| 摘要 |
PROBLEM TO BE SOLVED: To provide a PWM motor-drive device that drives each phase of a motor with pulses and controls the electric energy to be supplied to the motor according to the duty ratio of the pulses, and more smoothly controls the motor. SOLUTION: A three-phase forming circuit 2 generates absolute signals Z1, Z2, and Z3 that are obtained by calculating the absolute value of signals A1, A2, and A3 being outputted from a Hall amplifier 1. A ripple cancellation circuit 3 generates a ripple cancellation signal ICAN whose waveform becomes similar to that obtained by the minimum value of the absolute signals Z1, Z2, and Z3. Then, the duty ratio of pulses for driving each phase of a motor according to the signals obtained by adding a signal ICTL according to the error between the actual speed of the motor being outputted from a control amplifier 4 and a setting speed to the ripple cancellation signal ICAN is controlled.
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