JP5381303B2 - Battery pack capacity adjustment device - Google Patents

Description

  The present invention relates to a battery pack capacity adjustment device for equalizing the capacities of unit batteries constituting the battery pack, as a battery pack as a series connection of unit batteries that are one or a plurality of adjacent battery cells.

  As this type of capacity adjusting device, as shown in, for example, Patent Document 1 below, an apparatus that performs capacity adjustment (equalization processing) when temperature variation in a portion of the assembled battery is large has been proposed. Here, in view of the fact that the temperature of the battery has a correlation with the self-discharge rate of the battery, when the temperature variation is small, it is determined that the variation in self-discharge between the batteries to be equalized is also small. If the self-discharge variation is small, the equalization process is not performed.

JP 2007-325458 A

  By the way, the actual capacity variation between the equalization targets (unit batteries) differs depending on the usage state of the assembled battery. For this reason, if it is determined whether or not the equalization process is performed based on the current temperature distribution of the assembled battery, it is not possible to appropriately determine whether or not the equalization process is performed according to the degree of variation in the unit battery capacity. There is a fear.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to configure the assembled battery as an assembled battery as a serially connected unit battery that is one or a plurality of adjacent battery cells. An object of the present invention is to provide an assembled battery capacity adjusting device capable of more appropriately performing capacity equalization processing between unit batteries.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  The invention according to claim 1 is the capacity of the assembled battery that equalizes the capacity of the unit batteries constituting the assembled battery with respect to the assembled battery as a series connection body of unit batteries that are one or a plurality of adjacent battery cells. In the adjustment device, an estimation means for estimating a variation in capacity between the unit batteries according to a charge / discharge history of the assembled battery based on a monitoring of a charging / discharging current of the assembled battery, and a variation in the estimated capacity And a variable means for variably setting an execution mode of the capacity equalization process.

  The amount of increase in the capacity of the unit battery when the charging current flows through the unit battery is not uniquely determined depending on the charging current, but depends on the amount lost due to heat generation in the internal resistance. Also, the amount of decrease in the capacity of the unit battery when the discharge current flows through the unit battery is not uniquely determined depending on the charging current, and depends on the amount lost by the heat generation in the internal resistance. For this reason, it is thought that the dispersion | variation in the capacity | capacitance between unit cells is decided according to the charge / discharge history. In the above invention, in view of this point, it is possible to perform the equalization process in an appropriate manner according to the degree of capacity variation by estimating the capacity variation between unit cells.

  The variable means is means for issuing a command relating to the capacity equalization processing to hardware means for executing the capacity equalization processing based on the variation in capacity estimated by the estimation means. Also good. In this case, the variable means may be configured not to include means for acquiring the voltage value of the unit battery.

The invention according to claim 1 is characterized in that the estimating means quantifies the variation in the capacity based on an integrated value of a variation parameter calculated according to the detected value of the charge / discharge current.

  In the above invention, the variation in capacity can be easily quantified by the integrated value by regarding the charge / discharge history as the value of the variation parameter corresponding to the detected value.

  The variation parameter is desirably proportional to the square of the detected value of the charge / discharge current.

The invention according to claim 1 is characterized in that the variation parameter is calculated based on a detected value of the charge / discharge current and a parameter relating to an internal resistance of the unit battery.

  As described above, the capacity change of the unit battery due to the charge / discharge current depends on the amount lost due to heat generation in the internal resistance. For this reason, it depends on the internal resistance. In the above invention, in view of this point, the variation parameter is calculated based on the parameter relating to the internal resistance.

  It is desirable that the variation parameter be a value indicating that the variation is larger as the parameter relating to the internal resistance corresponds to the larger internal resistance. Moreover, it is desirable that the variation parameter is proportional to the square of the detected value of the charge / discharge current.

The invention according to claim 2 is the invention according to claim 1 , characterized in that the parameter relating to the internal resistance is a detected value of temperature.

  There is a correlation between the temperature of the unit cell and the internal resistance of the unit cell. For this reason, the temperature of a unit battery or an assembled battery becomes a parameter regarding internal resistance.

According to a third aspect of the present invention, in the invention according to the first or second aspect , the variable means includes a judging means for judging whether or not the capacity equalization process is executed based on the estimated capacity variation. It is characterized by providing.

  In the above-described invention, by including the determination unit, it is possible to appropriately determine whether or not the equalization process is performed regardless of whether the voltage value or capacity value of the unit battery can be acquired.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the variable means sets the capacity equalization processing time based on the estimated capacity variation. A time setting means is provided.

  In the said invention, processing time can be set appropriately by using the dispersion | variation in the estimated capacity | capacitance.

In the first configuration, when the equalization process is performed, the estimation unit estimates the capacity variation according to the equalization process time.

