Driving circuit for brushless DC motor
AssigneeHitachi, Ltd.
InventorsHiroshi Morozumi, Hiroyasu Kanemaru
Life of this patent
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Abstract
A driving circuit for a brushless DC motor provided with an element for detecting the angular position of the rotor of the motor, characterized in that by the output of the differential amplifier for amplifying the output of the detecting element, a switching element is rendered on and off during a certain portion of the duration of the output of the detecting element and that the motor is rotated at a constant speed by applying a rotation control voltage to an element for energizing the stator winding of the motor during the non-conductive period.
Claims13
A driving circuit for a brushless DC motor consisting mainly of a rotor of permanent magnet having a pair of N and S poles, a stator winding having a plurality of coils and at least one detecting element for detecting the angular position of said rotor;
- said driving circuit comprising
- a first means for amplifying the AC voltage derived from said detecting element and for converting the amplified voltage to an AC current;
- a second means for supplying a predetermined constant current;
- a third means for obtaining a current as the difference of the current from said first means and said constant current from said second means;
- a fourth means for generating a control signal corresponding to a desired speed;
- a fifth means for determining the conduction angle in accordance with the difference current derived from said third means and said control signal derived from said fourth means;
- and
- a sixth means for controlling the currents flowing through said coils of said stator winding in accordance with said conduction angle determined by said fifth means.
Dependencies are inferred from the claim text.