A Two-Phase Separately Randomized Pulse Position PWM (SRP-PWM) Scheme With Low Switching Noise Characteristics Over the Entire Modulation Index

This paper describes a two-phase separately randomized pulse position pulsewidth modulation scheme that can obtain the randomization effect on the switching noise spectra over the entire modulation index ( M) range. In the proposed scheme, the zero vector is selected as V(1 1 1) when M ≥ 0.7 and as V(0 0 0) when M <; 0.7. For the validity of the proposed method, a 16-bit microcontroller SAB-C167 was used and the experiments were performed on a 1.5-kW three-phase induction motor which is coupled an eddy current brake load. The switching noise was measured in the anechoic room using a RION SA-01. Experiment results were measured at a distance of 0.15 m away from the side of induction motor. The experimental results show that the harmonic spectra spread over a wideband area, and the switching noise for all the M is reduced by the proposed method.