Vehicle, method of estimating state of charge of secondary battery, and method of controlling vehicle

• US 8,509,975 B2
• Filed: 10/17/2008
• Issued: 08/13/2013
• Est. Priority Date: 02/19/2008
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Izumi, Junta
• Primary Examiner(s): Trammell, James
• Assistant Examiner(s): SMITH-STEWART, DEMETRA R
• Application Number:
  US12/864,577
• Publication Number:
  US 20100318252A1
• Time in Patent Office: 1,761 Days
• Field of Search: None
• US Class Current: 701/22
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/28 characterised by the electric energy storing means, e.g. batteries or capacitors
• 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 2240/80 Time limits
• 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 58/20 having different nominal voltages
• 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 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• 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 2050/0031 Mathematical model of the vehicle
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/3832 without measurement of battery voltage
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H02J 7/0071 : with a programmable schedule
• CPC Class Codes: H02J 7/1423 : with multiple batteries
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• 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

Abstract

A vehicle comprising a chargeable/dischargeable battery, a current sensor for detecting the current from the battery, and a control unit for estimating the charged state of the battery and controlling the charging/discharging of the battery according to the charged state. In a first operation mode in which charging and discharging cycles are repeated, the control unit estimates the open-circuit voltage of the battery, and determines the charged state on the basis of the value which is obtained by correcting the open-circuit voltage according to the polarization. In a second operation mode in which either one of charging and discharging is continued, the control unit determines the charged state on the basis of the result of integration of the current detected by the current sensor. Hence, the charged and discharged amperehours are large, thereby providing a vehicle which can effectively utilize the secondary battery.

Claims

1. A vehicle comprising:

a chargeable and dischargeable secondary battery;

a current sensor for detecting electric current of said secondary battery; and

a controller for estimating a state of charge of said secondary battery and controlling charging and discharging of said secondary battery based on said state of charge,

in a first operation mode in which a charging cycle and a discharging cycle are repeated, said controller estimating the state of charge of said secondary battery by a first estimation method of estimating an open circuit voltage of said secondary battery and determining said state of charge based on a value obtained by correcting said open circuit voltage based on polarization, and

in a second operation mode in which one of charging and discharging is continued, said controller estimating the state of charge of said secondary battery by a second estimation method different from said first estimation method,

following said second estimation method, said controller determining said state of charge based on a result of integration of the electric current detected by said current sensor,

said vehicle being configured to be able to perform external charging by which said secondary battery is charged from a source external to the vehicle,

said second operation mode being selected when said external charging is performed,

said vehicle further comprising an air conditioning apparatus capable of executing pre-ride air conditioning using electric power supplied from said secondary battery,

said second operation mode being selected when said external charging is performed and when said pre-ride air conditioning is performed, and

when one of said external charging and said pre-ride air conditioning is executed as a preprocess and the other of said external charging and said pre-ride air conditioning is executed as a post-process performed subsequently to said preprocess, said controller storing an offset value of said current sensor before said preprocess is executed and, when said post-process is executed, said controller using said offset value stored before said preprocess is executed, to correct the electric current detected by said current sensor.

2. The vehicle according to claim 1, further comprising an electric motor capable of executing a power-running operation and a regenerative operation, wherein

said first operation mode is selected when the vehicle travels in such a manner that said power-running operation and said regenerative operation can be repeated.

3. A method of estimating a state of charge of a secondary battery that is chargeable and dischargeable, comprising the steps of:

determining an operation mode in which said secondary battery is used;

estimating the state of charge of said secondary battery by a first estimation method of estimating an open circuit voltage of said secondary battery and determining said state of charge based on a value obtained by correcting said open circuit voltage based on polarization, when said step of determining an operation mode determines that said operation mode is a first operation mode in which a charging cycle and a discharging cycle are repeated; and

estimating the state of charge of said secondary battery by a second estimation method different from said first estimation method, determining said state of charge based on a result of integration of electric current detected by the current sensor, when said step of determining an operation mode determines that said operation mode is a second operation mode in which one of charging and discharging is continued,

said second estimation method determining said state of charge based on a result of integration of electric current detected by the current sensor,

said secondary battery being mounted on a vehicle,

said vehicle being configured to be able to perform external charging by which said secondary battery is charged from a source external to the vehicle,

said step of determining an operation mode determining that the operation mode is said second operation mode when said external charging is performed,

said vehicle further including an air conditioning apparatus capable of executing pre-ride air conditioning using electric power supplied from said secondary battery,

said second operation mode being selected when said external charging is performed and when said pre-ride air conditioning is performed, and

said method further comprising the step of storing, when one of said external charging and said pre-ride air conditioning is executed as a preprocess and the other of said external charging and said pre-ride air conditioning is executed as a post-process performed subsequently to said preprocess, an offset value of said current sensor before said preprocess is executed and, when said post-process is executed, using said offset value stored before said preprocess is executed, to correct the electric current detected by said current sensor.

4. The method of estimating a state of charge of a secondary battery according to claim 3, wherein

said vehicle further includes an electric motor capable of executing a power-running operation and a regenerative operation, and

said step of determining an operation mode determines that the operation mode is said first operation mode when the vehicle is traveling in such a manner that said power-running operation and said regenerative operation can be repeated.

5. A vehicle comprising:

a secondary battery configured to be capable of being charged from a source external to the vehicle;

a current sensor for detecting electric current of said secondary battery;

an air conditioning apparatus capable of executing pre-ride air conditioning using electric power supplied from said secondary battery; and

a controller receiving an output of said current sensor for controlling charging and discharging of said secondary battery,

when said secondary battery is discharged and said pre-ride air conditioning is executed, said controller calculating an amount of discharge current by integrating the discharge current and, when said secondary battery is charged from a source external to the vehicle immediately after said pre-ride air conditioning is ended, said controller performing control by calculating an integral of charge current so that said secondary battery is charged with the charge current of the integral equal to said calculated amount of discharge current.

6. A method of controlling a vehicle,

said vehicle including:

a secondary battery configured to be capable of being charged from a source external to the vehicle;

a current sensor for detecting electric current of said secondary battery; and

an air conditioning apparatus capable of executing pre-ride air conditioning using electric power supplied from said secondary battery,

said method comprising the steps of;

calculating, when said secondary battery is discharged and said pre-ride air conditioning is executed, an amount of discharge current by integrating discharge current detected by said current sensor; and

calculating, when said secondary battery is charged from a source external to the vehicle immediately after said pre-ride air conditioning is ended, an integral of charge current detected by said current sensor so that said secondary battery is charged with the charge current of the integral equal to said calculated amount of discharge current.