JP6299963B2 - Secondary battery management device - Google Patents

Description

  The present invention relates to a management device that manages the state of charge of a secondary battery mounted on, for example, a vehicle.

  In recent years, for example, many electric vehicles such as electric vehicles and hybrid vehicles have been put into practical use. A rechargeable secondary battery such as a lithium ion battery is used as a driving battery mounted on an electric vehicle. Secondary batteries such as lithium ion batteries are also used in various fields such as household power supplies, various AV devices, personal computers, and portable terminals.

  It is known that such a secondary battery deteriorates as it continues to be used, but its deterioration rate changes depending on the state of charge (SOC). For example, it is known that when the state of charge (SOC) is in a predetermined region, the deterioration rate of the battery is accelerated as compared with other regions. Furthermore, it is known that the area where the deterioration rate accelerates (deterioration acceleration area) differs for each type of secondary battery.

  And the technique which suppresses deterioration of a secondary battery by shortening the time which SOC of a secondary battery exists in a deterioration acceleration area | region is proposed. For example, by increasing the discharge current for a high-temperature storage battery among a plurality of storage batteries (secondary batteries) connected in parallel, the time during which the SOC is in the deterioration acceleration region is shortened compared to other storage batteries, There is one in which the deterioration rate of each storage battery is adjusted (see Patent Document 1).

JP 2012-65449 A

  As in Patent Document 1, the progress of deterioration of the secondary battery can be delayed by shortening the time during which the SOC is in the deterioration acceleration region by increasing the discharge current or the like. However, on the other hand, there is a demerit that the usable capacity of the secondary battery is reduced by shortening the time during which the SOC of the secondary battery is in the deterioration acceleration region.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a secondary battery management device capable of delaying the progress of deterioration while suppressing a decrease in usable capacity of the secondary battery. To do.

  A first aspect of the present invention that solves the above-described problem is a secondary battery management device that performs input / output control of a secondary battery, wherein at least one parameter indicating a state of the secondary battery is predetermined. A deterioration acceleration region setting unit that sets a part of the used region as a deterioration acceleration region, and avoidance control for forcibly discharging the secondary battery to avoid using the secondary battery in the deterioration acceleration region An avoidance control unit, and the avoidance control unit is required for the forced discharge according to the stay permission time determining means for determining a stay permission time that is a time in which the stay can stay in the deterioration acceleration region. And a control current calculating means for calculating a control current which is a small current.

  According to a second aspect of the present invention, in the secondary battery management device according to the first aspect, the stay permission time determining means determines the stay permission time according to a deterioration rate in the deterioration acceleration region. It is in the management apparatus of the secondary battery characterized.

According to a third aspect of the present invention, in the secondary battery management device according to the first or second aspect, the deterioration acceleration region setting unit further presets a plurality of speed deterioration regions in the deterioration acceleration region, The stay permission time determining means determines the stay permission time of the plurality of speed deterioration areas according to the deterioration speed corresponding to each speed deterioration area, respectively.

  According to a fourth aspect of the present invention, in the secondary battery management device according to any one of the first to third aspects, the deterioration acceleration region setting unit is configured to perform the deterioration acceleration region according to a usage state of the secondary battery. The secondary battery management apparatus is characterized in that the setting range is changed.

  According to the secondary battery management apparatus of the present invention, it is possible to suppress wasteful power consumption in the deterioration acceleration region and to efficiently pass the deterioration acceleration region at an appropriate power consumption speed.

It is a figure showing the schematic structure of the vehicles carrying the management device concerning one embodiment. It is a block diagram which shows the structure of the management apparatus of the secondary battery which concerns on one Embodiment. It is a graph for demonstrating an example of the map which concerns on one Embodiment. It is a graph for demonstrating an example of the map which concerns on one Embodiment. It is a graph for demonstrating an example of the map which concerns on one Embodiment. It is a flowchart which shows an example of the avoidance control which concerns on one Embodiment.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In addition, the following embodiment demonstrates the example which mounted the secondary battery and its management apparatus in the vehicle.

  First, an example of a vehicle equipped with a secondary battery will be described. As shown in FIG. 1, a vehicle 1 according to the present embodiment is a plug-in hybrid electric vehicle (PHEV) that is a kind of electric vehicle, and includes a driving battery 3 that is a secondary battery in addition to an engine 2. Yes. The drive battery 3 is a battery unit in which a plurality of battery cells are connected in series, and each battery cell is made of, for example, a lithium ion secondary battery.

