Rotation drive control circuit of multiphases direct current motor and the start-up method thereof

Abstract

In start-up control of a motor in which currents are caused to flow through any two of three phase coils to detect the polarity of a voltage induced in each de-energized phase, thereby determining the corresponding energized phase at start-up thereof, based on the polarity of the detected induced voltage, the levels of induced voltages are detected in addition to the polarity of the induced voltage for the de-energized phase to thereby determine the relationship between the magnitudes thereof, and the energized phase at the start-up is determined based on the relationship of magnitude between the polarity of each induced voltage and the level thereof. In drive control of a multi-phase DC motor wherein a driver for allowing a drive current to flow through each coil is controlled by PWM control signals, and a sine wave-shaped current is caused to flow through each coil to thereby rotatably drive the motor, positive-phase and negative-phase signals are generated as triangular wave carrier signals for generating the PWM control signals, and the PWM control signal related to the corresponding phase coil of the respective phase coils, to which a voltage of an intermediate level is applied by the driver, is generated using a carrier signal opposite in phase to a triangular wave signal used to generate the PWM control signals for other phase coils.