Utilization of median filters in power electronics: Traction drive applications

This paper presents three different applications of median filters in power electronic systems, specifically, in traction motor drives. While median filters are commonly used in signal processing, literature regarding their utilization in power electronics is very limited. The theory behind median filters is first introduced and then three example applications are discussed: speed estimation for an induction motor drive, current sensing in a three-phase inverter, and dc bus voltage sensing in a half-bridge inverter. Simulation and experimental results verify the simplicity and applicability of median filters for control and sensing in power electronics applications. Results show significant improvement in the filter output quality for all three applications compared to the filter input where numerical errors, data acquisition glitches, and noise are significantly reduced or eliminated in the output.