JP5154076B2 - Battery pack and battery module and hybrid vehicle using the same - Google Patents

Description

  The present invention is preferably implemented in a hybrid vehicle or the like, and relates to an assembled battery obtained by combining a plurality of cell blocks of a nonaqueous electrolyte secondary battery in series, a battery module using the assembled battery, and the hybrid vehicle.

Patent Document 1 and Patent Document 2 propose non-aqueous electrolyte secondary batteries that are expected to have a high capacity suitable for the above-described hybrid vehicles. According to those prior art, a negative electrode comprising a lithium metal or lithium from absorbing and releasing material capable, and a positive electrode, as the active material of the positive _{electrode, Li a M b Ni c Co} d O e (M is Al , Mn, Sn, In, Fe, Cu, Mg, Ti, Zn, and Mo).
Japanese Patent No. 3244314 International Publication No. 02/0708105 Pamphlet

  Here, rapid charging / discharging characteristics are important for electric vehicles, particularly hybrid vehicles, and input / output values are important for power supplies. The rapid charge / discharge characteristics are determined by the maximum input / output value (power), which can be obtained from the following.

Maximum input / output value = I x (OCV-I x DCIR)
I is a current value, OCV is an open circuit voltage of the cell block, and DCIR is a direct current resistance.

  However, in the above-described conventional technology capable of increasing the capacity, there is a problem that the OCV and DCIR vary greatly depending on SOC (State Of Charge). FIG. 4 is a graph showing the relationship of the OCV change to the SOC change in such a non-aqueous electrolyte secondary battery. As can be understood from FIG. 4, there is a predetermined inclination, and the change in the OCV is abrupt especially when fully charged and with a small remaining amount. On the other hand, FIG. 5 is a graph showing the relationship of DCIR change to SOC change in such a non-aqueous electrolyte secondary battery. As can be understood from FIG. 5, it is understood that the change in DCIR is abrupt with a small remaining amount, particularly during discharging, although it differs between charging and discharging.

  Therefore, when such a nonaqueous electrolyte secondary battery is used, the maximum input value (inputtable power value) and the maximum output value (outputtable power value) of the battery in each SOC are shown in FIGS. 6 and 7, respectively. Will change as shown. At the time of charging, the maximum input is, as shown in FIG. 6, mainly from the characteristics shown in FIG. 4, when the SOC exceeds 50%, the upper limit value of the battery charging voltage (4.2 V in the example of FIG. 4) is As the difference between the values decreases (SOC increases), it decreases. On the other hand, at the time of discharging, as shown in FIG. 7, from the fully charged to the SOC of about 30%, mainly from the characteristics shown in FIG. Mainly from the characteristics shown in FIG.

  Therefore, when such a battery is used, there is a problem that the power that can be input / output fluctuates rapidly and is difficult to handle. For this reason, in a hybrid vehicle, the SOC is normally used within a range of ± 20% centering on 50%.

  The objective of this invention is providing the assembled battery which can suppress the rapid fall of maximum input / output electric power, a battery module using the same, and a hybrid vehicle.

An assembled battery of the present invention is an assembled battery in which a plurality of cell blocks of a nonaqueous electrolyte secondary battery having a negative electrode made of lithium metal or a material capable of occluding and releasing lithium and a positive electrode are combined in series. Ri formed by combining a cell block having an SOC different from each other, variation in the SOC, based on the 50% of cell blocks, 10% and +, and + 15%, and wherein the combination der Rukoto of + 20% To do.

Moreover, the assembled battery of the present invention is an assembled battery in which a plurality of cell blocks of a nonaqueous electrolyte secondary battery having a negative electrode made of lithium metal or a material capable of occluding and releasing lithium and a positive electrode are combined in series. It is characterized by combining cell blocks having different maximum input / output power changes with respect to SOC changes.

  According to said structure, it is used for a motor vehicle etc., and comprises the negative electrode which consists of a lithium metal or the material which can occlude / release lithium, and the non-aqueous electrolyte secondary battery cell which has a positive electrode, and combines two or more in single or in parallel. In constructing an assembled battery formed by combining a plurality of cell blocks in series, cell blocks having different voltages (SOC) are intentionally combined.

