초록 ▼

An angular position detector for generating trains of A- and B-phase pulses which are 90.degree. out of phase with each other and a C-phase pulse per rotation are mounted on a permanent-magnet synchronous motor such that a magnetic pole origin of permanent magnets and a position where the C-phase pu

An angular position detector for generating trains of A- and B-phase pulses which are 90.degree. out of phase with each other and a C-phase pulse per rotation are mounted on a permanent-magnet synchronous motor such that a magnetic pole origin of permanent magnets and a position where the C-phase pulse is generated agree with each other. After a power supply voltage is applied and in an initial stage before the permanent-magnet synchronous motor is operated normally, a motor control apparatus operates a current control loop with an alternating current command having a constant amplitude and a low frequency to supply an alternating current having a low frequency to the permanent-magnet synchronous motor for thereby rotating the rotor of the permanent-magnet synchronous motor from a stop at a low speed. The motor control apparatus then detects arrival at a magnetic pole reference when a C-phase pulse is detected, and detects an angular displacement of the magnetic poles of the rotor using counts of the A- and B-phase pulses counted in synchronism with the rotation of the rotor after the C-phase pulse is detected.

대표청구항 ▼

[ We claim:] [1.] A method of starting a permanent-magnet synchronous motor in a permanent-magnet synchronous motor system which includes the permanent-magnet synchronous motor which has a rotor having permanent magnets as magnetic poles for driving the rotor, and an angular position detector mounte

[ We claim:] [1.] A method of starting a permanent-magnet synchronous motor in a permanent-magnet synchronous motor system which includes the permanent-magnet synchronous motor which has a rotor having permanent magnets as magnetic poles for driving the rotor, and an angular position detector mounted on a rotatable shaft of the permanent-magnet synchronous motor and having an A- and B-phase pulse train generating means for generating a number of A- and B-phase pulses per rotation which have respective electrical angles that are 90.degree. out of phase with each other and a C-phase pulse train generating means for generating a C-phase pulse per rotation, and a motor control apparatus having a speed control loop and a current control loop for energizing the permanent-magnet synchronous motor said angular position detector being installed such that a magnetic pole reference of the permanent magnets of the rotor and a position where the C-phase pulse is generated agree with each other, said method comprising the steps of:when a power supply voltage is applied and in an initial stage before the permanent-magnet synchronous motor is operated normally, for starting to operate the permanent-magnet synchronous motor, supplying an angular displacement signal for a current command to the current command loop at a predetermined angle in each preset unit time, operating the speed control loop with a speed signal, which represents an angle change in said each preset unit time, as a command for a speed controller, for thereby controlling an amplitude of said current command, causing said motor control apparatus to supply an alternating current having a low frequency to the permanent-magnet synchronous motor for thereby rotating the rotor of the permanent-magnet synchronous motor from a stop at a low speed; anddetecting arrival at the magnetic pole reference when a C-phase pulse is detected, switching the angular displacement signal for the current command to an angular displacement signal for the current command which is produced using counts of the A- and B-phase pulses counted in synchronism with the rotation of the rotor with the position of the C-phase pulse being used as an origin, and switching the command for the speed controller to a predetermined speed command for the speed control to a predetermined speed command for thereby operating the permanent-magnet synchronous motor.