A power control system may use power semiconductor devices such as insulated gate bipolar transistors (IGBT's) in a switching unit to provide motor control. The IGBT's may be cooled with a system that is configured and sized to provide proper cooling at steady-state operating conditions of the switching unit. The IGBT's may be placed in thermal communication with a compartment that may contain phase change material (PCM). When and if the switching unit is operated under transient high load conditions, excess heat may be absorbed by melting of the PCM. When steady state operating conditions are restored the PCM may solidify and release its latent heat to a coolant. The PCM may thus act as a thermal buffer for the cooling system and thus may provide that the cooling system may be minimally sized.