High-Precision Soft-Switching Converter With Low Voltage Stress and Fast Response Characteristics Based on SiC Power Devices

Due to the characteristic of no blanking time, dual buck topology is attractive in high-precision applications and the bias current is injected to eliminate zero crossing distortion. However, with the extension of bus voltage, it is difficult to ensure the current response speed and accuracy due to the limitation of bias current operation and the impact of parasitic parameters of switching devices. Thus, this article proposes a low voltage stress resonant dual buck soft-switching topology combined with a SiC power device for achieving fast response and high precision. At first, the principle of the bias current and soft-switching topology is introduced. Then, combined with the bias current decoupling and the realization of zero current switching and zero voltage switching, the control strategy is analyzed. Moreover, based on the resonant circuit considering parasitic parameters, the factors that affect the voltage and current stress are presented. Finally, a prototype of 500 V bus voltage with 100 kHz switching frequency is built to verify the theory analysis.