Device and method of 6-step controlling inverter of motor driving system

Patent metadata

Field	Value
Publication number	US-9634588-B2
Application number	US-201414566583-A
Country	US
Kind code	B2
Filing date	Dec 10, 2014
Priority date	Jul 4, 2014
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

A device and a method of 6-step controlling of an inverter of a motor driving system are provided. The device and method and apply a voltage to a motor by adopting a 6-step control scheme capable of maximally using an input voltage of the inverter to improve output efficiency of the inverter and the motor and thus improve fuel efficiency of an environmentally friendly vehicle.

First claim

What is claimed is:

1. A device for 6-step controlling an inverter of a motor driving system, comprising:
a current controller that is connected to a current sensor disposed at an output side of an inverter and a current command map and is configured to generate a voltage command using a difference component between a d/q axis current requested by the current command map and a d/q axis current actually measured by a current sensor disposed at the output side of the inverter; and
an inverter 6-step controller disposed at an input side of the inverter;
wherein the inverter 6-step controller includes:
a frequency updating unit including a 12-sample phase control switching frequency calculating unit for calculating a switching frequency component for 12-sample phase control by using voltage vector phase obtained through the voltage vector phase detecting unit;
a current control task unit including a voltage vector phase detecting unit, which detects a voltage vector phase by using a voltage command output from the current controller and provides the 12-sample phase control switching frequency calculating units with the detected voltage vector phase; and
a high gain over voltage modulation (HOVM) controller, which generates a high gain over voltage modulated output voltage (VdqssHOVM) by multiplying an output voltage (VdqssRef) of the current controller by a gain, generates the high gain over voltage modulated output voltage (VdqssHOVM) by 12 times per one period of a fundamental wave based on switching frequencies for the 12-sample phase control, adjusts a voltage vector phase by changing a pulse width modulation (PWM) period so that voltage vectors are symmetric based on vertexes so as to converge actual voltage vector to the vertexes of a hexagon of a voltage vector diagram, and applies a voltage command corresponding to the vertexes of a hexagon of a voltage vector diagram to the inverter through minimum distance overmodulation control.

2. The device of claim 1 , wherein the inverter 6-step controller is configured to switch one of the switching frequencies for the calculated 12-sample phase control or predetermined switching frequencies to an updated frequency signal.

3. A method of 6-step controlling an inverter of a motor driving system, comprising:
generating, by a current controller, a voltage command using a difference component between a d/q axis current requested by a current command map and an actually measured d/q axis current by a current sensor disposed at an output side of an inverter;
detecting, by a voltage vector phase detecting unit, a voltage vector phase from the voltage command; and
6-step controlling an inverter by generating, by an inverter 6-step controller, switching frequencies for 12-sample phase control using the detected voltage vector phase component, and applying a voltage command that corresponds to each of vertexes of a hexagon of a voltage vector diagram corresponding to a maximum voltage use rate using the generated frequencies to the inverter;
wherein the 6-step controlling of the inverter includes:
when the voltage command that corresponds to each of the vertexes of the hexagon of the voltage vector diagram is applied to the inverter, generating, by a high gain over voltage modulation(HOVM) controller of the inverter 6-step controller, a high gain over voltage modulated output voltage by multiplying an output voltage of a current controller by a gain;
generating, by the high gain over voltage modulation(HOVM) controller, the high gain over voltage modulated output voltage by 12 times per one period of a fundamental wave based on the switching frequencies for the 12-sample phase control;
changing, by the high gain over voltage modulation(HOVM) controller, a pulse width modulation (PWM) period to cause voltage vectors to be symmetric based on the vertexes to converge the actual voltage vector to the vertex of the hexagon of the voltage vector diagram, and adjusting a voltage vector phase; and
applying, by the high gain over voltage modulation(HOVM) controller, a voltage command that corresponds to the vertex of the hexagon of the voltage vector diagram to the inverter through minimum distance overmodulation control.

4. The method of claim 3 , wherein the minimum distance overmodulation control is performed to cause the voltage applied to the inverter to generate a waveform with the 6 steps to a square wave, and includes:
calculating, by the high gain over voltage modulation(HOVM) controller, a virtual vector value obtained by multiplying a voltage vector that corresponds to an inscribed circle of the hexagon of the voltage vector diagram indicating 100% of an inverter voltage use rate by a constant; and
virtually drawing a vertical line converged to the vertex of the hexagon indicating 110% or greater of the inverter voltage use rate from the virtual vector value.

5. The method of claim 3 , wherein the 6-step controlling of the inverter further includes:
generating, by the inverter 6-step controller, the switching frequencies for the 12-sample phase control; and
determining, by the inverter 6-step controller, whether to perform the 6-step control of the inverter based on whether the switching frequencies satisfy a 12-sample phase control condition.

6. The method of claim 5 , wherein the 12-sample phase control condition is set based on a speed and a torque of a motor, and an input voltage of the inverter.

7. The method of claim 5 , wherein when the 12-sample phase control condition is not satisfied, a PWM signal, which is a final output voltage signal for the inverter, is synchronized to a predetermined switching frequency to be used for the control of the inverter.

8. The method of claim 5 , wherein when the 12-sample phase control condition is satisfied, a PWM signal, which is a final output voltage signal for the inverter, is synchronized to the switching frequencies for the 12-sample phase control to be used for the control of the inverter.

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Park Hong Geuk
• Kwak Mu Shin
• Kim Sung Kyu
• Bae Su Hyun

Classifications

• F16H2059/366

  Engine or motor speed · CPC title

• H02M7/53873

  with digital control · CPC title

• H02P27/085

  wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency · CPC title

• H02P6/14 Primary

  Electronic commutators · CPC title

• H02M7/5395

  by pulse-width modulation · CPC title