| 摘要 |
PURPOSE:To rotate rapidly and stably at a set speed by obtaining a presumed phase angle form a predetermined time until an induction motor compensated for starting at a predetermined phase angle reaches the set speed, and then using the presumed phase angle as an initial value. CONSTITUTION:When set rotating speed data NS is inputted to a terminal 12, a start signal is input to a terminal 8, and a starting compensating phase angle phi2 is inputted to a terminal 11, a start compensator 7 is set, a trigger pulse of phase phi2 is generated from an output terminal Q of a generator 5, and a motor 3 is started via a triac 2. The rotating speed detected by a sensor 6 is compared with the output of a subtracter 13 by a coincidence detector 14, a time until it arrives at the set rotating speed is measured by a measuring unit 15 to obtain a rising time of a motor to a predetermined speed. A calculator 16 presumes a phase angle for maintaining the set rotating speed NS from the rising time, sets the presumed phase angle in an integrator 18, generates a trigger pulse by the generator 5, and maintains the rotation of the motor 3 via the triac 2. Thus, even if a load and a power source voltage are varied, a stable rotation is obtained. |
