Battery system

• US 10,189,464 B2
• Filed: 08/19/2016
• Issued: 01/29/2019
• Est. Priority Date: 08/25/2015
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Aridome, Koji
• Primary Examiner(s): Nguyen, Bao Long T
• Application Number:
  US15/241,559
• Publication Number:
  US 20170057486A1
• Time in Patent Office: 893 Days
• Field of Search: 701 22, 180 651, 180 6521, 180 65265, 180 65275, 180 6528, 180 65285, 180 6529, 903907
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60L 2260/26 Transition between different drive modes
• CPC Class Codes: B60L 2260/44 by parameter estimation
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• 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 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2710/06 Combustion engines, Gas turbines
• CPC Class Codes: B60W 2710/08 Electric propulsion units
• CPC Class Codes: B60W 2710/244 Charge state
• CPC Class Codes: B60W 30/192 Mitigating problems related to power-up or power-down of the driveline, e.g. start-up of a cold engine
• CPC Class Codes: B60Y 2400/3086 Electric voltages sensors
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• 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: Y10S 903/907 : Electricity storage, e.g. battery, capacitor

Abstract

A battery system includes an electricity storage device including a plurality of battery units. The electronic control device is configured to switch a travel mode of the vehicle between a CD mode and a CS mode. The electronic control device is configured to calculate a vehicle state of charge at a higher value than an average state of charge when the average state of charge is higher than a threshold value, and calculate the vehicle state of charge at a lower value than the average state of charge when the average state of charge is lower than the threshold value. The threshold value is set at a lower value than a center value between an upper limit value and a lower limit value of the vehicle state of charge.

Claims

1. A battery system installed in a vehicle, the vehicle comprising:

a motor-generator; and

an internal combustion engine, the vehicle being configured to switch between electric travel in which the vehicle uses power from the motor-generator but not the internal combustion engine and hybrid travel in which the vehicle uses power from both the internal combustion engine and the motor-generator during the hybrid travel,

the battery system comprising;

an electricity storage device comprising a plurality of battery units connected in series, the electricity storage device being configured to receive power from the motor-generator and to supply power to the motor-generator; and

an electronic control unit (ECU), the ECU being configured to;

calculate a vehicle state of charge (SOC) and an average SOC, the vehicle SOC being a ratio of a remaining amount of power of the electricity storage device to a total amount of power that can be charged to the electricity storage device, and the average SOC being an average of a maximum unit SOC and a minimum unit SOC among a plurality of unit SOCs corresponding respectively to each battery unit of the plurality of battery units,

switch a travel mode of the vehicle between a charge depleting (CD) mode and a charge sustaining (CS) mode, the CD mode being a travel mode in which electric travel is performed, and the CS mode being a travel mode in which an amount of power stored in the electricity storage device is maintained within a predetermined range by switching between electric travel and hybrid travel,

cause the vehicle to travel in the CD mode when the vehicle SOC is higher than a predetermined value, and switch from the CD mode to the CS mode and cause the vehicle to travel in the CS mode when the vehicle SOC falls below the predetermined value, and

calculate the vehicle SOC at a higher value than the average SOC when the average SOC is higher than a threshold value, and calculate the vehicle SOC at a lower value than the average SOC when the average SOC is lower than the threshold value, and the threshold value being set at a lower value than a center value between an upper limit value and a lower limit value of the vehicle SOC.

2. The battery system according to claim 1, wherein

the ECU is configured to calculate a difference between the maximum unit SOC and the minimum unit SOC, and

the ECU is configured to increase the threshold value as the difference between the maximum unit SOC and the minimum unit SOC increases.

3. The battery system according to claim 2, wherein

the ECU is configured to increase the threshold value up to the center value as the difference between the maximum unit SOC and the minimum unit SOC increases.

4. The battery system according to claim 1, wherein

the ECU is configured to calculate the vehicle SOC using a first calculation formula when the average SOC is higher than the threshold value and using a second calculation formula when the average SOC is lower than the threshold value,

the first calculation formula being a formula according to which the vehicle SOC equals the upper SOC limit value when the maximum unit SOC is at the upper SOC limit value and the vehicle SOC equals the threshold value when the average SOC is at the threshold value, and

the second calculation formula being a formula according to which the vehicle SOC equals the threshold value when the average SOC is at the threshold value and the vehicle SOC equals the lower SOC limit value when the minimum unit SOC is at the lower SOC limit value.

5. A method of operating a battery system installed in a vehicle, the vehicle comprising a motor-generator and an internal combustion engine, the vehicle being configured to switch between electric travel in which the vehicle uses power from the motor-generator but not the internal combustion engine and hybrid travel in which the vehicle uses power from both the motor-generator and the internal combustion engine, the battery system comprising an electricity storage device and an electronic control unit (ECU), the electricity storage device comprising a plurality of battery units connected in series, the electricity storage device being configured to receive power from the motor-generator and to supply power to the motor-generator, the method comprising:

calculating a vehicle state of charge (SOC) and an average SOC using the ECU, the vehicle SOC being a ratio of a remaining amount of power of the electricity storage device to a total amount of power that can be charged to the electricity storage device, and the average SOC being an average of a maximum unit SOC and a minimum unit SOC among a plurality of SOCs corresponding respectively to each battery unit of the plurality of battery units;

switching a travel mode of the vehicle between a charge depleting (CD) mode and a charge sustaining (CS) mode using the ECU, the CD mode being a travel mode in which electric travel is performed, and the CS mode being a travel mode in which an amount of power stored in the electricity storage device is maintained within a predetermined range by switching between electric travel and hybrid travel;

causing the vehicle to travel in the CD mode when the vehicle SOC is higher than a predetermined value, and switching from the CD mode to the CS mode and causing the vehicle to travel in the CS mode when the vehicle SOC falls below the predetermined value; and

calculating the vehicle SOC at a higher value than the average SOC when the average SOC is higher than a threshold value, and calculating the vehicle SOC at a lower value than the average SOC when the average SOC is lower than the threshold value, the threshold value being set at a value lower than a center value of an upper limit value and a lower limit value of the vehicle SOC.

6. The method of operating a battery system according to claim 5, further comprising:

calculating a difference between the maximum unit SOC and the minimum unit SOC using the ECU, and increasing the threshold value using the ECU as the difference between the maximum unit SOC and the minimum unit SOC increases.

7. The method of operating a battery system according to claim 6, further comprising:

increasing the threshold value up to the center value as the difference between the maximum unit SOC and the minimum unit SOC increases.

8. The method of operating a battery system according to claim 5, further comprising:

calculating the vehicle SOC using a first calculation formula when the average SOC is higher than the threshold value and using a second calculation formula when the average SOC is lower than the threshold value,

the first calculation formula being a formula according to which the vehicle SOC equals the upper SOC limit value when the maximum unit SOC is at the upper SOC limit value and the vehicle SOC equals the threshold value when the average SOC is at the threshold value, and

the second calculation formula being a formula according to which the vehicle SOC equals the threshold value when the average SOC is at the threshold value and the vehicle SOC takes the lower SOC limit value when the minimum unit SOC is at the lower SOC limit value.

9. The method of operating a battery system according to claim 5, wherein the method is executed repeatedly at predetermined period intervals.