JP4305410B2 - Current control device and current control method - Google Patents

Description

  The present invention relates to a current control device and a current control method for controlling a current discharged from a battery to a load such as a motor.

  A non-aqueous electrolyte secondary battery having a high energy density using a lithium ion conductive non-aqueous electrolyte with a material capable of occluding and releasing lithium ions as a positive electrode active material and a negative electrode active material has sufficient battery capacity remaining. Even in the case where a large current discharge occurs, it is conventionally known that the voltage of the battery may suddenly decrease (see, for example, Patent Document 1).

When a sudden voltage drop occurs with large current discharge in this way, the voltage supplied from the battery may drop below the operable voltage of the load such as a motor, and the load operation may stop. .
JP-A-9-97625

An object of this invention is to provide the current control apparatus and current control method which can prevent the rapid voltage drop of a battery.
In order to achieve the above object, according to the present invention, there is provided a current control device for controlling a current discharged from a battery, the current detecting means capable of detecting the current discharged from the battery, and the current detecting means. Control means for controlling the current discharged from the battery based on the current value detected by the control circuit, the control means squares the current value detected by the current detection means, and further calculates the value. There is provided a current control device that performs a control to limit a current discharged from the battery based on the current square integrated value by calculating the current square integrated value by integrating according to a time series.

  In order to achieve the above object, according to the present invention, there is provided a current control method for controlling a current discharged from a battery, the detection step for detecting the current discharged from the battery, and the detection step. A square value calculation step for calculating a current square value by squaring the detected current value, and the detection step and the square value calculation step are repeated, and each current square value calculated in each square value calculation step is time-series. An integrated value calculating step for calculating a current square integrated value by integrating according to the above, and a limiting step for performing control for limiting the current discharged from the battery based on the current square integrated value calculated in the integrated value calculating step A current control method is provided.

  In the present invention, in preparation for the occurrence of a voltage drop, the current discharged from the battery is detected, the detected value is squared, the current square value is integrated according to the time series, and the current square integrated value is calculated. Based on the integrated value, control is performed so as to limit the current discharged from the battery to a load such as a motor. As a result of intensive studies by the present inventors, it has been clarified that the occurrence of voltage drop and the current square integrated value have a correlation. Therefore, by determining the limit of the current discharged from the battery based on the current square integrated value, it becomes possible to limit the discharge current value before the voltage suddenly drops. A sudden voltage drop can be prevented.

  Although not particularly limited in the above invention, in the current control device, the control means is an outputable current value that the battery can output continuously for a predetermined time based on the calculated current square integrated value. It is preferable to perform control for limiting the current discharged from the battery based on the output possible current value.

  Although not particularly limited in the above invention, in the current control method, the battery can output continuously for a predetermined time based on the current square integrated value calculated in the integrated value calculating step. A current value calculating step for calculating a current value that can be output; and in the limiting step, a control for limiting a current discharged from the battery based on the current value that can be output calculated in the current value calculating step. Preferably it is done.

  In the present invention, when the output of the battery is limited, an outputable current value is calculated based on the integrated current square value, and the output of the battery is limited based on the outputable current value. Thereby, while limiting the output of the battery in order to prevent a rapid voltage drop, the battery can be used effectively by allowing the output within the range that can be used at that time.

  Although not particularly limited in the above invention, in the current control device, the control means can calculate a subtraction value obtained by subtracting a predetermined integrated value from the calculated current square integrated value, and the output is possible based on the subtracted value. It is preferable to perform control for recalculating the current value and changing the limit of the current discharged from the battery based on the outputtable current value.

  Further, although not particularly limited in the above invention, in the current control method, a subtraction value obtained by subtracting a predetermined integration value from the current square integration value calculated in the integration value calculation step is calculated, and based on the subtraction value. It is preferable that the method further includes a changing step of recalculating the outputtable current value and performing control to change the limit of the current discharged from the battery based on the outputtable current value.

  In the present invention, in releasing the battery output restriction, the output possible current value is recalculated based on a subtracted value obtained by subtracting the predetermined integrated value from the current square integrated value, and the battery output restriction is determined based on the output possible current value. To change. Thereby, since the output restriction of the battery is gradually released, it is possible to prevent the output from changing extremely when the output restriction is released.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a system configuration diagram showing an electric vehicle drive system using a current control device according to an embodiment of the present invention.

