CONTROL APPARATUS FOR ELECTRIC VEHICLE

• US 20100235043A1
• Filed: 02/24/2010
• Published: 09/16/2010
• Est. Priority Date: 03/11/2009
• Status: Active Grant

• Current Assignee: Subaru Corp.
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Ohtomo, Yosuke, Seta, Itaru
• Granted Patent: US 8,634,987 B2
• Time in Patent Office: Days
• US Class Current: 701/34
• CPC Class Codes: B60L 15/2063 for creeping
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 3/0038 relating to sensors
• CPC Class Codes: B60L 3/0076 relating to braking
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/105 Longitudinal acceleration
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 30/18063 Creeping
• CPC Class Codes: B60W 50/029 Adapting to failures or work around with other constraints, e.g. circumvention by avoiding use of failed parts
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A creep travel capability of an electric vehicle is secured when an abnormality occurs in a brake sensor. When an accelerator operation amount reaches 0% in a low vehicle speed region, a target creep torque is set, whereupon a motor-generator is controlled toward the target creep torque. The target creep torque is reduced as a brake pedal is depressed in order to suppress heat generation and the like in the motor-generator during vehicle braking. Hence, in an electric vehicle in which the target creep torque is varied in accordance with the brake operation amount, when an abnormality occurs (step S11) in a brake sensor for detecting a brake operation amount, a preset prescribed creep torque is employed as the target creep torque regardless of the brake operation amount (step S15). The prescribed creep torque is set at a required magnitude for securing the creep travel capability.

Claims

1. A control apparatus for an electric vehicle having an electric motor for driving vehicle wheels, a brake sensor for detecting a brake operation amount, and a vehicle speed sensor for detecting a vehicle speed, comprising:

torque setting means for setting a target creep torque of said electric motor based on of said brake operation amount and said vehicle speed;

motor controlling means for drive-controlling said electric motor based on said target creep torque; and

sensor abnormality detecting means for detecting an abnormality in said brake sensor,

wherein, when an abnormality occurs in said brake sensor, said torque setting means sets said target creep torque at or above a predetermined value regardless of said brake operation amount.

2. The control apparatus for an electric vehicle according to claim 1, further comprising an acceleration sensor for detecting a vehicle acceleration,

wherein said torque setting means changes said target creep torque set when an abnormality occurs in said brake sensor, based on said vehicle acceleration.

3. The control apparatus for an electric vehicle according to claim 1, wherein said torque setting means sets said target creep torque by multiplying a basic creep torque determined from said vehicle speed by a coefficient determined from said brake operation amount by, and maintains said coefficient regardless of said brake operation amount when an abnormality occurs in said brake sensor.

4. The control apparatus for an electric vehicle according to claim 1, wherein

said brake sensor changes an output signal within a predetermined range according to said brake operation amount, and

said sensor abnormality detecting means detects an abnormality in said brake sensor when said output signal from said brake sensor deviates from said predetermined range.

5. The control apparatus for an electric vehicle according to claim 1, further comprising an auxiliary brake sensor for detecting said brake operation amount,

wherein said sensor abnormality detecting means detects an abnormality in said brake sensor by comparing an output signal from said brake sensor with an output signal from said auxiliary brake sensor.

6. The control apparatus for an electric vehicle according to claim 1, further comprising a brake switch for determining whether or not said brake operation amount exceeds a predetermined value,

wherein said sensor abnormality detecting means detects an abnormality in said brake sensor by comparing an output signal from said brake sensor with an output signal from said brake switch.

7. The control apparatus for an electric vehicle according to claim 1, further comprising notifying means for notifying an occupant of an abnormality in said brake sensor.