| 摘要 |
PROBLEM TO BE SOLVED: To obtain a control apparatus by which a voltage sufficient to start an induction motor is given from a PWM inverter and which prevents an excessive current from flowing to the induction motor by a method wherein a forcing amount is added to a d-shaft voltage command value, a q-shaft voltage command value or a voltage-command absolute value only for a prescribed period from the start of the induction motor. SOLUTION: In a start detector 31, a frequency command value (f) and a start command which is issued from the outside are input, and a start signal is output under condition where the start signal exists and that the frequency command value (f) exists. Then, a forcing-amount computing unit 32 outputs a q-shaft-voltage forcing amount and a d-shaft-voltage forcing amount only for a prescribed period so as to be added respectively to a q-shaft-voltage command value and a d-shaft-voltage command-value by addition computing units 33, 34. On the basis of an added forcing amount, a sufficient output voltage is given to an induction motor 2 from a PWM inverter 20, an excessive current does not flow to the induction motor 2, the magnetic flux of the induction motor 2 is established, and the induction motor 2 is accelerated. |
