Reliability analysis and electrical characterization of a Class-E resonant inverter

One of the most interesting challenges in power electronics is increasing the circuit reliability. This can be achieved by reducing the power losses and, therefore, increasing the power conversion efficiency. Conduction and switching losses in power MOSFETs are the major contributions to the converter overall power loss, which becomes a serious problem in high-power conversion applications. Resonant converters, which represent an interesting solution to reduce switching losses, are based on a resonant tank composed of inductors and capacitors tuned to resonate at a specific frequency. The resonance forms the voltage and/or current waveforms so that, under optimal conditions, the MOSFET turns on at zero-voltage switching (ZVS) and zero-derivative switching (ZCS). This drastically reduces the switching losses. Also, new semiconductor materials such as SiC or GaN are capable to operate at an increased switching frequency and reduced both conduction and switching losses. In this paper, the reliability of a Class-E resonant inverter is analyzed to identify the most critical elements of the circuit. The reliability prediction has been carried out based on MIL-HDBK-217 handbook. The Mean Time Between Failures (MTBF) and the failure rate λp are derived. Voltage and current values of all components utilized in this analysis are based on data achieved by experimental results.