JP2007195359A - Charging and discharging control device of secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging and discharging control device capable of functioning equipment such as a motor as well as exploiting the full potential of charging performance and discharging performance of a secondary battery. <P>SOLUTION: A control unit 14 controls the charging and discharging amount of a battery according to a limiting value. That is, when a temperature detected by a temperature sensor 24, or a temperature Tbat reaches the predetermined temperature due to the temperature rise of the battery or a battery unit B0 to Bn, the control unit 14 causes the limiting value to change according to an elapsed time from the point in time when the temperature of the battery reaches the predetermined time. This enables the battery to sufficiently exercise the charging performance and discharging performance within the limiting temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charge / discharge control device for a secondary battery (battery), and more particularly to a charge / discharge control device for a secondary battery mounted on a vehicle.

  In recent years, vehicles such as electric vehicles, hybrid vehicles, and fuel cell vehicles that employ a motor as a driving source for vehicle propulsion and have a large-capacity battery that stores electric power for driving the motor have appeared. .

  In secondary batteries, it is known that when discharging or charging is continued, a temperature rise accompanying heat generation occurs. An increase in battery temperature is a factor that affects battery performance. Therefore, a method of controlling the charge / discharge amount of the battery using the battery temperature as a parameter has been conventionally used.

For example, Japanese Patent Application Laid-Open No. 11-224697 (Patent Document 1) discloses a control device for a secondary battery that can make maximum use of the output performance of the battery within a range where the temperature of the battery does not exceed the upper limit temperature of use. The This control device obtains a discharge depth representing the current discharge degree with respect to the output power when the battery is fully charged. And this control apparatus calculates | requires the temperature which starts the restriction | limiting of the output power of a battery based on the calculated depth of discharge. Here, when the battery temperature is higher than the output limit start temperature, the control device obtains the output limit value of the battery based on the battery temperature. The control device limits the output power of the battery based on the output limit value. Therefore, the output performance of the battery can be used without reducing the battery life.
Japanese Patent Application Laid-Open No. 11-224697 JP-A-11-187777 JP-A-9-74605 JP 2005-20955 A

  For example, in the case of the hybrid vehicle as described above, when the control device greatly limits the charge / discharge amount of the secondary battery in response to the temperature of the secondary battery exceeding the limit start temperature, the operation of the drive source for vehicle propulsion is performed. It may be possible to affect the Specifically, for example, a user who drives a vehicle feels that the power performance according to his / her intention cannot be obtained. In order to solve such a problem, it is preferable to reduce the limit value as gently as possible with respect to the temperature rise.

  On the other hand, it is necessary to control the temperature of the secondary battery so as not to exceed a temperature that lowers the life of the secondary battery (hereinafter referred to as “limit temperature”). In order to decrease the limit value as slowly as possible with respect to the temperature rise, and to prevent the secondary battery temperature from exceeding the limit temperature, limit the temperature of the secondary battery when starting to decrease the limit value. It is necessary to set it sufficiently lower than the temperature.

  However, when limiting the amount of charge / discharge when the secondary battery temperature is low, the power actually input / output to / from the secondary battery at a certain temperature will be significantly lower than the capacity of the secondary battery. Can be considered. A method for solving such a problem is not specifically disclosed in Japanese Patent Laid-Open No. 11-224697 (Patent Document 1).

  The objective of this invention is providing the charging / discharging control apparatus of a secondary battery which can operate apparatuses, such as a motor, fully drawing out the charging performance and discharge performance of a secondary battery.

  In summary, the present invention is a charge / discharge control device for a secondary battery, and includes a temperature detection unit and a control unit. The temperature detection unit detects the temperature of the secondary battery. The control unit controls the charge / discharge amount of the secondary battery according to the limit value. When the detection temperature of the secondary battery transmitted from the temperature detection unit exceeds a predetermined temperature, the control unit changes the limit value according to the elapsed time from the time when the detection temperature reaches the predetermined temperature.

  Preferably, the control unit changes the limit value using a function in which the limit value monotonously decreases with respect to the elapsed time.

  More preferably, when the control unit detects that the detected temperature has reached the return temperature lower than the predetermined temperature, the control unit increases the limit value according to the elapsed time from the time when the detected temperature reaches the return temperature. .

