An electric vehicle power battery pack internal resistance monitoring system and monitoring method thereof

Abstract

The invention provides an electric vehicle power battery internal resistance monitoring system and a monitoring method thereof. The system includes a microprocessor, a signal generator, a frequency-locked phase-locked circuit, and a sampling resistor. The microprocessor is connected to the signal generator and frequency-locked respectively. The phase-locking circuit is connected, the signal generator is connected with the isolation coupling circuit, the frequency-locking phase-locking circuit is respectively connected with the reference signal collector and the differential amplifier circuit, the output end of the isolation coupling circuit is connected with the input end of the low-frequency signal driving circuit, and the sampling resistor is connected with the input end of the low-frequency signal drive circuit. The low-frequency signal driving circuit and the power battery pack are connected in series to form a low-frequency AC constant current signal loading circuit, the reference signal collector is connected to the sampling resistor, and the differential amplifier circuit is connected in parallel at both ends of the power battery pack. The invention also provides a monitoring method for the internal resistance monitoring system of the power battery pack of the electric vehicle. The invention only needs to inject a small current to realize safe on-line monitoring, and has the advantages of high measurement accuracy, fast speed, strong anti-interference ability and the like.

Description

technical field [0001] The invention relates to the technical field of internal resistance detection of power battery packs, in particular to an electric vehicle power battery pack internal resistance monitoring system and a monitoring method thereof. Background technique [0002] The internal resistance of the automotive power battery pack is one of the important parameters that reflect the performance of the power battery. Therefore, the online evaluation of the capacity and health status of the power battery pack can be realized by monitoring the internal resistance of the power battery pack. At present, the internal resistance of the power battery pack is generally measured by the DC discharge method and the AC injection method. [0003] The DC discharge method is to discharge the battery pack with a short time of high current, capture the change of the terminal voltage of the battery pack during discharge, and realize the measurement of the internal resistance. The int...

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Problems solved by technology

However, the signal measured by this method is very weak, and it is easily overwhelmed by the noise in the on-board charger and the surrounding power environment. There is a capacitive component on the impedance in the battery pack, which makes the phase shift of the feedback voltage signal generated at both ends of the battery pack.

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