Comparative Evaluation of ARCP and Three-Level TCM Soft-Switching Bridge-Legs for High-Frequency SiC Converter Systems

Abstract

Soft-switching bridge-legs facilitate high-efficiency three-phase PV inverters or PFC rectifiers. By extending a half-bridge with a resonant auxiliary circuit, including two additional transistors, zero-voltage switching (ZVS) of the main transistors can be realized (Active Resonant Commutated Pole, ARCP). Alternatively, a similar T-type bridge-leg structure achieves ZVS by operating the output filter inductor with a sufficiently high current ripple (with 3-level Triangular Current Modulation, 3L-TCM). We provide a comparative evaluation of these two concepts for the realization of 2.2 kW (per phase), 800 V DC bridge-legs with latest-generation 1200 V and 650 V SiC MOSFETs, discussing chip-area optimization, filter design for compliance with current and future EMI limits, and qualitative limits and design criteria. The calculated loss-vs.-volume Pareto fronts indicate advantages for the 3L-TCM approach, with peak switching frequencies of 72 kHz or 144 kHz and an efficiency (semiconductors and EMI filter) of about 99.6 %. The ARCP concept seems more suitable for applications that do not necessarily require EMI filters but benefit from limited switch-node dv/dt (in the order of 1.5 V/ns) such as variable-speed drives.