  Preferably, the control unit temporarily determines a limit value corresponding to the detected temperature for each predetermined period using a function in which the temperature of the secondary battery is associated with the limit value. The control unit obtains an absolute value of a difference between the first limit value that is the temporarily determined limit value and the second limit value that is the current limit value. When the absolute value of the difference is equal to or less than the predetermined value, the control unit updates the second limit value using the first limit value as it is. When the absolute value of the difference exceeds the predetermined value, the control unit corrects the first limit value using the predetermined value, and updates the second limit value using the corrected first limit value. To do.

  Preferably, any of the above-described secondary batteries supplies power to a drive source that drives the vehicle.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to operate apparatuses, such as a motor, fully drawing out the charging performance and discharge performance of a secondary battery.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
FIG. 1 is a diagram showing an application example of a charge / discharge control device for a secondary battery according to the first embodiment.

  Referring to FIG. 1, the secondary battery charge / discharge control device according to the first embodiment is mounted, for example, in a hybrid vehicle.

  The hybrid vehicle 1 includes front wheels 20R, 20L, rear wheels 22R, 22L, an engine 2, a planetary gear 16, a differential gear 18, and gears 4, 6.

  The hybrid vehicle 1 further includes a battery 12 disposed behind the vehicle, a booster unit 32 that boosts the DC power output from the battery 12, an inverter 36 that transfers DC power between the booster unit 32, and the planetary gear 16. Includes a motor generator MG1 that receives power from the engine 2 to generate power and a motor generator MG2 whose rotating shaft is connected to the planetary gear 16. Inverter 36 is connected to motor generators MG1 and MG2, and converts AC power and DC power from the booster circuit.

  Planetary gear 16 has first to third rotation shafts. The first rotation shaft is connected to engine 2, the second rotation shaft is connected to motor generator MG1, and the third rotation shaft is connected to motor generator MG2.

  A gear 4 is attached to the third rotating shaft, and the gear 4 drives the gear 6 to transmit power to the differential gear 18. The differential gear 18 transmits the power received from the gear 6 to the front wheels 20R, 20L, and transmits the rotational force of the front wheels 20R, 20L to the third rotating shaft of the planetary gear via the gears 6, 4.

  Planetary gear 16 serves to divide the power between engine 2 and motor generators MG1, MG2. That is, if the rotation of two of the three rotation shafts of the planetary gear 16 is determined, the rotation of the remaining one rotation shaft is naturally determined. Accordingly, the vehicle speed is controlled by controlling the power generation amount of the motor generator MG1 and driving the motor generator MG2 while operating the engine 2 in the most efficient region, thereby realizing an overall energy efficient vehicle. Yes.

  The battery 12, which is a DC power supply, supplies DC power to the boost unit 32 and is charged with DC power from the boost unit 32. The battery 12 is specifically a lithium ion battery, but may be a nickel metal hydride battery.

  Boost unit 32 boosts the DC voltage received from battery 12 and supplies the boosted DC voltage to inverter 36. Inverter 36 converts the supplied DC voltage into AC voltage, and drives and controls motor generator MG1 when the engine is started. Further, after the engine is started, AC power generated by motor generator MG1 is converted to DC by inverter 36 and converted to a voltage suitable for charging battery 12 by boosting unit 32, and battery 12 is charged.

  Inverter 36 drives motor generator MG2. Motor generator MG2 assists engine 2 to drive front wheels 20R and 20L. During braking, the motor generator performs a regenerative operation and converts the rotational energy of the wheels into electric energy. The obtained electric energy is returned to the battery 12 via the inverter 36 and the booster unit 32.

  System main relays 28 and 30 are provided between the booster unit 32 and the battery 12, and the high voltage is cut off when the vehicle is not in operation.

  Battery 12 is an assembled battery that supplies power to drive sources (motor generators MG1, MG2) that drive hybrid vehicle 1. The battery 12 includes a plurality of battery units B0 to Bn connected in series.

  The hybrid vehicle 1 further includes a temperature sensor 24 attached to the battery 12, a voltage sensor 26, and a control unit 14 that controls the engine 2, the inverter 36, and the boosting unit 32 according to the outputs of the temperature sensor 24 and the voltage sensor 26. including. The temperature sensor 24 detects the temperature Tbat of the battery 12 and transmits it to the control unit 14. The voltage sensor 26 detects the terminal voltages V0 to Vn of the battery units B0 to Bn and transmits them to the control unit 14. Further, the control unit 14 operates the fan 27 when it is determined that the battery 12 needs to be cooled based on the temperature detected by the temperature sensor 24 (temperature Tbat).

