Reduce Harmonic Distortion using Pseudorandom PWM Technique

Abstract

Due to harmonic content in the voltage and current wave forms in the power electronic devices working at high frequencies cause mechanical vibrations, acoustic noise, and EMI interference makes the workers uncomfortable. Proposed work deals with a new and effective technique to possess low acoustic noise and mechanical vibration when lower switching frequency is chosen. Pseudo random pulse width modulation the new established technique is used to eliminate this undesirable effect. A pseudorandom carrier modulation scheme and its harmonic spectra spread effect is described in this paper. By the random synthesis of the two triangular carriers, each of same fixed frequency, but opposite phase are used to produce the pseudorandom carrier of the proposed scheme.  By pseudorandom binary sequence (PRBS) random bit’s states, the random selection of the two triangular carriers are decided. The random selector of the PRBS random bits is Multiplexer, produces the resultant pseudorandom frequency carrier waveform. In order to verify the validity of the proposed method, the simulations were conducted with single phase full bridge inverter.