| 摘要 |
A synchronous motor control system includes a synchronous motor 1, an inverter 3 and a controller 4 wherein a current differential detecting unit 13 detects a variation of a motor current when the three phases of the motor 1 is short circuited by the inverter 3, namely at the moment when a carrier wave in a PWM signal generator 9 assumes maximum or minimum value, in a calculating unit 14 a phase gamma from alpha axis of a stationary coordinate system to a three phase short circuited current differential vector is calculated, a phase delta is estimated from d axis to the three phase short circuited current differential vector by making use of d axis current id and q axis current iq on d-q axes coordinate system in the controller 4, thereafter the magnetic pole position theta with respect to alpha axis is calculated from the phases gamma and delta, based on thus calculated magnetic pole position theta, d-q axes control units 11, 7 and 8 are constituted to control the synchronous motor, thereby a highly reliable control system for the motor which permits a detection of the magnetic pole position without affecting a state of applied voltage thereto while performing a usual PWM control with a low cost controller.
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