  The control unit 14 controls the charge / discharge amount of the battery 12 according to the limit value. More specifically, when the detected temperature (temperature Tbat) of the temperature sensor 24 exceeds a predetermined temperature, the control unit 14 changes the limit value according to the elapsed time from when the detected temperature reaches the predetermined temperature. Thereby, the battery 12 can fully exhibit the charging performance and the discharging performance without reaching the limit temperature. That is, even when the temperature of the battery 12 exceeds the predetermined temperature, more power than in the past can be returned to the battery 12, or more power than in the past can be taken out from the battery 12. For example, more energy can be returned to the battery 12 during regenerative operation of the motor generator. Further, when the user drives the vehicle, more energy can be extracted from the battery, so that the influence on the behavior of the vehicle can be minimized.

FIG. 2 is a diagram illustrating the configuration of the control unit 14 of FIG.
Referring to FIG. 2, control unit 14 includes a processing unit 41, a storage unit 42, and a counter 43. The processing unit 41 is a main part of the control unit 14 and determines a limit value for the charge / discharge amount of the battery 12 based on the temperature Tbat. The counter 43 increases or decreases the count value at regular time intervals (for example, every second). The storage unit 42 stores a function indicating the relationship between the count value and the limit value. Note that the processing unit 41, the storage unit 42, and the counter 43 may be realized by hardware, or may be realized by software executed on the control unit 14.

  When the processing unit 41 detects that the temperature Tbat has reached a predetermined temperature (hereinafter referred to as temperature T0), the processing unit 41 starts the operation of the counter 43. The counter 43 increases the count value from 0 at intervals of 1 second, for example. The processing unit 41 acquires a count value from the counter 43 at a predetermined timing (for example, at intervals of 1 second). The processing unit 41 determines a limit value using the count value and the function f (x) stored in the storage unit 42.

  According to this function f (x), the limit value of the charge / discharge amount changes with respect to the elapsed time after the temperature Tbat reaches the temperature T0. As the function f (x), various functions can be applied as long as the limit value of the charge / discharge amount monotonously decreases with respect to the elapsed time. In the following example, it is assumed that the function f (x) makes the change amount of the limit value proportional to the elapsed time.

FIG. 3 is a diagram illustrating control of the charge / discharge amount of the battery 12 by the control unit 14 of FIG.
Referring to FIG. 3, the temperature Tbat of the battery 12 rises from the temperature TA by charging or discharging the battery. Until the temperature Tbat reaches the temperature T0, the limit value Win of the charge amount and the limit value Wout of the discharge amount remain constant at the limit value WA.

  When the temperature Tbat reaches the temperature T0 at time t0, the control unit 14 decreases the limit values Win and Wout and operates the fan 27 of FIG. As described above, the reduction amount of the limit value is proportional to the elapsed time from time t0. The temperature Tbat once rises to the temperature Tmax, but then falls. The temperature Tmax is lower than the temperature Tlim, which is the limit temperature of the battery 12 in FIG.

  The controller 14 decreases the limit values (limit values Win and Wout) until the temperature Tbat rises from the temperature T0 to the temperature Tmax and then returns to the temperature T0 again. When temperature Tbat reaches temperature T0 at time t1, control unit 14 controls the charge / discharge amount of the battery using limit value WB at time t1. After time t1, the limit value used by control unit 14 remains constant at limit value WB, but temperature Tbat further decreases.

  At time t2, the processing unit 41 detects that the temperature Tbat has reached a temperature T1 (recovery temperature) lower than the temperature T0. The control unit 14 increases the limit value from the limit value WB according to the elapsed time from the time t2. The increase amount of the limit value is proportional to the elapsed time from time t2. When the limit value reaches the limit value WA, the control unit 14 thereafter controls the charge / discharge amount of the battery using the limit value WA. The subsequent operation is the same as the operation at the above-described times t0 to t2.

