Lifetime Evaluation of Switching Devices for High-Power ELF Inverter

ELF inverter is widely used in deep ground resource detection, earthquake prediction as well as underwater communication. Because ELF inverter is of high power level and operates at extremely low-frequency range lower than 30Hz even at 0.1 Hz, it requires relatively high reliability to ensure long-term stable operation. Since the operation frequency of ELF inverter is of extremely low-frequency, the reliability evaluation of switching devices in common cases will not be applicable. This paper analyzes the instantaneous power loss of switching devices over time at different ELF operation frequency under 1kW. Based on switching devices thermal model, the variation of junction temperature over time at different ELF operation frequency is obtained and verified by simulation results. Lifetime of switching devices at different ELF operation frequency is evaluated using Coffin-Manson-Arrhenius model. Analysis and simulation results can illustrate the influence of ELF operation frequency on the thermal behavior and lifetime of switching devices providing guidance for high-power ELF inverter design and maintenance.