Analysis of a Capacitively Isolated Inverter

Abstract

This paper proposes a transformerless, capacitively isolated inverter employing a full-bridge topology. Unlike conventional capacitively isolated converters, the proposed design eliminates the mean voltage across the isolation capacitors, significantly reducing voltage stress. A previous experimental validation of a capacitive isolated DC/DC converter demonstrated operation at switching frequencies up to 500 kHz and power levels of 6 kW (500 V, 12 A), achieving a peak efficiency exceeding 98% with negligible loss contribution from the isolating capacitors. Building on these results, the topology is extended to a single-stage inverter to leverage capacitive isolation for loss minimization. The inverter design was simulated, and key operating waveforms are presented to validate its functionality. Analysis of the DC/DC converter assessed the rectifying diodes as dominant contributors to power losses at elevated switching frequencies and are omitted in the inverter stage. This elimination, combined with the minimal impact of isolating capacitors, enables a projected inverter peak efficiency exceeding 99%, as derived from experimental data and analytical modeling.