  An electric vehicle 1 using a current control device according to an embodiment of the present invention will be described. As shown in FIG. 1, an electric vehicle 1 is supplied from a battery 3 using a lithium secondary battery or the like as a unit cell, an inverter 5 that converts direct current output from the battery 3 into alternating current, and the inverter 5. A motor 7 that is rotationally driven by alternating current, a motor control unit 9 that performs drive control of the motor 7 via the inverter 5 based on command signals from the accelerator pedal 11 and the transmission gear 13, a current detector 15, and a temperature detector. 17 and a battery control unit 21 that controls the battery 3 based on the detection results of the voltage detector 19. The battery 3 in the present embodiment corresponds to the battery in the present invention, and the current detector 15, the temperature detector 17, the voltage detector 19, and the battery control unit 21 in the present embodiment correspond to the current control device in the present invention. To do.

  The battery 3 is an assembled battery in which a plurality of lithium ion secondary batteries using a lithium ion conductive non-aqueous electrolyte are connected using a substance capable of inserting and extracting lithium ions as a positive electrode active material and a negative electrode active material.

Examples of the positive electrode active material used in the lithium ion secondary battery include lithium composite oxides such as lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), and lithium cobaltate (LiCoO ₂ ), and chalcogen (S , Se, Te) and the like.

  Examples of the negative electrode active material include amorphous carbon, non-graphitizable carbon, graphitizable carbon, and graphite.

Examples of the non-aqueous electrolyte include a liquid electrolyte in which a lithium salt is a solute in an organic liquid solvent. Examples of the non-aqueous electrolyte organic liquid solvent include ester solvents such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC); Examples thereof include ether solvents such as butylactone (γ-BL) and diethyloxyethane (DEE), and other mixed and formulated organic liquid solvents. Examples of the lithium salt of the non-aqueous electrolyte include lithium perchlorate (LiClO ₄ ), lithium borofluoride (LiBF ₄ ), and lithium hexafluorophosphate (LiPF ₆ ).

  The inverter 5 has a plurality of switching elements inside, although not particularly shown. Then, the inverter 5 converts the direct current supplied from the battery 3 into a three-phase alternating current by performing on / off control of each switching element in accordance with the PWM signal sent from the motor control unit 9. The output torque of the motor 7 can be controlled by on / off control of the switching element.

  The motor 7 is, for example, a three-phase AC motor that can be rotationally driven by the alternating current supplied from the inverter 5, and transmits the rotational driving force to wheels (not shown) via a transmission, a drive shaft, etc. 1 can be run.

  The motor control unit 9 is connected to an accelerator pedal 11 and a shift lever 13 operated by a driver, and outputs a PWM signal according to a torque command value corresponding to an accelerator opening degree of the accelerator pedal 11 and a shift position of the shift lever 13. By generating and sending it to the inverter 5, PWM (Pulse Width Modulation) control of the inverter 5 can be performed. In addition, the motor control unit 9 can perform limiter control to limit the output of the battery 3 in accordance with the output limit value PL that can be changed in the range of 0 to 100% set by the battery control unit 21. It has become.

  The current detector 15 is provided so as to be able to detect the direct current I supplied from the battery 3 to the inverter 5, and is connected so that the detected current value I can be sent to the battery control unit 21.

  The temperature detector 17 is a temperature sensor provided so as to be able to detect the temperature T of the battery 3 that has generated heat during power supply, and is connected so that the detected temperature value T can be sent to the battery control unit 21.

  The voltage detector 19 is provided so as to be able to detect the DC voltage V supplied from the battery 3 to the inverter 5, and is connected so that the detected voltage value V can be sent to the battery control unit 21.

  The battery control unit 21 includes a CPU, a ROM, a RAM (memory unit), a timer, and the like. The current value I detected by the current detector 15, the temperature T detected by the temperature detector 17, and the voltage Based on the voltage value V detected by the detector 19, an output limit value PL for limiting the output of the battery 3 is calculated, and the output limit value PL is sent to the motor control unit 9 at predetermined time intervals. Is possible.

  The current control method according to this embodiment will be described below.

  FIG. 2 is a flowchart showing the current control method according to the first embodiment of the present invention, FIG. 3 is a graph showing the relationship between the battery temperature and the threshold, FIG. 4 is a graph showing the relationship between the SOC and the threshold, and FIG. It is a graph which shows the relationship between output limit value.

