Experimental Evaluation of Thermal Performance of Oil-Immersed Power Converter

The quest for component size reduction raises concerns regarding device temperatures, particularly in power semi-conductor devices. In the pursuit of improved heat dissipation, several strategies can be used to optimize the heat transfer. This paper investigates the use of an oil immersed converter to enhance temperature performance in power converters. Prototypes were developed and tested in both air and Cargill FR3 oil. The case temperature of the IGBTs was monitored under various test scenarios involving power flow and switching frequency variations. The results consistently demonstrated lower IGBT temperatures in the oil-immersed converter across all test scenarios. In steady state, the temperature difference reached a significant 52% reduction compared to the ambient-air converter at the same operating point. These findings highlight the effectiveness of oil immersion in improving thermal performance in power converters. Hi-Pot tests demonstrate that when submerged in oil, high voltage levels can be applied to the board without experiencing voltage breakdown accompanied by sparks.