Analysis, design, and implementation of a random frequency PWM inverter

Random pulse width modulation (RPWM) approaches can make the harmonic spect rum of inverter output voltage be continuously distributed without affectin g the fundamental frequency component, and thus the acoustic noise and mech anical vibration of an inverter-fed ac motor drive are greatly reduced. How ever, the analysis and design of the RPWM mechanisms are generally not so t rivial for practical engineers that their applications are limited. In this paper, a random frequency PWM (RFPWM) inverter and its practical design pr ocedure are presented. First, the effects of the attributes of random signa l on the inverter output harmonic spectrum distribution characteristics are analyzed using intuitive concept. Then based on which, the quantitative de sign, Simulink simulation and implementation of the proposed RFPWM inverter are introduced, The proposed RFPWM inverter is employed to power an indire ct field-oriented induction motor drive. The simulated and measured results indicate that uniform random distribution of inverter output harmonic spec trum and thus smaller acoustic noise and mechanical vibration are obtained by the proposed RFPWM scheme.