First, in step S10 of FIG. 2, when the battery 3 starts discharging to the inverter 5 and current is detected by the current detector 15 (I> 0), the battery control unit 21 is detected by the current detector 15. The square of the current value I is calculated, and the value is integrated according to a time series, and the calculation of the current square integrated value S is started. For example, the current square integrated value S calculated by the battery control unit 21 can be expressed by the following equation (1). The current square integrated value S is, for example, a current square integrated value integrated within a predetermined time of about several tens of seconds, and the length of the predetermined time is obtained experimentally according to the battery.

However, in the above equation (1), n is a natural number indicating the number of times of sampling of the current value by the current detector 15, and In is a current value detected by the current detector 15 at the nth sampling in time series. .

  Next, the temperature T of the battery 3 is detected by the temperature detector 17 (step S20). In step S30, the relationship between the battery temperature T and the threshold value U as shown in FIG. Thus, the threshold value U corresponding to the temperature T detected in step S20 is determined. The threshold value U shown in FIG. 3 indicates the square integrated value of the current value at which the output restriction should be started. The current that flows until the voltage drop occurs is experimentally obtained in advance for each temperature, and the current value is Based on this, the output limit described later is set to be performed before the voltage drop occurs.

  Note that the square value of the current value at which output restriction should be started may change depending on the SOC (State Of Charge) of the battery 3 in addition to the battery temperature T, or depending on the degree of deterioration of the battery 3. Therefore, as a parameter for determining the threshold value U, SOC may be used instead of the temperature T, or the degree of deterioration of the battery may be considered in addition to the temperature T or SOC.

  When using the SOC as a parameter for determining the threshold value U, in step S30, according to the SOC grasped by the battery control unit 21 based on the detection result by the voltage detector 19 and the like, the SOC and the threshold value U as shown in FIG. Referring to the relationship, the threshold value U corresponding to the grasped SOC is determined. The threshold value U shown in FIG. 4 is obtained so that the current flowing until the voltage drop occurs is experimentally obtained in advance for each SOC, and based on the current value, the output limitation described later is performed before the voltage drop occurs. Is set. As a parameter for determining the threshold value U, not only the temperature T and SOC of the battery 3 are used alone, but both the temperature T and SOC of the battery 3 may be used in combination.

When considering the degree of deterioration of the battery in addition to the temperature T and SOC as a parameter for determining the threshold value U, for example, in step S30, the parameter is set according to the degree of deterioration of the battery ascertained by the battery control unit 21. The deterioration coefficient is multiplied by the threshold value U determined according to the battery temperature T and SOC in the above manner. For example, when the capacity of the battery 3 is reduced to X%, (X / 100) ² can be used as the deterioration coefficient.

  Next, in step S40, the current square integrated value S integrated so far is compared with the threshold value U determined in step S30.

  In the comparison of step S40, when current square integrated value S is larger than threshold value U (YES in step S40, S> U), in step S50, battery control unit 21 has a time as shown in FIG. An output limit value PL that gradually decreases as time passes is sent to the motor control unit 9. The motor control unit 9 performs limiter control for limiting the output of the battery 3 to the inverter 5 by multiplying the output limit value PL by the current value discharged from the battery 3 to the inverter 5. FIG. 5 shows an example in which the output limit value PL decreases linearly. However, the present invention is not particularly limited to this, and for example, the output limit value PL may decrease in a curve.

  In the comparison of step S40, when the current square integrated value S is equal to or less than the threshold value U (NO in step S40, S ≦ U), the process proceeds to step S60 without performing output limitation.

  Next, in step S60, when the discharge from the battery 3 to the inverter 5 is finished and no current is detected by the current detector 15, the calculation of the current square integrated value S is finished (YES in step S60, I ≦ 0). On the other hand, if the current is still detected by the current detector 15 in step S60 (NO in step S60, I> 0), the process returns to step S10 in FIG. Continue calculation.

[Second Embodiment]
The current control method according to the second embodiment of the present invention will be described below. FIG. 6 shows a flowchart of a current control method according to the second embodiment of the present invention.

  Unlike the current control method according to the first embodiment, the current control method according to the second embodiment of the present invention compares the current value I detected by the current detector 15 with a predetermined current value in step S5 of FIG. To do. The predetermined current value used in step S5 is, for example, a large current value that is relatively large with respect to a normal flowing current value (a current value that may cause a voltage drop due to a large current discharge). In the calculation of the current square integrated value in step S10 ′, which will be described later, it is possible to prevent normal current from being integrated, and to perform current control with high accuracy.

