting module is used for setting an inverter charging current regulation threshold in a grading manner based on the current SOC value and the actual internal resistance of the battery, adaptively regulating the charging current of the inverter to enable the charging current to be matched with the current health state and the residual electric quantity of the battery, reducing the heating value in the battery charging process, simultaneously monitoring the change rate of the total equivalent impedance and the change trend of the actual internal resistance of the battery in real time, and setting a multi-dimensional risk early warning threshold in a grading manner; And when the monitoring value exceeds the corresponding set risk early warning threshold value, the early warning treatment management and control module triggers a corresponding grade risk early warning signal and a matched treatment action to perform full-flow management and control of battery state real-time monitoring, charging current self-adaptive regulation and risk early warning.
  8. 8. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor executing the program to implement an off-grid inverter battery protection and charge control method based on impedance detection as claimed in any one of claims 1-6.
  9. 9. A computer readable storage medium having stored thereon a computer program or instructions, which when executed, is adapted to carry out an off-grid inverter battery protection and charge control method based on impedance detection as claimed in any one of claims 1 to 6.
  10. 10. A computer program product comprising computer programs or instructions which, when executed, implement an off-grid inverter battery protection and charge control method based on impedance detection as claimed in any one of claims 1 to 6.

Description

Off-grid inverter battery protection and charging control method and system based on impedance detection Technical Field The invention belongs to the technical field of off-grid inverters and battery management, and particularly relates to an off-grid inverter battery protection and charging control method and system based on impedance detection. Background The off-grid inverter is core equipment of an independent photovoltaic and energy storage plasma grid system, and has the main functions of converting direct current output by a battery into alternating current to supply power for a load and simultaneously bears the function of controlling the charging of the battery. Lithium batteries are used as the most commonly used energy storage elements in off-grid systems, and the service life and safety of the lithium batteries directly affect the stability and economy of the whole off-grid system. In the existing off-grid system, the inverter mostly adopts a fixed current charging mode for charging control of the battery, or simply adjusts according to the voltage of the battery terminal, and the influence of the internal resistance of the battery and the impedance of a connecting wire is not considered. Meanwhile, the aging of the connecting wires and loosening of the joints can lead to the increase of the wires and the contact resistance, thereby increasing the pressure drop and the heating value in the battery charging process, accelerating the battery degradation and even causing potential safety hazards such as poor contact, overheat, and the like. At present, to realize the detection of the internal resistance of the battery and the impedance of the lead and the battery protection, an independent hardware device such as a battery management system BMS, an impedance tester, a temperature sensor and the like is usually additionally arranged, which undoubtedly increases the hardware cost and the installation complexity of the off-grid system and is not beneficial to popularization and application. In addition, the integrated method for monitoring the states of the battery and the lead wires in real time, automatically adjusting the charging current and realizing risk early warning is lacked in the prior art without adding additional hardware, so that the battery in the off-grid system is short in service life, poor in charging safety and high in maintenance cost. Therefore, how to realize the detection of the impedance of the battery and the connecting wire through the existing sampling module of the inverter on the basis of not increasing the hardware cost of the off-grid system, and automatically adjust the charging current, reduce the heat productivity of the battery, delay the service life of the battery and realize real-time risk early warning by combining the corresponding relation between the SOC and the internal resistance of the battery becomes the technical problem to be solved currently urgently. Disclosure of Invention The application provides an off-grid inverter battery protection and charging control method and system based on impedance detection, which are used for solving the problems of short service life, poor charging safety and the like of a battery in the prior art. The embodiment of the first aspect of the application provides an off-grid inverter battery protection and charging control method based on impedance detection, which comprises the following steps of collecting battery input parameters under two different load working conditions of no-load or light-load and load; based on the battery input parameters under the two different load working conditions, an ohm law analysis algorithm is adopted according to a direct current voltage drop principle, total equivalent impedance of a battery, a connecting wire and a contact part is calculated, a corresponding relation model of lithium battery residual capacity SOC and battery internal resistance adapting to off-grid working conditions is preset, a preset connecting wire and a contact resistance reference value are subtracted from the total equivalent impedance, the current actual internal resistance of the battery is obtained, a preset SOC-internal resistance corresponding relation model is input, the current SOC value of the battery is obtained by back-pushing, an inverter charging current adjustment threshold value is set in a grading mode based on the current SOC value and the actual internal resistance of the battery, the charging current of the inverter is adaptively adjusted to be matched with the current health state and the residual electric quantity of the battery, the heating value in the battery charging process is reduced, meanwhile, the change rate of the total equivalent impedance and the change trend of the actual internal resistance of the battery are monitored in real time, a multi-dimensional risk threshold value is set in a grading mode, and when the monitored value exceeds the corresponding set risk threshold value,