Vehicle control device and vehicle control method

• US 8,521,350 B2
• Filed: 03/01/2012
• Issued: 08/27/2013
• Est. Priority Date: 03/02/2011
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Minamiura, Keiichi
• Primary Examiner(s): Nguyen, John Q
• Assistant Examiner(s): Stroud, James E
• Application Number:
  US13/409,283
• Publication Number:
  US 20120226402A1
• Time in Patent Office: 544 Days
• Field of Search: 303/3, 303/7, 303/15, 303/20, 303/113.4, 303/191, 303/151, 303/152, 303/124, 701/22, 318/139, 318/261, 318/281, 318/376, 318/369, 318/375, 318/371, 320/132, 320/134, 320/135, 320/136, 307/9.1, 307/10.1, 307/10.7
• US Class Current: 701/22
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/62 charged by low-power generators primarily intended to support the batteries, e.g. range extenders
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/16 responding to battery ageing, e.g. to the number of charging cycles or the state of health [SoH]
• CPC Class Codes: B60L 7/18 Controlling the braking effect B60L7/12, B60L7/14, B60L7/16 take precedence
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60T 1/10 by utilising wheel movement for accumulating energy, e.g. driving air compressors
• CPC Class Codes: B60T 13/588 both fluid and mechanical assistance or drive
• CPC Class Codes: B60T 13/662 characterised by specified functions of the control system components
• CPC Class Codes: B60T 13/686 in hydraulic systems or parts thereof
• CPC Class Codes: B60T 13/745 acting on a hydraulic system, e.g. a master cylinder
• CPC Class Codes: B60T 2270/604 Merging friction therewith; Adjusting their repartition
• CPC Class Codes: B60T 8/4081 Systems with stroke simulating devices for driver input B60T8/4077 takes precedence
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/188 hydraulic brakes
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/12 : Brake pedal position
• CPC Class Codes: B60W 2710/083 : Torque
• CPC Class Codes: B60W 30/18127 : Regenerative braking
• CPC Class Codes: H02J 2310/48 : for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 7/00714 : in response to battery charging or discharging current
• CPC Class Codes: H02J 7/04 : Regulation of charging current or voltage
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/92 : Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles

Abstract

A control device for a vehicle includes: a charge control portion that adjusts an upper limit of charging power to a battery to prevent a negative electrode potential of the battery from dropping to a lithium reference potential, based on a charge/discharge history of the battery; a braking control portion that detects a sharing ratio between hydraulic braking force by a braking device and regenerative braking force for desired braking force according to a brake pedal depression amount so that a motor generator generates a regenerative braking force within a range of the adjusted upper limit of charging power; and a setting portion that variably sets, according to the hydraulic response rate detected by the detection portion, a degree of limitation of the upper limit when restricting charging current to the battery by restricting the upper limit.

Claims

1. A control device for a vehicle having:

a battery formed of a lithium ion secondary battery;

a braking device configured to exert braking force on a drive wheel according to hydraulic pressure supplied from a hydraulic pressure generation circuit;

a motor generator configured to transmit rotation force reciprocally with the drive wheel; and

a power controller that performs bidirectional power conversion between the battery and the motor generator to control output torque of the motor generator,

the control device comprising;

a charge control portion that adjusts an upper limit of charging power to the battery so as to prevent a negative electrode potential of the battery caused by lithium metal deposits on the negative electrode of the battery causing the battery to drop to a lithium reference potential, based on a charge and discharge history of the battery;

a braking control portion that determines a sharing ratio between a hydraulic braking force by the braking device and a regenerative braking force for desired braking force according to a brake pedal depression amount so that the motor generator generates the regenerative braking force within a range of the adjusted upper limit of charging power;

a detection portion that calculates an actual value of a hydraulic response rate in the hydraulic pressure generation circuit by dividing a hydraulic pressure variation amount by a delay time amount, the hydraulic pressure variation amount is a difference between a target hydraulic pressure and an actual hydraulic pressure supplied from the hydraulic pressure generation circuit to a brake caliper of the braking device, and the delay time amount is a period of time required for the actual hydraulic pressure to reach the target hydraulic pressure; and

a setting portion that variably sets, according to the hydraulic response rate calculated by the detection portion, a degree of limitation of the upper limit of charging power when restricting charging current to the battery by restricting the upper limit of charging power.

2. The control device according to claim 1, wherein:

when restricting the charging current to the battery, the setting portion sets a limitation rate indicating a time-change rate of reducing the upper limit of charging power to a higher value as the hydraulic response rate becomes higher; and

the charge control portion includes;

a) a portion that successively sets an allowable input current value as a maximum current that does not cause deposition of lithium metal on the negative electrode of the battery, based on the charge and discharge history, and the portion determines an input current limit target value for the allowable input current value so as to have a margin that is set to a smaller value as the limitation rate becomes higher; and

b) a portion that reduces the upper limit of charging power according to the limitation rate when the charging current to the battery exceeds the input current limit target value.

3. The control device according to claim 2, wherein the setting portion includes:

c) a portion that converts the hydraulic response rate detected by the detection portion into a change rate of braking force of the braking device; and

d) a portion that sets the limitation rate based on a product of the converted change rate of braking force and rotational speed of the motor generator.

4. The control device according to claim 1, wherein a condition for starting limitation of the upper limit of charging power is alleviated further as the degree of limitation becomes higher.

6. The control device according to claim 1, wherein the braking device exerts the braking force on the drive wheel according to the hydraulic pressure supplied from the hydraulic pressure generation circuit to a brake caliper.

5. A control method for a vehicle having:

a battery formed of a lithium ion secondary battery;

a braking device configured to exert braking force on a drive wheel according to hydraulic pressure supplied from a hydraulic pressure generation circuit;

a motor generator configured to transmit rotation force reciprocally with the drive wheel; and

a power controller that performs bidirectional power conversion between the battery and the motor generator to control output torque of the motor generator,

the control method comprising;

adjusting an upper limit of charging power to the battery so as to prevent a negative electrode potential of the battery caused by lithium metal deposits on the negative electrode of the battery causing the battery to drop to a lithium reference potential, based on a charge and discharge history of the battery;

determining a sharing ratio between a hydraulic braking force by the braking device and a regenerative braking force for desired braking force according to a brake pedal depression amount so that the motor generator generates the regenerative braking force within a range of the adjusted upper limit of charging power;

calculating an actual value of a hydraulic response rate in the hydraulic pressure generation circuit by dividing a hydraulic pressure variation amount by a delay time amount, the hydraulic pressure variation amount is a difference between a target hydraulic pressure and an actual hydraulic pressure supplied from the hydraulic pressure generation circuit to a brake caliper, and the delay time amount is a period of time required for the actual hydraulic pressure to reach the target hydraulic pressure; and

variably setting, according to the detected hydraulic response rate, a degree of limitation of the upper limit of charging power when restricting charging current to the battery by restricting the upper limit of charging power.

7. The control method according to claim 5, wherein the braking device exerts the braking force on the drive wheel according to the hydraulic pressure supplied from the hydraulic pressure generation circuit to a brake caliper.