Spread Spectrum Technique for Decreasing EM Noise in High-Frequency APWM HB Resonant Converter With Reduced EMI Filter Size

A spread spectrum technique (SST) has been proposed as a solution to mitigate electromagnetic (EM) interference in power converters. In the previous research, the SST has been widely applied to the power converters that have insensitive voltage gain according to switching frequency variation, such as buck, boost and flyback topologies. However, resonant converters have sensitive voltage gain according to the switching frequency variation, which cannot regulate the output voltage with the SST. In this paper, a high-frequency (HF) half-bridge (HB) resonant converter employing the SST is developed for power supply applications with 100-W power capability. The design methodology of its resonant tank and the SST is proposed to obtain the tight output voltage regulation performance and the EM noise reduction. In addition, the size reduction of EM noise filters is analyzed by employing the SST. The output voltage regulation performance and the filter size reduction will be experimentally verified using a 100-W prototype HF HB resonant converter.