Battery internal resistance measuring and calculating method and circuit of battery pack management system

Abstract

The invention discloses a battery internal resistance measuring and calculating method and circuit of a battery pack management system. The method includes: respectively using a first cycle and a second cycle to collect and cache the voltage of the single battery in a battery pack and the currents of a battery stack cathode; addressing and selecting the cached voltage to fine a first voltage point V1 and a second voltage point V2, and saving the first voltage point V1 and the second voltage point V2; addressing and selecting the cached currents to find a first current point I1 and a second current point I2, and saving the first current point I1 and the second current point I2; calculating the internal resistance R of the single battery according to the following relation: R=(V2-V1) / (I2-I1). By the arrangement, the method has the advantages that adding of a battery internal resistance exciting bank or measuring device is not needed, current and voltage detecting are not limited to discharge conditions, current detecting and voltage detecting are separated and asynchronous, the sample space of battery internal resistance measuring is increased, and internal resistance measuring is simplified, the real-time variation condition of battery internal resistance can be monitored conveniently, equipment can be reduced, and cost is lowered.

Description

technical field [0001] The invention relates to the field of energy storage power station and electric vehicle control, in particular to a method and circuit for measuring and calculating the battery internal resistance of a battery pack management system. Background technique [0002] Internal resistance is an important technical indicator to measure battery performance. When the battery is in different power states, its internal resistance is different; when the battery is in different service life, its internal resistance is also different. 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, detecting internal resistance has become a popular way to judge whether a battery is good or bad. [0003] The existing method for detecting the internal resistance of the battery in the battery pack uses a separate device to discharge the battery, which...

AI Technical Summary

Problems solved by technology

[0003] The existing method for detecting the internal resistance of the battery in the battery pack uses a separate device to discharge the battery, which increases the number of components and costs, and requires simultaneous measurement of voltage and current, or there are specific measurement conditions, such as self-test discharge, That is, the measurement of the internal resistance of the battery is only carried out during the self-test discharge, and the voltage value is detected and recorded while the current value is recorded. It is not suitable for the energy storage system where the voltage acquisition module and the current acquisition module are detected separately.

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