  The period from time t0 to time t1 is appropriately determined, for example, from several seconds to several tens of seconds. Further, during this period, the control unit 14 of FIG. 1 reduces the influence on the vehicle behavior by gradually changing the ratio of the output of the engine 2 and the output of the motor, for example.

  FIG. 4 is a flowchart for explaining setting of limit values performed by the control unit 14 of FIG.

  4 and 2, when the process is started, first, in step S1, processing unit 41 determines whether or not temperature Tbat is higher than temperature T0. If temperature Tbat is higher than temperature T0 in step S1 (YES in step S1), the process proceeds to step S2. On the other hand, when temperature Tbat is equal to or lower than temperature T0 (NO in step S1), the process proceeds to step S5 described later.

  In step S <b> 2, the processing unit 41 determines whether the count value C acquired from the counter 43 is greater than the set value α. If count value C is larger than set value α (YES in step S2), the process proceeds to step S3. On the other hand, when count value C is equal to or smaller than set value α (NO in step S2), the process returns to step S1 again.

  In step S <b> 3, the processing unit 41 determines the limit values Win and Wout using the function f (x) stored in the storage unit 42. The value of the function f (x) decreases in proportion to the elapsed time from the reference time (in this case, time t0 in FIG. 3). The processing unit 41 sets the value f (C) obtained by substituting the count value C into the variable x as the limit values Win and Wout.

  Subsequently, in step S4, the counter 43 increases the count value C. When the process of step S4 ends, the process returns to step S1 again.

  Then, the process after step S5 is demonstrated. In step S5, the processing unit 41 determines whether or not the temperature Tbat is lower than the temperature T1. If temperature Tbat is lower than temperature T1 in step S5 (YES in step S5), the process proceeds to step S6. On the other hand, when temperature Tbat is equal to or higher than temperature T1 in step S5 (NO in step S5), the process returns to step S1 again.

  In step S <b> 6, the processing unit 41 determines whether the count value C acquired from the counter 43 is greater than zero. If count value C is greater than 0 in step S6 (YES in step S6), the process proceeds to step S7. On the other hand, when count value C is 0 or less (NO in step S6), the process returns to step S1 again.

  In step S7, the control unit 14 determines the limit values Win and Wout by substituting the count value C into the variable x of the function f (x) as in step S3. Subsequently, in step S8, the counter 43 decreases the count value C. When the process of step S8 ends, the process returns to step S1 again.

  That is, the control unit 14 in FIG. 2 decreases the limit values Win and Wout in proportion to the elapsed time from the time t0 in FIG. 3 by performing the processes in steps S2 to S4, and performs the processes in steps S6 to S8. The limit values Win and Wout are increased in proportion to the elapsed time from time t2 in FIG.

  Next, differences between the method for controlling the charge / discharge amount of the battery according to only the temperature of the battery and the control method of the first embodiment will be described. In the former case, the control unit 14 in FIG. 1 changes the limit value using, for example, a map shown below.

  FIG. 5 is a diagram showing an example of a map used in a method for controlling the charge / discharge amount of a battery according to only the temperature of the battery.

  Referring to FIG. 5, when limit value Win exceeds temperature Ta, it decreases as temperature Tbat increases. Further, when the limit value Wout exceeds the temperature Tb, the limit value Wout decreases as the temperature Tbat increases. By changing the limit value as gently as possible with respect to the temperature rise, the influence on the behavior of the vehicle can be reduced. Therefore, the temperatures Ta and Tb are set to temperatures sufficiently lower than the limit temperature that decreases the life of the battery. The temperatures Ta and Tb are set so that Ta <Tb. This is because the temperature generally tends to increase greatly during charging than during discharging.

  Hereinafter, a change in the limit value Win during discharge will be described as an example. Points P1 to P3 on the map indicate the limit value Win on the map with respect to the battery temperature (that is, the temperature Tmax in FIG. 3) when the increase in the temperature Tbat stops.

  When the limit value Win is changed according to this map, the decrease of the limit value Win starts from a temperature Ta that is considerably lower than the limit temperature. Further, when the rate of battery temperature rise (the amount of heat generated by the battery per unit time) is different, the rate of change of the limit value is different. For these reasons, as indicated by points P1 to P3, it is considered that the temperature Tmax and the limit value Win vary when the rate of temperature rise of the battery (the amount of heat generated by the battery per unit time) is different.