  When the equalization process is performed, it is considered that the variation in capacity is reduced according to the equalization process time. In view of this point, the above invention takes the equalization processing time into account when estimating the variation in capacity.

The invention according to claim 5 is the invention according to any one of claims 1 to 4 , wherein the means for performing the equalization processing is the predetermined number connected in parallel to a predetermined number of adjacent unit cells. A series connection body of resistors, means for comparing the potential at each connection point between the resistors and the potential at each connection point between the unit cells, and the predetermined number of unit cells based on the comparison result And a discharging means for discharging a battery whose voltage is assumed to be high.

  In the above invention, since means for equalizing these capacities without directly detecting the voltages of a predetermined number of unit cells is provided, it is particularly desirable to accurately determine the equalization time and whether or not equalization is performed. . For this reason, the above-described invention is particularly advantageous in that it includes an estimation unit and a variable unit.

  The predetermined number may be a value smaller than the total number of unit batteries constituting the assembled battery (for example, a value obtained by dividing the total number of unit batteries constituting the assembled battery by an integer of 2 or more), but is the total number of unit batteries. May be.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the predetermined number of adjacent unit batteries constitute a block in which the assembled battery is grouped, and a block for detecting a voltage of each of these blocks A voltage detecting unit; and an inter-block equalizing unit that discharges a voltage of a high-voltage block based on a detection result of the block voltage detecting unit, wherein the variable unit is configured to block the block based on the estimated variation. It is characterized in that it determines whether or not to perform the discharge process by the interval equalizing means.

  In the said invention, the capacity | capacitances between blocks change by the equalization process of the capacity | capacitance of the unit battery in a block. For this reason, it is difficult to determine with high accuracy whether or not the equalization process between blocks should be executed until the capacity equalization process in the block is completed. In this regard, in the above-described invention, it is possible to determine whether or not to perform the equalization process between blocks regardless of whether or not the capacity equalization process in the block is completed by providing the estimation unit.

According to a seventh aspect of the invention, in the fifth or sixth aspect of the invention, the predetermined number of adjacent unit cells constitute a block in which the assembled battery is grouped, and the voltage of each block is detected. Block voltage detecting means, and an inter-block equalizing means for discharging the voltage of the high voltage block based on the detection result of the block voltage detecting means, and the variable means is based on the estimated variation, The discharge process by the inter-block equalizing means is performed after the time point when the discharge process by the discharge means is assumed to be completed.

  In the said invention, the capacity | capacitances between blocks change by the equalization process of the capacity | capacitance of the unit battery in a block. For this reason, it is difficult to appropriately execute the equalization process between blocks until the capacity equalization process in the block is completed. In this regard, in the above invention, by providing the estimation means, the equalization process between blocks can be executed after the capacity equalization process in the block is completed.

The invention according to claim 8 is the invention according to any one of claims 1 to 7 , wherein the assembled battery is connected to a rotating machine as an in-vehicle main machine via a power conversion circuit, The equalization process is characterized in that the equalization process is performed on condition that the power conversion circuit is stopped.

  When the charge / discharge current amount of the assembled battery is small, the voltage and capacity of the unit battery have a substantially one-to-one relationship, so that the equalization process can be easily performed with high accuracy. In the said invention, in view of this point, it is set as the conditions of the equalization process that the power conversion circuit, which is a situation where the charge / discharge current amount of the assembled battery is reduced, is stopped.

The system block diagram concerning one Embodiment. The circuit diagram which shows the circuit structure of the equalization unit concerning the embodiment. The figure which shows the relationship between the temperature of a battery cell, and internal resistance. The figure which shows the parameter used for the estimation of the dispersion | variation in capacity between battery cells in the said embodiment. The flowchart which shows the procedure of the equalization discharge process concerning the embodiment. The time chart which shows the equalization discharge process aspect concerning the embodiment.

  Hereinafter, a first embodiment in which an assembled battery capacity adjustment device according to the present invention is applied to an in-vehicle hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows an overall configuration of a system according to the present embodiment.

  The illustrated assembled battery 10 is a series connection body of battery cells Cij (i = 1 to n, j = 1 to 4) which are secondary batteries. These battery cells Cij are lithium ion secondary batteries. These battery cells Cij are grouped by four adjacent to each other to form a block.

  Both ends of the block constituted by the battery cells Ci1 to Ci4 are connected to switching elements Si and S (i + 1) constituting the multiplexer MPX. The switching elements Si, S (i + 1) are switches that electrically open and close the both ends of the block and the flying capacitor 11. Both ends of the flying capacitor 11 are connected to the voltage detection circuit 12 through switching elements Sa and Sb. The switching elements Sa and Sb are switches that perform electrical switching between both ends of the flying capacitor 11 and a pair of input terminals of the voltage detection circuit 12.

