A simple approach of generating CPWM for reducing conducted emission in switched mode power supplies

In this work, the problem of improving the performance of switched mode power supply (SMPS) by reducing the electromagnetic interference (EMI) using simplified chaotic pulse width modulation (CPWM) generation method is addressed. The key is the generation of CPWM by modulating chaotic pulse position modulation (CPPM) and PWM. The advantage of the scheme is the simplicity and the easy implementation in the feedback path of the converter without the need of any huge external chaotic generator circuit. The proposed method is found to be effective in reducing the peak EMI in SMPS. The effectiveness of the proposed method on spreading those dominating frequencies, compared to the conventional PWM scheme is evaluated by spectral analysis. Finally, levels of conductive EMI are experimentally verified to comply with the CISPR 22 regulations.