Improved spectral performance of random PWM schemes with altered chaotic behavior [for PWM invertors]

The authors present a statistical approach to the analysis of random PWM (RPWM) methods, for use in DC/AC power conversion, which generate PWM signals by comparing a reference modulating function with random numbers or signals. Such an approach is used to analyse and optimise a new weighted RPWM (WRPWM) method and also a standard trapezoidal RPWM method. Both theoretical and experimental results confirm that the optimised WRPWM method has better spectral performance over the standard RPWM schemes and has attractive features such as potential of third harmonic boosting, reduced acoustic noise and minimal low-order harmonics under over-modulation condition for electronic drive applications.