Suppression of common-mode and shaft voltages in inverter-driven induction motor
Liqiang Yuan · Journal of Tsinghua University(Science and Technology) · 2009
A selective harmonics elimination pulse width modulation(SHEPWM) scheme was used to suppress common mode and shaft voltages in a three-level neutral-point-clamped inverter-driven induction motor system.A figure of merit for the harmonics was used to find the correct switching angles for the scheme.An improved SHEPWM which eliminates tripling order harmonics was used at 40～45 Hz,while the conventional SHEPWM was used at 45～50 Hz.The switching between the two modes at 45 Hz is very smooth.Together with a well-designed passive common mode filter,the harmonics eliminates scheme significantly reduces both the common mode voltage and the shaft voltage within the frequency range of interest.