  Each block is provided with an equalization unit Ui. The equalization unit Ui is a dedicated hardware means for performing processing (equalization processing) for reducing variation in capacity between the battery cells Ci1 to Ci4 constituting the block, and is configured by an integrated circuit. Note that the equalization unit Ui uses a corresponding block as a power source, and the power supply terminal and the block of the logic circuit in the equalization unit Ui are opened and closed via the switch Sc. The switch Sc is a switch that opens and closes between the block and the equalizing unit Ui in accordance with an external command. In particular, the switch Sc has a function of maintaining a closed state until a new open command signal is input when a pulsed close command signal is input.

  On the other hand, the microcomputer (microcomputer 14) acquires the temperature detection value of the assembled battery 10 by the temperature sensor 15, the detection value I of the charge / discharge current of the assembled battery 10 by the current sensor 17, and the voltage detection result by the voltage detection circuit 12. Or an instruction to perform equalization processing to the equalization unit Ui. Here, the microcomputer 14 constitutes a vehicle-mounted low-voltage system, and this vehicle-mounted low-voltage system is insulated from the vehicle-mounted high-voltage system including the assembled battery 10. For this reason, the microcomputer 14 performs communication with the equalization unit Ui via the interface 16 configured to include an insulating means such as a photocoupler.

  The assembled battery 10 is connected to the in-vehicle power conversion circuit via the main relays 18 and 20. Here, the in-vehicle power conversion circuit refers to an inverter connected to a motor generator as an in-vehicle main machine, a step-down converter that steps down the voltage of the assembled battery 10 and applies it to the power source (low voltage battery) of the in-vehicle auxiliary equipment. It is.

  FIG. 2A shows a circuit configuration of the equalization unit Ui. This circuit is based on the magnitude comparison between the potential of the connection point between adjacent ones of the battery cells Ci1 to Ci4 and the potentials obtained by equally dividing the voltages at both ends of the battery cells Ci1 to Ci4 by the number of battery cells. This is a circuit that discharges the battery cells Ci1 to Ci4 having a high voltage.

  Specifically, a series connection body of resistors R1 to R4 and NPN type bipolar transistors (discharge switches SW1 to SW4) is connected in parallel to each of the battery cells Ci1 to Ci4. And the output of OR circuit OR1-OR4 is applied to the conduction control terminal (base) of discharge switch SW1-SW4. As a result, the logical sum circuits OR1 to OR4 output a logic “H” signal, so that the discharge switches SW1 to SW4 are turned on, via the discharge circuit including the resistors R1 to R4 and the discharge switches SW1 to SW4. Battery cells Ci1-Ci4 are discharged.

  Each of the OR circuits OR1 to OR4 is a two-input circuit, and one terminal thereof has battery cells Ci1 to Ci4 in the block in order to reduce variations in voltage of the battery cells Ci1 to Ci4 in the block. A signal for discharging a battery cell having a high voltage is input. This is realized by a circuit described below.

  At both ends of the block (both ends of the series connection body of battery cells Ci1 to Ci4), a series connection body of resistors 31 to 34 equal in number to the number of battery cells constituting the block is connected in parallel. These resistors 31 to 34 are set to have the same resistance value. For this reason, the potential of the connection point of the resistors 31 to 34 is the connection point potential between the battery cells in the block (battery cells Ci2, Ci3, Ci4) that is assumed when the voltages of the battery cells Ci1 to Ci4 in the block are equal. Positive electrode potential).

  The connection point potential between the battery cells in the block (the positive potential of the battery cells Ci2, Ci3, Ci4) and the potential at the connection point of the corresponding resistors 31-34 are respectively the cell terminal C of the comparison circuit CMP and the divided voltage. Input to terminal R. The comparison circuit CMP includes a high voltage terminal H and a low voltage terminal L as output terminals. Then, as shown in FIG. 2B, when the potential of the cell terminal C is higher than the potential of the voltage dividing terminal R by a predetermined value Δ or more, the high voltage terminal H becomes logic “H”, and the cell terminal C Is lower than the potential of the voltage dividing terminal R by a predetermined value Δ or more, the low voltage terminal L becomes logic “H”.

  The output voltage of the low voltage terminal L having the highest potential in the comparison circuit CMP is applied to the OR circuit OR1 having the highest potential, and the output voltage of the high voltage terminal H having the lowest potential is the logical sum of the lowest potential. Applied to circuit OR4. Further, the output voltage of the logic circuit LC is applied to the intermediate OR circuits OR2 and OR3.

