On-line DC detection method and system for battery internal resistance

Abstract

The invention discloses an on-line DC detection method for the internal resistance of a storage battery, which comprises the following steps: detecting the discharge current of the storage battery during self-test discharge in a power supply device, and recording it as the first when the instantaneous value of the discharge current is greater than the set upper limit value A current value, and detect the voltage of the single cell in the storage battery at this moment, and record it as the first voltage value; when the instantaneous value of the discharge current is less than the set lower limit value, record it as the second current value, and detect this The voltage of the single battery at a moment is recorded as the second voltage value; the difference between the first voltage value and the second voltage value is divided by the difference between the first current value and the second current value to obtain the internal resistance of the single battery. Also disclosed is an on-line direct current detection system for storage battery internal resistance using the detection method. Utilizing the self-test discharge of the power supply equipment itself, the invention provides a method and system for on-line detection of battery internal resistance with simple test means and high detection accuracy.

Description

technical field [0001] The invention relates to storage batteries, in particular to a method and system for on-line DC detection of storage battery internal resistance. Background technique [0002] As a backup power source for power system failures, batteries have been widely used in industries such as industrial production, transportation and communications. If the battery fails or the capacity is insufficient, it may cause a major accident, so it is necessary to carry out comprehensive online monitoring of the operating parameters of the battery. One of the important signs of the state of the battery is its internal resistance. Whether the battery is about to fail, the capacity is insufficient, or the charge and discharge are improper, it can be reflected in the change of its internal resistance. Therefore, the working state of the battery can be evaluated by measuring the internal resistance of the battery. At present, the common methods for measuring the internal res...

AI Technical Summary

Problems solved by technology

For example: for a UPS system, the tester using the DC discharge method discharges a battery in the battery pack at 50A at a certain moment to measure the internal resistance, but at the same time, the UPS charger may be discharging the battery at 40A. To charge the battery, the tester must also take into account the influence of the charging current to accurately calculate the internal resistance of the battery

Similarly, for a tester using the AC injection method, a 100HZ 500mA current may be injected into a certain battery cell in the battery pack at a certain moment. For a common UPS storage battery, this injection may obtain hundreds of microvolts to 1 millivolts. voltage response in volts

During the operation of the power supply equipment, the voltage response to the AC current of various frequencies injected by the battery may reach hundreds of millivolts, and the internal resistance tester must accurately select the microvolts corresponding to the injected current from the background voltage of several hundred millivolts. Level response, but this usually requires complex circuits, and the accuracy is bound to be difficult to guarantee

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