Driving apparatus for electric motor

Patent metadata

Field	Value
Publication number	US-9602035-B2
Application number	US-201415028855-A
Country	US
Kind code	B2
Filing date	Sep 25, 2014
Priority date	Oct 17, 2013
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

The present invention relates to a driving apparatus which performs vector control based on an output current of an inverter. The driving apparatus of the present invention includes a vector controller ( 11 ) for transforming three-phase output currents of an inverter ( 10 ) into a torque current and a magnetization current, and controlling the torque current and the magnetization current. The vector controller ( 11 ) includes a torque-voltage control section ( 21 ) for determining a torque-voltage command value based on a deviation between a torque-current command value and the torque current, a magnetization-voltage output section ( 23 ) for outputting 0 as a magnetization-voltage command value, a target-magnetization-current determination section ( 26 ) for determining a magnetization-current command value based on a deviation between a torque-voltage command value and a target-output-voltage value, and a target-output-voltage determination section ( 27 ) for determining the target-output-voltage value.

First claim

What is claimed is:

1. A driving apparatus for an electric motor, comprising:
an inverter;
a current detector configured to detect an output current of the inverter; and
a vector controller configured to transform the output current, detected by the current detector, into a torque current and a magnetization current, and to control the torque current and the magnetization current,
wherein the vector controller comprises:
a three-to-two phase transformation section configured to transform three-phase currents, detected by the current detector, into two-phase currents;
a stationary-to-rotational coordinate transformation section configured to transform the two-phase currents on a stationary coordinate system, which have been transformed by the three-to-two phase transformation section, into a torque current and a magnetization current on a rotating coordinate system;
a torque-voltage control section configured to determine a torque-voltage command value based on a deviation between a torque-current command value and the torque current;
a magnetization-voltage output section configured to output 0 as a magnetization-voltage command value;
a rotational-to-stationary coordinate transformation section configured to transform the torque-voltage command value and the magnetization-voltage command value on a rotating coordinate system into a torque-voltage command value and a magnetization-voltage command value on a stationary coordinate system;
a two-to-three phase transformation section configured to transform the torque-voltage command value and the magnetization-voltage command value, which have been transformed by the rotational-to-stationary coordinate transformation section, into three-phase voltage command values;
a velocity calculator configured to calculate an angular velocity of a rotor of the electric motor from the magnetization current, a magnetization-current command value, and the torque-voltage command value;
a target-torque-current determination section configured to determine the torque-current command value based on a deviation between the angular velocity and an angular-velocity command value;
a target-output-voltage determination section configured to determine a target-output-voltage value from the angular velocity of the rotor; and
a target-magnetization-current determination section configured to determine the magnetization-current command value based on a deviation between the torque-voltage command value and the target-output-voltage value.

2. The driving apparatus according to claim 1 , wherein the target-output-voltage determination section stores a V/ω pattern in advance, the V/ω pattern indicating a relationship between the target-output-voltage value and the angular velocity, and the target-output-voltage determination section is configured to determine the target-output-voltage value from the angular velocity according to the V/ω pattern.

3. The driving apparatus according to claim 2 , wherein the relationship between the target-output-voltage value and the angular velocity, indicated by the V/ω pattern, is a relationship in which a ratio between the target-output-voltage value and the angular velocity is constant.

4. The driving apparatus according to claim 2 , wherein the relationship between the target-output-voltage value and the angular velocity, indicated by the V/ω pattern, is a relationship in which a ratio between the target-output-voltage value and the angular velocity is expressed by a square reduction curve.

5. The driving apparatus according to claim 2 , wherein the target-output-voltage determination section stores a plurality of V/ω patterns in advance, each of the plurality of V/ω patterns indicating a relationship between the target-output-voltage value and the angular velocity, and the target-output-voltage determination section is configured to determine the target-output-voltage value from the angular velocity according to one V/ω pattern selected from the plurality of V/ω patterns.

6. The driving apparatus according to claim 2 , wherein the relationship between the target-output-voltage value and the angular velocity, indicated by the V/ω pattern, is a relationship in which the target-output -voltage value is kept constant at a rated voltage of the electric motor after the target-output-voltage value has reached the rated voltage.

7. The driving apparatus according to claim 2 , wherein the relationship between the target-output-voltage value and the angular velocity, indicated by the V/ω pattern, is a relationship in which the target-output-voltage value is kept constant at a rated output voltage of the inverter after the target-output-voltage value has reached the rated output voltage.

8. The driving apparatus according to claim 1 , wherein the target-magnetization-current determination section stores therein a lower limit value in advance, and is configured to output the lower limit value as the magnetization-current command value when the angular velocity is not more than a predetermined value.

9. The driving apparatus according to claim 1 , wherein the target-output-voltage determination section stores therein a lower limit value in advance, and is configured to output the lower limit value as the target-output-voltage value when the angular velocity is not more than a predetermined value.

Assignees

• Ebara Corp

Inventors

• Tsukakoshi Kenta
• Komai Masakazu

Classifications

• H02P21/22

  Current control, e.g. using a current control loop · CPC title

• H02P27/04 Primary

  using variable-frequency supply voltage, e.g. inverter or converter supply voltage · CPC title

• H02P21/24 Primary

  Vector control not involving the use of rotor position or rotor speed sensors · CPC title

• H02P6/18

  without separate position detecting elements · CPC title

• H02P21/141

  Flux estimation · CPC title