  The logic circuit LC receives the signals of a pair of adjacent comparison circuits CMP as inputs and generates an output signal. FIG. 2C shows a circuit configuration of the logic circuit LC. As illustrated, the logic circuit LC includes a logic inverting circuit 40 that logically inverts an output signal of the low voltage terminal L of the high potential side comparison circuit CMP, and an output of the low voltage terminal L of the low potential side comparison circuit CMP. A logical product circuit for generating a logical product signal of the signal and the output voltage of the logical inversion circuit. Further, the logic inversion circuit 44 that logically inverts the output signal of the high voltage terminal H of the comparison circuit CMP on the low potential side, the output signal of the high voltage terminal H of the comparison circuit CMP on the high potential side, and the output voltage of the logic inversion circuit 44. And a logical product circuit 46 for generating a logical product signal. Further, an OR circuit 48 for generating an OR signal of the output signals of these AND circuits 42 and 46 is provided.

  According to such a configuration, the logic circuit LC has the cell terminal C of the high-potential side comparison circuit CMP higher than the potential of the voltage dividing terminal R by a predetermined value Δ and the cell terminal C of the low-potential side comparison circuit CMP. Becomes “H” when the potential is not higher than the potential of the voltage dividing terminal R by a predetermined value Δ or more. In addition, the logic circuit LC is configured such that the potential of the cell terminal C of the high potential side comparison circuit CMP is not lower than the potential of the voltage dividing terminal R by a predetermined value Δ and the potential of the cell terminal C of the low potential side comparison circuit CMP. Is “H” when the voltage is lower than the potential of the voltage dividing terminal R by a predetermined value Δ or more.

  According to the equalization unit Ui having such a configuration, based on the comparison between the divided voltage value by the resistors 31 to 34 and the corresponding positive electrode potential without detecting the absolute value of the voltage of the battery cells Ci1 to Ci4 in the block. A cell having a high voltage can be selectively discharged.

  On the other hand, a terminal T1 for receiving a command signal from the microcomputer 14 is connected to the other input terminals of the OR circuits OR1 to OR4. As a result, when a logic “H” signal is input from the microcomputer 14 via the terminal T1, all the discharge switches SW1 to SW4 are turned on, and all the battery cells Ci1 to Ci4 in the block are discharged. This is used when processing for reducing voltage variation between blocks is performed. That is, when the microcomputer 14 detects the voltage of each block using the flying capacitor 11, the microcomputer 14 outputs a discharge command signal to the terminal Ti of the equalization unit Ui corresponding to the high voltage block based on the detection result. Thereby, the voltage variation between blocks can also be reduced. As described above, in the present embodiment, by using the equalization unit Ui, not only the process of reducing the voltage variation of the battery cells Ci1 to Ci4 in the block (intra-block equalization process) but also the voltage between the blocks. It is also possible to perform processing for reducing variation (inter-block equalization processing).

  In the present embodiment, the equalization process is performed when the start switch of the vehicle is turned off. This is in view of the fact that a unique relationship is established between the voltage of the battery cell Cij and the remaining capacity (SOC) when the charge / discharge current of the battery cell Cij is zero. That is, when a charge / discharge current flows through the battery cell Cij, the voltage of the battery cell Cij depends not only on the SOC but also on the voltage drop amount in the internal resistance. For this reason, when there is a variation in internal resistance between the battery cells Cij, there is a possibility that the variation in the SOC cannot be accurately grasped from the variation in the voltage of the battery cell Cij or the block. For this reason, the equalizing discharge process is performed in a situation where the amount of charge / discharge current is reduced to eliminate the influence of the internal resistance as much as possible, that is, in a situation where the start switch is turned off. The activation switch is a switch for activating the vehicle control system and can be operated by the user. Here, the operation by the user does not necessarily mean that the user manually operates, but includes that the user brings a portable wireless transmitter that outputs a predetermined wireless signal close to the vehicle, for example.

  In the present embodiment, after performing the process of reducing the capacity variation within the block, the process of reducing the capacity variation between the blocks is performed. Here, the block equalization process is performed by stopping the microcomputer 14 after the switch Sc is closed by the microcomputer 14 so that the power of the block is supplied to the equalization unit Ui. Thereby, power consumption can be reduced compared with the case where the microcomputer 14 is made into an operation state during the process by the equalization unit Ui.

  However, the time required for the equalization process depends on the degree of capacity variation at the start of the equalization process. Here, in this embodiment, since the microcomputer 14 does not have a means for acquiring the detected value of each voltage of the battery cells Ci1 to Ci4 in the block, the capacity variation degree at the start of the equalization process is determined by the battery cell. It cannot be grasped based on the voltage values of Ci1 to Ci4. Here, when it is determined that the block equalization process has been completed by eliminating the change in the block voltage, it is necessary to start the microcomputer 14 many times, which leads to an increase in power consumption of the microcomputer 14. . In addition, in the case where the intra-block equalization process is performed over a predetermined time, it is necessary to make this time redundant, and therefore the voltage of the battery cells Ci1 to Ci4 in the block. After the variation is reduced, useless power consumption by the equalization unit Ui may occur.