  The driving battery 3 is electrically connected to the traveling motor 5 and the generator 6 via a control unit 4 including a control unit 100 described later. The travel motor 5 and the generator 6 are connected to drive wheels (front wheels) 7 via a drive transmission mechanism (not shown).

  In the vehicle 1 according to the present embodiment, the electric power stored in the drive battery 3 is converted from direct current to alternating current by the inverter of the control unit 4 and flows into the travel motor 5 (discharge), whereby the travel motor 5 Is driven. Then, the driving force of the traveling motor 5 is transmitted to driving wheels (front wheels) 7 so that the vehicle 1 travels.

  Here, as shown in FIG. 2, the control unit 100 includes a charging state detection unit 10 that detects a charging state such as a charging rate of the driving battery 3, a battery deterioration state detection unit 20, and a deterioration acceleration region setting unit 30. And an avoidance control execution unit 40.

  In this embodiment, the charge state detection unit 10 includes a battery temperature detection unit 11 that detects the temperature of the drive battery 3, and an SOC detection unit 12 that detects a state of charge (SOC) of the drive battery 3. It is equipped with. The SOC detection means 12 may be simply replaced with a voltage detection means for detecting the voltage of the driving battery 3.

  The battery deterioration state detection unit 20 detects a deterioration state of the driving battery 3 (hereinafter also referred to as a battery deterioration state). In the present embodiment, the battery deterioration state detection unit 20 detects the capacity deterioration of the driving battery 3 as the battery deterioration state, but may detect the resistance deterioration separated from the capacity deterioration together with the capacity deterioration. Such a battery deterioration state can be detected according to a conventional method. The battery deterioration state detected in this way is sent to the deterioration acceleration region setting unit 30.

  The degradation acceleration region setting unit 30 holds, as a map, data on the degradation acceleration region defined from the results measured in advance for each battery degradation state. Based on this map, the degradation acceleration region corresponding to the current battery degradation state is stored. Set as appropriate. Thereby, the deterioration acceleration area | region which changes with battery deterioration states can be set appropriately.

  Here, it is known that the deterioration acceleration region varies depending on the temperature of the driving battery 3 (hereinafter also referred to as battery temperature). For this reason, in addition to the battery deterioration state, the deterioration acceleration region data may be held as a map for each battery temperature, and the deterioration acceleration region may be set in consideration of the battery deterioration state and the battery temperature. Thereby, a deterioration acceleration region suitable for the state of the driving battery 3 can be set.

  Next, data (map) of the deterioration acceleration area prepared in advance will be described. In order to obtain the deterioration acceleration region, the actual deterioration rate is measured under various environments, and a range where the deterioration rate is high is defined as the deterioration acceleration region based on the result. As will be described below, in the present embodiment, the parameter indicating the state of the secondary battery is the charge rate (SOC) of the drive battery 3, and a predetermined usage range is set for the charge rate (SOC). Is set as the deterioration acceleration region.

  FIG. 3 is a graph showing the relationship between the SOC of the drive battery 3 and the deterioration rate for each deterioration state. Specifically, this graph shows that the battery deterioration state is small (for example, the capacity deterioration is in the range of 0 to 10%, 0% in this case), and the battery deterioration state is medium (for example, the capacity deterioration is 10 to 25%. In this case, the relationship between the SOC of the driving battery 3 and the deterioration rate when the battery deterioration state is large (for example, the capacity deterioration is 25 to 50% and 40% in this case) is shown.

  In this graph, data (map) in which a predetermined SOC range including the peak of the deterioration rate is defined as the deterioration acceleration region is prepared in advance. In this example, the deterioration acceleration region A1 when the battery deterioration state is small is defined as a range where the SOC is 25% to 35%, and the deterioration acceleration region A2 when the battery deterioration state is medium is the SOC between 35% and 45%. The deterioration acceleration region A3 when the battery deterioration state is large is specified as a SOC range of 45% to 55%. When the capacity deterioration is 50% or more, the battery capacity is remarkably reduced. Therefore, the use is usually stopped and the drive battery 3 is replaced with a new one.

