Battery pack controller

• US 20070013347A1
• Filed: 07/11/2006
• Published: 01/18/2007
• Est. Priority Date: 07/12/2005
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Kamohara, Hideaki
• Granted Patent: US 7,583,053 B2
• Time in Patent Office: Days
• US Class Current: 320/160
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• 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 2240/662 Temperature
• CPC Class Codes: B60L 2260/26 Transition between different drive modes
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/04 Cutting off the power supply under fault conditions protective devices and circuit arrangements in general H01H; H02H
• 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 58/21 having the same nominal voltage
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2510/246 Temperature
• CPC Class Codes: F02N 11/04 the motors being associated with current generators
• CPC Class Codes: F02N 11/0862 characterised by the electrical power supply means, e.g. battery
• CPC Class Codes: F02N 11/0866 comprising several power sources, e.g. battery and capacitor or two batteries
• CPC Class Codes: F02N 2200/061 Battery state of charge [SOC]
• CPC Class Codes: F02N 2200/063 Battery voltage
• CPC Class Codes: F02N 2200/064 : Battery temperature
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• 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 90/16 : Information or communication technologies improving the operation of electric vehicles

Abstract

The invention provides a specific battery detection means that specifies single batteries believed to be in an excess discharge state during operation of the electric motor for starting the engine, based on data for each battery pack detected prior to starting the engine. With the specific battery detection means, a change in voltage for specific single batteries is measured for a drop in voltage of a single battery by the discharge via the voltage detection means. The specific battery detection means is configured such that if the results of this measurement are outside a predetermined threshold value, the power supplied to the electric motor for starting the engine is limited.

Claims

1. A battery pack controller connected with a battery pack, the battery pack including a plurality of batteries to supply electric power to a motor/generator, the battery pack controller comprising:

a voltage detector to detect a voltage of each of the batteries;

a detected voltage transmitter to retrieve voltage detected on the plurality of batteries from a plurality of voltage detectors and continuously transmit each voltage detected,

a specific battery detector that, based on the transmitted voltage detected, specifies as target batteries for voltage detection those batteries having minimal voltage when the electric motor is operated; and

a power supply controller that controls power supplied from the battery pack to the electric motor when the battery voltage detected by the voltage detector is below a preset threshold voltage value, wherein the voltage detector detects a voltage for the target battery prior to operating the electric motor for starting an internal combustion engine.

2. A battery pack controller as claimed in claim 1, wherein the specific battery detector detects a battery of the plurality of batteries having the lowest power available for discharge, up to a threshold voltage value that acts as an excess discharge limit startup voltage that activates battery discharge limits.

3. A battery pack controller as claimed in claim 1, wherein an amount of power available for discharge is calculated from an open voltage for the specified batteries, an internal resistance calculated from a load current during operation prior the time of calculation, and the threshold voltage value.

4. A battery pack controller as claimed in claim 1, further comprising:

a map of a relationship between a temperature previously measured and an internal resistance;

a temperature detector to detect a temperature in the battery pack; and

an internal resistance corrector to correct an internal resistance value of a battery in the battery pack based on the temperature detected by the temperature detector according to the map.

5. A battery pack controller as claimed in claim 1, wherein a threshold voltage value to control a charge state of the specific single battery is set according to one of a vehicle state consisting of one of engine operation or startup, a single battery temperature, or combination of battery temperatures, such that:

wherein when a battery temperature is lower than a prescribed temperature, an excess discharge is detected, and a voltage threshold value to control a power output and a voltage threshold value prohibiting output are set lower than during a normal state wherein the battery temperature is higher than the prescribed value, and

wherein when the battery temperature is higher that the prescribed temperature, a hypothetical internal resistance is calculated for the charge state for a lower control of the specified single battery from the calculated internal resistance and the battery temperature, and a maximum battery output value is estimated using the hypothetical internal resistance to determine a control startup voltage threshold value.

6. A battery pack controller as claimed in claim 1, wherein the controller does not stop the internal combustion engine after an ignition switch is turned ON until a battery temperature exceeds a prescribed temperature, except when the ignition switch is turned OFF.

7. A battery pack controller as claimed in claim 1, further comprising:

an output power controller that controls the charge state of the single battery such that during one of an excess discharge state or an excess charge detection state for all of the single batteries within the battery pack, when an excess discharge or excess charge state is entered due to detection of a single battery outside a first threshold value that is a discharge power control startup voltage, voltage detection for the single batteries is conducted with a cell controller, and a single battery exceeding the threshold value is specified,

and wherein voltage detection on the specified single battery is conducted one of continuously or at a cycle shorter than the drop in single battery voltage due to discharge, such that the specified single battery does not reach a second threshold value, wherein the second threshold value is an irreversible deterioration voltage for the single battery designated by battery controller software.

8. A vehicle equipped with an internal combustion engine, comprising:

an electric motor for internal combustion engine startup capable of starting the internal combustion engine;

a battery pack including a plurality of single batteries that supply power to the electric motor;

a voltage detector capable of detecting the voltage of each of the single batteries,

a detected voltage transmitter capable of retrieving voltage detected on the plurality of single batteries from a plurality of voltage detectors and continuously transmitting each voltage detected;

a specific battery detector that, based on the transmitted voltage detected, specifies as target single batteries for voltage detection those single batteries believed to have minimal voltage when the electric motor is operated; and

a power supply controller that controls power supplied from the battery pack to the electric motor when the single battery voltage detected by the voltage detector is below a preset threshold voltage value, wherein the voltage detector detects a voltage for the target single battery prior to operating the electric motor for starting the internal combustion engine.

