摘要 |
If there is a possibility of a coolant of a cooler being frozen, switching elements are made to generate heat by feeding a current through the switching elements. Two kinds of sensors for measuring a temperature on the side of a heat receiving portion and the side of a heat radiating portion are installed for the cooler. The thermal resistance of the whole of the cooler is calculated from an amount of heat generated by the current of the switching elements, the temperature on the side of the heat receiving portion, the temperature on the side of the heat radiating portion. If the value of the thermal resistance is equal to or higher than a certain value, it is determined that the coolant is frozen. When it is determined that the coolant is frozen, the thermal resistance of the cooler is calculated, and warm-up operation is started. |