  It may be determined as appropriate which range of the SOC is set as the deterioration acceleration region with respect to the peak of the deterioration rate. For example, it may be determined in consideration of the balance between the avoidance control load described later and the effect of avoidance control. In this example, the half width of each peak is defined as the deterioration acceleration region. Further, the relationship between the SOC and the deterioration rate of the driving battery 3 varies depending on the type and standard of the secondary battery, but there is no individual difference. For this reason, the deterioration acceleration region may be defined for each type and standard of the secondary battery used as the driving battery 3. Then, the deterioration acceleration region setting unit 30 appropriately sets the current deterioration acceleration region based on such data (map).

Further, which range of the SOC is set as the deterioration acceleration region with respect to the peak of the deterioration speed may be appropriately set according to the travel mode of the vehicle 1 selected by the driver, for example. Specifically, the driver can select the first traveling mode in which the deterioration of the driving battery 3 is emphasized and the second traveling mode in which the traveling distance of the vehicle 1 is emphasized. When the driver selects the first travel mode, for example, as shown in FIG. 4, a relatively wide deterioration acceleration region A4 is set, and when the second travel mode is selected, the deterioration occurs. A region narrower than the acceleration region A4 may be set as the deterioration acceleration region A5. That is, when the second travel mode is selected, the determination line L2 for determining whether or not the deterioration of the driving battery 3 is accelerated is compared with the determination line L1 when the first travel mode is selected. You may make it set high. Thus, by setting the deterioration acceleration region according to the driving mode requested by the driver, it is possible to execute avoidance control suitable for the driving mode requested by the driver. The deterioration acceleration region A5 and a range excluding the deterioration acceleration region A5 in the deterioration acceleration region A4 correspond to “a plurality of speed deterioration regions” described in the claims. The avoidance control will be described later in detail. Further, the deterioration acceleration area need not always be set according to the selection of the driver, and may be automatically selected and set according to a predetermined determination condition.

  FIG. 5 is a graph showing the relationship between the SOC of the driving battery 3 (large deterioration in FIG. 3) and the deterioration rate changed with the temperature change. Specifically, this graph shows that the temperature of the driving battery 3 is high (eg, in the range of 30 ° C. to 50 ° C., in this case 45 ° C.), normal temperature (eg, in the range of 10 ° C. to 30 ° C., in this case) The relationship between the SOC of the drive battery 3 and the deterioration rate in the case of 25 ° C.) and low temperature (for example, 0 ° C. in the range of 10 ° C. or less) is shown. In such a graph, data (map) defining a predetermined SOC range including the peak of the deterioration rate as the deterioration acceleration region may be prepared in advance.

  In this example, the degradation acceleration region A6 at high temperature is defined as a range of SOC of 45% to 55%, and the degradation acceleration region A7 at normal temperature is defined as a range of SOC from 15% to 25%. When the temperature of the driving battery 3 is constant, no deterioration speed peak exists, so the deterioration acceleration region is not defined.

  By preparing such data of the deterioration acceleration region in advance, the deterioration acceleration region setting unit 30 appropriately sets the deterioration acceleration region according to the current state of the driving battery 3 based on these data. be able to. Information on the deterioration acceleration region set by the deterioration acceleration region setting unit 30 is sent to the avoidance control execution unit 40.

  When the avoidance control execution unit 40 receives the information on the deterioration acceleration region, the avoidance control execution unit 40 appropriately executes avoidance control for avoiding the use of the driving battery 3 in the deterioration acceleration region. In this avoidance control, the drive battery 3 is forcibly discharged, thereby increasing the speed at which the SOC of the drive battery 3 leaves the deterioration acceleration region.

  In this embodiment, the avoidance control execution unit 40 includes a stay permission time determination unit 41 and a control current calculation unit 42.

The stay permission time determination unit 41 determines a stay permission time that is a time during which the user can stay in the deterioration acceleration region. The stay permission time can be calculated (determined) from the following formula (1), for example.
Residence permission time = Allowable deterioration amount / Deterioration speed (1)

  Here, the “deterioration rate” in the above equation (1) is basically an average value of the deterioration rates in the deterioration acceleration region, and is obtained based on the graph (map) shown in FIG. However, the “deterioration rate” is not limited to an average value, and may be a weighted average value obtained by weighting, for example. The “allowable deterioration amount” is the deterioration amount of the driving battery 3 allowed in each deterioration acceleration region, and is set as appropriate based on various conditions such as the current battery deterioration state. For example, when the current battery deterioration state is small, the allowable deterioration amount is increased, and when the current battery deterioration state is large, the allowable deterioration amount is decreased. Of course, this allowable deterioration amount does not need to be set according to the battery deterioration state or the like, and may be a predetermined constant value.