  When the current value I is equal to or smaller than the predetermined value in the comparison in step S5 (NO in step S5, current value I ≦ predetermined current value), the calculation of the current square integrated value S is not started, and the current value I The comparison with the predetermined current value is repeated.

  On the other hand, if the current value I is greater than the predetermined current value in the comparison in step S5 (YES in step S5, current value I> predetermined current value), the current square integrated value S is determined in step S10 ′. Start the calculation. Thereafter, as in the first embodiment, from step S20 to step S50, control for limiting the output of the battery 3 based on the current square integrated value is performed, and then detected by the current detector 15 in step S60 ′. The current value I is compared with the predetermined current value.

  In the comparison of step S60 ′, when the current value I detected by the current detector 15 falls below a predetermined value, the calculation of the current square integrated value S is terminated (YES in step S60 ′, current value I ≦ Predetermined current value). On the other hand, when the current value I detected by the current detector 15 is larger than the predetermined current value in step S60 ′ (NO in step S60 ′, current value I> predetermined value), the step of FIG. Returning to S10 ′, the calculation of the current square integrated value S is continued.

  As described above, in the first and second embodiments of the present invention, in preparation for the occurrence of a voltage drop, the current flowing from the battery 3 to the inverter 5 is detected, the detected value is squared, and the current square value is time-series. Then, the current square integrated value S is calculated by performing the control according to the following, and control is performed so as to limit the current supplied from the battery 3 to the inverter 5 based on the current square integrated value S. By determining the limit of the current discharged from the battery 3 to the inverter 5 based on the current square integrated value S that has a relatively strong correlation with the occurrence of the voltage drop, the discharge current value is set before the voltage suddenly drops. Since it can be limited, it is possible to prevent a rapid voltage drop during large current discharge.

  In particular, in the second embodiment, when the calculation of the current square integration value S is started, the current value I detected by the current detector 15 is compared with a predetermined current value, so that the current square integration is performed simultaneously with the start of discharge from the battery 3. Compared with the first embodiment in which the calculation of the value S is started, the current control of the battery can be performed with high accuracy.

[Third Embodiment]
The current control method according to the third embodiment of the present invention will be described below. 7A and 7B are flowcharts showing a current control method according to the third embodiment of the present invention, and FIG. 8 is a graph showing a relationship between an outputtable current value and a current square integrated value.

  First, in step S100 of FIG. 7A, the current value I detected by the current detector 15 is compared with a predetermined current value. As in the second embodiment, the predetermined current value used in step S100 is, for example, a large current value that is relatively large with respect to a normal flowing current value (a current that may cause a voltage drop due to a large current discharge). Value). Thereby, in the calculation of the current square integrated value S in step S110, which will be described later, it is possible to prevent the normal current from being integrated and to perform the current control with high accuracy. Of course, in step S100, as in step S10 of the first embodiment, it is possible to proceed to step S110 described later on the condition that the discharge is started.

  If it is determined in step S100 that the current value I flowing from the battery 3 to the inverter 5 is greater than the predetermined current value (YES in step S100), the battery control unit 21 detects the current detected by the current detector 15. The square of the value I is calculated, and the value is integrated according to the time series, and the calculation of the current square integrated value S is started. The current square integrated value S can be expressed by, for example, the expression (1) described in the first embodiment.

  Next, in step S120, the temperature of the battery 3 is detected by the temperature detector 17, and in step S130, according to the detected temperature T, the battery temperature T and the threshold value U as shown in FIG. 3 described in the first embodiment. The threshold value U corresponding to the temperature T detected in step S120 is determined. Similar to the first embodiment, as a parameter for determining the threshold value U, in addition to the temperature T, the SOC and the degree of deterioration of the battery 3 may be considered.

  Next, in step S140, the current square integrated value S integrated so far is compared with the threshold value U determined in step S130. In the comparison of step S140, when current square integrated value S is equal to or smaller than threshold value U (NO in step S140, S ≦ U), the process returns to step S100.

  If the current square integrated value S is larger than the threshold value U in comparison with step S140 (YES in step S140, S> U), output restriction processing of the battery 3 is performed in steps S150 to S180.

  First, in step S150, based on the current square integrated value S, an outputable current value Ix that the battery 3 can output continuously for a predetermined time is calculated. Examples of the predetermined time for defining the output possible current value Ix include a motor assist duration set for each vehicle in the case of a hybrid vehicle. In the present embodiment, as shown in FIG. 8, current value data in which an outputable current value corresponding to the current square integrated value S is obtained in advance by experiments or the like is stored in the battery control unit 21. In step S150, the current square integrated value S calculated in step S110 is checked against this current value data to calculate an output possible current value Ix.

