# US 2013/0278186 A1 · Ac motor control apparatus

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- Number: US 2013/0278186 A1
- Document ID: US20130278186A1
- Status: Published application
- Kind: A1
- Application number: 13/867,319
- Filed: 2013-04-22
- Published: 2013-10-24
- Earliest claimed: 2012-04-22
- Assignees: Denso Corporation
- Applicants: Denso Corporation
- Inventors: Takashi SUZUKI; Takeshi ITOH; Hirofumi KAKO
- Web page: https://patentgrep.com/patent/US20130278186A1

## CPC

- H02P 21/14: Estimation or adaptation of machine parameters, e.g. flux, current or voltage
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS

## Abstract

A control apparatus for a three-phase AC motor includes a current sensor and a current estimation section. The current sensor detects current flowing through one phase of the motor. The current estimation section repeats dq transformation and inverse dq transformation in a predetermined cycle. In the dq transformation, a d-axis current estimation value and a q-axis current estimation value in a rotating coordinate system of the AC motor are calculated based on the detected current and a previous current estimation value of another phase of the AC motor. In the inverse dq transformation, a present current estimation value of the other phase to be obtained at a time of angle advance of one period of the cycle is calculated based on smoothed values of the d-axis current estimation value and the q-axis current estimation value.

## Claims

### Claim 1

A control apparatus for controlling a three-phase AC motor, the control apparatus comprising
a current sensor configured to detect electric current flowing through one phase of the AC motor, the one phase being defined as a sensor phase; and
a current estimation section configured to repeatedly perform both dq transformation and inverse dq transformation in a predetermined calculation cycle, wherein
in the dq transformation, a d-axis current estimation value and a q-axis current estimation value in a rotating coordinate system of the AC motor are calculated based on the current detected by the current sensor and a previous current estimation value of another phase of the AC motor, and
in the inverse dq transformation, a present current estimation value of the other phase to be obtained at a time of angle advance of one period of the calculation cycle is calculated based on a smoothed d-axis current estimation value and a smoothed q-axis current estimation value into which the d-axis current estimation value and the q-axis current estimation value are respectively smoothed.

### Claim 2 (depends on 1)

The control apparatus according to claim 1, wherein
the current estimation section performs the inverse dq transformation by using a predicted electrical angle, and
the predicted electrical angle is advanced with respect to a present electrical angle by one period of the calculation cycle.

### Claim 3 (depends on 2)

The control apparatus according to claim 2, wherein
the current estimation section calculates an electrical angle displacement for one period of the calculation cycle based on the calculation cycle and a rotation speed of the AC motor, and
the current estimation section calculates the predicted electrical angle by adding the electrical angle displacement to the present electrical angle.

### Claim 4 (depends on 1)

The control apparatus according to claim 1, further comprising:
a control section configured to control energization of the AC motor based on the d-axis current estimation value and the q-axis current estimation value.

### Claim 5 (depends on 2)

The control apparatus according to claim 2, further comprising:
a control section configured to control energization of the AC motor based on the d-axis current estimation value and the q-axis current estimation value.

### Claim 6 (depends on 3)

The control apparatus according to claim 3, further comprising:
a control section configured to control energization of the AC motor based on the d-axis current estimation value and the q-axis current estimation value.