Accordingly, examples of the active material of the positive _{electrode, Li a M b Ni c Co} d O e (M is Al, Mn, Sn, In, Fe, Cu, Mg, Ti, Zn, at least one metal of Mo, preferably LiMnNiCoO ₂ ) In the assembled battery using the secondary battery having a large discharge capacity per unit volume, the change in at least one of OCV and DCIR with respect to the SOC change in each cell block is more than a predetermined level, or At the timing of charging / discharging, each cell block in series has different maximum input / output power due to the difference in SOC, and as a whole assembled battery, the sudden drop of the maximum input / output power with respect to the SOC change is suppressed and easy to handle. A battery can be realized.

In addition, by the variation of the previous SL SOC 10-20% while suppressing the sharp drop of the maximum output power for the SOC variation, it is possible to prevent overdischarge and overcharge. In particular , by using a combination of + 10%, + 15%, and + 20% as described above on the basis of a cell block of S OC = 50%, for example, the input characteristics are almost equal to the case of + 20% only, Compared with the case where the output characteristic is only + 20%, the drop on the low SOC side becomes smaller, and it can be made closer to linear.

  Furthermore, the battery module of the present invention includes the assembled battery, and measures each of at least the terminal voltage and the cell temperature of each cell block in the assembled battery, and each of the above-described values based on the measurement result of the measuring means. The calculation means for determining the SOC of the cell block and the overcharge is determined when at least one of the SOC calculated by the calculation means is equal to or greater than a predetermined first value, and overdischarge is determined when the SOC is equal to or less than a predetermined second value. And charging / discharging control means for stopping charging / discharging of the assembled battery.

  According to the above configuration, if the SOC is intentionally varied as described above, the possibility of overdischarge or overcharge is increased in a cell block having a large variation during charge / discharge. On the other hand, at least the terminal voltage and the cell temperature of each cell block are measured by the measurement means, and the calculation means obtains the SOC of each cell block based on the measurement result. When the overcharge level is reached, the charge / discharge control means stops charging / discharging the assembled battery.

  Therefore, even if the SOC is intentionally varied as described above, overdischarge and overcharge can be reliably prevented.

  The battery module of the present invention includes the assembled battery, and includes a measuring unit that measures at least a terminal voltage and a cell temperature of each cell block in the assembled battery, and each cell based on a measurement result of the measuring unit. Calculation means for obtaining the SOC of the block; and charge / discharge means capable of performing at least one of discharge or charge by short-circuiting between terminals or applying a charge voltage between the terminals with respect to at least some cell blocks; When charging / discharging is stopped, when the SOC determined by the calculating means is shifted more than a predetermined value with respect to a predetermined SOC for each cell block, the charging / discharging means is driven, and each cell block And calibrating means for returning to a predetermined SOC.

Furthermore, the battery module of the present invention comprises an assembled battery formed by combining a plurality of cell blocks of a nonaqueous electrolyte secondary battery having a negative electrode made of lithium metal or a material capable of occluding and releasing lithium and a positive electrode in series. A measuring means for measuring at least a terminal voltage and a cell temperature of each cell block in the assembled battery, a calculating means for obtaining an SOC of each cell block based on a measurement result of the measuring means, and at least some cells With respect to the block, charging / discharging means capable of performing at least one of discharging or charging by short-circuiting between terminals or applying a charging voltage between the terminals, and the SOC determined by the calculating means when charging / discharging is stopped Caused a difference of more than a predetermined value for different SOCs determined in advance for each cell block. The drives the charge and discharge means, characterized in that it comprises a respective cell blocks calibration means for returning to said predetermined are SOC to.

  According to the above configuration, for example, even if the hybrid vehicle is run for one day, the variation in the SOC that has been held in advance does not deviate by several percent, but to prevent it from accumulating. The measurement means measures at least the terminal voltage and the cell temperature of each cell block, and the calculation means obtains the SOC of each cell block based on the measurement result, charging / discharging stops, and the SOC deviation is predetermined. If it is equal to or greater than the value, the calibration means drives the charge / discharge means to return each cell block to the predetermined SOC.

