| 摘要 |
PURPOSE:To prevent excess current from flowing to a motor when DC damping is applied to the motor, by computing a PWM pulse pattern according to magnetic flux phase. CONSTITUTION:By a magnetic flux phase computer 3, running frequency command is received and the magnetic flux phase of a motor is computed. By a PWM output unit 4, the pulse pattern of a PWM is computed through the magnetic flux phase from the magnetic flux phase computer 3 and voltage command in proportion to the root-mean-square value of output voltage. As a result, at the time of DC damping, the rotation of the magnetic flux phase is stopped first, and with one voltage vector closest to the magnetic flux phase in the rotational direction among voltage vectors used for the PWM pattern in the phase, and a zero vector, damping voltage is formed. |
