Abstract: In an electric vehicle, the traction motor is driven from a battery by way of a controllable electric power switcher. In operation of the switcher, the power losses of the switches depends upon the power being handled; during acceleration the power is high, and at constant speed on level ground the power is small. Thus, the power “dissipated” by the switches varies with time. A cooler transfers heat from the switcher. During acceleration, the cooler may not be sufficient to limit the instantaneous switch temperature. A phase-change heat “sink” coupled to the switches absorbs heat from the switches during hard acceleration, and returns the heat to the cooler under more constant-speed conditions.

Abstract: In an electric vehicle, the traction motor is driven from a battery by way of a controllable electric power switcher. In operation of the switcher, the power losses of the switches depends upon the power being handled; during acceleration the power is high, and at constant speed on level ground the power is small. Thus, the power “dissipated” by the switches varies with time. A cooler transfers heat from the switcher. During acceleration, the cooler may not be sufficient to limit the instantaneous switch temperature. A phase-change heat “sink” coupled to the switches absorbs heat from the switches during hard acceleration, and returns the heat to the cooler under more constant-speed conditions.

Abstract: In an electric vehicle, the traction motor is driven from a battery by way of a controllable electric power switching arrangement. In normal operation of the switches of the switching arrangement, the power losses or heating of the switches depends upon the power being handled; during hard acceleration the power is high, and at constant speed on level ground the power is relatively small. Thus, the power “dissipated” by the switches varies with time. A cooling system transfers heat from the switching arrangement to ambient. During acceleration, the cooling system may not be able to limit the instantaneous temperature of the switches to the desired value. A phase-change heat “sink” coupled to the switches absorbs heat from the switches during hard acceleration, and returns the heat to the cooling system under more constant-speed conditions.