Optimized Dual Randomized PWM Technique for Reducing Conducted EMI in DC-DC Converters

Abstract

This paper deals with the control of the full bridge dc- dc voltage converter by the Random Pulse Width Modulation (RPWM) technique. We propose a RPWM scheme based on a triangular carrier having two randomized parameters: the period T and the peak position  (half period)  First, we propose the modulating principle, then the voltage analysis based on Power Spectral Density (PSD) shows the advantage from the point of view of Electro-Magnetic Compatibility (EMC) of this scheme compared to conventional RPWM schemes having only one randomized parameter. Moreover, this analysis reveals the existence of an optimal value of the variation interval of parameter  for a maximum spread of the PSD. Once the optimization problem modeled, the resolution is performed using two powerful nonlinear methods: the trust region method and the simplex algorithm.