Wide-Load-Range Efficiency Improvement for High-Frequency SiC-Based Boost Converter With Hybrid Discontinuous Current Mode

This paper proposes a hybrid current mode between triangular current mode (TCM) and discontinuous current mode (DCM) in order to improve a wide-load-range efficiency for a high-frequency SiC-based boost converter. At rated load, TCM, where the zero-voltage switching (ZVS) is achieved, is used in order to increase the switching frequency and minimize the boost converter. At light load, the hybrid discontinuous current mode (HDCM), where the TCM current is flown during the zero-current interval of DCM, is applied in order to achieve both ZVS and a reduction of a current ripple. This maintains a high efficiency over a wide load range. A 1-kW prototype is realized to compare HDCM over continuous current mode (CCM), DCM, and TCM. Compared to TCM, the root-mean-square current is reduced up to 56.6% with HDCM. Consequently, the efficiency of HDCM at light load of 0.1 p.u. is improved by 3.1%. Compared to DCM, the average-current ripple in HDCM is reduced by 82.3%, whereas the efficiency of HDCM at light load of 0.1 p.u. is improved by 1.5%. Finally, when the current ripple of CCM is designed to be half of TCM, the efficiency of HDCM at rated load is improved by 0.9% compared to CCM.