Optimization of Current Zero-Crossings in a Dead-Time-Effect Elimination PWM for SiC-Device-based High-Switching-Frequency Converters

The dead-time elimination pulse-width-modulation (PWM) can be used to avoid the negative effect of dead-time for high-switching-frequency silicon-carbide (SiC) converters, where the upper and the lower drive pulses are alternately enabled according to the polarity of output currents. However, the alternation of drive pulses can cause current jumps at zero-crossings, distorting the output current. In this paper, to suppress current jumps at zero-crossings, a `dead-time-effect elimination PWM' is developed based on the dead-time elimination PWM, and the modulation waves are further adjusted according to a current threshold. The current clamping phenomena before and after the amplitude-adjustment are analyzed around the current zero-crossing. Finally, the optimized current zero-crossing is verified on a SiC converter at a 100kHz switching frequency, showing the suppressed zero-crossing distortion and improved THD of currents.