Patent ID: 7095155
Filing Date: 2006-08-22
Classification: H02P

Abstract:
1. A motor drive system comprising a movable body and a plurality of electromagnetic coils disposed as a stator in a non-contact manner on said movable body to which a plurality of permanent magnets alternately magnetized at opposite poles is continuously disposed thereon, and said movable body is capable of moving based on an attraction-repulsion between said movable body and electromagnetic coils generated by supplying an excitation current to said electromagnetic coils; wherein a sensor for detecting the periodical magnetic field change caused by the movement of said permanent magnets, a gain controller for adjusting a peak value of an analog output of the sensor, a rotation direction instruction unit for a motor, and a PWM control unit for creating a pattern for exciting said electromagnetic coils based on an output of said rotation direction instruction unit by performing PWM control on an output of said gain controller, and directly supplying said electromagnetic coils with that pattern as a waveform for driving said electromagnetic coils are provided, wherein said electromagnetic coils are comprised of a two-phased pair of A and B phase coils, said movable body is interposed between said A and B phase coils, a sensor for said A phase coil and a sensor for said B phase coil are provided, and the phase for establishing said A phase coil sensor and said B phase coil sensor is shifted and wherein said movable body is constituted to have a plurality of constitutions in which the heteropolar arrangement of two different permanent magnets constitutes a pair, and, when the position between said heteropolar arrangement constituting a pair is 2π, said A phase sensor and said B phase sensor are able to linearly detect an arbitrary position between said 2π, and said A phase sensor is provided to said A phase coil, and said B phase sensor is provided to said B phase coil.