JP2005117765A - Protection controller for battery pack, and protection control method for battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent the overdischarge of cells which constitute a battery pack. <P>SOLUTION: The voltages in respective modules M1-M20 which constitute the battery pack are detected by voltage sensors 20a-20t and selected one after another by a multiplexer 21, and is inputted into a MPU23 via an A/D converter 22. The MPU23 controls the multiplexer 21 to select only the voltage of a module which fulfills specified conditions, when it judges that the conditions that the rate of drop of the voltage of each module M1-M20 increases are fulfilled. It stops the discharge of the battery pack 1 in case that the module voltage inputted via the multiplexer 21 is lower than the specified voltage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus and a method for controlling a plurality of batteries constituting an assembled battery so as not to be overdischarged.

  The voltage of a plurality of cells constituting the assembled battery is detected, the detected voltage is compared with a predetermined voltage, and before the cell reaches overdischarge, the switch circuit interrupts between the assembled battery and the load, An apparatus for protecting an assembled battery is known (see Patent Document 1).

JP 2001-238358 A

  However, in nickel (Ni) -based secondary batteries, the voltage drop rate is fast in the region near overdischarge. Therefore, when the previous cell voltage was detected, the current cell voltage was detected even if the cell voltage was higher than the specified voltage. Sometimes, it may be below a predetermined voltage. In this case, the cell may be over-discharged even if shut-off control is performed by the switch circuit.

  The battery pack protection control apparatus and battery pack protection control method according to the present invention is configured to select a predetermined battery among a plurality of batteries when a condition for increasing the voltage drop rate of the batteries constituting the battery pack is satisfied. A battery voltage satisfying the above condition is selectively detected, and when the detected voltage is lower than a predetermined voltage, discharging from a battery having a voltage lower than the predetermined voltage is stopped at least.

  According to the battery pack protection control device and battery pack protection control method of the present invention, the voltage of the battery that satisfies the predetermined condition is selectively detected when the condition for increasing the voltage drop rate is satisfied. The battery detection interval can be shortened. This can reliably prevent the battery from being overdischarged before stopping the discharge.

  FIG. 1 is a diagram showing a configuration of an embodiment in which a battery pack protection control device according to the present invention is applied to a hybrid electric vehicle. In FIG. 1, the strong electric line is indicated by a thick solid line, the weak electric line is indicated by a thin solid line, and the control signal line is indicated by a dotted line. This hybrid electric vehicle includes an engine 1 and a motor generator 4 (hereinafter simply referred to as a motor 4) as a vehicle driving source. That is, the driving force of both or either of the engine 1 and the motor 4 is transmitted to the drive wheels 17a and 17b via the speed reducer 6.

  Generally, an electric motor (motor) is a power running operation by converting electric power into driving force, but can be regenerated by reversely converting driving force into electric power with the same structure. In addition, the generator (generator) converts the driving force into electric power for power generation operation (equivalent to regenerative operation), but it can be converted to electric power for driving operation with the same structure. It is. That is, the electric motor (motor) and the generator (generator) basically have the same structure, and both can be driven (power running) and generated (regenerated). Therefore, in this specification, a rotating electrical machine having both the function of an electric motor (motor) that converts electrical energy (electric power) into rotational energy (driving force) and the function of a generator (generator) that converts rotational energy into electrical energy. Is called a motor generator or simply a motor.

  The motor generator 3 (hereinafter simply referred to as the motor 3) is connected to the engine 2 and is used to start the engine 2 and is also driven by the engine 2 to generate electric power. The engine 2 is connected to the speed reducer 6 and the motor 4 via a power split mechanism 35. That is, the driving force of the engine 2 is transmitted to the drive wheels 17 a and 17 b and the motor 4 by the power split mechanism 35. As described above, the motor 4 is used as a vehicle drive source, and generates power by performing a regenerative operation when the vehicle is decelerated. Motor 3 and motor 4 are three-phase AC motors.

