A new switching method for PWM inverter with uniform distribution of output current's spectrum

Abstract

In this paper, in order to reduce the dominant harmonic clusters in the output current's spectrum, a new switching method for PWM inverters is proposed. When an inverter with a constant switching frequency is used, it would result in narrow-band harmonics. These harmonic clusters can make acoustic noises and Electromagnetic Interference (EMI). In order to reduce the noises and EMI effect of these harmonic clusters, random-switching PWM techniques have been introduced. The concept of random-switching PWM technique is to spread the original narrow-band harmonic throughout a wide range of frequencies. With the method which is proposed in this paper acoustic noises and EMI are reduced uniformly in output current's spectrum. Proposed switching pattern is discussed and compared by other switching pattern that proposed earlier. Simulation results of proposed method are shown for a Permanent Magnet Synchronous Motor (PMSM) that is fed by PWM inverter and controlled by Field Oriented Control (FOC) algorithm.