| 摘要 |
PURPOSE:To accurately control an induction motor against a variation in a secondary resistance due to temperature, etc. by vector-controlling it by always correcting the resistance. CONSTITUTION:A primary current is supplied by a current comparison type PWM inverter 2 to an induction motor 1, and its rotating speed is detected by a resolver 3 and a speed detector 4. A controller A compares the detected speed value with a set speed value, a speed control amplifier 5 proportionally integrates it to output a torque current command value. An exciting current command value is given as a fixed value, and a slip angle frequency calculator 6 obtains a slip angle frequency from both the command values and a secondary time constant. An inverter frequency is obtained by the addition of the slip angle frequency and the detected speed value, and sine and cosine signals are obtained by a trigonometric function generator 7 from the inverter frequency. Multipliers 8, 9 amplitude-regulate the sine and cosine waves with a current command value as an amplitude control signal, and output 3-phase current command values. A calculator B periodically regulates a secondary resistance.
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