EMI Filter Size Reduction using Balance in PFC converters
CPES has proposed balance technique to reduce common mode (CM) noise of PFC converters. It is simple and effective compared to other CM noise reduction techniques. The biggest challenge of noise reduction is how to minimize the high frequency noise where parasitics play important part in the noise propagation. High frequency model is proposed for the balance technique to predict its CM noise emission. Guidelines are provided to achieve CM noise reduction up to 10 MHz. EMI filters are designed to demonstrate the benefit of balance technique on EMI filter size reduction. With balance technique, CM choke size can be reduced by 88% and the total EMI filter size (including both CM and DM filter) can be reduced by 20%.