| CPC H02P 27/06 (2013.01) [H02P 21/22 (2016.02)] | 4 Claims |

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1. A motor drive device that drives a motor using a three-phase alternating current as a power source, the motor drive device comprising:
a rectifier circuit that rectifies the three-phase alternating current to generate a rectified current;
a current detection circuit that detects the rectified current rectified by the rectifier circuit;
a cross point detection circuit that detects a cross point between the rectified current detected by the current detection circuit and a predetermined current value, counts a number of times of the detection of the cross point in one cycle of the three-phase alternating current, and outputs a control signal indicating whether or not to drive the motor based on the number of times of the detection of the cross point in one cycle of the three-phase alternating current; and
a power calculation circuit that calculates a power for driving the motor, wherein:
the cross point detection circuit outputs the control signal indicating that the motor is not to be driven in a case where the number of times of the detection of the cross point in one cycle of the three-phase alternating current is 2, and
the cross point detection circuit suppresses an output of the control signal indicating that the motor is not to be driven, in a case where a power calculated by the power calculation circuit is smaller than a predetermined power value.
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