  The inverter 5 converts the DC power stored in the assembled battery 1 (high-power battery) into three-phase AC power and supplies it to the motor 4 to drive (power running) the motor 4. Further, the inverter 5 converts the three-phase AC power generated by the regenerative operation of the motor 3 or the motor 4 into DC power. The converted DC power is used for charging the assembled battery 1, and is stepped down by the DC / DC converter 7 and used for charging the 12V battery 8.

  The DC power stored in the 12V battery 8 is used to drive an auxiliary machine (not shown) and is boosted by the DC / DC converter 7 in accordance with the SOC of the assembled battery 1 to Also used when charging.

  The vehicle controller 9 controls the traveling of the vehicle by controlling the engine 2, the battery controller 10, and the motor controller 11. The vehicle controller 9, the battery controller 10, and the motor controller 11 are connected by an in-vehicle communication line 15, and exchange various information. The motor controller 11 controls the inverter 5 in order to control the operation modes of the motor 3 and the motor 4, that is, the power running operation mode and the regenerative operation mode.

  The battery controller 10 detects the voltage of each module constituting the assembled battery 1 and controls charging and discharging of the assembled battery 1 based on the detected module voltage. A detailed configuration of the battery controller 10 and a method for detecting the voltage of each module will be described later.

  The current sensor 12 detects a discharge current flowing from the assembled battery 1 to the inverter 5 and a charging current flowing from the inverter 5 to the assembled battery 1 and outputs the detected current to the battery controller 10. The cooling fan 14 is provided in the vicinity of the assembled battery 1, and cools the assembled battery 1 based on a command from the battery controller 10. The relay 30 is provided on a high power line between the assembled battery 1 and the inverter 5, and is connected / disconnected by the battery controller 10.

  FIG. 2 is a diagram illustrating a detailed configuration of the assembled battery 1 and the battery controller 10. The assembled battery 1 is configured by connecting 20 modules M1 to M20 in series. Each of the modules M1 to M20 is configured by connecting 12 cells in series. For example, the module M1 includes cells s1 to s12. The cells s1 to s240 constituting each of the modules M1 to M20 are, for example, nickel hydrogen batteries having a rated capacity of 6.5 (Ah) and a rated voltage of 1.2 (V).

  The temperature sensors 13a to 13t are provided for each of the modules M1 to M20, detect the temperatures of the corresponding modules M1 to M20, and output them to the battery controller 10.

  The battery controller 10 includes voltage sensors 20 a to 20 t, a multiplexer (MPX) 21, an A / D converter 22, a microprocessor 23 (hereinafter referred to as MPU 23), and a memory 24. The voltage sensors 20 a to 20 t are provided for each of the modules M 1 to M 20, detect the voltages of the corresponding modules M 1 to M 20, and output them to the multiplexer 21.

  FIG. 3 is a diagram illustrating a configuration concept of the multiplexer 21. The multiplexer 21 includes a switch 21a, and sequentially selects one voltage value (for example, 20a → 20b →... → 20t) from among the voltage values input from the voltage sensors 20a to 20t. Output to. The A / D converter 22 converts the voltage value, which is analog data input from the multiplexer 21, into a digital value and outputs the digital value to the MPU 23. The MPU 23 controls the multiplexer 21 to select and detect a voltage value of a predetermined module among all the modules M1 to M20 when a predetermined condition described later is satisfied. The contents of control performed by the MPU 23 will be described with reference to a flowchart shown in FIG.

  In addition, when the module voltage detected by the voltage sensors 20a to 20t is lower than the predetermined voltage, the MPU 23 stops the discharge of the assembled battery 1 by blocking the relay 30, thereby preventing the module from being overdischarged. To do. At this time, the warning lamp 16 is turned on via the vehicle controller 9 to notify the passenger that an abnormality has occurred.

  The memory 24 stores the current value detected by the current sensor 12 and the voltage value detected by the voltage sensors 20a to 20t.