  FIG. 6 is a diagram for explaining the charge / discharge control of the battery 12 performed by the control unit 14 of FIG. 1 in more detail.

  Referring to FIG. 6, control unit 14 in FIG. 1 decreases the limit value from limit value WA in proportion to the elapsed time from when temperature Tbat reaches temperature T0 regardless of the rate of temperature increase. As a result, it is possible to reduce variations in the temperature Tmax when the temperature increase stops regardless of the temperature increase rate.

  Therefore, according to Embodiment 1, the difference between the limit temperature (temperature Tlim in FIG. 3) and the battery temperature Tmax when the temperature increase stops can be reduced. That is, according to the first embodiment, it is possible to accurately manage the temperature of the battery while taking out as much energy as possible from the battery or giving as much energy as possible to the battery.

  As described above, according to the first embodiment, since the control unit changes the limit value according to the elapsed time after the temperature of the secondary battery reaches the predetermined temperature, the charging performance and the discharging performance of the secondary battery are sufficiently improved. A device such as a motor can be operated while being pulled out.

[Embodiment 2]
The configuration of the hybrid vehicle including the secondary battery charge / discharge control device according to the second embodiment is the same as the configuration of hybrid vehicle 1 shown in FIG. Moreover, the structure of the control part contained in this charging / discharging control apparatus is the same as that of the control part 14 shown in FIG. Therefore, the following description regarding the configuration of the secondary battery charge / discharge control device according to the second embodiment will not be repeated.

  In the second embodiment, the limit value setting process performed by the control unit 14 of FIG. 1 is different from that of the first embodiment. Therefore, the process of the control unit 14 will be described below.

  FIG. 7 is a flowchart for illustrating setting of limit values performed by the charge / discharge control device for a secondary battery according to the second embodiment.

  Referring to FIGS. 7 and 2, when the process is started, in step S <b> 11, processing unit 41 refers to storage unit 42, and whether the “restricting flag” stored in storage unit 42 is turned on. Determine whether or not.

  For example, the restricting flag has a value of “0” or “1”. In the following, it is assumed that the restricting flag is “off” and “on” when the restricting flag is “0” and “1”, respectively. The on-limit flag being in an on state means a state in which the charge / discharge amount of the battery is being controlled. That is, the state where the restricting flag is “ON” means a state in which the temperature detected by the temperature sensor 24 in FIG. 1 (temperature Tbat) is equal to or higher than a predetermined temperature (temperature T0).

  When the restricting flag is on in step S11 (YES in step S11), the process proceeds to step S12. On the other hand, when the restricting flag is off (NO in step S11), the process proceeds to step S18 described later.

  In step S12, the processing unit 41 acquires the value of the temperature Tbat from the temperature sensor 24 of FIG. The storage unit 42 stores a map in which the temperature Tbat and the limit values Win and Wout are associated with each other. The processing unit 41 refers to the map and acquires the limit values Win and Wout associated with the temperature Tbat. The processing unit 41 temporarily stores the acquired limit values Win and Wout internally (storage area). The limit values Win and Wout temporarily stored in the processing unit 41 are limit values (first limit values) temporarily determined by the processing unit 41 from the temperature Tbat.

FIG. 8 is a diagram for explaining a map used for the processing in step S12.
Referring to FIG. 8, limit values Win and Wout are constant values at temperature T0 or lower. When the temperature Tbat is between the temperature T0 and the temperature Tlim, the limit values Win and Wout decrease as the temperature Tbat increases.

The processes after step S12 will be described with reference to FIGS. 7 and 2 again.
In step S13, the processing unit 41 determines the absolute value of the difference between the temporarily determined limit values Win and Wout and the limit values (second limit values) Win and Wout currently used for controlling the charge / discharge amount of the battery. It is determined whether it is below a predetermined value. When the absolute value of this difference is equal to or smaller than the predetermined value (YES in step S13), in step S14, the processing unit 41 directly substitutes the temporarily determined limit values into the current limit values Win and Wout. That is, in the process of step S14, the processing unit 41 updates the current limit values Win and Wout using the temporarily determined limit values as they are.

