Thermal management of three insulated-gate bipolar transistor (IGBT) modules with application in power inverters is studied numerically with two different cooling approaches, an air-cooled heat sink and a liquid-cooled cold plate. Four air-cooled heat sink configurations have been studied and compared: a natural-convection configuration, a forced parallel-flow configuration, and two forced impingement-flow configurations with different fans. For the cold plate, a suitable coolant is chosen based on the operating conditions of the current study. The maximum total heat dissipation rate of the three IGBT modules, which includes switching and conductive power dissipation rates, is calculated to be 1200 W at peak load. The air-cooled and liquid-cooled cases are studied under a variety of operating conditions, including different ambient temperatures and heat dissipation rates. The results show that natural convection can only be used for total heat dissipation rates below 300 W. Whereas, the forced impingement-flow air cooling configuration with large fans and the liquid cooling configuration can keep the junction temperature of the IGBTs below the maximum permissible value under all the operating conditions used in this study. The liquid-cooled cold plate has the lowest thermal resistance and because of retaining the largest safety margin for junction temperature, this method is suitable for power dissipation rates higher than 1200 W. The results indicate that the performance of the air-cooled heat sinks is not a strong function of air flow direction and mainly depends on air flow rate.