Automated Excitation Signal Generation System for Time-Domain Impedance Spectroscopy

Increasing application of lithium batteries and other electrochemical power sources in the fields of portable devices, electric vehicles, ships, aircrafts, robots, etc. requires a new diagnostic tool, which provides enough accuracy, is expensive, and does not require long response time. One of the best candidates for this role is time domain electrochemical impedance spectroscopy. The approach to provide the high quality excitation signal for corresponding system is presented. The approach allows to use energy of the electrochemical power source under test to generate excitation signal reducing complexity, weight, sizes and cost of the measuring apparatus. The proposed system consists of two main parts operating mode controller and controllable load. Operating mode controller uses information about actual voltage and current of the device under test. The system is able to generate any excitation signal. It is proposed to store set of PID-coefficients into the memory and select the appropriate coefficients on the basis of actual voltage proving by the electrochemical power under test to prevent change of the excitation signal parameters with device under test voltage variation. Diagnostic method, experimental installation and modeling results are presented in this paper. The presented approach allows to provide reliable and inexpensive tool to generate excitation signal for time domain electrochemical impedance spectroscopy systems.