Switching Current Measurement Based on Power Module Parasitics

This paper introduces a current sensor scheme based on the parasitic inductance between the kelvin source and power source terminals of a power module. The current sensor using the traditional Op-amp integration method and the impact of the parasitic resistance on its performance are thoroughly investigated. Then, a current sensor scheme with feedback compensation is proposed to cope with the large deviation in the output of the current sensor caused by the parasitic resistance. The feedback loop is further modified so that impact of the temperature on the current sensor’s performance is mitigated. Simulation and experiment results are provided to demonstrate the effectiveness of the proposed current sensor scheme, as well as its performance compared to that of a commercial Rogowski probe.