| 摘要 |
PROBLEM TO BE SOLVED: To enable acquisition of the number of revolutions and the direction of revolution, by connecting an electrical detection circuit for the number of revolutions and the like with the secondary-side rotor of a wound-rotor motor without using a detector. SOLUTION: Output from the light projecting section of a photocoupler 15 is subjected to waveform shaping, voltage limiting and voltage protection by Zener diodes 19, 30 for rectification in a voltage conversion section 34 again A current-limiting resistor 24 protects the current in the light receiving section of the photocoupler 15, and a current-limiting resistor 25 protects the current in the Zener diodes 19, 30 for rectification. An integrator comprising an operational amplifier 28 for integrator, a capacitor 32 and a variable resistor 33 integrates the negative portion of differential waveform, and the magnitude of the integration value is adjusted through the variable resistor 33. The secondary frequency of a wound-rotor motor is inversely proportional to the number of revolutions, and the secondary frequency is reduced with increase in the number of revolutions. Therefore, the output of the operational amplifier 28 for integrator is inversely proportional to the number of revolutions of the wound-rotor type motor. Since the secondary-side frequency and phase are utilized, the number of revolutions and a direction of revolution are acquired regardless of the characteristics, such as voltage, current and resistance, on the secondary side. |
