Adaptive Hysteresis Current Control For Improved EMI Performance in Fast Switching Motor Drives

Electromagnetic interference (EMI) in pulse width modulated converters is exacerbated through carrier based modulation techniques that are associated with sharp spectral peaks around multiples of the switching frequency. As a mitigation measure, spread spectrum techniques are used, that distribute the carrier spectral energy over a certain frequency range to attenuate the EMI spectrum. This paper presents an alternative implementation of spread spectrum modulation through adaptive hysteresis bands, that regulate the moving average of switching frequency in a current controlled permanent magnet synchronous motor drive. Simulation results are presented through a comparison of input EMI and common mode voltage spectra for different modulation techniques. The proposed method demonstrates notable attenuation of spectral peaks when compared to carrier based modulation, while simultaneously overcoming large switching frequency deviations that are otherwise prevalent in classical hysteresis current control.