  FIG. 4 is a flowchart showing an embodiment of an abnormal module detection program executed by the MPU 23. The process starting from step S10 is started together with the start of the vehicle, for example. In step S10, the charge / discharge current I of the assembled battery 1 detected by the current sensor 12 is acquired, and the temperatures of the modules M1 to M20 detected by the temperature sensors 13a to 13t are acquired. Further, the voltages V1 to V20 of the modules M1 to M20 detected by the voltage sensors 20a to 20t and input via the multiplexer 21 and the A / D converter 22 are acquired.

  In step S20 following step S10, SOC (State Of Charge) and internal resistances r1 to r20 of each of the modules M1 to M20 are calculated. The SOCs of the modules M1 to M20 can be obtained by integrating the current I detected in step S10.

  FIG. 5 is a diagram for explaining a method of calculating the internal resistances r1 to r20 of the modules M1 to M20. The MPU 23 performs a linear regression operation based on a plurality of data obtained by combining the module voltage detected by the voltage sensors 20a to 20t and the current detected by the current sensor 12 at that time, and the regression as shown in FIG. Find a straight line. The slope of the regression line obtained is the internal resistance. The internal resistance increases as charging / discharging is repeated. When the internal resistances r1 to r20 of all the modules M1 to M20 are calculated and stored in the memory 24, the process proceeds to step S30.

  In step S30 and step S40 to be described later, it is determined whether or not a condition for increasing the module voltage decrease rate is satisfied. In step S30, it is determined whether or not the lowest temperature Tmin among the temperatures of the modules M1 to M20 detected in step S10 is lower than a predetermined temperature T1. If it is determined that Tmin <T1 holds, the process proceeds to step S50, and if it is determined that Tmin <T1 does not hold, the process proceeds to step S40.

  In step S40, it is determined whether or not SOCmin, which is the smallest value among the SOCs of the modules M1 to M20 calculated in step S20, is smaller than a predetermined value SOC1. If it is determined that SOCmin <SOC1 is satisfied, the process proceeds to step S50. If it is determined that SOCmin <SOC1 is not satisfied, the process proceeds to step S120.

  In step S50, among the internal resistances of the modules M1 to M20 calculated in step S20, five modules are extracted in descending order of the internal resistance, and the extracted module numbers are stored in the memory 24. When the numbers of the five modules having high internal resistance are stored in the memory 24, the process proceeds to step S60.

  In step S60, the switch 21a of the multiplexer 21 is controlled so that only the voltage value of the module having the number stored in the memory 24 in step S50 is selected. If each module is charged and discharged under the same conditions, the SOC of the module having a high internal resistance is lowered. Therefore, selecting only the module having a high internal resistance by the multiplexer 21 means that the voltage of the module having a low SOC is detected preferentially. As a result, the voltage measurement cycle can be shortened. That is, by detecting the voltages of the five modules, the voltage measurement speed can be quadrupled compared to the case of detecting the voltages of the 20 modules.

  In step S70 following step S60, it is determined whether or not the lowest voltage Vmin among the module voltages selected by the multiplexer 21 in step S60 is smaller than a predetermined threshold value. If it is determined that the minimum voltage Vmin is equal to or higher than the predetermined threshold value, the process proceeds to step S80, and if it is determined that the minimum voltage Vmin is lower than the predetermined threshold value, the process proceeds to step S140. In step S140, since the module having the lowest voltage may be overdischarged, the relay 30 is disconnected and the process is terminated.

  On the other hand, in step S80, the charge / discharge current I of the assembled battery 1 detected by the current sensor 12 is acquired, and the temperatures of the modules M1 to M20 detected by the temperature sensors 13a to 13t are acquired. When the charge / discharge current I and the temperatures of the modules M1 to M20 are acquired, the process proceeds to step S90. In step S90, the SOC of each module M1 to M20 is calculated based on the charge / discharge current acquired in step S80. Since the SOC calculation method has been described in step S20, the description thereof is omitted here. When the SOC of each of the modules M1 to M20 is calculated, the process proceeds to step S100.

  In step S100 and step S110, which will be described later, whether or not the multiplexer 21 that has been controlled to select only five module voltages in step S60 is again controlled to sequentially select the voltages of all modules. Make a decision.

