Design and implementation of current source based on battery AC impedance method

In view of the practical application of battery's internal resistance test, a current source which meets the requirements of the AC impedance test is designed. The current source uses DDS (Direct Digital Synthesizer) technology to generate sinusoidal AC signals at each frequency band and inject them into the improved Howland circuit which is a kindle of voltage controlled current source circuit. After the power amplification of the Howland circuit, sinusoidal AC signals change into the stable sinusoidal AC current which meets the frequency and amplitude requirements. Then the AC current is injected into the battery to test the internal resistance. In this paper, the experimental results show that the designed current source system can produce the required AC current quickly and stably, and reduce the noise interference caused by the instability of the current source in the measurement of battery internal resistance.