In this paper, the quaternary random pulse position modulation (QRPPM) is proposed to further reduce the energy of dominant harmonic clusters. From the analysis of the power and power spectral density, the minimum integer-harmonics power dispersion rate (PDR) is increased from 50.0% of the conventional random center/edge alignment PWM (RCEA-PWM) to 75.0% of the proposed QRPPM without the increase of the switching number and switching loss. Some simulated results are provided to validate the proposed method.
