Battery system, battery monitoring method and apparatus

• US 7,173,397 B2
• Filed: 02/25/2004
• Issued: 02/06/2007
• Est. Priority Date: 06/10/2003
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd., Shin-Kobe Electric Machinery Company Limited (Resonac Holdings Corp.)
• Original Assignee: Hitachi, Ltd., Shin-Kobe Electric Machinery Company Limited (Resonac Holdings Corp.)
• Inventors: Emori, Akihiko, Miyazaki, Hideki, Kinoshita, Takuya, Hirasawa, Tokiyoshi, Okoshi, Tetsuro
• Primary Examiner(s): Easthom; Karl
• Assistant Examiner(s): Muralidar; Richard V.
• Application Number:
  US10/785,408
• Publication Number:
  US 20040251875A1
• Time in Patent Office: 1,077 Days
• Field of Search: 320/134, 324/433
• US Class Current: 320/134
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/14 for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A battery performance monitoring system anticipates the sudden fall of battery output. The system measures the battery voltage at a time point when the discharge current of a battery becomes smaller than the reference current value or at a time point when the current to the load which is connected to the battery becomes smaller than the reference current value, and judges the battery to be abnormal if the difference of the measured battery voltage from the approximate formula in regard to the current-voltage relation in the former half of a same discharge event becomes out of the reference range.

Claims

1. A method of monitoring the abnormality of battery equipment which stores electric power by being charged and discharges the stored power to a load, the method comprising the steps of:

measuring the voltage and current of the battery equipment at each power discharging to the load;

predicting the recovery pattern of discharge voltage from the peak time of the discharge current of the battery equipment based on the measured voltage and current; and

judging the battery equipment to be abnormal if the discharge voltage which has been measured immediately before or after the ceasing of discharge to the load is lower by a predetermined value than the predicted discharge voltage on the recovery pattern at the same time point as of the discharge voltage immediately before or after the ceasing of discharge.

2. A method of monitoring the abnormality of battery equipment which stores electric power by being charged and discharges the stored power to a load, the method comprising the steps of:

measuring the voltage and current of the battery equipment at each power discharging to the load;

getting an approximate formula of the recovery pattern of discharge voltage from the peak time of the discharge current of the battery equipment based on the measured voltage and current; and

judging the battery equipment to be abnormal if the correlation factor between the approximate data used for the calculation of the approximate formula and the approximate formula is equal to or smaller than a threshold value or if the square mean error of the approximate data from the approximate formula is larger than a reference value.

3. Apparatus for monitoring the abnormality of battery equipment, which stores electric power by being charged and discharges the stored power to a load, based on the voltage and current of the battery equipment,

wherein the apparatus predicts the recovery pattern of discharge voltage from the peak time of the discharge current of the battery equipment, and judges the battery equipment to be abnormal if the discharge voltage which has been measured immediately before or after the ceasing of discharge to the load is lower by a predetermined value than the predicted discharge voltage on the recovery pattern at the same time point as of the discharge voltage immediately before or after the ceasing of discharge.

4. Apparatus for monitoring the abnormality of battery equipment, which stores electric power by being charged and discharges the stored power to a load, based on the voltage and current of the battery equipment,

the apparatus comprising:

a section for monitoring at least the variation of recovering voltage immediately before or after the ceasing of discharge to the load in regard to the discharge voltage recovery characteristics to the discharge current of the battery equipment, and diagnosing the abnormality of the battery equipment; and

a battery replacement judgment section which accumulates the value of current which has been charged since the emergence of battery abnormality until the end of full-charging, and indicates the need of battery replacement if the cumulative current value is smaller than a cumulative current judgment value.

5. A battery system comprising:

battery equipment which stores electric power by being charged and discharges the stored power to a load;

a voltage sensor which measures the charging voltage and discharging voltage of the battery equipment;

a current sensor which measures the charging current and discharging current of the battery equipment; and

a controller for predicting the recovery pattern of discharge voltage from the peak time of the discharge current of the battery equipment, and judging the battery equipment to be abnormal if the discharge voltage which has been measured immediately before or after the ceasing of discharge to the load is lower by a predetermined value than the predicted discharge voltage on the recovery pattern at the same time point as of the discharge voltage immediately before or after the ceasing of discharge.

6. A battery system comprising:

battery equipment which stores electric power by being charged and discharges the stored power to a load;

a voltage sensor which measures the charging voltage and discharging voltage of the battery equipment;

a current sensor which measures the charging current and discharging current of the battery equipment; and

a controller which takes in the outputs of the voltage sensor and the current sensor and controls the charging and discharging of the battery equipment, the controller monitoring at least the variation of recovering voltage immediately before or after the ceasing of discharge to the load in regard to the discharge voltage recovery characteristics to the discharge current of the battery equipment, and diagnosing the abnormality of the battery equipment;

a battery replacement judgment section which accumulates the value of current which has been charged since the emergence of battery abnormality until the end of full-charging, and indicates the need of battery replacement if the cumulative current value is smaller than a cumulative current judgment value.

7. A battery system comprising:

battery equipment which stores electric power by being charged and discharges the stored power to a load;

a voltage sensor which measures the charging voltage and discharging voltage of the battery equipment;

a current sensor which measures the charging current and discharging current of the battery equipment; and

a controller for predicting the recovery pattern of discharge voltage from the peak time of the discharge current of the battery equipment, and judging the battery equipment to be abnormal if the discharge voltage which has been measured immediately before or after the ceasing of discharge to the load is lower by a predetermined value than the predicted discharge voltage on the recovery pattern at the same time point as of the discharge voltage immediately before or after the ceasing of discharge;

wherein the battery equipment comprises a secondary battery which is installed on a vehicle such as a motor car and used as energy source for engine starting, and the controller comprises a battery controller which controls the energy flow of the starter motor and generator, and the battery system is applied to the drive system of the car.

