JP5704063B2 - Equalized discharge device for battery pack - Google Patents

Description

  The present invention provides an assembled battery applied to a vehicle equipped with a rotating machine as an in-vehicle main machine and a secondary battery serving as a power source for the rotating machine and capable of charging the secondary battery with electric energy of a power source external to the vehicle. The present invention relates to an equalizing discharge device.

  As this type of equalizing discharge device, as seen in Patent Document 1 below, based on the frequency distribution of the open-circuit voltage of the battery cells constituting the assembled battery mounted on the electric vehicle, an adjustment target voltage is set, A battery that discharges until the terminal voltage of each battery cell reaches the adjustment target voltage has been proposed.

JP-A-10-322925

  By the way, in recent years, a so-called plug-in hybrid vehicle has been proposed that includes an internal combustion engine and a rotating machine and includes a means for charging a battery by an external commercial power source or the like. In a plug-in hybrid vehicle, normally, when the charging rate of the battery is high, the internal combustion engine is stopped, and an EV mode in which the vehicle is driven only by the rotating machine is set. On the other hand, when the charging rate of the battery decreases, the HV mode is performed in which the battery is charged by converting the power of the internal combustion engine into electric energy. In such a vehicle, the charging rate of the battery when the vehicle that stops the rotating machine is largely in two states of a substantially fully charged state and a relatively low charging rate state. That is, after the vehicle is stopped, the battery is almost fully charged by being charged by the commercial power source. On the other hand, when charging by a commercial power source is not performed, the charging rate in the HV mode is obtained.

  Here, for example, when determining a battery cell to be discharged for equalization of the charging rate between the battery cells constituting the battery at the time of starting the vehicle, two states of a substantially full charge state and a low charge rate state are set. Either way, equalization processing will be performed. Here, a case is considered in which, after equalization is performed in the low charge rate state, the battery is charged by the commercial power source, and then equalization processing is performed. In this case, it is a deteriorated battery cell that the terminal voltage rises earliest by the charging process from the low charge rate state. This is because the full charge amount decreases due to deterioration. For this reason, after the charging process, it is the deteriorated battery cells that are targeted for discharging by the equalization process. Therefore, the equalization process performed after the charging process minimizes the charge amount of the deteriorated battery cells, and thus the travelable distance of the vehicle with the internal combustion engine stopped is shortened.

  Further, when the equalization process is performed only in a substantially fully charged state, an opportunity to perform the equalization process cannot be ensured in a situation where the period during which the battery is not charged by an external commercial power source becomes long.

  The present invention has been made in the process of solving the above-mentioned problems, and an object of the present invention is to mount a rotating machine as an in-vehicle main machine and a secondary battery as a power source of the rotating machine, and to provide electric energy of a power source outside the vehicle. Is to provide a new battery pack equalizing / discharging device applied to a vehicle capable of charging the secondary battery.

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

A first aspect of the present invention is equipped with a secondary battery as a power source of the rotating machine and該回turning point as an in-vehicle main engine, applies an external electrical energy supply of the vehicle rechargeable vehicle to the secondary battery, wherein The secondary battery is an assembled battery as a series connection body of a plurality of battery cells, and has a charging rate between unit batteries that are either a single battery cell constituting the assembled battery or a plurality of adjacent battery cells. When it is determined that the variation in the charging rate is large by the variation detection unit that detects variation, the discharge unit that selectively discharges a specific unit battery constituting the assembled battery, and the variation detection unit Determining means for determining a unit battery having a large charging rate as a discharge target by the discharging means; and operating means for operating the discharging means to discharge the unit battery determined by the determining means. The determining means is configured to charge the charging rate of the unit battery to be referred to when determining the discharge target when the charging rate of the secondary battery is in a specified region lower than the median value of the region that can be taken when the secondary battery is normal. It is characterized by comprising limiting means for limiting the rate.

  In the above invention, by providing the limiting means, the discharge process for equalization is not performed after the charging by the external power source shifts from the low charging rate state to the substantially full charging state. For this reason, in a substantially fully charged state, it can be avoided that a unit battery having a small full charge amount is a discharge target for equalization.

