Drive unit of synchronous motor
View Patent ↗Provided is drive unit of a synchronous motor capable of improving the accuracy of magnetic flux operations with a simple configuration. To this end, the drive unit has a magnetic flux operation part which, in the case where a direction of a magnetic field pole of the synchronous motor is regarded as a d-axis and a direction orthogonal to the d-axis is regarded as a q-axis, calculates a magnetic flux of the d-axis and a magnetic flux of the q-axis on the basis of a current of the d-axis, a current of the q-axis, and a field current of the synchronous motor; and a magnetic flux operation error correcting part which calculates a phase difference between an input voltage and an input current of the synchronous motor and corrects an inner-phase difference angle calculated from the magnetic flux of the d-axis and the magnetic flux of the q-axis on the basis of the phase difference.
1. A drive unit of a synchronous motor comprising:
a magnetic flux operation circuitry configured to, in the case where a direction of a magnetic field pole of the synchronous motor is regarded as a d-axis and a direction orthogonal to the d-axis is regarded as a q-axis, calculate a magnetic flux of the d-axis and a magnetic flux of the q-axis on the basis of a current of the d-axis, a current of the q-axis, and a field current of the synchronous motor; and
a magnetic flux operation error correcting circuitry configured to
calculate a phase difference between a voltage and a current of the synchronous motor being inputted into the magnetic flux operation error correcting circuitry;
calculate an inner-phase difference angle from the magnetic flux of the d-axis and the magnetic flux of the q-axis, wherein the inner-phase difference angle=tan −1 X, where X=(the magnetic flux of the q-axis)/(the magnetic flux of the d-axis); and
correct the inner-phase difference angle on the basis of the phase difference, wherein
the drive unit is configured to drive the synchronous motor with the corrected inner-phase difference angle, and
the magnetic flux operation error correcting circuitry calculates a corrected magnetic flux of the q-axis on the basis of the magnetic flux of the d-axis, the magnetic flux of the q-axis, and the corrected inner-phase difference angle, wherein the corrected magnetic flux of the q-axis=√{square root over (A)}·sin B, where A=(the magnetic flux of the d-axis) 2 +(the magnetic flux of the q-axis) 2 , and B=the corrected inner-phase difference angle.
2. The drive unit of the synchronous motor according to claim 1 , wherein the magnetic flux operation error correcting circuitry calculates the phase difference on the basis of a voltage reference and a current detection value of the synchronous motor being inputted into the magnetic flux operation error correcting circuitry.
3. The drive unit of the synchronous motor according to claim 1 , wherein the magnetic flux operation error correcting circuitry calculates the phase difference on the basis of a voltage detection value and a current detection value of the synchronous motor being inputted into the magnetic flux operation error correcting circuitry.