Control device for hybrid vehicle

• US 6,659,213 B2
• Filed: 11/13/2001
• Issued: 12/09/2003
• Est. Priority Date: 03/21/2000
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Kubo, Asami, Goto, Kenichi
• Primary Examiner(s): VANAMAN, FRANK BENNETT
• Application Number:
  US09/959,910
• Publication Number:
  US 20020157882A1
• Time in Patent Office: 756 Days
• Field of Search: 180/65.2, 180/65.3, 180/65.4, 180/65.6, 180/65.8, 320/15, 320/32, 701/22
• US Class Current: 180/65.26
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 6/28 characterised by the electric energy storing means, e.g. batteries or capacitors
• CPC Class Codes: B60K 6/485 Motor-assist type
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2260/22 Standstill, e.g. zero speed
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 58/14 Preventing excessive discharging
• CPC Class Codes: B60L 58/15 Preventing overcharging
• 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 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/06 Ignition switch
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/065 Idle condition
• CPC Class Codes: B60W 30/18054 : at stand still, e.g. engine in idling state hill holding B60W30/18118
• CPC Class Codes: Y02T 10/40 : Engine management systems
• 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 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y10S 903/907 : Electricity storage, e.g. battery, capacitor

Abstract

A vehicle is provided including a high-voltage battery for a motor/generator power source, a low-voltage battery for electrical loads, an inverter for controlling the motor/generator, sensors which detect a condition of the high-voltage battery, a rotation speed of the engine, a vehicle speed, and a depression of an accelerator pedal, and a microprocessor. The microprocessor is programmed to compute a state of charge (SOC) of the high-voltage battery, compute a degree of deterioration of the high-voltage battery, control a current generated by the motor/generator so that the SOC of the high-voltage battery coincides with a target SOC, vary the target SOC according to the degree of deterioration of the high-voltage battery, determine whether or not the vehicle is decelerating, and set the target SOC to the low target SOC when the vehicle is not decelerating and to the high target SOC when the vehicle is decelerating.

Claims

1. A control device for a hybrid vehicle which comprises an engine as a power source for running the vehicle and a motor/generator, comprising:

a high-voltage battery which functions as a power source for the motor/generator;

a low-voltage battery for vehicle-mounted electrical loads which has a lower voltage than the high-voltage battery;

an inverter for controlling the motor/generator;

a sensor which detects a condition of the high-voltage battery;

a sensor which detects a rotation speed of the engine;

a sensor which detects a vehicle speed;

a sensor which detects depression of an accelerator pedal; and

a microprocessor which is programmed to;

compute a state of charge (SOC) of the high-voltage battery based on the condition of the high-voltage battery;

compute a degree of deterioration of the high-voltage battery based on the condition of the high-voltage battery;

control a current generated by the motor/generator so that the SOC of the high-voltage battery coincides with a target SOC;

vary the target SOC according to the degree of deterioration of the high-voltage battery;

determine whether or not the vehicle is decelerating, based on the rotation speed of the engine, the vehicle speed and the depression of the accelerator pedal; and

set the target SOC to a low target SOC when the vehicle is not decelerating and to set the target SOC to a high target SOC when the vehicle is decelerating,

wherein the low target SOC is lower than the high target SOC.

2. The control device as defined in claim 1, wherein the microprocessor is further programmed to decrease the low target SOC with an increase in the degree of deterioration in the high-voltage battery.

3. The control device as defined in claim 1, wherein the microprocessor is further programmed to decrease the high target SOC with an increase in the degree of deterioration in the high-voltage battery.

4. A control device for a hybrid vehicle which comprises an engine as a power source for running the vehicle and a motor/generator, comprising:

a high-voltage battery which functions as a power source for the motor/generator;

a low-voltage battery for vehicle-mounted electrical loads which has a lower voltage than the high-voltage battery;

an inverter for controlling the motor/generator;

a sensor which detects a condition of the high-voltage battery; and

a microprocessor which is programmed to;

compute a state of charge (SOC) of the high-voltage battery based on the condition of the high-voltage battery;

compute a degree of deterioration of the high-voltage battery based on the condition of the high-voltage battery;

control a current generated by the motor/generator so that the SOC of the high-voltage battery coincides with a target SOC;

vary the target SOC according to the degree of deterioration of the high-voltage battery;

determine whether or not the high-voltage battery is self-discharging, based on the condition of the high-voltage battery; and

command the motor/generator to generate a predetermined current when the high-voltage battery is self-discharging.

5. A control device for a hybrid vehicle which comprises an engine as a power source for running the vehicle and a motor/generator, comprising:

a high-voltage battery which functions as a power source for the motor/generator;

a low-voltage battery for vehicle-mounted electrical loads which has a lower voltage than the high-voltage battery;

an inverter for controlling the motor/generator;

a sensor which detects a condition of the high-voltage battery; and

a microprocessor which is programmed to;

compute a state of charge (SOC) of the high-voltage battery based on the condition of the high-voltage battery;

compute a degree of deterioration of the high-voltage battery based on the condition of the high-voltage battery;

control a current generated by the motor/generator so that the SOC of the high-voltage battery coincides with a target SOC;

vary the target SOC according to the degree of deterioration of the high-voltage battery; and

compute the degree of deterioration of the high-voltage battery when a start switch is placed in an ON position and a time which has elapsed after a key has been placed in an OFF position is greater than or equal to a predetermined time.

6. A control device for a hybrid vehicle which comprises an engine as a power source for running the vehicle and a motor/generator, comprising:

a high-voltage battery which functions as a power source of the motor/generator;

a low-voltage battery for vehicle-mounted electrical loads which has a lower voltage than the high-voltage battery;

an inverter for controlling the motor/generator;

a sensor which detects a condition of the high-voltage battery;

a sensor which detects a rotation speed of the engine;

a sensor which detects a vehicle speed;

a sensor which detects depression of an accelerator pedal;

a sensor which detects depression of a brake pedal; and

a microprocessor programmed to;

compute a state of charge (SOC) of the high-voltage battery based on the condition of the high-voltage battery;

determine whether or not the vehicle is brought to a temporary halt with the engine running at idle speed, based on the rotation speed of the engine, the vehicle speed, the depression of the accelerator pedal, and the depression of the brake pedal;

stop the engine when the SOC of the high-voltage battery is greater than or equal to a threshold value and when the vehicle is brought to the temporary halt with the engine running at the idle speed;

compute a degree of deterioration of the high-voltage battery based on the condition of the high-voltage battery; and

vary the threshold value according to the degree of deterioration of the high-voltage battery; and

compute the degree of deterioration of the high-voltage battery when a start switch is placed in an ON position and a time which has elapsed after a key has been placed in an OFF position is greater than or equal to a predetermined time.