The second invention according to the first invention, the vehicle is to mount a conversion means for converting an internal combustion engine, and the power of the internal combustion engine into electrical energy, the vehicle includes a traveling in the EV mode Travel control means for selectively performing travel in the HV mode, wherein the EV mode is a travel mode in which the internal combustion engine is stopped and the rotating machine is driven, and the HV mode is the internal combustion engine and the A travel mode in which the charging unit of the secondary battery is limited to a predetermined HV region by operating the conversion unit, the specified region is the HV region, and the limiting unit determines the discharge target. In this case, the charging rate of the unit battery to be referred to is limited to the charging rate in the HV region.

  In the said invention, since it has HV mode, the frequency in which the charging rate of a secondary battery will be in a low state becomes high. For this reason, even if it is a case where a limiting means is provided, the opportunity which can perform the process which equalizes the charging rate of a terminal voltage is fully securable.

According to a third aspect of the present invention, in the first or second aspect of the invention, the variation detecting means calculates a value of the terminal voltage of the secondary battery in a state where power is not transferred between the secondary battery and the rotating machine. The variation is detected by substituting as the charging rate.

  It can be considered that there is a one-to-one correspondence between the charging rate of the secondary battery and the open-circuit voltage. On the other hand, in a situation where power is not exchanged between the secondary battery and the rotating machine, the charge / discharge current of the secondary battery is small, so that the terminal voltage can be regarded as the open circuit voltage. In the said invention, it was set as the said setting in view of this point.

The fourth invention is the first to third any one invention of the variation detection means, at least one of the conditions that running permission switch of the vehicle is possible and the OFF state is switched to the on state, the The variation is detected by substituting the value of the terminal voltage of the secondary battery in the stopped state of the rotating machine as the charging rate.

  It can be considered that there is a one-to-one correspondence between the charging rate of the secondary battery and the open-circuit voltage. On the other hand, it is considered that immediately after the travel permission switch is switched to the on state, the rotating machine is in a stopped state, and the charge / discharge current amount of the secondary battery is small. In addition, when the travel permission switch is in the off state, the rotating machine is in a stopped state, and the charge / discharge current amount of the secondary battery is considered to be small. When the charge / discharge current of the secondary battery is small, the terminal voltage can be regarded as an open-circuit voltage. In the said invention, it was set as the said setting in view of this point.

According to a fifth invention, in the invention of the third or 4, wherein the variation detection means, each time the running permission switch of the vehicle is switched on, and each time the time of connection with the external power source and the secondary battery The variation is detected.

  When the frequency of charging the secondary battery using the commercial power source is low, the charging rate when the travel permission switch is switched to the on state is often in the specified region. For this reason, it is possible to secure a sufficient opportunity to perform the variation detection process by the variation detection unit and the determination process by the determination unit, and thus it is possible to ensure a sufficient opportunity for the equalization process.

  On the other hand, when the frequency of charging the secondary battery using the commercial power supply is high, the charging rate when the travel permission switch is switched to the on state is often higher than the specified region. In this case, if only the fact that the travel permission switch is switched to the on state is used as a trigger for the variation detection processing by the variation detection means, it becomes difficult to ensure an equalization processing opportunity. In this regard, in the above invention, the charging process of the secondary battery using the commercial power source can be performed by using the trigger for the variation detection process by the variation detection means also when the external power source is connected to the secondary battery. Even when the frequency of being performed is high, a sufficient opportunity for equalization processing can be secured.

According to a sixth aspect, in any one invention of a 3-5, wherein said determining means includes a function of determining the discharge time of the determined unit cell to the discharge target, said operating means, said determination The discharge process by the discharge means is terminated when the discharged time has elapsed.

  In the said invention, since it has the function to determine discharge time, the situation where discharge processing time becomes excessively long can be avoided. In addition, when the discharge time is set, the discharge target does not change even if the magnitude relationship of the terminal voltage changes, so that it is well suited to the configuration of the limiting means.

A seventh aspect of the third to sixth any one invention of the variation detection means performs a process of running permission switch of the vehicle to detect the variation per prescribed time in a state being turned off, The determination means updates the discharge target every time processing for detecting the variation is performed when the specified time is reached.

Advantageously, in the invention of the seventh, the discharge means, when the command signal from the operating means is inputted, has a function of continuing the processing instructed by the finger command signal, running permission of the vehicle On the condition that the switch is turned off, an off-operation shut-off process, which is a process of shutting off power supply to the determining means and the operating means, is performed, and the determining means and the operating means are activated when the specified time is reached. It has a starting means, It is characterized by the above-mentioned.