  Therefore, in the present embodiment, the degree of capacity variation between the battery cells Cij is estimated according to the charge / discharge history of the assembled battery 10 based on the monitoring of the charge / discharge current of the assembled battery 10 each time. Based on the estimation result, not only the intra-block equalization processing time but also whether or not the equalization processing is performed is determined. Hereinafter, the process for estimating the degree of variation in capacity will be described in detail.

  The amount of change in the SOC of the battery cell Cij due to charging / discharging of the battery cell Cij is considered to depend on the amount of heat generated by the internal resistance of the battery cell Cij. Here, the heat generation amount can be expressed as “RII” using the internal resistance R and the detected value I of the charge / discharge current. When this calorific value varies between battery cells Cij, it is considered that this causes a variation in capacity of battery cells Cij. Variations in the amount of heat generated can occur due to variations in internal resistance. For this reason, when the variation ΔR of the internal resistance is fixed, the larger the detected value I of the charge / discharge current, the larger the variation “ΔRII” of the heat generation amount.

  However, in practice, the variation in internal resistance is considered to change according to temperature. This is because there is a relationship shown in FIG. 3 between the temperature of the battery cell Cij and the internal resistance value. That is, as shown in the figure, the internal resistance decreases as the temperature of the battery cell Cij increases. Here, it is considered that the difference in the value of the internal resistance due to the individual difference between the battery cells Cij increases as the absolute value of the internal resistance increases. For this reason, it is considered that the variation in internal resistance increases as the temperature decreases.

  From the above, in this embodiment, it is estimated that the degree of variation increases as the charge / discharge current amount increases and the temperature decreases. In order to quantify the degree of variation estimated in this manner, it is effective to integrate each time the product “βII” of the parameter β that increases as the temperature decreases and the square of the charge / discharge current detection value I. it is conceivable that. Therefore, in the present embodiment, as shown in FIG. 4A, a coefficient α that is proportional to the absolute value of the detected value I of the charge / discharge current and increases as the temperature decreases is defined. By multiplying the absolute values, the amount to be integrated (current value for integration) shown in FIG. 4B is calculated. By integrating the current value for integration every time, the degree of variation can be quantified by the integrated value.

  FIG. 5 shows the procedure of the estimation process and the equalization process. This process is repeatedly executed by the microcomputer 14 or the like, for example, at a predetermined cycle.

  In this series of processing, first, in step S10, it is determined whether or not the intra-block equalization flag F is “1”. This process is for determining whether or not the block equalization process is being performed. If a negative determination is made in step S10, it is determined in step S12 whether or not it is immediately after the start switch is turned off. This process is for determining whether one of the equalization process execution conditions is satisfied. If a negative determination is made in step S12, it is determined in step S14 whether or not the start switch is on. This process is for determining whether or not to update the estimated value (integrated value) of the degree of variation. And when a starting switch is an ON state, processing of Steps S16-S20 is performed in order to update an integrated value.

  Here, first, in step S16, a detection value I of the charge / discharge current amount and a detection value Tem of the temperature of the assembled battery 10 are acquired. In subsequent step S18, the charge / discharge current detection value I and the temperature detection value Tem are input, and the coefficient α is subjected to a map calculation. In step S20, the integrated value In is updated by newly integrating a value obtained by multiplying the detection value I of the charge / discharge current by the coefficient α. As a result, the estimated value of the degree of variation is updated by the detected value Tem of the current temperature and the detected value I of the charge / discharge current.

  On the other hand, when a positive determination is made in step S12, the process proceeds to step S22. In step S22, it is determined whether or not the integrated value In is greater than or equal to a threshold value InL. This process is for determining whether another execution condition of the equalization process is satisfied. Here, the integrated value In is quantified as a parameter having a positive correlation with the variation degree of the battery cell Cij (since it is a parameter that increases as the variation degree of the battery cell Cij increases), the threshold value described above. Based on the comparison with InL, it can be determined whether or not the degree of variation has reached a level that requires equalization processing. If an affirmative determination is made in step S22, the intra-block equalization flag F is set to “1” in step S24, assuming that the execution condition for the intra-block equalization process is satisfied.

  When the process of step S24 is completed or when an affirmative determination is made in step S10, an intra-block equalization process is performed in step S26. That is, the microcomputer 14 is stopped after the microcomputer 14 is operated to close the switch Sc. In a succeeding step S28, it is determined whether or not the start switch is turned on. This process is for determining whether or not the execution condition of the intra-block equalization process is not satisfied.

