Patent ID: 8423317

Claim:
A power conversion apparatus comprising: a power rectifying portion, a smoothing portion, and a power inverting portion including a plurality of power semiconductor devices to provide 3-phase AC power as an output to a load, a cooling fin to which the power semiconductor devices are attached, a circuit board mounted on the cooling fin, and a thermistor mounted on the circuit board to provide a detection output of temperature measured by said thermistor, wherein the thermistor is directly connected to a pattern wiring which is formed on the circuit board and is electrically connected to an emitter terminal or a collector terminal of one of the power semiconductor devices, and a photo coupler connected between the detection output of the thermistor and a control circuit for determining a temperature of the thermistor from the detection output and for controlling electric power applied to the power inverting portion, to provide the detection output of the thermistor to the control circuit in an electrically isolated state.