  In the above-described invention, it is possible to appropriately execute the processing while reducing the power consumption of the determining means and the operating means.

A ninth aspect of the first to eighth any one aspect of the present invention, the discharge means, the discharge time required to eliminate the smallest variation in the case where it is determined that the variation is large by the variation detection means 24 It is characterized by being over time.

  In the above invention, since it takes a long time to eliminate the variation, for example, when the equalization process is executed only when the travel permission switch is turned on, the processing for eliminating the variation is sufficiently performed. You may not be able to do it. For this reason, the merit of having the invention specific matters of claims 8 and 9 is particularly great.

The system block diagram concerning one Embodiment. The figure which shows the travel mode concerning the embodiment. The figure which shows the relationship between the charging rate concerning the same embodiment, and equalization discharge current. The figure which shows the solution subject of the embodiment. 6 is a flowchart showing a processing procedure when the main microcomputer according to the embodiment is activated. 6 is a flowchart showing a processing procedure when the main microcomputer according to the embodiment is activated. 6 is a flowchart showing a processing procedure of a sub-microcomputer according to the embodiment. The time chart which shows the equalization process concerning the embodiment.

  Hereinafter, an embodiment in which an equalized discharge device for an assembled battery according to the present invention is applied to a series hybrid vehicle will be described with reference to the drawings.

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

  The illustrated high voltage battery 10 is an assembled battery as a series connection body of battery cells C11 to Cnm, and has an open end voltage of, for example, 100 V or more. The battery cell Cij (i = 1 to n, j = 1 to m) is a secondary battery such as lithium ion. The battery cells C11 to Cnm have the same configuration except for individual differences. That is, the relationship of the open-circuit voltage with respect to the charging rate (SOC: ratio of the actual charge amount to the full charge amount), the full charge amount, the internal resistance value, and the like are equal to each other.

  The negative electrode potential of the high voltage battery 10 is set to a potential different from the vehicle body potential. Specifically, in the present embodiment, the median value of the positive electrode potential and the negative electrode potential of the high voltage battery 10 is set to be the vehicle body potential. This means that a series connection body of a pair of capacitors and a series connection body of a pair of resistors are connected between the positive electrode and the negative electrode of the high-voltage battery 10, and the connection points of the capacitors or the resistors are connected to the vehicle body. Can be done.

  An AC / DC converter circuit 11 is connected to the high voltage battery 10 via a main relay MR. After the AC power of the commercial power source outside the vehicle is converted into DC power by the AC / DC converter circuit 11, It is input to the battery 10.

  The high voltage battery 10 is connected to the second motor generator 14 via the main relay MR and the inverter 12. The second motor generator 14 is an in-vehicle main machine, and its rotor is mechanically connected to the drive wheels 16.

  The high voltage battery 10 is connected to the first motor generator 20 via the main relay MR and the inverter 18. The rotor of the first motor generator 20 is mechanically connected to the crankshaft 24 of the internal combustion engine 22. The first motor generator 20 functions as a generator that converts the power of the crankshaft 24 into electrical energy, and as an initial rotation imparting means (starter) that imparts initial rotation to the crankshaft 24 when the internal combustion engine 22 is stopped. It has the function of.

  In the present embodiment, the second motor generator 14, the first motor generator 20, and the internal combustion engine 22 are controlled by a control device (not shown) that controls them, so that the HV mode that drives the internal combustion engine 22, and the internal combustion engine The EV mode in which the vehicle travels with 22 stopped is appropriately selected.

  These HV mode and EV mode are switched according to the charging rate of the high-voltage battery 10 as shown in FIG. That is, the vehicle travels in the EV mode in a region where the charging rate is relatively high. This is in view of the fact that fuel combustion energy has a higher energy cost than electric energy charged from a commercial power source. Specifically, the vehicle travels in the EV mode in a region where the EV upper limit charging rate Px is equal to or lower than the EV lower limit charging rate Py. On the other hand, in the region where the charging rate is low (Pz ≦ SOC <Py), the vehicle travels in the HV mode. Here, in the traveling in the HV mode, the process of increasing the power generation amount of the first motor generator 20 by the power of the internal combustion engine 22 due to the decrease in the charging rate of the high voltage battery 10 is performed, so that FIG. As shown in FIG. 4, the charging rate is limited between the EV lower limit charging rate Py and the HV lower limit charging rate Pz. However, even when traveling in the HV mode, for example, when regenerative braking operation is frequently used during downhill traveling, the charging rate of the high-voltage battery 10 is set to the EV lower limit charging rate Py from the viewpoint of energy cost reduction. Control to raise the above is performed.

