This digest proposes a new full-range zero-voltage switching (ZVS) modulation technique for the DC-link voltage balancing circuit, utilizing a resonant switched-capacitor converter (RSCC) to improve efficiency in split-phase inverter applications. A DC-link voltage balancer is needed for a split-phase inverter to compensate load imbalance between two output phases and commonly operates under slight unbalanced (light-load) conditions. While the existing phase-shift control of RSCC can achieve high efficiency with ZVS operation, it has inherent non-ZVS regions, and a notable efficiency decline at light-loads. Light load efficiency decline is also evident with the typical zero-current switching (ZCS) modulation of the RSCC. To address these issues and to improve efficiency across the entire load-range, the proposed ZVS modulation scheme for the RSCC introduces additional boost subintervals to maintain a minimum current, ensuring ZVS for all switching devices. Experimental results from a 5-kW hardware prototype confirmed the efficiency improvement for both balanced and unbalanced load conditions over the full load-range.
