Apparatus for and method of calculating output deterioration in secondary battery

• US 20030030414A1
• Filed: 08/06/2002
• Published: 02/13/2003
• Est. Priority Date: 08/08/2001
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Suzuki, Kouhei
• Granted Patent: US 6,747,457 B2
• Time in Patent Office: Days
• US Class Current: 320/136
• CPC Class Codes: B60L 1/003 to auxiliary motors, e.g. for pumps, compressors
• CPC Class Codes: B60L 2210/30 AC to DC converters
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2250/16 by display
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• 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 58/21 having the same nominal voltage
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• 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: Y02E 60/10 Energy storage using batteries
• 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: Y02T 90/12 : Electric charging stations
• CPC Class Codes: Y02T 90/14 : Plug-in electric vehicles

Abstract

In a secondary battery output deterioration calculating apparatus that calculates a battery output deterioration in conformance to the output ratio of the battery output ascertained as a secondary battery becomes depleted and an initial battery output, the extent of depletion of the secondary battery is calculated through an arithmetic operation by calculating an output ratio based upon the open circuit voltage of the secondary battery and the voltage manifesting while the secondary battery is charged with a constant current.

Claims

1. A secondary battery output deterioration calculating method for calculating a battery output deterioration based upon an output ratio of a battery output ascertained as a secondary battery becomes depleted and an initial battery output, comprising:

detecting an open circuit voltage of the secondary battery;

detecting a voltage while the secondary battery is charged with a constant current; and

calculating the output ratio of the open circuit voltage of the secondary battery having been detected and the voltage detected while the secondary battery is charged with the constant current.

2. A secondary battery output deterioration calculating apparatus that calculates a battery output deterioration based upon an output ratio of a battery output ascertained as a secondary battery becomes depleted and an initial battery output, wherein:

the output ratio is calculated in correspondence to the open circuit voltage of the secondary battery and a voltage detected while the secondary battery is charged with a constant current.

3. A secondary battery output deterioration calculating apparatus according to claim 2, comprising:

an open circuit voltage detection device that detects the open circuit voltage of the secondary battery;

a no-load internal resistance detection device that calculates an internal resistance of the secondary battery corresponding to the open circuit voltage detected by the open circuit voltage detection device;

a constant current charge operation voltage detection device that detects the voltage manifesting while the secondary battery is charged with a constant current;

a charge operation internal resistance calculation device that calculates the internal resistance in the secondary battery corresponding to the voltage detected by the constant current charge operation voltage detection device while the secondary battery is charged with the constant current; and

an output deterioration calculation device that calculates the output deterioration based upon a ratio of the internal no-load resistance and the internal charge resistance.

4. A secondary battery output deterioration calculating apparatus according to claim 3, further comprising:

a subtraction stage estimating device that estimates a number of stages over which a current is to be reduced during a multistage constant current charge operation performed to charge the secondary battery by sequentially reducing the current until the charge operation is completed; and

an output ratio correction device that corrects the output ratio calculated by the output deterioration calculation device based upon the number of subtraction stages estimated by the subtraction stage estimating device.

5. A secondary battery output deterioration calculating apparatus according to claim 4, wherein:

if the charge operation is halted before shifting to the multistage constant current charge operation, the output deterioration calculation device calculates the output ratio after the charge operation is halted.

6. A secondary battery output deterioration calculating apparatus according to claim 5, wherein:

the output ratio calculated by the output deterioration calculation device after the charge operation is halted is calculated based upon a current value and a voltage value detected immediately before the charge operation is halted and a voltage value detected after the charge operation is halted.

7. A secondary battery output deterioration calculating apparatus according to claim 3, wherein:

the open circuit voltage detection device includes a temperature detection device which detects the temperature of the secondary battery and a temperature correction device that corrects the open circuit voltage of the secondary battery based upon the temperature of the secondary battery detected by the temperature detection device.

8. A secondary battery output deterioration calculating apparatus that calculates a battery output deterioration based upon an output ratio of a battery output ascertained as a secondary battery becomes depleted and an initial battery output, comprising:

an open circuit voltage detection means for detecting an open circuit voltage of the secondary battery;

a no-load internal resistance detection means for calculating an internal resistance of the secondary battery corresponding to the open circuit voltage detected by the open circuit voltage detection means;

a constant current charge operation voltage detection means for detecting the voltage manifesting while the secondary battery is charged with a constant current;

a charge operation internal resistance detection means for calculating the internal resistance of the secondary battery corresponding to the voltage detected by the voltage detection means while the secondary battery is charged with the constant current; and

an output deterioration calculation means for calculating the output deterioration based upon a ratio of the internal no-load resistance and the internal charge resistance.