  As shown in FIG. 1, the battery cells C11 to Cnm that constitute the high voltage battery 10 are modularized with m (> 2) adjacent to each other in the same group. Here, the i-th module includes battery cells Ci1 to Cim.

  Each of these modules is provided with a monitoring unit Ui (i = 1 to n). The monitoring units U1 to Un are equipped with the same functions. Specifically, as illustrated for the monitoring unit Un, the discharge resistor 30 and the switching element 32 connected in parallel to each of the battery cells Ci1 to Cim, and the discharge control unit 34 that selectively turns on the switching element 32; It has. Further, a multiplexer 36 that selectively applies one of the terminal voltages of the battery cells Ci1 to Cim to the differential amplifier circuit 38 is provided. Thereby, each terminal voltage of battery cell Ci1-Cim is input into the analog-digital converter 40 via the differential amplifier circuit 38, and is converted into digital data here.

  On the other hand, the control device 50 controls the state of the high voltage battery 10 by operating the monitoring unit Ui. The control device 50 includes a pair of microcomputers (a main microcomputer 52 and a sub microcomputer 54). These are all software processing means including a central processing unit and a memory. Here, the main microcomputer 52 has a function of inputting digital data (detection signal Sv) output from the analog-digital converter 40 and outputting a command signal Sc to the discharge control unit 34 of the monitoring unit Ui based on this. Here, the command signal Sc is used to command which of the battery cells Ci1 to Cim is to be discharged using the discharging resistor 30 (and whether to stop the discharge). The main microcomputer 52 also has a function of opening and closing the main relay MR. In the figure, one main relay MR connected between each power conversion circuit and the high voltage battery 10 is described as one, but this is for simplification of the drawing. It is desirable to further include a main relay, or a main relay on the negative electrode side.

  On the other hand, the sub-microcomputer 54 is a means for monitoring the main microcomputer 52. For this reason, although it does not have a function of operating the main relay MR or outputting the command signal Sc to the monitoring unit Ui, it consumes less power than the main microcomputer 52.

  Each of the main microcomputer 52 and the sub-microcomputer 54 uses a low-voltage battery 56 having a terminal voltage lower than that of the high-voltage battery 10 and a vehicle body potential as a reference potential as a power source. Specifically, the main microcomputer 52 is connected to the low voltage battery 56 via the relay 58. The relay 58 is closed when an IG signal is input by turning on a travel permission switch by a user or an operation signal Ss from the sub-microcomputer 54 is input. On the other hand, the sub-microcomputer 54 is connected to the low voltage battery 56 via the relay 60. The relay 60 is closed when an IG signal is input by turning on a travel permission switch by the user or an operation signal Ss from the sub-microcomputer 54 is input.

  Based on the detection signal Sv, the control device 50 outputs a command signal Sc to discharge a battery cell having a high charge rate when the charge rate between the battery cells C11 to Cnm is more than a specified amount. When the equalizing discharge time has elapsed, a discharge stop command is output. Here, the equalizing discharge time is set to a relatively long time (for example, 1 hour or more). This is because the discharge current I using the discharging resistor 30 is relatively small as shown in FIG. FIG. 3 illustrates a case where discharge is performed at a charging rate of 10% or more by performing the discharge treatment with the specified amount being 10%. In this case, the time required for discharging 10% of the full charge amount Ah0 is “Ah0 / (10 · I)”. In the present embodiment, it is assumed that this time is 24 hours or more.

