Design of a Passive Filter to Reduce Common-Mode and Differential-Mode Voltage Generated by Voltage-Source PWM Inverter

In this paper, a novel passive filter installed at PWM inverter output terminals is proposed with an objective of eliminating the common-mode and differential-mode voltage generated by PWM inverter simultaneously. For determining the parameters of filter, the filter transfer function is utilized to achieve a desirable filtering performance. The detailed design procedure of the filter parameters is given. The validity and effectiveness of proposed filter are supported by the simulation and experimental results carried out on 380V/3kW induction motor system. Further investigations also demonstrate that the proposed filter permits motor to be connected with inverter through a long cable. The side-effects induced by common-mode and differential-mode voltage such as shaft voltage, bearing current and leakage current are mitigated effectively.