  If a negative determination is made in step S28, it is determined in step S30 whether or not the duration of the intra-block equalization process has reached the specified time Tdis. Here, the prescribed time Tdis is set to a longer time as it is estimated that the degree of capacity variation is larger based on the integrated value In. For example, this process may be a process of starting the microcomputer 14 when the time measured by a timer externally attached to the microcomputer 14 reaches a specified time Tdis. Further, for example, a process for turning on the main power supply of the microcomputer 14 when the microcomputer 14 includes a timer that maintains the power supply state regardless of the state of the main power supply and when the measured time reaches a predetermined time Tdis. Also good.

  When an affirmative determination is made in step S30, in step S32, the integrated value In is set to zero, the intra-block equalization flag is set to “0”, and equalization processing between blocks is started.

  On the other hand, when an affirmative determination is made in step S28, in step S34, the integrated value In is corrected according to the intra-block equalization processing time, and the intra-block equalization flag F is set to “0”. The affirmative determination in step S28 is not performed when the microcomputer 14 is stopped, but is a process performed when the microcomputer 14 is activated by turning on the activation switch.

  When a negative determination is made in steps S14 and S22 described above, or when the processes of steps S20, S32, and S34 are completed, the series of processes is temporarily terminated.

  FIG. 6 illustrates an equalization processing mode by the above processing. 6 (a1), 6 (b1), 6 (c1), 6 (a2), 6 (b2), 6 (c2), 6 (a3), 6 (b3) ) And FIG. 6C3 are a first example, a second example, and a third example of equalization processing, respectively. Here, FIGS. 6 (a1), 6 (a2) and 6 (a3) show the transition of the start switch, and FIGS. 6 (b1), 6 (b2) and 6 (b3) show the integrated values. FIG. 6 (c1), FIG. 6 (c2), and FIG. 6 (c3) show the transition of whether or not the equalization process is executed. Here, the first example shown in FIGS. 6 (a1), 6 (b1), and 6 (c1) is the same as the first example shown in FIGS. 6 (a2), 6 (b2), and 6 (c2). Since the integrated value In when the start switch is turned off is larger than in the example of 2, the equalization processing time is also increased.

  6A3, FIG. 6B3, and FIG. 6C3 illustrate a case where the start switch is turned on again before the specified time Tdis determined from the integrated value In elapses. . In this case, the integrated value In is corrected according to the time during which the equalization process is performed.

  Incidentally, FIG. 6 shows an example in which the equalization process is performed after waiting for a certain time after the start switch is turned off. This is based on the voltage due to the influence of polarization immediately after the start switch is turned off. This is because it is difficult to grasp the SOC with high accuracy.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The capacity variation between the battery cells Cij was estimated according to the charge / discharge history of the battery pack 10, and the execution mode of the equalization process was variably set based on the estimated capacity variation. Thereby, equalization processing can be performed in an appropriate manner according to the degree of variation in capacity.

  (2) The variation in capacity was quantified by the integrated value In of the dispersion parameter (current value for integration) calculated according to the detected value I of the charge / discharge current. Thereby, the dispersion | variation in a capacity | capacitance can be easily quantified with integrated value In.

  (3) The variation parameter (accumulation current value) was calculated based on the detected value Tem of the temperature of the assembled battery 10. Thereby, the current value for integration can be calculated based on the temperature dependency of the variation degree of the internal resistance of the battery cell Cij (difference between the internal resistance values).

  (4) Based on the estimated variation in capacity (integrated value In), it was determined whether or not the equalization process was performed. Thereby, after the start switch is turned off, the microcomputer 14 can quickly determine whether the equalization process is necessary.

  (5) The equalization processing time (specified time Tdis) is variably set based on the estimated capacity variation (integrated value In). Thereby, the equalization processing time can be set appropriately.

  (6) The variation in capacity (integrated value In) was corrected according to the equalization processing time. Thereby, the dispersion | variation in a capacity | capacitance can be estimated with high precision.

  (7) As hardware means for equalization, based on a comparison between the potentials of the connection points of the resistors 31 to 34 and the potentials of the connection points of the corresponding battery cells Cij, the battery cells Ci1 to Ci4 Among these, an equalizing unit Ui for discharging what is assumed to be high in voltage was provided. The time required for equalization by the microcomputer 14 is not based on the voltage information by not providing the means (microcomputer 14) for instructing the equalization process with means for acquiring the voltage detection value of the battery cell Cij. It is particularly desirable to determine whether or not equalization is performed with high accuracy. For this reason, the merit which performs the said equalization process using integrated value In is especially big.

  (8) The execution condition of the equalization process includes that the power conversion circuit is stopped. Thereby, since the equalization process can be performed when the voltage and the capacity of the unit battery have a substantially one-to-one relationship, the capacity equalization process based on the voltage value can be performed with high accuracy.

(Other embodiments)
The above embodiment may be modified as follows.