  In the present embodiment, detection of the charging rate for the equalizing discharge is limited to a region where the charging rate is low. Specifically, it is limited to when it is in the HV region. This is a setting for avoiding a situation where a deteriorated battery cell is discharged as shown in FIG. That is, as shown in the left side of FIG. 4, when the charging rate is lowered by traveling in the EV mode from the region where the charging rate is high, the open-circuit voltage of the deteriorated battery cell becomes low. This is because, since the full charge amount of the deteriorated battery cell is small, the rate of decrease in the charge rate increases even if the discharge amount is the same. At this time, the battery cell having a high terminal voltage is a battery cell that has not deteriorated (described as a new battery in the figure).

  On the other hand, as shown on the right side of FIG. 4, when open-circuit voltages are in a region where the charging rate is low, when the charging rate is increased by charging commercial power, the battery cell is deteriorated. Has the highest open-circuit voltage. This is because, since the fully charged amount of the deteriorated battery is small, the rate of increase in the charging rate is increased even if the charged amount of charge is the same. In this state, if a battery cell having a high terminal voltage is set as a discharge target in order to equalize the charging rate, the deteriorated battery will be discharged. Therefore, the time during which the vehicle can travel in the EV mode (the charging rate is up to the EV lower limit charging rate Py). The time required for the decrease is shortened.

  FIG. 5 shows a procedure of processing performed by the main microcomputer 52 particularly regarding the equalization processing according to the present embodiment. This process is triggered by the start of power supply to the main microcomputer 52 when the travel permission switch is turned on or when the commercial power source and the high voltage battery 10 are connected (at the time of PlugIn). Executed.

  In this series of processing, first, in step S10, a detection value of each cell voltage Vij of the battery cell Cij constituting the high voltage battery 10 is acquired. In the subsequent step S12, it is determined whether or not the charging rate SOC of the high voltage battery 10 is equal to or higher than the equalization lower limit charging rate SOCL and lower than or equal to the EV lower limit charging rate Py. This process is for determining whether or not the charge rate is allowed to be executed in the charge rate equalization process. Here, the equalization lower limit charge rate SOCL is set to a value larger than the HV lower limit charge rate Pz in the present embodiment. In this setting, the power of the high-voltage battery 10 is consumed by the monitoring unit Ui or the like when the travel permission switch is in the off state and the external power is not charged, so that the terminal voltage becomes the allowable lower limit. This is to avoid a situation where the value is reached. Note that the charging rate SOC of the high voltage battery 10 may be an average value of the charging rates of the battery cells C11 to Cnm, for example. At this time, the charging rate of the battery cells C11 to Cnm may be calculated from the open-circuit voltage, and in this case, the detection value acquired by the process of step S10 can be used.

  If an affirmative determination is made in step S12, it is determined in step S14 whether or not the difference between the highest value (maximum voltage Vmax) and the lowest value (minimum voltage Vmin) of the cell voltages V11 to Vnm is greater than the threshold value ΔVth. This process determines whether the variation in the charging rate is so large that the equalizing discharge process is required. Here, the reason why the terminal voltage is directly used as the charging rate is that the second motor generator 14 and the first motor generator 20 are stopped (preferably the main relay). This is because the charge / discharge current amount of the high-voltage battery 10 is small and the terminal voltage can be regarded as an open-circuit voltage.

  If an affirmative determination is made in step S14, the battery cell Ckl to be discharged for equalization is specified in step S16. Here, a battery cell having a terminal voltage at which the amount exceeding the minimum voltage Vmin is equal to or greater than the threshold value ΔVth is a discharge target. In subsequent step S18, a discharge command (command signal Sc) is output to the corresponding monitoring unit Ui so as to discharge the battery cell Ckl to be discharged. Incidentally, in this process, the battery cells that are the target of the discharge command are all the battery cells specified in step S16. For this reason, there may be one or more battery cells to be discharged. Further, the number of battery cells to be discharged by a specific monitoring unit Ui may be 0 or m.

  In the subsequent step S20, the equalization time Td is determined. In view of the discharge capability of the monitoring unit Ui, this is preferably set in units of 1 hour, and more preferably about 8 hours. In the subsequent step S22, the flag F indicating that the equalizing discharge process is being performed is set to “1”, and the fact that the flag F is “1” is output to the sub-microcomputer 54. If the equalization time Td elapses before the power supply to the main microcomputer 52 is cut off (step S24: YES), a command for stopping the equalization (command signal Sc) is output to the monitoring unit Ui in step S26. At the same time, the flag F is set to 0 and the fact is notified to the sub-microcomputer 54.