Next, in step S160, based on the output possible current value Ix calculated in step S150, the output possible power value Px that the battery 3 can output continuously for a predetermined time is calculated. This output possible power value Px can be expressed by the following equation (2).

However, in the above equation (2), E ₀ is the open circuit voltage of the battery 3, and R is the internal resistance of the battery 3.

The open circuit voltage E ₀ in the above equation (2) is obtained as follows, for example. That is, first, the voltage of the battery 3 is detected when the vehicle is activated (when no load is connected to the battery 3). Next, the SOC at the time of vehicle start-up is obtained by collating the voltage value detected at the time of vehicle start-up with an [open-circuit voltage-SOC] map in which the relationship between the open-circuit voltage and the SOC is predetermined. Simultaneously with the start of the vehicle, the integration of the current value is started, and the current SOC is obtained based on the integrated value and the SOC at the time of starting the vehicle. Then, the current open-circuit voltage E ₀ is obtained by comparing the present SOC calculated as described above with the [open-circuit voltage-SOC] map.

  Regarding R in the above equation (2), the current SOC obtained as described above is collated with an [internal resistance-SOC] map in which the relationship between the internal resistance and the SOC is predetermined, or a temperature detector. The current internal resistance R is calculated by collating the temperature T of the battery 3 detected in 17 with a [Internal Resistance Ratio-Battery Temperature] map in which the relationship between the internal resistance ratio and the battery temperature is predetermined. In addition to these, the degradation coefficient described in the first embodiment may be added to the parameter for calculating the internal resistance.

  Next, in step S170, output restriction of the battery 3 is started based on the output possible power value Px calculated in step S160. At this time, similarly to the first embodiment, the battery control unit 21 gives the motor control unit 9 an output limit value PL that gradually decreases with the passage of time as shown in FIG. 5 described in the first embodiment. Send it out. The motor control unit 9 performs limiter control for limiting the output of the battery 3 to the inverter 5 by multiplying the output limit value PL by the current value discharged from the battery 3 to the inverter 5.

  Next, in step S180, the current value I actually detected by the current detector 15 is compared with the output possible current value Ix calculated in step S150.

  If the actually detected current value I is equal to or greater than the output possible current value Ix (NO in step S180, I ≧ Ix) in the comparison in step S180, the process returns to step S170 to limit the output of the battery 3. continue.

In the comparison of step S180, when current value I actually detected is less than outputable current value Ix (YES in step S180, I <Ix), battery control unit 21 calculates subtraction value S ′ _{m + 1} . (Step S190). This subtraction value S ′ _{m + 1} is a virtual current square integrated value for gradually releasing the output restriction of the battery 3, and can be expressed by the following equation (3).

However, in the above equation (3), S ′ _{m + 1} is the m + 1th (for example, m + 1 second) subtraction value, _S′m is the mth (for example, mth) subtraction value, and β is a predetermined value. Current square integrated value (coefficient for subtraction). In the above equation (3), the first term S ′ ₁ (m = 1) is the current square integrated value S determined to be larger than the threshold value U in step S140.

Next, in step S200, the square of the current value I detected by the current detector 15 is calculated in the same manner as in step S110, and the current square summation value S is calculated again by adding the values in time series. To do. In step S210, the subtraction value S′m _{+ 1} calculated in step S190 is compared with the current square integrated value S calculated in step S200.

In the comparison of step S210, when it is determined that the subtraction value S ′ _{m + 1} calculated in step S190 is larger than the current square integrated value S calculated in step S200 (YES in step S210, S ′ _{m + 1} > S) In step S220, based on the subtraction value S ′ _{m + 1} , the output limiting current value Ix is recalculated in the same manner as in step S150.

  Next, in step S230, based on the output limit current value Ix recalculated in step S220, the output possible power value Px is recalculated in the same manner as in step S160. Next, in step S240, the battery control unit 21 controls the motor control unit 9 to change the output limit of the battery 3 based on the recalculated output possible power value Px. The motor control unit 9 changes the content of the limiter control of the inverter 5 based on this control. After the control in step S240, the process returns to step S190. At this time, in step S260, m + 1 that has been used in the calculation so far is set as m for the next calculation.

In the comparison in step S210, when it is determined that the subtraction value S ′ _{m + 1} calculated in step S190 is equal to or less than the current square integrated value S calculated in step S200 (NO in step S210, S ′ _{m + 1} In step S250, the battery control unit 21 controls the motor control unit 9 to end the output limitation of the battery 3.