9. A vehicle as claimed in claim 8, wherein the specific battery detector detects single batteries of the plurality of single batteries having the lowest power available for discharge, up to a threshold voltage value that acts as an excess discharge limit startup voltage that activates battery discharge limits.

10. A vehicle as claimed in claim 9, wherein an amount of power available for discharge is calculated from an open voltage for the specified single batteries, an internal resistance calculated from a load current during operation prior the time of calculation, and the threshold voltage value.

11. A vehicle as claimed in claim 8, further comprising:

a map of a relationship between a temperature previously measured and an internal resistance;

a temperature detector to detect a temperature in the battery pack; and

an internal resistance corrector to correct an internal resistance value of the specific battery based on the temperature detected by the temperature detector according to the map.

12. A vehicle as claimed in claim 8, wherein a threshold voltage value to control a charge state of the specific single battery is set according to one of a vehicle state consisting of one of engine operation or startup, a single battery temperature, or combination of battery temperatures, such that:

wherein when a battery temperature is lower than a prescribed temperature, an excess discharge is detected, and a voltage threshold value to control a power output and a voltage threshold value prohibiting output are set lower than during a normal state wherein the battery temperature is higher than the prescribed value, and

wherein when the battery temperature is higher that the prescribed temperature, a hypothetical internal resistance is calculated for the charge state for a lower control of the specified single battery from the calculated internal resistance and the battery temperature, and a maximum battery output value is estimated using the hypothetical internal resistance to determine a control startup voltage threshold value.

13. A vehicle as claimed in claim 8, wherein stopping the internal combustion engine after an initial internal combustion engine startup after an ignition switch is turned ON is not allowed until a battery temperature exceeds a prescribed temperature, except when the ignition switch is turned OFF.

14. A vehicle as claimed in claim 8, further comprising:

an output power controller that controls the charge state of the single battery such that during one of an excess discharge state or an excess charge detection state for all of the single batteries within the battery pack, when an excess discharge or excess charge state is entered due to detection of a single battery outside a first threshold value that is a discharge power control startup voltage, voltage detection for the single batteries is conducted with a cell controller, and a single battery exceeding the threshold value is specified,

and wherein voltage detection on the specified single battery is conducted one of continuously or at a cycle shorter than the drop in single battery voltage due to discharge,

such that the specified single battery does not reach a second threshold value, wherein the second threshold value is an irreversible deterioration voltage for the single battery designated by battery controller software.

15. A battery pack controller connecting a plurality of single batteries that comprise a battery pack and that supply power to an electric motor for starting an internal combustion engine, comprising:

means for detecting a voltage of each of the plurality of single batteries and supplying power to the electric motor;

means for retrieving the voltage detected of the plurality of single batteries and continuously transmitting each voltage detected;

means for specifying as target single batteries for voltage detection those single batteries believed to have minimum voltage when the electric motor is operated, based on the transmitted voltage detected; and

means for detecting a voltage for the target single battery prior to operating the electric motor for starting the internal combustion engine and controlling power supplied from the battery pack to the electric motor for starting the internal combustion engine when the detected target single battery voltage is less than a prescribed threshold voltage value.

16. A method comprising:

detecting a voltage of each of a plurality of single batteries that comprise a battery pack and that supply power to an electric motor for starting an internal combustion engine;

retrieving the voltage detected on the plurality of single batteries;

continuously transmitting each voltage detected;

based on the transmitted voltage detected, specifying as target single batteries for voltage detection those single batteries believed to have minimum voltage when the electric motor is operated;

detecting a voltage for the target single battery prior to operating the electric motor for starting the internal combustion engine; and

controlling power supplied from the battery pack to the electric motor for starting the internal combustion engine when the detected target single battery voltage is less than a prescribed threshold voltage value.

17. The method of claim 16, further comprising:

calculating an amount of power available for discharge from an open voltage for the specified single batteries, an internal resistance calculated from a load current during operation prior the time of calculation, and the threshold voltage value; and

detecting single batteries of the plurality of single batteries having the lowest power available for discharge, up to a threshold voltage value that acts as an excess discharge limit startup voltage that activates battery discharge limits.

18. The method of claim 16, further comprising:

storing a map of a relationship between a temperature previously measured and an internal resistance;

detecting a temperature in the battery pack; and

correcting an internal resistance value of the specific battery based on the temperature detected by the temperature detector according to the map.

19. The method of claim 16, further comprising:

setting a threshold voltage value to control a charge state of the specific single battery according to one of a vehicle state consisting of one of engine operation or startup, a single battery temperature, or combination of battery temperatures, such that;

wherein when a battery temperature is lower than a prescribed temperature, an excess discharge is detected, and a voltage threshold value to control a power output and a voltage threshold value prohibiting output are set lower than during a normal state wherein the battery temperature is higher than the prescribed value, and

wherein when the battery temperature is higher that the prescribed temperature, a hypothetical internal resistance is calculated for the charge state for a lower control of the specified single battery from the calculated internal resistance and the battery temperature, and a maximum battery output value is estimated using the hypothetical internal resistance to determine a control startup voltage threshold value.

20. The method of claim 16, further comprising:

controlling the charge state of the single battery such that during one of an excess discharge state or an excess charge detection state for all of the single batteries within the battery pack, when an excess discharge or excess charge state is entered due to detection of a single battery outside a first threshold value that is a discharge power control startup voltage, voltage detection for the single batteries is conducted with a cell controller, and a single battery exceeding the threshold value is specified; and

conducting voltage detection on the specified single battery one of continuously or at a cycle shorter than the drop in single battery voltage due to discharge, such that the specified single battery does not reach a second threshold value, wherein the second threshold value is an irreversible deterioration voltage for the single battery designated by battery controller software.