  In the above embodiment, the coefficient α is calculated based on the detected value I of the charge / discharge current and the detected value Tem of the temperature, and the coefficient α is multiplied by the absolute value of the detected value I, thereby obtaining the variation parameter (accumulation current value). ) Is calculated, but is not limited thereto. A map that defines the relationship between the detection values I and Tem and the parameter to be integrated may be used.

  The parameter relating to the internal resistance of the battery cell Cij is not limited to a parameter having a negative correlation with the internal resistance, such as temperature. For example, the block estimated and calculated based on a plurality of sets of the voltage of the block (battery cells Ci1 to Ci4) detected using the flying capacitor 11 and the voltage detection circuit 12 and the charge / discharge current of the block at that time. It may be an internal resistance. Here, what is necessary is just to estimate that the dispersion | variation degree of internal resistance of the battery cells Ci1-Ci4 in a block becomes large, so that the internal resistance of a block is large.

  The integrated value In is not limited to integrating the variation parameter calculated using the internal resistance parameter as an input. For example, the square of the detected value I of the charge / discharge current may be used as a variation parameter and integrated. Considering that there is an individual difference in the internal resistance of the battery cell Cij, the integrated value calculated in this way is considered to be a parameter quantifying the variation in capacity.

  In the above embodiment, based on the integrated value In, both whether to perform equalization processing and the equalization processing time (specified time Tdis) in the block are set, but this is not limitative. For example, the microcomputer 14 can obtain the logical sum signals of the OR circuits OR1 to OR4 shown in FIG. 2, and the microcomputer 14 is activated every time the equalization processing in the block is performed for a predetermined time. It may be determined whether or not becomes “L”. Here, when the logical sum signal is logical “L” means that the equalization within the block has been completed, the equalization processing within the block may be terminated on this condition.

  Further, for example, the switch Sc may be turned on over a period in which the start switch is turned off. Even in this case, since the completion time of equalization within a block can be predicted based on the integrated value In, the number of times the microcomputer 14 is activated for equalization between blocks can be reduced. It can also be determined whether or not the equalization process between blocks should be executed. On the other hand, in the case where no means for predicting the equalization processing time within the block based on the integrated value In is provided, the microcomputer 14 is activated every predetermined time, detects the voltage between the blocks, and performs the equalization processing between the blocks. It becomes necessary to determine whether or not to perform. For this reason, the power consumption accompanying the starting of the microcomputer 14 increases. In addition, there is a possibility that the equalization process between the blocks is performed before the intra-block equalization is completed. In this case, the normally closed type switch may be used as the switch Sc.

  In the above embodiment, the equalization processing is performed in two stages, that is, equalization within a block and equalization between blocks. However, the present invention is not limited to this. For example, a dedicated hardware unit having a function like the equalization unit Ui may be designed and used so as to discharge a high voltage of all the battery cells C11 to Cn4 of the assembled battery 10. . Even in this case, since the capacity value (voltage value) of each battery cell Cij cannot be obtained from this hardware means, it is effective to estimate the capacity variation in the manner of the above embodiment.

  Further, at this time, the lower the temperature representative of the assembled battery 10, the larger the variation in capacity among the battery cells Cij, and the process is not limited to the process of increasing the variation parameter. For example, temperature sensors may be provided at a plurality of locations of the assembled battery 10 to further consider these temperature variations. For example, the variation parameter calculated using the average value of the detection values of the plurality of temperature sensors may be corrected by increasing the degree of variation of the detection value.

  In the above embodiment, when the start switch is turned on, the integrated value In is changed according to the time during which the equalizing discharge process is performed, but the present invention is not limited to this. For example, the integrated value In may be gradually decreased according to the processing time during the equalizing discharge process.

  The method for determining whether or not the in-vehicle power conversion circuit is stopped is not limited to whether the start switch is off or on. For example, the main relays 18 and 20 may be off or on.

  -The equalization process is not limited to that performed on condition that the in-vehicle power conversion circuit is stopped. For example, when it is performed while the in-vehicle power conversion circuit is operating, it is difficult to accurately determine the capacity variation between the blocks based on the detected value of the block voltage due to the influence of the charge / discharge current. For this reason, it is effective to determine whether or not the equalization process is performed based on the integrated value In. Further, whether or not the equalization process is performed may be determined based on both the degree of variation between the detected values of the block voltage and the integrated value In. That is, in a situation where the variation in capacity cannot be determined with high accuracy depending on the detected voltage value due to the charge / discharge current of the block, the variation in capacity is determined with high accuracy by adding the integrated value In. It becomes possible.

