| 摘要 |
PURPOSE:To eliminate the variation in the control characteristics the inverter irrespective of the variation in the secondary resistor in response to temperature by detecting the torque operation of the primary current of and exciting current component of the motor and controlling slip frequency and primary voltage thereof. CONSTITUTION:An induction motor 4 is energized through a PWM inverter 3. Its torque operation component is picked up on the basis of the primary current dtected by a current detector 8, the motor speed of the speed detector 8, and a command of a speed instructing circit 5, and are applied through 2-phase oscillator 12 to multipliers 16, 17. On the other hand, exciting current component is synthesized with the torque operation component through the multiplier 15 with the difference signal between the current component detector 9 and the exciting current instructing circuit 13, and the inverter 3 is controlled through a comparator 20 and a gate amplifier 21. Since the secondary resistance is accordingly varied according to the temperature, the effective component of the primary current can be controlled to predetermined value, and the variation in the torque can be prevented beforehand. |
