Excessive temperature detecting system of electric motor controller

An excessive temperature detecting system of an electric motor controller comprising an inverter device for controlling driving electric power supplied to a motor arranged in a vehicle by controlling a semiconductor element for large electric power;

• a voltage detecting section for detecting the voltage of a filter capacitor inserted on a direct current side of said inverter device;
• an electric current detecting section for detecting an output electric current of said inverter device;
• a temperature detecting section arranged in cooling means of said semiconductor element;
• a junction temperature calculating section for sequentially calculating loss caused by a switching operation of said semiconductor element by a detecting signal from each of said detecting sections, and calculating junction temperature of said semiconductor element on the basis of the calculated loss value;
• and a comparing section for generating an excessive temperature detecting output when an output of said junction temperature calculating section reaches a predetermined allowable temperature.