| 摘要 |
PROBLEM TO BE SOLVED: To prevent insulation deterioration of the winding of a motor due to overheating when the motor is overloaded, and to prevent the rotor and the stator of the motor from coming into contact with each other due to the thermal expansion of the rotor caused by the heat of the rotor, by detecting the relative displacement between the stator and the rotor and, at the same time, controlling the output of the motor by discriminating the loaded condition of the motor from the detected displacement. SOLUTION: A displacement sensor 9 detects the relative displacement between the stator 5 and the rotor 6 of a motor due to the thermal expansion of the rotor 6, and an arithmetic device 11 of a control section 10 compares the detected displacement with a preset amount of thermal expansion and, when the detected displacement exceeds the preset amount, outputs a command to an inverter 12 of the control section 10 to lower the output of the motor. The inverter 12 controls the output of the motor by suppressing the electric current supplied to the stator 5, until the detected displacement becomes smaller than the preset amount. Therefore, the insulation deterioration of the winding 8 of the motor and the contact between the stator 5 and the rotor 6 caused by overheating can be prevented. |
