CONTROL DEVICE FOR THREE-PHASE ROTATING MACHINE

• US 20130285591A1
• Filed: 04/24/2013
• Published: 10/31/2013
• Est. Priority Date: 04/26/2012
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: SUZUKI, Takashi
• Granted Patent: US 8,952,637 B2
• Time in Patent Office: Days
• US Class Current: 318/724
• CPC Class Codes: H02P 21/22 Current control, e.g. using a current control loop
• CPC Class Codes: H02P 25/22 Multiple windings; Windings for more than three phases
• CPC Class Codes: H02P 6/10 Arrangements for controlling torque ripple, e.g. providing reduced torque ripple

Abstract

In a control device for a three-phase rotating machine with first and second winding sets, a current feedback computing section includes a current sum controller and a current difference controller. The current sum controller multiplies, by a sum gain, an error between a sum of current command values for alternating currents output from first and second inverters and a sum of sensed current values and computes a sum of voltage command values. The current difference controller multiplies, by a difference gain, an error between a difference of the current command values and a difference between the sensed current values, and computes a difference of voltage command values. In a variable-responsiveness mode, a gain ratio between the sum gain and the difference gain is varied according to a reference frequency such that the current sum controller and the current different controller are different in responsiveness.

Claims

1. A control device for a three-phase rotating machine having a first three-phase winding set and a second three-phase winding set, the first and second three-phase winding sets being coupled magnetically to each other, the control device comprising:

a first power converter outputting a first alternating current to the first three-phase winding set;

a second power converter outputting a second alternating current to the second three-phase winding set, the first and second alternating currents differing in phase by an angle of 30±

60°

×

n from each other, the n being an integer;

a first current sensing section sensing the first alternating current and outputting a first sensed current value;

a second current sensing section sensing the second alternating current and outputting a second sensed current value; and

a current feedback computing section including a current sum controller and a current difference controller, wherein

the current sum controller multiplies a sum error by a sum gain and computes a sum of a first voltage command value for the first power converter and a second voltage command value for the second power converter, the sum error being an error between a sum of the first sensed current value and the second sensed current value and a sum of a first current command value for the first alternating current and a second current command value for the second alternating current,

the current difference controller multiplies a difference error by a difference gain and computes a difference between the first voltage command value and the second voltage command value, the difference error being an error between a difference between the first sensed current value and the second sensed current value and a difference between the first current command value and the second current command value,

the current feedback computing section performs a feedback control in a variable-responsiveness mode in which the current sum controller and the current difference controller are difference in responsiveness, and

in the variable-responsiveness mode, the current feedback computing section varies a gain ratio between the sum gain and the difference gain according to a reference frequency corresponding to a frequency of the first and second alternating currents.

2. The control device according to claim 1, wherein

the current sum controller computes the sum of the first voltage command value and the second voltage command value based on an inverse model of the three-phase rotating machine, the model including a magnetic coupling of the first three-phase winding set and the second three-phase winding set, and

the current difference controller computes the difference between the first voltage command value and the second voltage command value based on the inverse model.

3. The control device according to claim 1, further comprising:

a first malfunction determining section determining whether the first sensed current value is within a normal range; and

a second malfunction determining section determining whether the second sensed current value is within the normal range, wherein,

when one of the first sensed current value and the second sensed current value exceeds an upper limit value of the normal range, the current feedback computing section performs the feedback control in a fixed-responsiveness mode, and

in the fixed-responsiveness mode, the current feedback computing section sets the gain ratio to a constant value regardless of the reference frequency.

4. The control device according to claim 3, wherein

when the first sensed current value and the second current value are within the normal range in the fixed-responsiveness mode, the current feedback computing section switches from the fixed-responsiveness mode to the variable-responsiveness mode.

5. The control device according to claim 1, wherein

in the variable-responsiveness mode, the current feedback computing section sets the gain ratio to a constant value in a frequency range where a strain component of an induced voltage of the three-phase rotating machine is smaller than a predetermined value.

6. The control device according to claim 1, wherein

the current feedback computing section varies the gain ratio by fixing the sum gain and varying the difference gain.

7. The control device according to claim 1, further comprising:

a frequency calculating section that calculates the reference frequency by converting an electrical angular velocity of the three-phase rotating machine, and provides the reference frequency to the current feedback computing section.

8. The control device according to claim 1, wherein

the three-phase rotating machine is used as a steering assist motor for generating steering assist torque in an electric steering apparatus of a vehicle,

the control device further comprising:

a frequency calculating section that calculates the reference frequency by converting a steering speed of a steering shaft of the vehicle, and provides the reference frequency to the current feedback computing section.