  Therefore, it is possible to always keep the error of SOC variation within a predetermined range and maintain desired input / output characteristics.

  Furthermore, the hybrid vehicle of the present invention is equipped with the battery module.

  According to said structure, the change of the maximum input / output electric power with respect to SOC change is few, and the hybrid vehicle which can improve driving | running | working characteristics is realizable.

  As described above, the assembled battery of the present invention is used in automobiles and the like, and a non-aqueous electrolyte secondary battery cell having a negative electrode made of lithium metal or a material capable of occluding and releasing lithium and a positive electrode is used alone or in parallel. In constructing a battery pack in which a plurality of cell blocks are combined in series, a plurality of cell blocks having different voltages (SOC) are intentionally combined.

Therefore, Li _{a Mb} Ni _c Co _d O _e (M is at least one metal of Al, Mn, Sn, In, Fe, Cu, Mg, Ti, Zn, and Mo) as the active material of the positive electrode. In an assembled battery using a secondary battery with a large discharge capacity per unit volume, even if at least one of OCV and DCIR with respect to SOC change is more than a predetermined level in each cell block, a certain charge / discharge In this timing, each cell block in series has different maximum input / output power due to the difference in the SOC, and as a whole assembled battery, a sudden drop in the maximum input / output power with respect to the SOC change is suppressed, and an easy-to-handle battery is realized. can do.

In addition, by the variation of the previous SL SOC range of 10% to 20%, while suppressing the sharp drop of the maximum output power for the SOC variation, it is possible to prevent overdischarge and overcharge.

  Furthermore, as described above, when the battery module of the present invention intentionally varies in SOC, there is a possibility of overdischarge or overcharge in a cell block having a large variation during charge / discharge. On the other hand, at least the terminal voltage and the cell temperature of each cell block are measured, and the SOC of each cell block is obtained based on the measurement result, and at least one of the overdischarge and overcharge is determined. If it becomes the level of, it will stop charging / discharging to the said assembled battery.

  Therefore, even if the SOC is intentionally varied as described above, overdischarge and overcharge can be reliably prevented.

  In addition, as described above, the battery module of the present invention measures at least the terminal voltage and the cell temperature of each cell block, obtains the SOC of each cell block based on the measurement results, and stops charging and discharging. If the SOC deviation is equal to or greater than a predetermined value, each cell block is returned to the predetermined SOC.

  Therefore, it is possible to always suppress an error in SOC variation within a predetermined range and maintain desired input / output characteristics.

  Furthermore, the hybrid vehicle of the present invention is equipped with the battery module as described above.

  Therefore, it is possible to realize a hybrid vehicle in which the change in the maximum input / output power with respect to the SOC change is small and the running characteristics can be improved.

[Embodiment 1]
FIG. 1 is a block diagram showing an electrical configuration in a power system of a hybrid vehicle 1 according to an embodiment of the present invention. Therefore, the configuration of the power system by the internal combustion engine and other electrical auxiliary machines is also omitted. The hybrid vehicle 1 can travel by boosting the electric power from the assembled battery 2 via the converter 3, converting it into a three-phase alternating current by the inverter 4 and applying it to the motor 5 as a load. The electric power regenerated in (2) is converted into direct current by the inverter 4 and is stepped down by the converter 3 to be used for charging the assembled battery 2 to increase energy efficiency.

  The assembled battery 2 constitutes a battery module 7 together with a BMU (battery management unit) 6. When the BMU 6 monitors the state of the assembled battery 2 and determines an abnormality from the monitoring result, the BMU 6 performs a protection operation by turning off the switch 8 interposed in series between the assembled battery 2 and the converter 3, and The monitoring result is transmitted to the device control apparatus 9 that controls the entire automobile 1. Further, the BMU 6 performs SOC shift control of the assembled battery 2 as described later.

