Motor driving device and detection method for detecting malfunction in heat radiation performance of heatsink

A motor driving device comprising:

• a heat generating element;
• a heatsink which cools the heat generating element;
• an electric power detecting part which detects a consumed power of the heat generating element;
• a temperature detecting part which detects a temperature of the motor driving device;
• a temperature change calculating part which calculates an amount of change in the temperature within a predetermined time as a detected amount of change, based on the temperature detected by the temperature detecting part;
• a reference determination part which determines a reference amount of change in the temperature, based on the temperature detected by the temperature detecting part and on the consumed power detected by the electric power detecting part;
• a temperature change judging part which compares the reference amount of change determined by the reference determination part with the detected amount of change calculated by the temperature change calculating part, and judges whether the detected amount of change is different from the reference amount of change;
• and
• a steady state judging part which judges whether a temperature change of the motor driving device is in a steady state, wherein
• the temperature change calculating part calculates the detected amount of change when the steady state judging part judges that the temperature change of the motor driving device is not in a steady state.