Patent ID: 8362723
Filing Date: 2013-01-29
Classification: H02P

Abstract:
1. A motor drive circuit that drives a three-phase motor by supplying a drive current to the three-phase motor, the motor drive circuit comprising: a first Hall amplifier, a second Hall amplifier and a third Hall amplifier, each of which is provided for each phase of the three-phase motor and receives a pair of Hall signals from a corresponding phase Hall element to generate each phase sine wave voltage by amplifying a difference between the pair of Hall signals; a first pulse modulation comparator, a second pulse modulation comparator and a third pulse modulation comparator, each of which is provided for each phase of the three-phase motor and compares the corresponding phase sine wave voltage with a periodic voltage to generate each phase pulse modulated signal; a drive unit operative to subject a phase coil, a target to be driven, to pulse drive by using the pulse modulated signal from the corresponding phase pulse modulation comparator; and a gain setting unit that sets a gain of the first Hall amplifier, the second Hall amplifier or the third Hall amplifier based on an error between a detection voltage corresponding to at least one of the sine wave voltages of the first Hall amplifier, the second Hall amplifier and the third Hall amplifier and a torque setting voltage indicating a torque exerted on the three-phase motor.