The assembled battery 2 has a negative electrode made of lithium metal or a material capable of occluding and releasing lithium, and a positive electrode. As an active material of the positive electrode, Li _{a Mb} Ni _c Co _d O _e (M is Al, Mn, A large discharge capacity per unit volume using at least one metal of Sn, In, Fe, Cu, Mg, Ti, Zn, Mo, preferably the composition described in Patent Document 2, particularly preferably LiMnNiCoO ₂ A non-aqueous electrolyte secondary battery cell S is composed of a plurality of (10 in the example of FIG. 1) cell blocks B that are combined in series (single or two in the example of FIG. 1) in series. The

  The voltage of each cell block B is obtained from the difference between each terminal voltage input to the voltage measurement circuit 11 in the BMU 6. The control microcomputer 12 causes the voltage measurement circuit 11 to perform a multiplex operation and sequentially reads the cell voltages. The current flowing through the assembled battery 2 is detected by the current sensor 22 and input to the control microcomputer 12 via the current measurement circuit 13 in the BMU 6. The temperature of each cell block B is detected by the temperature sensor 21 and input to the control microcomputer 12 in the BMU 6.

  The control microcomputer 12 has an SOC table corresponding to the temperature and the cell voltage in advance in a nonvolatile memory such as an EEPROM, and obtains the SOC from the detection results of the measurement circuits 11 and 13 and the temperature sensor 21. The obtained SOC value is transmitted to the device control apparatus 9. In response to this, the device control apparatus 9 determines that the SOC value is within a range of 30 to 70% (± 20% centered on 50%), which is an actual use range in the hybrid vehicle 1. When the value is small, the internal combustion engine generates more power than is necessary for traveling, or the regenerative energy generated during deceleration is used to cause the motor 5 to generate power. When the SOC value is large, the internal combustion engine travels. Power below the required power is generated to generate power in the motor 5. In this case, the SOC value may be controlled so that the representative value (50% ± 20% as described above, 50% is the representative value) falls within the above range.

  Further, it is determined whether or not the overcharge protection circuit 14 is overcharged from the voltage of each cell block B, and it is determined from the detection result of the current sensor 22 whether or not the overcurrent protection circuit 15 is overcurrent. Therefore, the temperature protection circuit 16 determines whether or not each cell block B is in an overtemperature state from the detection result of the temperature sensor 21, and if any abnormality is determined, the OR circuit 17 The switch 8 is turned off to perform the protection operation.

In the battery module 7 configured as described above, the cell S in the assembled battery 2, as an active material for the positive electrode as mentioned _{above, Li a M b Ni c Co} d O e (M is Al, Mn, Sn, Non-aqueous system having a large discharge capacity per unit volume using at least one kind of metal of In, Fe, Cu, Mg, Ti, Zn, and Mo, preferably the composition described in Patent Document 2, particularly preferably LiMnNiCoO _2. In the case of an electrolyte secondary battery, the OCV change with respect to the SOC change is severe as shown in FIG. 4 and the DCIR change with respect to the SOC change is strong as shown in FIG. Then, the assembled battery 2 is intentionally configured by combining cell blocks having different voltages (SOC).

  2 and 3 are graphs showing the experiment results of the inventors of the present invention, and show the maximum input / output values of the assembled battery 2 in each SOC. FIG. 2 shows the maximum input / output values at + 10%, + 20%, and + 30% with SOC = 50% as a reference (0%). From FIG. 2, when the SOC shift amount reaches 30%, the maximum input power decreases greatly, that is, the input remaining power is small, and when there is no shift (0%), the SOC is small from the above-described increase in DCIR. Therefore, it is understood that the maximum output power is greatly reduced, and therefore the shift amount is preferably 10 to 20%.

  Further, FIG. 3 shows the maximum input / output values in a combination of + 10% simple substance, + 20% simple substance, and + 10%, + 15%, and + 20% with SOC = 50% as a reference (0%). From FIG. 3, it is understood that relatively flat characteristics can be obtained for both input and output by combining and shifting the SOC shift amount by the above-described values, which is particularly suitable. Therefore, in the present embodiment, the SOC of each cell block B in the assembled battery 2 is configured by combining + 10%, + 15%, and + 20% from the 50% standard (0%). I decided to.