  When the process of step S26 is completed or when a negative determination is made in step S10, this series of processes is temporarily terminated.

  FIG. 6 shows the equalization processing according to the present embodiment. In particular, the main microcomputer 52 performs the processing described later by the sub-microcomputer 54 in a state where the travel permission switch is turned off in the processing procedure performed by the main microcomputer 52. Is executed as a trigger. In FIG. 6, the same reference numerals are assigned for convenience to those corresponding to the processing shown in FIG. 5.

  In this series of processes, when the process of step S18 is completed, the process proceeds to step S22a. In step S22a, the flag F indicating that the equalizing discharge process is being performed is set to “1”, and the fact that the flag F is “1” and the cycle for starting the main microcomputer 52 are output to the sub-microcomputer 54. . The activation period may be variably set according to the degree of variation in the charging rate, but may be a fixed value in units of 30 to 1 hour, for example.

  FIG. 7 shows a procedure of processing performed by the sub-microcomputer 54 in particular regarding the equalization processing according to the present embodiment. This process is repeatedly executed at a predetermined cycle in a state where the power supply of the sub microcomputer 54 is continued and the power supply of the main microcomputer 52 is stopped.

  In this series of processing, first, in step S30, it is determined whether or not the flag F is “1”. If it is determined in step S30 that it is “1”, it is determined in step S32 whether or not the activation cycle Tu has elapsed since the main microcomputer 52 was turned off. If it is determined that the activation cycle Tu has elapsed, the main microcomputer 52 is activated by closing the relay 58 in step S34. As a result, the main microcomputer 52 executes the process shown in FIG. In a succeeding step S36, it is determined whether equalization is necessary. This is a process for determining whether or not an affirmative determination is made in step S14 of FIG. 6 by the main microcomputer 52. For example, whether or not the flag F is “1” within a predetermined time is notified. Judgment can be made. If equalization is necessary, in step S38, the power supply to the main microcomputer 52 is interrupted, and this series of processes is temporarily terminated. Thereby, every time it is determined in step S32 that the activation cycle Tu has elapsed, the main microcomputer 52 is periodically activated. Thus, the main microcomputer 52 is periodically started in order to reduce power consumption as much as possible.

  On the other hand, if a negative determination is made in steps S30 and S36, the sub-microcomputer 54 is stopped by setting the flag F to “0” and opening the relay 60 in step S40. This is a setting for reducing the power consumption as much as possible because the equalizing discharge is not required and the main microcomputer 52 is not required to be activated every activation period Tu.

  FIG. 8 shows an example of the equalized discharge process according to the present embodiment. Specifically, FIG. 8 (a) shows vehicle modes including a driving mode, FIG. 8 (b) shows the transition of the terminal voltage of the battery cell Cij, and FIG. 8 (c) shows the presence or absence of equalization. FIG. 8D shows whether the main microcomputer 52 and the sub-microcomputer 54 are fed. “PlugIn” in FIG. 8A is a mode for charging external power, and “equalization at IGON” and “equalization at IGOFF” in FIG. Shows equalization when is on and off.

  In the figure, as exemplified by the equalization periods T1 and T2, the discharge process of the battery cell determined as the equalization target when the charge rate is in the HV mode region is related to the change in the charge rate due to the external charge process or the like. Will continue. The discharge target is updated when the main microcomputer 52 is activated by the process of step S34 of FIG. 7 or the turning-on operation of the travel permission switch, and the equalizing discharge process is required.

  As described above, after the discharge target is set in the region where the charging rate is low, the equalization process is continued for a relatively long time, so that the charging rate is used even though the monitoring unit Ui having a small discharging current I is used. The variation of is preferably reduced. In addition, by setting the discharge target in the low charge rate region, it is possible to easily avoid the situation where the deteriorated battery cell is discharged without particularly performing the process of identifying the deteriorated battery cell. Can do.

  Furthermore, not only is the trigger that the travel permission switch is switched to the on state, but also the execution of the processing shown in FIG. 5 by using the trigger when the high voltage battery 10 is connected to the commercial power source. Thus, it is possible to cope with both cases where the charging process of the high voltage battery 10 by the commercial power source is frequently performed and when the charging process is not frequently performed.

