Simulation-Based Design of the Common-Mode Transformer-Less Hybrid EMI Filter in DC-Fed Motor Drive Systems

This article presents a circuit simulation-based design method for common-mode (CM) transformer-less hybrid EMI filters (HEFs) to obtain the required CM current attenuation. First, a simulation-based design method of the HEF, including the passive filtering components, is presented. The prototype HEF is implemented in a DC-fed three-phase motor drive system to validate the design method and evaluate the HEF's performance. The measured results validate the presented design method and show that the HEF can increase the CM current attenuation of a passive EMI filter (PEF) up to 8.2 dB in the frequency range from 100 kHz to 1.4 MHz. Furthermore, the measured result clarifies that implementing a voltage-sensing parallel-compensating active feedback circuit can reduce the volume of the CMI used in a PEF designed to achieve the same attenuation of the HEF by about 75 %.