  Thus, by intentionally combining the cell blocks B having different voltages (SOCs), the cell block B has the above-described composition. In each cell block B, at least one of OCV and DCIR changes with respect to the SOC change at a predetermined level. Even if it is more intense than the above, at a certain charge / discharge timing, each cell block B in series has a different maximum input / output power due to the difference in the SOC, and the assembled battery 2 as a whole has a maximum input / output power with respect to the SOC change. A battery that is easy to handle can be realized.

  In addition, by setting the SOC variation to 10 to 20%, it is possible to prevent overdischarge and overcharge while suppressing a sudden drop in the maximum input / output power with respect to the SOC change. In particular, for example, by using a combination of + 10%, + 15%, and + 20% on the basis of a cell block of SOC = 50%, for example, the input characteristics are almost the same as the case of only + 20%, but the output characteristics are The drop on the low SOC side becomes smaller than the case of only + 20%, and it can be closer to linear.

  And once the dispersion | variation of the SOC value as mentioned above is set, even if it drive | works for 1 day with respect to subsequent charging / discharging, a shift | offset | difference will not arise for several percent. However, to prevent the deviation from accumulating, the control microcomputer 12 causes the SOC adjustment circuit 18 to set the SOC value of each cell block B to + 5% from the SOC value of the reference cell block by the SOC adjustment circuit 18. Calibration is performed by appropriately charging and discharging so as to be + 10%. Here, the reference cell block has an ideal value of 60% in the case of 50% + 10%, and the control microcomputer 12 makes the SOC value of the reference cell block 60% during traveling. As described above, the charge / discharge control is performed in cooperation with the device control apparatus 9, but the possibility that the ideal value is reached at the end of traveling is small. Therefore, at the time of calibration, the SOC value relative to the cell block serving as the reference is + 5% and + 10% so that the voltage value of the SOC value corresponds to the temperature of the cell block at that time. To charge / discharge. That is, the control microcomputer 12 which is a calculation means and a calibration means is IGOFF, or after a predetermined time has elapsed, the voltage and temperature of the reference cell block are supplied to the voltage measurement circuit 11 and the temperature sensor 21 which are measurement means. The corresponding SOC value is read from the table, the SOC value obtained by adding 5% and 10% to the SOC value is obtained, the voltage corresponding to the SOC value and the temperature of the cell block is read from the table, In order for the cell voltage detected by the voltage measurement circuit 11 to be the voltage, the SOC adjustment circuit 18 as charge / discharge means performs charge / discharge, and returns (calibrates) to a predetermined SOC. The SOC adjusting circuit 18 can be realized by a short-circuit resistor capable of gently short-circuiting the terminals of the cell S, a switch connected in series thereto, a charging circuit, or the like.

  In this way, it is possible to always keep the error of SOC variation between the cell blocks within a predetermined range and maintain desired input / output characteristics. The SOC value is not uniquely read from the cell voltage and temperature with reference to a table, but is charged / discharged from a predetermined SOC value, for example, 100% full charge state or 0% empty state. You may obtain | require by integrating | accumulating an electric current.

  Furthermore, the control microcomputer 12 which is a calculation means monitors the SOC value of each cell block B as described above during traveling, and the SOC value is a predetermined first value, for example, 90% or more. When it is determined that overcharge occurs, it is determined that overdischarge occurs when a predetermined second value, for example, 10% or less, and when the device controller 9 serving as a master controller is overcharged, When the battery 2 is over-discharged, a signal is output to stop the discharge.

  With this configuration, the SOC is deliberately varied as described above, so that the possibility of overdischarge or overcharge is increased in a cell block having a large variation during charge / discharge. However, the actual overdischarge or overcharge can be prevented.

