Soft-switched DC-DC Converter with 240CPWM in DC-AC Inverter for Highly Efficient EV/HEV Powertrains

240°-Clamped Pulse Width Modulation (240CPWM) is the lowest switching-loss PWM for cascaded architectures consisting of a DC-DC stage followed by a DC-AC stage. At unity power factor, 240CPWM reduces switching losses in the DC-AC stage by 85% compared to conventional Space Vector PWM (CSVPWM). This method requires a six-pulse, dynamically varying DC link voltage, which is shaped by the front-end DC-DC converter, making it suitable for two-stage architectures. However, an extra power stage (DC-DC converter) in cascaded architecture reduces overall efficiency in electric and hybrid electric vehicle (EV/HEV) powertrains compared to single-stage topologies. To address this, we propose a high-efficiency powertrain that minimizes losses in both stages simultaneously. The DC-DC stage employs a soft-switching technique while the DC-AC stage uses 240CPWM. The coordinated control of both the stages is implemented for seamless operation. The detailed loss breakdown of both the DC-DC and DC-AC stages is presented analytically and then verified experimentally. Experimental results demonstrate that the proposed architecture achieves an overall efficiency of 96.16% for the DC-DC and DC-AC stages combined, compared to 92.65% for a cascaded architecture with a hard-switched DC-DC stage followed by a DC-AC stage with CSVPWM, demonstrating 3.51% improvement in overall powertrain efficiency. This efficiency improvement is achieved while maintaining a similar total harmonic distortion (THD) of around 5% in the line currents compared to the conventional architecture.