Drive unit of synchronous motor

• US 9,948,223 B2
• Filed: 09/03/2012
• Issued: 04/17/2018
• Est. Priority Date: 09/03/2012
• Status: Active Grant

• Current Assignee: Toshiba Mitsubishi-Electric Industrial Systems Corporation (Toshiba Corporation)
• Original Assignee: Toshiba Mitsubishi-Electric Industrial Systems Corporation (Toshiba Corporation)
• Inventors: Ishida, Takashi
• Primary Examiner(s): Santana, Eduardo Colon
• Assistant Examiner(s): COOK, CORTEZ M
• Application Number:
  US14/420,948
• Publication Number:
  US 20150222215A1
• Time in Patent Office: 2,052 Days
• Field of Search: 31840002, 318727
• CPC Class Codes: H02P 21/10 Direct field-oriented control; Rotor flux feed-back control
• CPC Class Codes: H02P 21/141 Flux estimation
• CPC Class Codes: H02P 25/024 controlled by supply frequency

Abstract

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.

Claims

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<sup>−

1</sup> 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.