Modeling and Practical Design Dual-Mode Sinewave and Common Mode Filter for PWM Motor Drives System Using Tricore Laminations

A dual-mode sinewave output filter that eliminates motor problems due to the PWM waveforms in both common mode and differential mode operation is proposed. A three-phase inductor constructed with tricore laminations. The windings possess differential mode inductance and proportionally every large common mode inductance characteristic. In voltage source converters, the common mode voltage is mainly distributed in the switching frequency range, therefore the common mode voltage in this filter design is in the medium frequency range referring to the switching frequency and sidebands of its integral multiples. The single integrated inductor with the capacitors creates a LC low-pass filter in both common mode and differential mode operation. This proposed filter offers a complete solution with reliable, practical and cost-effective to the issues caused by common mode voltage in power converter systems. Three different rating of 5A, 45A and 160A prototypes were built, and test results presented.