Patent ID: 8575885

Claim:
A motor drive system comprising: a motor comprising a plurality of phase coils of five phases or more, in which, among the plurality of phase coils, first and second phase coils, the phases of which are not adjacent to each other, are connected to each other; third and fourth phase coils, the phases of which are not adjacent to each other, are connected to each other; and the first phase coil, the third phase coil, and a fifth phase coil are connected in a star connection; an inverter connected to one end of each of the phase coils, the inverter being configured to convert a DC power into an AC power and supply the AC power to each phase of the motor; a power relay configured so as to be able to cut off a supply power to at least one phase coil among the plurality of phase coils of the motor by using a first contact point disposed at other ends of the first and second phase coils and interposed between the star-connected coils, a second contact point disposed at other ends of the third and fourth phase coils and interposed between the star-connected coils, and a third contact point disposed at another end of the fifth phase coil and interposed between the star-connected coils; and a control unit that generates a control signal for the inverter and thereby controls driving of the motor, wherein, when one or more phase of the motor fails, the control unit opens a contact point of the power relay corresponding to the failed phase and drives three or more phases that are disposed at roughly equal phase-intervals among a plurality of remaining phases.