Motor control apparatus

• US 6,768,280 B2
• Filed: 06/26/2002
• Issued: 07/27/2004
• Est. Priority Date: 06/29/2001
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Kitajima, Yasuhiko
• Primary Examiner(s): Nappi, Robert
• Assistant Examiner(s): San Martin, Edgardo
• Application Number:
  US10/179,973
• Publication Number:
  US 20030001536A1
• Time in Patent Office: 762 Days
• Field of Search: 318/432, 318/806, 318/433, 318/434, 318/689, 318/635, 318/720-724, 318/798-811, 323/204, 323/246, 323/274-281, 323/312, 323/348, 363/45, 363/46, 363/39
• US Class Current: 318/432
• CPC Class Codes: H02P 21/0089 using field weakening
• CPC Class Codes: H02P 21/06 Rotor flux based control involving the use of rotor position or rotor speed sensors
• CPC Class Codes: H02P 6/10 Arrangements for controlling torque ripple, e.g. providing reduced torque ripple

Abstract

A motor control apparatus includes a fundamental wave current control system that controls a fundamental wave component of a motor current in an orthogonal coordinate system and a higher harmonic current control system that controls a higher harmonic component contained in the motor current in an orthogonal coordinate system. In the motor control apparatus, it is judged whether an output voltage from the power conversion device is in a saturated state, and a current control gain for the higher harmonic current control system is reduced if it is judged that the output voltage is in the saturated state.

Claims

1. A motor control apparatus comprising:

a fundamental wave current control system that controls a fundamental wave component of a motor current in an orthogonal coordinate system which hypothetically rotates in synchronization with a rotation of a 3-phase AC motor;

a higher harmonic current control system that controls a higher harmonic component contained in the motor current in an orthogonal coordinate system hypothetically rotating with a frequency which is an integral multiple of the frequency of the fundamental wave component of the motor current;

a voltage command value generating device that generates 3-phase AC voltage command values by adding an output from said fundamental wave current control system and an output from said higher harmonic current control system;

a power conversion device that converts a DC source voltage to a 3-phase AC voltage corresponding to the 3-phase AC voltage command values and outputs the 3-phase AC voltage to the 3-phase AC motor;

a voltage saturation detection device which detects that an output voltage from said power conversion device is in a saturated state; and

a gain adjustment device that reduces a current control gain for said higher harmonic current control system if said voltage saturation detection device detects an output voltage-saturated state.

2. A motor control apparatus according to claim 1, wherein:

said voltage saturation detection device judges that an output voltage from said power conversion device is in a saturated state when the 3-phase AC motor is operating in a preset high-output operating range.

3. A motor control apparatus according to claim 1, wherein:

said voltage saturation detection device judges that an output voltage from said power conversion device is in a saturated state if any of the 3-phase AC voltage command values exceeds a judging reference value.

4. A motor control apparatus according to claim 1, wherein:

said voltage saturation detection device calculates an amplitude of an output voltage from said power conversion device based upon the output from said fundamental wave current control system and the output from said higher harmonic current control system and judges that an output voltage from said power conversion device is in a saturated state if the amplitude of an output voltage exceeds a judging reference value.

5. A motor control apparatus according to claim 1, wherein:

said gain adjustment device sets the output of said higher harmonic current control system to 0 if said voltage saturation detection device detects an output voltage-saturated state.

6. A motor control apparatus according to claim 1, wherein:

said high harmonic current control system implements proportional integral control on a deviation of a higher harmonic actual current relative to a higher harmonic current command value; and

said gain adjustment device reduces an integral control gain for said higher harmonic current control system if said voltage saturation detection device detects an output voltage-saturated state.

7. A motor control apparatus according to claim 1, wherein:

said gain adjustment device continuously reduces a current control gain over a predetermined length of time when an output voltage-saturated state is no longer detected by said voltage saturation detection device.

8. A motor control apparatus comprising:

a fundamental wave current control system that controls a fundamental wave component of a motor current in an orthogonal coordinate system which hypothetically rotates in synchronization with a rotation of a 3-phase AC motor;

a higher harmonic current control system that controls a higher harmonic component contained in the motor current in an orthogonal coordinate system hypothetically rotating with a frequency which is an integral multiple of the frequency of the fundamental wave component of the motor current;

a voltage command value generation means for generating 3-phase AC voltage command values by adding an output from said fundamental wave current control system and an output from said higher harmonic current control system;

a power conversion means for converting a DC source voltage to 3-phase AC voltage corresponding to the 3-phase AC voltage command values and outputs the 3 -phase AC voltage to the 3-phase AC motor;

a voltage saturation detection means for detecting that an output voltage from said power conversion means is in a saturated state; and

a gain adjustment means for reducing a current control gain for said higher harmonic current control system if said voltage saturation detection means detects that an output voltage is in a saturated state.

9. A motor control method adopted in a control system having a fundamental wave current control system that controls a fundamental wave component of motor currents in an orthogonal coordinate system hypothetically rotating in synchronization with the rotation of a 3-phase AC motor and a higher harmonic current control system that controls a higher harmonic component contained in the motor currents with an orthogonal coordinate system hypothetically rotating with a frequency which is an integral multiple of the frequency of the fundamental wave component of the motor currents, in said control system 3-phase AC voltage command values is generated by adding an output from said fundamental wave current control system and an output from said higher harmonic current control system, a DC source voltage is converted to 3-phase AC voltages corresponding to the 3-phase AC voltage command values and the 3-phase AC voltages is outputted to the 3-phase AC motor, comprising:

detecting whether or not the 3-phase AC voltages converted from the DC source voltage and output to the 3-phase AC motor are in a saturated state; and

reducing a current control gain for said higher harmonic current control system if an output voltage saturated state is detected.