| 摘要 |
PURPOSE:To diminish torque ripple by feedbacking a motor coil current having a torque ripple cancel waveform. CONSTITUTION:A driving circuit for a brushless motor 19 is composed of a magnetoresistance element 11, a comparator 14 of FG pulse from said element 11 via an amplifier 20 with a reference signal a loop compensating filter 17 and a driver 18, and changes a supply current to the motor 19 according to an input voltage. In this case, there is provided a corrective circuit 21. Said corrective circuit 21 produces a torque ripple cancel correction signal by a three-phase back electromotive force waveform. Said correction signal is made to overlap F-V output 15 by an adder 16 and being inputted to said filter 17. Thus, a torque ripple, which is going to be produced in a generated torque as a composite torque, is offset beforehand by a frequency component included in an electric current supplied to a coil. |
