Chipped PWM Strategy with SMPS for Noise Mitigation in PSDM-based Systems

Power/signal dual modulation (PSDM) is a promising integrated communication solution for intelligent switched-mode power supply (SMPS) systems. A common strategy is to utilize input/output switching ripples as information carriers, which transmit along common power bus. As the switching harmonics peaks are located in the same frequency band with communication signals, they may lead serious noise interference. To deal with this issue, random PWM is a proper solution, as it scatters the spectrum of switching harmonic peaks to a much wider and flatter one. This paper proposes a novel chipped PWM strategy to shape the switching harmonics to semi-Gaussian white noise. It breaks the periodicity of PWM sequence and releases more control freedom of the gate signal. Conventional PWM strategy is not used, but independent chips of high voltage level state and low voltage level state are introduced. They are combined in a pseudo random way, and the numbers of “on” and “off” chips in each pseudo random encoding interval are constant to ensure a desired equivalent duty-cycle. Therefore, switching harmonic suppression is achieved for improved communication performance with PSDM. Simulation and experimental results are presented to validate the proposed strategy.