  On the other hand, when the absolute value of the difference between the temporarily determined limit value and the limit value used for the current control exceeds a predetermined value (NO in step S13), in step S15, processing unit 41 temporarily determines using the predetermined value. Correct the limit value. For example, the processing unit 41 adds or subtracts a predetermined value to the limit value acquired from the map. Then, the processing unit 41 updates the current limit values Win and Wout using the corrected limit values.

  When the process of step S14 or step S15 ends, the process proceeds to step S16. In step S16, the processing unit 41 acquires the value of the battery temperature Tbat from the temperature sensor 24 of FIG. The processing unit 41 determines whether or not the temperature Tbat is lower than the temperature T0.

  When temperature Tbat is lower than temperature T0 (YES in step S16), the limit value during charging / discharging of the battery is a constant value. Therefore, in this case, the processing unit 41 turns off the restricting flag stored in the storage unit 42 in step S17. When the process of step S17 ends, the process returns to step S11 again. Even when temperature Tbat is equal to or higher than temperature T0 (YES in step S16), the process returns to step S11 again.

  Next, the processing after step S18 will be described. In step S18, the processing unit 41 acquires the value of the battery temperature Tbat from the temperature sensor 24 of FIG. The processing unit 41 determines whether or not the temperature Tbat is higher than the temperature T0.

  When the battery temperature rises, the temperature Tbat becomes higher than the temperature T0. In this case (YES in step S18), in step S19, the processing unit 41 switches the “restricting flag” stored in the storage unit 42 from “off” to “on”. When the process of step S19 ends, the process returns to step S11 again. Thereafter, the processing unit 41 executes the processes of steps S12 to S17 described above.

  On the other hand, when temperature Tbat is equal to or lower than temperature T0 (NO in step S18), the process proceeds to step S20. In step S20, the processing unit 41 refers to a map (map in FIG. 8) stored in the storage unit. Since Tbat ≦ T0, the limit values Win and Wout are constant values with respect to temperature changes. The processing unit 41 directly substitutes the limit value acquired from the map as the current limit value, and uses this value for controlling the charge / discharge amount of the battery. When the process in step S20 ends, the process returns to step S11 again.

  Since the process shown in the flowchart of FIG. 7 is repeatedly performed at predetermined intervals (for example, at intervals of several seconds), the process shown at step S12 is performed at predetermined intervals. That is, the processing unit 41 temporarily determines the limit values Win and Wout for the temperature Tbat with reference to the map for each predetermined period.

  Although the control value at the time of charging and the control value at the time of discharging are shown to be determined simultaneously in the flowchart of FIG. 7, the process of determining the control value at the time of charging according to the flowchart of FIG. 7 and the flowchart of FIG. The process for determining the control value at the time of discharging may be performed separately.

  FIG. 9 is a diagram illustrating the operation of the charge / discharge control device for the secondary battery according to the second embodiment in more detail.

  With reference to FIGS. 9 and 2, the locus (broken arrows) of changes in limit values Win and Wout set by controller 14 according to temperature Tbat is shown superimposed on a map stored by controller 14. The map in FIG. 9 is the same as the map in FIG.

  Immediately after the battery temperature Tbat exceeds the temperature T0, the absolute value of the difference between the limit values Win, Wout used for control by the control unit 14 and the map limit values Win, Wout becomes larger than a predetermined value. The process of step S15 in the flowchart of FIG. 7 is performed. That is, the control unit 14 corrects the limit values Win and Wout obtained by referring to the map, and controls the charge / discharge amount of the battery using the corrected limit values Win and Wout. Thereby, since the change of the limit value with respect to the temperature rise becomes gentler than the limit value is changed according to the map itself, the influence on the behavior of the vehicle can be reduced.

  When the control unit 14 repeats the above-described processing, the temperature Tbat changes from rising to falling. Similar to the first embodiment, in the second embodiment, the temperature Tbat at this time can be made closer to the temperature Tlim than in the prior art. Therefore, in Embodiment 2, as much power as possible can be taken from the battery, and as much power as possible can be returned to the battery. In the second embodiment, the temperature of the battery can be managed with high accuracy.

  When the battery temperature changes from rising to falling, each of the limit values Win and Wout for the temperature Tbat becomes equal to the limit value according to the map. Wout and Win corresponding to the points P11 and P21 on the map are equal to the limit values used for the control of the control unit 14 in this state.

