Control device equipped with motor protection function

A motor control device, comprising:

• position detecting means for detecting an angular position of a motor;
• speed control means for controlling a speed of the motor based on the angular position of the motor detected by the position detecting means;
• temperature estimation means for estimating a temperature of the motor from a current command value or a torque command value calculated by the speed control means;
• current control means for cutting off passage of current to the motor when the temperature of the motor estimated by the temperature estimation means reaches a threshold;
• operational state determination means for determining based on the angular position of the motor detected by the position detecting means that the motor is in a locked state when the angular position of the motor does not change and that the motor is in a rotating state when the angular position of the motor changes;
• and
• threshold change means for setting the threshold as a first threshold when it is determined by the operational state determination means that the motor is in a rotating state and setting the threshold as a second threshold, which is smaller than the first threshold, when it is determined by the operational state determination means that the motor is in a locked state.

A motor control method, comprising:

• a position detecting process for detecting an angular position of a motor;
• a speed control process for controlling a speed of the motor based on the angular position of the motor detected by the position detecting process;
• a temperature estimation process for estimating a temperature of the motor from a current command value or a torque command value calculated by the speed control process;
• a current control process for cutting off passage of current to the motor when the temperature of the motor estimated by the temperature estimation process reaches a threshold;
• an operational state determination process for determining based on the angular position of the motor detected by the position detecting process;
• that the motor is in a locked state when the angular position of the motor does not change and that the motor is in a rotating state when the angular position of the motor changes;
• and
• a threshold change process for setting the threshold as a first threshold when it is determined by the operational state determination process that the motor is in a rotating state and setting the threshold as a second threshold, which is smaller than the first threshold, when it is determined by the operational state determination process that the motor is in a locked state.