  As described above, the stay permission time determination unit 41 according to the present embodiment determines the stay permission time according to the deterioration speed in the deterioration acceleration region. For example, as shown in FIG. 5, the peak of the deterioration rate in the deterioration acceleration region A6 is larger than the peak of the deterioration rate in the deterioration acceleration region A7. That is, the deterioration rate in the deterioration acceleration region A6 is larger than the deterioration rate in the deterioration acceleration region A7. In such a case, the stay permission time determination means 41 sets the stay permission time in the deterioration acceleration area A6 to be shorter than the stay permission time in the deterioration acceleration area A7. Thereby, the amount of deterioration when the SOC of the drive battery 3 stays in each of the deterioration acceleration regions A6 and A7 is made uniform.

The control current calculation unit 42 calculates a control current, which is a current that needs to be discharged by forced discharge during avoidance control, according to the stay permission time determined by the stay permission time determination unit 41. The control current calculated by the control current calculation means 42 is expressed by the following formula (2).
Control current = Required current-Vehicle operating current (2)

  Here, the “necessary current” refers to a current required to leave the deterioration acceleration region at each stay permission time. For example, the stay permission time determined by the stay permission time determination means 41 for the battery capacity of the deterioration acceleration region. It is obtained by dividing by. The “vehicle use current” refers to a current that the vehicle 1 is currently using, for example, a current that is used by the traveling motor 5 or the like.

Then, when the SOC of the driving battery 3 enters the deterioration acceleration region, the avoidance control execution unit 40 drives for driving so as to exit the deterioration acceleration region with the stay permission time calculated (determined) by the stay permission time determination means 41. Avoidance control for forcibly discharging the battery 3 is executed. That is, the avoidance control execution unit 40 executes avoidance control and forcibly discharges the control current calculated by the control current calculation means 42 during the stay permission time. The method of forced discharge is not particularly limited. For example, the discharge may be promoted by stopping the use of the engine assist of the vehicle 1, or a predetermined resistance member is provided in the vehicle 1 and the resistance is reduced. You may make it promote discharge by supplying electric power to a member.

  In addition, the deterioration acceleration region may be exceeded within the stay permission time by controlling the execution amount of the forced discharge so that a current equal to or greater than the control current calculated by the control current calculation unit 42 always flows. It should be noted that the forced discharge may not be executed when a current equal to or greater than the control current is already flowing as the vehicle operating current. By doing so, there is an advantage that the avoidance operation can be further optimized, and a more usable current capacity can be secured by avoiding unnecessary forced discharge.

  As described above, in the present invention, the avoidance control is executed when the SOC of the driving battery 3 enters the deterioration acceleration region, and only the necessary amount is forcibly discharged when necessary to meet the stay permission time. . Thereby, the SOC of the drive battery 3 can be efficiently separated from the deterioration acceleration region while suppressing wasteful power consumption.

  For example, if the forced discharge amount in the avoidance control is increased to the maximum, the time required for the SOC of the drive battery 3 to escape from the deterioration acceleration region can be further shortened. On the other hand, the electric power of the driving battery 3 is wasted, resulting in a demerit that the travel distance is shortened. On the other hand, according to the present invention, the SOC of the drive battery 3 can be efficiently separated from the deterioration acceleration region while suppressing such disadvantages.

  Further, it is preferable that the avoidance control by the avoidance control execution unit 40 is efficiently performed by changing the avoidance control described above following the change in conditions in the deterioration acceleration region. That is, even when the avoidance control is executed, the deterioration acceleration region and the deterioration acceleration change as the battery deterioration state, the battery temperature, and the like change. For this reason, it is preferable that the control current calculation unit 42 calculates (updates) the control current at a predetermined timing even when avoidance control is executed, and executes avoidance control based on the latest control current.

  Hereinafter, an example of the execution procedure of the avoidance control in the drive battery 3 will be described with reference to the flowchart of FIG.