  In step S100, it is determined whether or not SOCmin, which is the smallest value among the SOCs of the modules M1 to M20 calculated in step S90, is equal to or greater than a predetermined value SOC1. If it is determined that SOCmin ≧ SOC1 holds, the process proceeds to step S110, and if it is determined that SOCmin ≧ SOC1 does not hold, the process returns to step S60.

  In step S110, it is determined whether or not Tmin which is the lowest temperature among the temperatures of the modules M1 to M20 acquired in step S80 is equal to or higher than a predetermined temperature T1. If it is determined that Tmin ≧ T1 holds, the process proceeds to step S120. If it is determined that Tmin ≧ T1 does not hold, the process returns to step S60.

  In step S120, normal multiplexer control is performed. That is, all the module voltages detected by the voltage sensors 20 a to 20 t are sequentially selected by the switch 21 a of the multiplexer 21 and output to the A / D converter 22. When the process of step S120 ends, the process proceeds to step S130.

  In step S130, whether the lowest voltage Vmin among the voltages V1 to V20 of each module M1 to M20 input via the multiplexer 21 in step S120 is smaller than a predetermined threshold value is the same as that in step S70. Determine whether or not. If it is determined that the minimum voltage Vmin is smaller than the predetermined threshold value, the process proceeds to step S140. If it is determined that the minimum voltage Vmin is equal to or higher than the predetermined threshold value, the process returns to step S10. Thereafter, the processes after step S10 described above are repeated.

  According to the assembled battery protection control device in the embodiment, when the condition for increasing the voltage decrease rate of the modules M1 to M20 constituting the assembled battery 1 is satisfied, the multiplexer 21 sets the predetermined condition. The voltage of the module to be filled is selectively detected. Thereby, compared with the case where the voltages of all the modules are sequentially detected, the voltage measurement period can be shortened, and the overdischarge of the module due to a sudden voltage drop can be prevented. In addition, since it is not necessary to use a plurality of A / D converters in order to shorten the voltage measurement cycle, for example, an increase in cost can be suppressed.

  In particular, in the battery pack protection control apparatus according to the embodiment, when there is a module whose SOC is lower than a predetermined SOC (SOC1), or when a module whose temperature is lower than a predetermined temperature T1 is present, the predetermined control is performed. The voltage of the module satisfying the condition is selectively detected. Thus, it is possible to determine whether or not a condition for increasing the voltage decrease rate in the overdischarge vicinity region is satisfied, and to prevent overdischarge of the module with certainty.

  In addition, when the voltage of the module is selectively detected, the voltage of a predetermined number of modules having a high internal resistance is detected. It can be surely prevented.

  The present invention is not limited to the embodiment described above. For example, in the above-described embodiment, it has been described that the voltages of the modules M1 to M20 configured by a plurality of cells are detected to prevent overdischarge in units of modules. However, the voltage may be detected in units of cells s1 to s240 to prevent overdischarge of each cell.

  In the above description, the number of modules for detecting the voltage is five. However, the number of modules corresponding to a desired voltage detection cycle may be selected.

  The assembled battery 1 has been described as being mounted on a hybrid electric vehicle. However, the assembled battery 1 may be mounted on an electric vehicle or may be an assembled battery used for other purposes than a vehicle. Further, the present invention is not limited by the number of cells and modules constituting the assembled battery 1 or the type of cells.

  In the above-described embodiment, when the lowest voltage Vmin among the module voltages is lower than a predetermined threshold, the battery pack 1 and the load are disconnected by the relay 30 to cut off the battery pack 1. The discharge was stopped. However, a module having a voltage lower than a predetermined threshold may be disconnected from the assembled battery 1 to stop discharging only the abnormal module. In this case, an output from another normal module can be obtained. In addition, when applying a method of detecting a voltage in cell units, an abnormal cell may be separated from the assembled battery 1.

