ELECTRIC DRIVE VEHICLE

Abstract

An electric drive vehicle having an induction motor for braking or driving wheels, a motor controller for controlling the induction motor, and mechanical brakes for braking the wheels, wherein while the vehicle is in halt in a state that the mechanical breaks are not operating, the motor controller applies DC voltage or AC voltage in a frequency range of −1 Hz to +1 Hz to the stator of the induction motor to make the induction motor generate torque for stopping the vehicle and maintain the vehicle in a halt state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative diagram showing a control system of an electric drive vehicle according to a first embodiment.

FIG. 2 is a timing chart illustrating an operation of the vehicle of the first embodiment when the vehicle in halt starts.

FIGS. 3A and 3B are graphs showing relations between current commands and an accelerator pedal opening degree.

FIG. 4 is a timing chart illustrating an operation of the vehicle of the first embodiment when the vehicle in roll stops.

FIG. 5 is an illustrative diagram showing a control system of an electric drive vehicle according to a second embodiment.

FIG. 6 is a timing chart illustrating an operation of the vehicle of the second embodiment when the vehicle in halt starts.

FIG. 7 is a timing chart illustrating an operation of the vehicle of the second embodiment when the vehicle in roll stops.

FIG. 8 is an illustrative diagram showing the structure of an electric drive vehicle according to a third embodiment.

Claims

1. An electric drive vehicle comprising: an induction motor for braking or driving wheels;a motor controller for controlling the induction motor; andmechanical brakes for braking the wheels,wherein while the vehicle is in halt, the motor controller applies DC voltage to a stator of the induction motor to make the induction motor generate torque for stopping the vehicle and maintain the vehicle in a halt state.

2. The electric drive vehicle according to claim 1, wherein the mechanical breaks are not operating while the vehicle is maintained in the halt state by the torque generated by the induction motor.

3. The electric drive vehicle according to claim 1, wherein when the vehicle starts, a frequency of the voltage applied to the stator of the induction motor is raised at a predetermined rate.

4. The electric drive vehicle according to claim 1, wherein when the vehicle in roll stops, a frequency of the voltage applied to the stator of the induction motor is lowered at a predetermined rate.

5. The electric drive vehicle according to claim 1, wherein the vehicle is equipped with an accelerator pedal, the motor controller is equipped with a current controller, and a current command supplied to the current controller changes with an opening degree of the accelerator pedal.

6. An electric drive vehicle comprising: an induction motor for braking or driving wheels;a motor controller for controlling the induction motor; andmechanical brakes for braking the wheels,wherein while the vehicle is in halt, the motor controller applies AC voltage in a frequency range of −1 Hz to +1 Hz to a stator of the induction motor to make the induction motor generate torque for stopping the vehicle and maintain the vehicle in a halt state.

7. The electric drive vehicle according to claim 6, wherein the mechanical breaks are not operating while the vehicle is maintained in the halt state by the torque generated by the induction motor.

8. The electric drive vehicle according to claim 6, wherein when the vehicle starts, a frequency of the voltage applied to the stator of the induction motor is raised at a predetermined rate.

9. The electric drive vehicle according to claim 6, wherein when the vehicle in roll stops, a frequency of the voltage applied to the stator of the induction motor is lowered at a predetermined rate.

10. The electric drive vehicle according to claim 6, wherein the vehicle is equipped with an accelerator pedal, the motor controller is equipped with a current controller, and a current command supplied to the current controller changes with an opening degree of the accelerator pedal.

11. An electric drive vehicle comprising: an induction motor for braking or driving wheels;a motor controller for controlling the induction motor; andmechanical brakes for braking the wheels,wherein when the vehicle starts in a state that the vehicle is in halt on a sloped road while the mechanical brakes are operating, the vehicle starts after the mechanical brakes are released.