  -Furthermore, it is not restricted to what is provided with the hardware means which performs an equalization process, without providing the means to detect the voltage of the equalization object like the said embodiment. For example, even when a means for detecting the voltage of each battery cell Cij is provided, as described above, when equalization is performed under the situation where the battery cells are charged and discharged, the voltage between the battery cells is In addition to the variation, it is considered that the presence or absence of equalization can be determined with high accuracy by adding the integrated value In. Further, for example, in the case where the equalization process is performed on the condition that the on-vehicle power conversion circuit is stopped, after the power conversion circuit is stopped, by determining the presence or absence of the equalization process based on the integrated value In, Compared with the case where the voltage of the battery cell is detected once and the presence / absence of the equalization process is determined based on this, it is possible to quickly determine whether or not the equalization process is performed.

  As a means for estimating the variation in capacity between battery cells in accordance with the charging / discharging history of the assembled battery based on the monitoring of the charging / discharging current amount of the assembled battery 10 each time, the detected value I of the charging / discharging current of the assembled battery 10 It is not restricted to the means which inputs. For example, it may be a means for inputting the running state of the vehicle or the operation state of the in-vehicle power conversion circuit. That is, the running state of the vehicle and the operation state of the in-vehicle power conversion circuit are parameters having a correlation with the charging / discharging current of the assembled battery. The current can be estimated, and as a result, it is possible to estimate the variation in capacity between the battery cells according to the charge / discharge history. For example, this is done by gradually increasing the degree of variation in capacity according to the ON time of the start switch and increasing the increasing speed of the degree of variation when there is a situation where the vehicle travels on an uphill road during this time. Can do.

  The battery cell Cij is not limited to a lithium secondary battery such as a lithium ion secondary battery, but may be an alkaline secondary battery such as a nickel metal hydride secondary battery.

  In the above embodiment, the present invention is applied to a hybrid vehicle. However, the present invention is not limited to this. For example, the present invention may be applied to an electric vehicle.

  DESCRIPTION OF SYMBOLS 10 ... Battery pack, 14 ... Microcomputer (one embodiment of an estimation means and a variable means), Cij ... Battery cell, Ui ... Equalization unit.

Claims (8)

About the assembled battery as a series connection body of unit batteries which are one or a plurality of adjacent battery cells, in the capacity adjustment device of the assembled battery for equalizing the capacity of the unit batteries constituting the assembled battery,
Estimating means for estimating the variation in capacity between the unit batteries according to the charge / discharge history of the assembled battery based on the monitoring of the charging / discharging current for each assembled battery;
Variable means for variably setting an execution mode of the capacity equalization processing based on the estimated capacity variation ;
The estimation means quantifies the variation in capacity by an integrated value of variation parameters calculated according to the detected value of the charge / discharge current,
The assembled battery capacity adjustment device , wherein the variation parameter is calculated based on a detected value of the charge / discharge current and a parameter relating to an internal resistance of the unit battery . Battery pack capacity adjustment apparatus according to claim 1, wherein the parameters relating to the internal resistance is detected values of the temperature. 3. The capacity adjustment of the assembled battery according to claim 1, wherein the variable unit includes a determination unit that determines whether or not the capacity equalization process is performed based on the estimated variation in capacity. apparatus. It said varying means, based on said variation of estimated capacity, the set according to any one of claims 1 to 3, characterized in that it comprises a processing time setting means for setting the equalization processing time period of the capacitor Battery capacity adjustment device. The means for performing the equalization process includes a series connection body of the predetermined number of resistors connected in parallel to a predetermined number of adjacent unit cells, and the unit corresponding to a potential at each connection point of the resistors. A means for comparing the potentials of the connection points between the batteries, and a discharge means for discharging a battery whose voltage is assumed to be high among the predetermined number of unit batteries based on the comparison result. Item 5. The capacity adjustment device for an assembled battery according to any one of Items 1 to 4 . The adjacent predetermined number of unit cells constitute a block in which the assembled batteries are grouped,
Block voltage detection means for detecting the voltage of each block;
Based on the detection result of the block voltage detecting means, further comprising an inter-block equalizing means for discharging the voltage of the high voltage block,
6. The assembled battery capacity adjustment apparatus according to claim 5 , wherein the variable means determines whether or not to perform a discharge process by the inter-block equalization means based on the estimated variation. The adjacent predetermined number of unit cells constitute a block in which the assembled batteries are grouped,
Block voltage detection means for detecting the voltage of each block;
Based on the detection result of the block voltage detecting means, further comprising an inter-block equalizing means for discharging the voltage of the high voltage block,
Said varying means, based on the variation to be the estimated that in the following the time when the discharge process by the discharging means is assumed to be complete, or claim 5, characterized in that performing a discharging process by the equalizing means between blocks 6 The capacity adjustment apparatus of the assembled battery as described. The assembled battery is connected to a rotating machine as an in-vehicle main machine via a power conversion circuit,
The equalization process, the on condition that the power conversion circuit is stopped, the battery pack capacity adjustment apparatus according to any one of claims 1 to 7, wherein: performing the equalization processing .

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