As an active material for the positive _electrode, SOC change _{Li a M b Ni c Co d} O e (M as adapted to use Al, Mn, Sn, In, Fe, Cu, Mg, Ti, Zn, at least one metal of Mo In a battery pack using a non-aqueous electrolyte secondary battery in which the OCV and DCIR changes drastically with respect to the battery, when a plurality of stages are connected in series, a sudden drop in the maximum input / output power caused by the change in the OCV and DCIR is intentionally reduced to the SOC. Therefore, a secondary battery having a large discharge capacity per unit volume can be preferably used, such as a hybrid vehicle, by combining the batteries with different ones.

1 is a block diagram showing an electrical configuration in a power system of a hybrid vehicle according to an embodiment of the present invention. It is a graph which shows the experiment result of this inventor, and shows the maximum input / output value of the assembled battery in each SOC. It is a graph which shows the experiment result of this inventor, and shows the maximum input / output value of the assembled battery in each SOC. Li _{a Mb} Ni _c Co _d O _e (M is a unit volume in which at least one metal of Al, Mn, Sn, In, Fe, Cu, Mg, Ti, Zn, and Mo is used as the positive electrode active material) It is a graph which shows OCV change with respect to SOC change in the nonaqueous electrolyte secondary battery with a large per unit discharge capacity. Li _{a Mb} Ni _c Co _d O _e (M is a unit volume in which at least one metal of Al, Mn, Sn, In, Fe, Cu, Mg, Ti, Zn, and Mo is used as the positive electrode active material) It is a graph which shows the DCIR change with respect to the SOC change in the nonaqueous electrolyte secondary battery with a large per unit discharge capacity. It is a graph which shows the maximum input value (electric power value which can be input) of the battery with respect to each SOC in the case of using the non-aqueous electrolyte secondary battery as described above. It is a graph which shows the maximum output value (electric power value which can be output) of the battery with respect to each SOC when using the non-aqueous electrolyte secondary battery as described above.

DESCRIPTION OF SYMBOLS 1 Hybrid vehicle 2 Battery assembly 3 Converter 4 Inverter 5 Motor 6 BMU
7 Battery module 8 Switch 9 Device control device 11 Voltage measurement circuit 12 Control microcomputer 13 Current measurement circuit 14 Overcharge protection circuit 15 Overcurrent protection circuit 16 Temperature protection circuit 17 OR circuit 18 SOC adjustment circuit 21 Temperature sensor 22 Current sensor B Cell block S cell

Claims (4)

In an assembled battery formed by combining a plurality of cell blocks of a nonaqueous electrolyte secondary battery having a negative electrode made of lithium metal or a material capable of occluding and releasing lithium and a positive electrode in series,
A plurality of cell blocks having different SOCs are combined, and the variation in the SOC is a combination of + 10%, + 15%, and + 20% with reference to 50% cell blocks. Assembled battery. Comprises a battery pack of claim 1 Symbol placement,
Measuring means for measuring at least the terminal voltage and the cell temperature of each cell block in the assembled battery,
Arithmetic means for obtaining the SOC of each cell block based on the measurement result of the measurement means;
When at least one of the SOCs calculated by the computing means is equal to or greater than a predetermined first value, it is determined that the battery is overcharged. When it is equal to or less than a predetermined second value, it is determined that the battery is overdischarged. A battery module comprising charge / discharge control means for stopping discharge. Comprises a battery pack of claim 1 Symbol placement,
Measuring means for measuring at least the terminal voltage and the cell temperature of each cell block in the assembled battery,
Arithmetic means for obtaining the SOC of each cell block based on the measurement result of the measurement means;
Charging / discharging means capable of performing at least one of discharging or charging by short-circuiting between terminals or applying a charging voltage between the terminals with respect to at least some cell blocks;
When charging / discharging is stopped, when the SOC determined by the calculating means is shifted more than a predetermined value with respect to a predetermined SOC for each cell block, the charging / discharging means is driven, and each cell block A battery module comprising: calibration means for returning the battery to the predetermined SOC. A hybrid vehicle comprising the battery module according to claim 2 or 3 mounted thereon.

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