Feasibility study of a 55-kW air-cooled automotive inverter

The purpose of this study is to determine the thermal feasibility of an air-cooled 55-kW power inverter with SiC devices. Air flow rate, ambient air temperature, voltage, and device switching frequency were studied parametrically by performing transient and steady-state simulations. The transient simulations were based on inverter current that represents the US06 supplemental federal test procedure from the US EPA. The results demonstrate the thermal feasibility of using air to cool a rectangular-shaped 55-kW SiC traction drive inverter. When the inverter model is subject to one or multiple current cycles, the maximum device temperature does not exceed 146°C for an inlet flow rate of 270 cfm, ambient temperature of 120°C, voltage of 650 V, and switching frequency of 20 kHz. The results show that the ideal blower power input for the entire inverter with a total inlet air flow rate of 540 cfm is 105 W.