8. A battery system comprising:

battery equipment which stores electric power by being charged and discharges the stored power to a load;

a voltage sensor which measures the charging voltage and discharging voltage of the battery equipment;

a current sensor which measures the charging current and discharging current of the battery equipment;

a controller for predicting the recovery pattern of discharge voltage from the peak time of the discharge current of the battery equipment, and judging the battery equipment to be abnormal if the discharge voltage which has been measured immediately before or after the ceasing of discharge to the load is lower by a predetermined value than the predicted discharge voltage on the recovery pattern at the same time point as of the discharge voltage immediately before or after the ceasing of discharge;

wherein the battery system is adapted to be applied a distributed electric power source which includes an AC-to-DC converter which charges the battery equipment up to the state of full-charge based on the commercial power source, and an electric generator which supplies, together with the battery equipment, electric power to the load by way of the AC-to-DC converter when the power supply from the commercial power source is shut off, with momentary load variations being treated by the battery equipment.

9. A battery system comprising:

battery equipment which stores electric power by being charged and discharges the stored power to a load;

a voltage sensor which measures the charging voltage and discharging voltage of the battery equipment;

a current sensor which measures the charging current and discharging current of the battery equipment; and

a controller for predicting the recovery pattern of discharge voltage from the peak time of the discharge current of the battery equipment, and judging the battery equipment to be abnormal if the discharge voltage which has been measured immediately before or after the ceasing of discharge to the load is lower by a predetermined value than the predicted discharge voltage on the recovery pattern at the same time point as of the discharge voltage immediately before or after the ceasing of discharge;

wherein the drive system of a fuel-cell car which includes a fuel cell which extracts electric power from fuel, and a motor controller which controls a motor based on power from the fuel cell and the battery equipment by way of an inverter, with momentary load variations being treated by the battery equipment the response of which is faster than that of the fuel cell.

10. A battery system comprising:

battery equipment which stores electric power by being charged and discharges the stored power to a load;

a voltage sensor which measures the charging voltage and discharging voltage of the battery equipment;

a current sensor which measures the charging current and discharging current of the battery equipment; and

a controller which takes in the outputs of the voltage sensor and the current sensor and controls the charging and discharging of the battery equipment, the controller monitoring at least the variation of recovering voltage immediately before or after the ceasing of discharge to the load in regard to the discharge voltage recovery characteristics to the discharge current of the battery equipment, and diagnosing the abnormality of the battery equipment; and

a battery replacement judgment section which accumulates the value of current which has been charged since the emergence of battery abnormality until the end of full-charging, and indicates the need of battery replacement if the cumulative current value is smaller than a cumulative current judgment value;

wherein the battery equipment comprises a secondary battery which is installed on a vehicle such as a motor car and used as energy source for engine starting, and a battery controller which controls the energy flow of the starter motor and generator, and the battery system is applied to the drive system of the car.

11. A battery system comprising:

battery equipment which stores electric power by being charged and discharges the stored power to a load;

a voltage sensor which measures the charging voltage and discharging voltage of the battery equipment;

a current sensor which measures the charging current and discharging current of the battery equipment; and

a controller which takes in the outputs of the voltage sensor and the current sensor and controls the charging and discharging of the battery equipment, the controller monitoring at least the variation of recovering voltage immediately before or after the ceasing of discharge to the load in regard to the discharge voltage recovery characteristics to the discharge current of the battery equipment, and diagnosing the abnormality of the battery equipment and;

a battery replacement judgment section which accumulates the value of current which has been charged since the emergence of battery abnormality until the end of full-charging, and indicates the need of battery replacement if the cumulative current value is smaller than a cumulative current judgment value;

wherein the battery system is adapted to be applied to a distributed electric power source which includes an AC-to-DC converter which charges the battery equipment up to the state of full-charge based on the commercial power source, and an electric generator which supplies, together with the battery equipment, electric power to the load by way of the AC-to-DC converter when the power supply from the commercial power source is shut off, with momentary load variations being treated by the battery equipment.

12. A battery system comprising:

battery equipment which stores electric power by being charged and discharges the stored power to a load;

a voltage sensor which measures the charging voltage and discharging voltage of the battery equipment;

a current sensor which measures the charging current and discharging current of the battery equipment; and

a controller which takes in the outputs of the voltage sensor and the current sensor and controls the charging and discharging of the battery equipment, the controller monitoring at least the variation of recovering voltage immediately before or after the ceasing of discharge to the load in regard to the discharge voltage recovery characteristics to the discharge current of the battery equipment, and diagnosing the abnormality of the battery equipment; and

a battery replacement judgment section which accumulates the value of current which has been charged since the emergence of battery abnormality until the end of full-charging, and indicates the need of battery replacement if the cumulative current value is smaller than a cumulative current judgment value;

wherein the battery system is adapted to be applied to a drive system of a fuel-cell car which includes a fuel cell which extracts electric power from fuel, and a motor controller which controls a motor based on power from the fuel cell and the battery equipment by way of an inverter, with momentary load variations being treated by the battery equipment the response of which is faster than that of the fuel cell.