Device for controlling electric vehicle and method of controlling electric vehicle

Patent metadata

Field	Value
Publication number	US-9315114-B2
Application number	US-201314394957-A
Country	US
Kind code	B2
Filing date	Mar 7, 2013
Priority date	Apr 18, 2012
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A device for controlling an electric vehicle includes: a feedforward computation unit that is configured to input a motor torque instruction value and compute a first torque target value by feedforward computation; and a motor torque control unit that is configured to control a motor torque according to the first torque target value. The feedforward computation unit includes: a vehicle model which is configured to input the motor torque instruction value to model a characteristic from the motor torque to a drive shaft torsional angular velocity; and a drive shaft torsional angular velocity feedback model which is configured to feed back the drive shaft torsional angular velocity output from the vehicle model to the motor torque instruction value to compute the first torque target value.

First claim

The invention claimed is:

1. A device for controlling an electric vehicle that is configured to set a motor torque instruction value based on vehicle information and control a torque of a motor connected to a drive wheel, the device comprising:
a feedforward computation unit that is configured to input the motor torque instruction value without inputting a detection value of a sensor provided in the electric vehicle and compute a first torque target value by feedforward computation; and
a motor torque control unit that is configured to control the motor torque according to the first torque target value,
wherein the feedforward computation unit includes: a vehicle model which is configured to input the motor torque instruction value to model a characteristic from the motor torque to a drive shaft torsional angular velocity; and a drive shaft torsional angular velocity feedback model which is configured to feed back the drive shaft torsional angular velocity output from the vehicle model to the motor torque instruction value to compute the first torque target value.

2. The device for controlling an electric vehicle according to claim 1 ,
wherein a drive force transmission system in the vehicle model includes a dead zone in which the motor torque is not transmitted to a drive shaft torque of the vehicle.

3. The device for controlling an electric vehicle according to claim 2 ,
wherein a width of the dead zone of the drive force transmission system in the vehicle model is a total of amounts of gear backlash from the motor to a drive shaft.

4. The device for controlling an electric vehicle according to claim 1 ,
wherein the feedforward computation unit is configured to perform, on the motor torque instruction value, lag processing corresponding to a lag element included in a control system, and thereafter perform the feedforward computation.

5. The device for controlling an electric vehicle according to claim 4 .
wherein the lag element included in the control system includes at least one of a time lag caused by detecting a vehicle state amount indicating a state of the vehicle and performing predetermined processing, a time lag necessary for calculating a torque target value for controlling the motor after the input of the motor torque instruction value and a time lag until the motor torque is actually produced for the torque target value for controlling the motor.

6. The device for controlling an electric vehicle according to claim 1 ,
wherein the vehicle model is configured to model the characteristic from the motor torque to the drive shaft torsional angular velocity and a characteristic from the motor torque to a motor rotation rate,
the device further includes:
a motor rotation rate detection unit that is configured to detect the motor rotation rate; and
a feedback computation unit that is configured to perform feedback computation based on a motor rotation rate estimation value output from the vehicle model and the motor rotation rate detection value so as to compute a second torque target value and

the motor torque control unit is configured to control the motor torque according to a final torque target value obtained by adding the first torque target value and the second torque target value.

7. The device for controlling an electric vehicle according to claim 6 ,
wherein the feedback computation unit is configured to perform, on the motor rotation rate estimation value, the lag processing corresponding to the lag element included in the control system, and perform the feedback computation based on the motor rotation rate estimation value on which the lag processing has been performed and the motor rotation rate detection value so as to compute the second torque target value.

8. The device for controlling an electric vehicle according to claim 7 ,
wherein the lag element included in the control system includes at least one of a time lag caused by detecting, with the motor rotation rate detection unit, the motor rotation rate and performing predetermined processing, a time lag necessary for calculating the final torque target value after the input of the motor torque instruction value and a time lag until the motor torque is actually produced for the final torque target value.

9. A method of controlling an electric vehicle that is configured to set a motor torque instruction value based on vehicle information and control a torque of a motor connected to a drive wheel, the method comprising:
a step of inputting the motor torque instruction value without inputting a detection value of a sensor provided in the electric vehicle and computing a first torque target value by feedforward computation; and
a step of controlling the motor torque according to the first torque target value,
wherein in the step of computing the first torque target value, a drive shaft torsional angular velocity is determined based on the motor torque instruction value, and the determined drive shaft torsional angular velocity is fed back to the motor torque instruction value such that first torque target value is computed.

Assignees

• Nissan Motor

Inventors

• Oono Shou
• Itou Ken

Classifications

• B60L15/20

  for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed · CPC title

• B60L15/06 Primary

  using substantially sinusoidal AC · CPC title

• B60L7/14

  for vehicles propelled by AC motors · CPC title

• H02P6/08

  Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) · CPC title

• B60L2240/421

  Speed · CPC title