  As shown in FIG. 6, first, in step S <b> 1, data (map) that defines the relationship between the SOC of the drive battery 3 and the deterioration rate is appropriately set according to selection conditions such as the deterioration state and temperature of the drive battery 3. select. Next, the deterioration acceleration region (SOC range) is set based on the map selected in step S2, and the capacity of the deterioration acceleration region is calculated (step S3). For example, when the battery capacity of the driving battery 3 is 50 [Ah] and the deterioration acceleration region is set to be in the range of 45 to 55 [%], the deterioration acceleration region (ΔSOC) is 10 [%]. The capacity of the deterioration acceleration region is 5 [Ah].

  Next, the stay permission time is determined in step S4. For example, the stay permission time is calculated (determined) based on the above formula (1) and the like. The stay permission time may be a fixed value set in advance, or a desired value may be input as appropriate. Next, in step S5, a control current is calculated based on the stay permission time. For example, the control current is calculated based on the above formula (2) and the like. Then, avoidance control is executed based on the control current calculated in this way (step S6). That is, when the SOC of the drive battery 3 enters the deterioration acceleration region, the discharge amount of the drive battery 3 is increased according to the control current.

  Thereafter, when discharging is performed for the capacity of the deterioration acceleration region (for example, 5 [Ah]) (step S7: Yes), the avoidance control is stopped (step S8), and the series of processes is terminated. If it is determined in step S7 that the battery has not been discharged by the capacity of the deterioration acceleration region (step S7: No), whether or not the change in map selection condition (selection condition) including the temperature of the drive battery 3 is within a predetermined range. Is determined (step S9). In step S9, specifically, whether the temperature change of the driving battery 3 from the start of the avoidance control is within a predetermined value, whether the elapsed time from the map selection (step S1) is within a certain time, etc. judge. If the change of the selection condition is within the predetermined range (step S9: Yes), the process returns to step S6 and the avoidance control is continued. If the selection condition is outside the predetermined range (step S9: No), the process returns to step S1, and a new map is selected based on the new selection condition.

  By executing the avoidance control in the drive battery 3 by such a procedure, the SOC of the drive battery 3 can be efficiently separated from the deterioration acceleration region while suppressing unnecessary power consumption as described above.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, an example in which the secondary battery and its management device are mounted on a vehicle has been described. However, the secondary battery management device according to the present invention includes a home auxiliary power supply, various AV devices, a personal computer, The present invention can also be applied to the management of a secondary battery mounted on a device other than a vehicle such as a mobile phone, and in that case, the same effect as that of the above-described embodiment can be obtained.

  In the above-described embodiment, the deterioration acceleration region is determined using at least one parameter indicating the state of the secondary battery as the charging rate (SOC). However, this parameter is not limited to the SOC. For example, the parameter may be a voltage value or the amount of current accumulated in the battery, and the deterioration acceleration region may be set in advance based on the parameter value.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Engine 3 Drive battery 4 Control unit 5 Traveling motor 6 Generator 7 Wheel (front wheel)
DESCRIPTION OF SYMBOLS 10 Charge state detection part 20 Battery deterioration state detection part 30 Deterioration acceleration area setting part 40 Avoidance control execution part 100 Control part

Claims (4)

A secondary battery management device that performs input / output control of a secondary battery,
For at least one parameter indicating the state of the secondary battery, a deterioration acceleration region setting unit that sets a part of a predetermined use region as a deterioration acceleration region;
An avoidance control unit for forcibly discharging the secondary battery and performing avoidance control for avoiding the use of the secondary battery in the deterioration acceleration region,
The avoidance control unit includes a stay permission time determination unit that determines a stay permission time that is a time during which the vehicle can stay in the deterioration acceleration region.
And a control current calculation unit that calculates a control current that is a current required for the forced discharge according to the stay permission time. The secondary battery management device according to claim 1,
The stay permission time determining means determines the stay permission time according to a deterioration rate in the deterioration acceleration region. In the management apparatus of the secondary battery of Claim 1 or 2,
The deterioration acceleration region setting unit further presets a plurality of speed deterioration regions in the deterioration acceleration region,
The stay permitting time determining means determines the stay permitting times of the plurality of speed deterioration regions according to deterioration rates corresponding to the respective speed deterioration regions, respectively. In the management apparatus of the secondary battery as described in any one of Claim 1 to 3,
The deterioration accelerating region setting unit changes a setting range of the deterioration accelerating region in accordance with a usage state of the secondary battery.