  That is, when the charging process of the high voltage battery 10 by the commercial power source is not performed so much, the process shown in FIG. 5 is executed as a trigger when the travel permission switch is switched to the ON state, thereby equalizing The probability that the process is executed is increased. This is because if the high voltage battery 10 is not charged while the travel permission switch is turned off, the probability that the charging rate of the high voltage battery 10 is equal to or lower than the EV lower limit charging rate Py is increased.

When the charging process of the high voltage battery 10 by the commercial power supply is frequently performed, the process shown in FIG. 5 is executed using the timing when the high voltage battery 10 is connected to the commercial power supply as a trigger. Thus, the probability that the equalization process is executed is increased. Incidentally, in this case, when the travel permission switch is switched to the ON state, the charging rate of the high voltage battery 10 is likely to exceed the EV lower limit charging rate Py, and the equalization process is difficult to be performed.
<Other embodiments>
The above embodiment may be modified as follows.

"Variation detection means"
The quantification is not limited to the difference from the minimum voltage Vmin. For example, it may be quantified as a difference from the average value of the cell voltages V11 to Vnm.

  The charging rate is not limited to the one that uniquely determines the charging rate from the terminal voltage when the charge / discharge current amount of the high-voltage battery 10 is assumed to be small. For example, the open-circuit voltage may be estimated using a plurality of sets of detected values of the charge / discharge current of the high-voltage battery 10 and the terminal voltage of the battery cell.

About the decision means
The discharge target is not limited to those having a terminal voltage whose difference from the minimum voltage Vmin is larger than the threshold value ΔVth. For example, a voltage that exceeds the average value of the cell voltages V11 to Vnm by a threshold value or more may be the discharge target.

"About operation means"
The monitoring unit Ui is not limited to outputting an equalization command and an equalization stop command. For example, if the monitoring unit Ui has a function of discharging to the target voltage and stopping the discharge when the target voltage is reached, means for outputting the target voltage may be used. Even in this case, the equalization process can be appropriately performed under the condition that the travel permission switch is turned off.

"About limiting means"
For example, without using the detection result of the variation when the charging rate immediately after the travel permission switch is switched on is in the HV region, after the travel permission switch is switched off and after a predetermined time has elapsed Further, it may be limited to a detection result of variation when the charging rate is in the HV region. Here, the predetermined time may be set to a value (for example, 1 hour or more) at which the influence of polarization becomes sufficiently small.

  What is not limited to the HV region is as described in the “About vehicle” column.

"Discharge means"
The discharge current is not limited to that exemplified in the above embodiment. If the discharge current is made larger, it becomes easy to set the equalization process not to be performed when the IG switch is off.

“Configuration method of equalizing discharge device”
The discharge means is not limited to hardware processing means (monitoring unit Ui), and the variation detection means, determination means, and operation means are not limited to software processing means (main microcomputer 52, sub-microcomputer 54). For example, the variation detection means may be configured in the monitoring unit Ui. Further, for example, the variation detection means, the determination means, and the operation means may be configured as a low voltage system and by hardware processing means.

  The system is not limited to the system including the main microcomputer 52 and the sub-microcomputer 54, and may include a single microcomputer. In this case, when the activation means is provided, it may be constituted by dedicated hardware processing means such as a timer instead of being constituted by the sub-microcomputer 54.

"Power supply and reference potential"
The potentials of the high voltage system and the low voltage system may be set to a common potential (for example, vehicle body potential), and the power source of the main microcomputer 52 and the sub microcomputer 54 may be battery cells Cn1 to Cnm. Even in this case, the power consumption can be reduced if the process of cutting off the power supply to the main microcomputer 52 is performed on condition that the travel permission switch is turned off. By the way, in this case, the battery cells C11 to C (n-1) 1 to C (n-1) m and the battery cells Cn1 to Cnm have different specifications, and the full charge amount of the battery cells Cn1 to Cnm is increased. Also good.

"About equalization targets"
It is not restricted to battery cell Cij. For example, some of the battery cells that are two or more adjacent battery cells and constitute the assembled battery (high voltage battery 10) may be unit batteries, and variation in the charging rate between unit batteries may be equalized.

