| 摘要 |
PURPOSE: To detect the temperature of the rotor of a motor and compute the value of secondary resistance by installing a phototransistor on the stator side in a position convenient for it to receive infrared rays generated from the coils of the rotor, and placing nearby a thermistor for detecting the temperature of primary coils. CONSTITUTION: A phototransistor 16 is installed on the stator of a three-phase induction motor 8. When a current is passed through secondary coils 11, the coils produce heat. This increases the temperature of a rotor 10, which then radiates infrared rays. Since the phototransistor 16 is disposed in a position convenient for it to receive the infrared rays, it detects the temperature of the rotor 10. When the temperature of the rotor 10 is increased, the resistance of the secondary coils 11 varies. The temperature of the secondary coils 11 is in proportion to that of the rotor 10; therefore, the resistance of the secondary coils 11 can be calculated from the temperature of the rotor. Even if the resistance of the secondary coils 11 is varied due to temperature, as a result, it is possible to continue intended efficiency-oriented, torque-oriented or high speed-oriented operation. |
