| 摘要 |
PURPOSE:To always fix a phase pull-in point without influences due to such as the change of load to be applied to a motor or offset of a system by detecting a phase error of a rotational phase signal from a reference signal by a digital procedure. CONSTITUTION:A phase error detector 9 inputted with a phase error signal (g) obtained from a digital phase comparator 2 samples the digital phase error signal (g) at the time of phase pull-in and writes the sampled value in a memory to calculate the average value as an average phase error phi. When the calculated average phase error phi is larger than an allowable maximum phase error phimax, only '1' is subtracted from an output value. Thereby, an output voltage (q) of a D/A converter 10 is also reduced, a motor current (m) outputted from a driving circuit 5 is increased and the motor 6 is accelerated and driven in a phase advancing direction. If the average phase error phi is smaller than an allowable minimum phase error phimin, only '1' is added to the output value, so that motor current (m) is reduced and the motor 6 is decelerated and driven in the phase delay direction.
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