  Thereafter, the control unit 14 increases the limit values Win and Wout, and returns each limit value to the limit value at a temperature lower than the temperature T0. At this time, if the control unit 14 changes the limit values in and Wout according to the map of FIG. 9, the change when the limit value increases is larger than the change when the limit value decreases. obtain. Therefore, the control unit 14 performs the process of step S15 in the flowchart of FIG. 7 in the same manner as when the limit value is decreased. That is, the control unit 14 corrects the limit values Win and Wout obtained by referring to the map, and controls the charge / discharge amount of the secondary battery using the corrected limit values Win and Wout. Thereby, the control values Wout and Win can be returned as gently as possible. Ultimately, the limit values Win and Wout reach points P22 and P12 on the map, respectively. The temperature Tbat at this time is lower than the temperature T0.

  As described above, according to the second embodiment, when the absolute value of the difference between the temporarily determined limit value and the limit value currently used for charge / discharge control exceeds a predetermined value, the temporarily determined limit value is corrected. Then, the charge / discharge amount of the battery is controlled using the corrected limit value. Therefore, according to the second embodiment, the limit value can be changed gradually with the passage of time, so that devices such as a motor can be operated while sufficiently drawing out the charging performance and discharging performance of the secondary battery. it can.

  Further, according to the second embodiment, it is possible to accurately control the battery temperature when the temperature of the secondary battery rises.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

It is a figure which shows the example of application of the charging / discharging control apparatus of the secondary battery according to Embodiment 1. It is a figure explaining the structure of the control part 14 of FIG. It is a figure explaining control of the charging / discharging amount of the battery 12 by the control part 14 of FIG. It is a flowchart for demonstrating the setting of the limit value which the control part 14 of FIG. 2 performs. It is a figure which shows the example of the map used for the method of controlling the charging / discharging amount of a battery only according to the temperature of a battery. It is a figure explaining the charging / discharging control of the battery 12 which the control part 14 of FIG. 1 performs in detail. 6 is a flowchart for illustrating setting of limit values performed by a charge / discharge control device for a secondary battery according to a second embodiment. It is a figure for demonstrating the map used for the process in step S12. It is a figure explaining the operation | movement of the charging / discharging control apparatus of the battery according to Embodiment 2 in detail.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Hybrid vehicle, 2 engine, 4,6 gear, 12 battery, 14 control part, 16 planetary gear, 18 differential gear, 20R, 20L front wheel, 22R, 22L rear wheel, 24 temperature sensor, 26 voltage sensor, 27 fan, 28, 30 system main relay, 32 boost unit, 36 inverter, 41 processing unit, 42 storage unit, 43 counter, B0-Bn battery unit, MG1, MG2 motor generator, P1-P3, P11, P12, P21, P22 points, S1- S20 step.

Claims (5)

A temperature detector for detecting the temperature of the secondary battery;
A control unit for controlling the charge / discharge amount of the secondary battery according to a limit value,
When the detected temperature of the secondary battery transmitted from the temperature detection unit exceeds a predetermined temperature, the control unit changes the limit value according to an elapsed time from when the detected temperature reaches the predetermined temperature. A charge / discharge control device for a secondary battery.   The charge / discharge control apparatus for a secondary battery according to claim 1, wherein the control unit changes the limit value using a function that monotonously decreases the limit value with respect to the elapsed time.   When the control unit detects that the detected temperature has reached a return temperature lower than the predetermined temperature, the control unit sets the limit value according to an elapsed time from when the detected temperature reaches the return temperature. The charging / discharging control apparatus of the secondary battery of Claim 2 made to increase. The control unit temporarily determines the limit value corresponding to the detected temperature for each predetermined period using a function in which the temperature of the secondary battery and the limit value are associated with each other, and temporarily determines the limit value. Obtaining an absolute value of a difference between the first limit value that is the limit value and the second limit value that is the current limit value;
When the absolute value of the difference is equal to or less than a predetermined value, the control unit updates the second limit value using the first limit value as it is, and the absolute value of the difference exceeds the predetermined value. In the case, the first limit value is corrected using the predetermined value, and the second limit value is updated using the corrected first limit value. Charge / discharge control device for secondary battery.   The charge / discharge control device for a secondary battery according to claim 1, wherein the secondary battery supplies electric power to a drive source that drives a vehicle.

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