Power and power spectral density in PWM inverters with randomized switching frequency

Theoretical and experimental investigation of the impact of randomization of switching frequency in pulse width modulated (PWM) three-phase inverters on the spectra of output voltage is presented. The case of random PWM with a limited set of employed values of switching frequency is analyzed with respect to both the power and power density spectral components. A novel method for accurate prediction of spectra of inverter voltage is introduced and experimentally verified. Experiments were also used to illustrate the important issue of required width of the range of switching frequencies.