  The correspondence between the constituent elements of the claims and the constituent elements of the embodiment is as follows. That is, the voltage sensors 20a to 20t and the multiplexer 21 are voltage detection means, the MPU 23 is a condition determination means and control means, the MPU 23 and the relay 30 are discharge stop means, the current sensor 12 and MPU 23 are SOC detection means, and the temperature sensor 13a. ˜13t constitutes the temperature detection means, and the voltage sensors 20a-20t, the current sensor 12 and the MPU 23 constitute the internal resistance detection means. In addition, unless the characteristic function of this invention is impaired, each component is not limited to the said structure.

The figure which shows the structure of one Embodiment which applied the protection control apparatus of the assembled battery by this invention to the hybrid electric vehicle. The figure which shows the detailed structure of an assembled battery and a battery controller Conceptual diagram showing the configuration of the multiplexer The flowchart which shows the processing content performed by the protection control apparatus of the assembled battery in one embodiment The figure for explaining the method of calculating the internal resistance of each module

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Assembly battery 2 ... Engine 3 ... Motor generator 4 ... Motor generator 5 ... Inverter 6 ... Reduction gear 7 ... DC / DC converter 8 ... 12V battery 9 ... Vehicle controller 10 ... Battery controller 11 ... Motor controller 12 ... Current sensor 13a- 13t ... temperature sensor 14 ... cooling fan 15 ... communication line 16 ... warning lights 17a, 17b ... wheels 20a-20t ... voltage sensor 21 ... multiplexer 22 ... A / D converter 23 ... microprocessor 24 ... memory 30 ... relay 35 ... power split Mechanisms M1 to M20 ... modules s1 to s240 ... cells

Claims (8)

In a battery pack protection control device comprising a plurality of batteries,
Voltage detecting means for detecting voltages of the plurality of batteries;
Condition determining means for determining whether or not a condition for increasing the rate of voltage decrease of the plurality of batteries is satisfied;
A control means for controlling the voltage detection means so as to selectively detect a voltage of a battery that satisfies a predetermined condition when the condition determination means determines that the condition for increasing the voltage decrease rate is satisfied;
A battery pack protection control device, comprising: a discharge stop unit that stops at least discharge from a battery having a voltage lower than the predetermined voltage when the voltage detected by the voltage detection unit is lower than a predetermined voltage. . In the assembled battery protection control device according to claim 1,
An SOC detection means for detecting the SOC of the plurality of batteries;
The condition determining means determines that the condition for increasing the voltage decrease rate is satisfied when any one of the plurality of SOCs detected by the SOC detecting means is lower than a predetermined SOC. A battery pack protection control device. The battery pack protection control device according to claim 1 or 2,
Temperature detecting means for detecting temperatures of the plurality of batteries;
The condition determining means determines that a condition for increasing the voltage decrease rate is satisfied when any one of the plurality of temperatures detected by the temperature detecting means is lower than a predetermined temperature. A battery pack protection control device. In the protection control apparatus of the assembled battery in any one of Claims 1-3,
Further comprising internal resistance detection means for detecting internal resistance of the plurality of batteries;
The battery that satisfies the predetermined condition is a predetermined number of batteries counted from the higher internal resistance among the plurality of internal resistances detected by the internal resistance detecting means. apparatus. In the protection control apparatus of the assembled battery in any one of Claims 1-4,
The assembled battery protection control device, wherein the discharge stopping means interrupts between the assembled battery and a load. In the protection control apparatus of the assembled battery in any one of Claims 1-4,
The discharge stop means disconnects a battery having a voltage lower than the predetermined voltage from the battery pack. In the protection control apparatus of the assembled battery in any one of Claims 1-6,
The battery pack constituting the battery pack is a cell or a module constituted by a plurality of cells. In a battery pack protection control method for sequentially detecting voltages of a plurality of batteries constituting a battery pack and stopping discharge from a battery having a voltage lower than the predetermined voltage when the detected voltage is lower than the predetermined voltage. ,
It is determined whether or not a condition for increasing the voltage decrease rate of the plurality of batteries is satisfied,
A battery pack protection control method comprising: selectively detecting a voltage of a battery that satisfies a predetermined condition when it is determined that a condition for increasing the voltage decrease rate is satisfied.

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