"About the vehicle"
The hybrid vehicle is not limited to a series hybrid vehicle, and may be, for example, a parallel series hybrid vehicle or a parallel hybrid vehicle.

  Moreover, it is not limited to a hybrid vehicle, and may be an electric vehicle not equipped with an internal combustion engine. Even in this case, for example, when the high-voltage battery 10 is used as a power storage unit in the smart grid, the frequency at which the charging rate is low during the stop period may be high. In such a case, if the charge rate detection condition used for the equalized discharge process is limited to a region where the charge rate is low, then the charge amount of the deteriorated battery cell is small when the charge rate is increased by charging. Can be suppressed as much as possible.

  DESCRIPTION OF SYMBOLS 10 ... High voltage battery (one Embodiment of assembled battery), 50 ... Control apparatus, 52 ... Main microcomputer, 54 ... Sub microcomputer.

Claims (8)

A rotating machine as an in-vehicle main unit and a secondary battery serving as a power source for the rotating machine are mounted, and applied to a vehicle capable of charging the secondary battery with electric energy of a power source outside the vehicle,
The secondary battery is an assembled battery as a series connection body of a plurality of battery cells,
A variation detecting means for detecting a variation in charging rate between unit batteries which are any one of a single battery cell and a plurality of adjacent battery cells constituting the assembled battery;
Discharging means for selectively discharging a specific one of the unit batteries constituting the assembled battery;
When the variation detection unit determines that the variation in the charging rate is large, a determination unit that determines a unit battery having a large charging rate as a discharge target by the discharging unit;
Operating means for operating the discharging means to discharge the unit battery determined by the determining means,
The determining means sets the charging rate of the unit battery to be referred to when determining the discharge target to the charging rate when the charging rate of the secondary battery is in a specified region lower than the median value of the region that can be taken when normal. With limiting means to limit ,
The vehicle is equipped with an internal combustion engine and conversion means for converting the power of the internal combustion engine into electric energy,
The vehicle includes traveling control means for selectively performing traveling in the EV mode and traveling in the HV mode,
The EV mode is a traveling mode in which the internal combustion engine is stopped and the rotating machine is driven,
The HV mode is a travel mode in which the internal combustion engine and the conversion means are operated to limit the charging rate of the secondary battery to a predetermined HV region,
The defined area is the HV area;
The limiting means limits the charging rate of the unit battery, which is referred to when determining the discharge target, to the charging rate when the unit battery is in the HV region. The variation detection means detects the variation by substituting the terminal voltage value of the secondary battery under the condition where power is not transferred between the secondary battery and the rotating machine as the charging rate. The equalized discharge apparatus for an assembled battery according to claim 1 . The variation detecting means charges the terminal voltage value of the secondary battery in the stopped state of the rotating machine on condition that at least one of a vehicle travel permission switch is switched to an on state and an off state. equalizing the discharge of the assembled battery according to claim 1 or 2, wherein the detecting the variation by substituting as a percentage. Said variation detecting means, each time the running permission switch of the vehicle is switched on, and each time the time of connection with the external power source and the secondary battery, according to claim, characterized in that detecting the variation 2 Or the equalization discharge apparatus of the assembled battery of 3 . The determination means has a function of determining a discharge time of the unit battery determined as the discharge target,
5. The equalized discharge device for an assembled battery according to claim 2 , wherein the operation unit terminates the discharge process by the discharge unit when the determined discharge time has elapsed. . The variation detection means performs a process of detecting the variation every specified time in a state where the travel permission switch of the vehicle is turned off,
6. The assembled battery according to claim 2 , wherein the determination unit updates the discharge target every time processing for detecting the variation is performed when the specified time is reached. Equalizing discharge device. The discharge unit has a function of continuing the process instructed by the command signal when the command signal from the operation unit is input;
An off-operation shut-off process, which is a process of shutting off the power supply to the determination means and the operation means, is performed on condition that the travel permission switch of the vehicle is turned off.
The equalized discharge device for an assembled battery according to claim 6 , further comprising an activation unit that activates the determination unit and the operation unit when the predetermined time is reached. Said discharge means, according to claim 1 to 7, the discharge time required to eliminate the smallest variation in the case where it is determined that a large variation by said variation detecting means, characterized in that the 24 hours or longer The equalized discharge apparatus of the assembled battery of any one of Claims.

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