| 摘要 |
<P>PROBLEM TO BE SOLVED: To highly precisely detect current zero cross even if detection of current zero cross timing is required in a non-PWM period when a PWM operation is not performed. <P>SOLUTION: A motor drive is provided with a drive circuit 2 including a plurality of half bridge circuits, a current phase detecting circuit 11 detecting a phase difference of current flowing in the drive circuit 2, a voltage signal generating circuit 10 receiving a signal from the current phase detecting circuit 11 and generating motor driving voltage of a prescribed profile, a PWM modulating circuit 14 making generated motor driving voltage into the signal by pulse width modulation, an overmodulation time current phase detection control circuit 15 receiving an output signal from the PWM modulating circuit 14 and an output signal from the voltage signal generating circuit 10 and detecting a current phase of the signal passing through the current phase detecting circuit 11 during overmodulation, and a driving signal generating circuit 9 receiving the output signal from the PWM modulating circuit 14 and an output signal from the overmodulation time current phase detection control circuit 15 and driving a half bridge circuit. <P>COPYRIGHT: (C)2009,JPO&INPIT |
