A Four-Switch Single-Stage Common-Ground Buck–Boost Inverter with Series-Capacitor Compensation

This paper proposes a single-stage common-ground series-capacitor-compensated buck–boost inverter (CG-SCC-BBI) for wide-input DC–AC applications. Featuring a common-ground neutral and a series-blocking film capacitor, the topology inherently suppresses high-frequency common-mode leakage-current excitation and blocks the structural DC offset. To counteract frequency-dependent voltage attenuation caused by the output network, a fundamental-frequency equivalent model is derived to pre-scale the modulation reference and fully restore output voltage amplitude. The four-switch power stage operates with single-active-leg PWM, confining high-frequency switching to a single half-bridge at any instant to significantly reduce the switching-loss budget. Furthermore, by eliminating the conventional line-frequency output filter choke and utilizing film capacitors exclusively, the topology completely avoids electrolytic capacitors, thereby enhancing long-term operational reliability and lifespan. The proposed inverter supports seamless transition between boost and buck operating modes across the entire input-voltage range. Its operating principles are validated through time-domain simulations, and these were experimentally verified on a 300 W SiC MOSFET standalone laboratory prototype. Experimental results confirm correct operation from 95 V to 400 V DC input, achieving maximum measured efficiencies of 96.79% at the rated 300 W under low-input operation and 97.66% at the rated 300 W under high-input operation, while maintaining an output-current total harmonic distortion (THD) below 2.5%.