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

Abstract

A motor driving device capable of reliably detecting a malfunction in the performance of a heatsink. The motor driving device includes a heat generating element, a heatsink, an electric power detecting part for detecting a consumed power of the heat generating element, a temperature detecting part for detecting a temperature of the motor driving device, a temperature change calculating part for calculating, as a detected valuation, an amount of change in the temperature within a predetermined time, a reference determination part for determining a reference amount of change in the temperature based on the temperature and the consumed power, and a temperature change judging part for comparing the reference amount of change with the detected amount of change, and judges whether the detected change is different from the reference change.

1 . 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; and   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.   
     
     
         2 . The motor driving device according to  claim 1 , wherein the temperature change judging part judges that the detected amount of change is different from the reference amount of change when the detected amount of change is out of an allowable range which is predetermined so as to include the reference amount of change. 
     
     
         3 . The motor driving device according to  claim 1 , wherein the temperature change judging part judges whether the detected amount of change is different from the reference amount of change when the consumed power is zero and the detected amount of change is a negative value. 
     
     
         4 . A motor driving device according to  claim 1 , further comprising:
 a fan which generates an air flow in the heatsink;   a rotation number detecting part which detects a rotation number of the fan; and   a rotation number judging part which judges whether the rotation number detected by the rotation number detecting part is different from a predetermined reference rotation number of the fan when the temperature change judging part judges that the detected amount of change is different from the reference amount of change.   
     
     
         5 . The motor driving device according to  claim 1 , further comprising a malfunction signal generating part which generates a signal indicating that a malfunction occurs in a performance of the heatsink when the temperature change judging part judges that the detected amount of change is different from the reference amount of change. 
     
     
         6 . The motor driving device according to  claim 4 , further comprising a malfunction signal generating part which:
 generates a signal indicating that a malfunction occurs in a performance of the heatsink when the temperature change judging part judges that the detected amount of change is different from the reference amount of change and the rotation number judging part judges that the rotation number is not different from the reference rotation number; and which   generates a signal indicating that a malfunction occurs in an operation of the fan when the temperature change judging part judges that the detected amount of change is different from the reference amount of change and the rotation number judging part judges that the rotation number is different from the reference rotation number.   
     
     
         7 . A motor driving device according to  claim 1 , further comprising 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.   
     
     
         8 . The motor driving device according to  claim 7 , wherein the steady state judging part judges that the temperature change of the motor driving device is in a steady state when the consumed power is constant for a predetermined period of time. 
     
     
         9 . The motor driving device according to  claim 7 , further comprising:
 a thermal resistance calculating part which calculates a thermal resistance of the motor driving device based on the consumed power and the temperature detected by the temperature detecting part when the steady state judging part judges that the temperature change of the motor driving device is in a steady state; and   a thermal resistance judging part which judges whether the thermal resistance calculated by the thermal resistance calculating part is different from a predetermined reference thermal resistance.   
     
     
         10 . A method of detecting a malfunction in the heat radiation performance of a heatsink provided at a motor driving device, the method comprising:
 detecting a consumed power of a heat generating element provided at the motor driving device;   detecting a temperature of the motor driving device;   calculating an amount of change in the temperature within a predetermined time as a detected amount of change, based on the detected temperature;   determining a reference amount of change in the temperature based on the detected consumed power and the detected temperature; and   comparing the determined reference amount of change with the calculated detected amount of change, and judging whether the detected amount of change is different from the reference amount of change.