  In the present embodiment, as in the first and second embodiments, in preparation for the occurrence of a voltage drop, the current flowing from the battery 3 to the inverter 5 is detected, the detected value is squared, and the current square value is followed in time series. Integration is performed to calculate a current square integrated value S, and control is performed based on the current square integrated value S so as to limit the current supplied from the battery 3 to the inverter 5. By determining the limit of the current discharged from the battery 3 to the inverter 5 based on the current square integrated value S that has a relatively strong correlation with the occurrence of the voltage drop, the discharge current value is set before the voltage suddenly drops. Since it can be limited, it is possible to prevent a rapid voltage drop during large current discharge.

  Further, in the present embodiment, as in the second embodiment, when the calculation of the current square integrated value S is started, the current value I detected by the current detector 15 is compared with a predetermined current value, so that Compared with the first embodiment in which the calculation of the current square integrated value S is started simultaneously with the start of discharging, the battery current control can be performed with high accuracy.

  Further, in the present embodiment, when the output of the battery 3 is limited, the output possible current value Ix is calculated based on the current square integrated value, and the output of the battery 3 is limited based on the output possible current value Ix. Thus, while the output of the battery 3 is limited in order to prevent a sudden voltage drop, the output can be allowed within the range that can be used at that time, and the battery 3 can be used effectively.

  Further, in the present embodiment, when the output restriction of the battery 3 is released, the output possible current value is recalculated based on the subtracted value obtained by subtracting the predetermined integrated value from the current square integrated value, and based on the output possible current value, The output limit of the battery 3 is changed. Thereby, since the output restriction of the battery 3 is gradually released, it is possible to prevent the output from changing drastically when the output restriction is released.

In the above embodiment, the current limit is determined based on the relational expression (1). However, for example, the current limit may be determined based on the following expression (4). good. In addition, when satisfying the relationship expressed by the following equation (5), an integrated value of the square root of the current square value may be used instead of the current square integrated value, thereby reducing a calculation load and the like. I can do it. However, in the following formulas (4) and (5), Tn is the discharge duration of the In current, and α is a coefficient.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

FIG. 1 is a system configuration diagram showing a drive system for an electric vehicle using a current control device according to an embodiment of the present invention. FIG. 2 is a flowchart showing a current control method according to the first embodiment of the present invention. FIG. 3 is a graph showing the relationship between the battery temperature and the threshold value. FIG. 4 is a graph showing the relationship between the SOC and the threshold value. FIG. 5 is a graph showing the relationship between time and the output limit value. FIG. 6 is a flowchart showing a current control method according to the second embodiment of the present invention. FIG. 7A is a flowchart (No. 1) showing a current control method according to the third embodiment of the present invention. FIG. 7B is a flowchart (part 2) illustrating the current control method according to the third embodiment of the present invention. FIG. 8 is a graph showing the relationship between the outputtable current value and the current square integrated value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric vehicle 3 ... Battery 5 ... Inverter 7 ... Motor 9 ... Motor control part 11 ... Accelerator pedal 13 ... Shift lever 15 ... Current detector 17 ... Temperature detector 19 ... Voltage detector 21 ... Battery control part

Claims (26)

A current control device for controlling a current discharged from a battery,
Current detection means capable of detecting a current discharged from the battery;
Control means for controlling the current discharged from the battery based on the current value detected by the current detection means,
The control means squares the current value detected by the current detection means, further calculates the current square integrated value by integrating the values according to a time series, and discharges from the battery based on the current square integrated value. Current control device for performing control to limit the current to be generated.   2. The current according to claim 1, wherein the control unit compares the current square integrated value with a predetermined threshold value, and performs control for limiting a current discharged from the battery when the current square integrated value is larger than the threshold value. Control device. A temperature detecting means capable of detecting the temperature of the battery;
The current control device according to claim 2, wherein the control unit determines the threshold based on the temperature detected by the temperature detection unit.   The current control device according to claim 2 or 3, wherein the control means determines the threshold value based on an SOC (State of Charge) of the battery.   The current control device according to claim 2, wherein the control unit determines the threshold based on a battery capacity of the battery.   The current control device according to claim 1, wherein the control unit starts calculating the current square integrated value simultaneously with the start of discharging of the battery.   The current control device according to claim 1, wherein the control unit starts calculating the current square integrated value when a current discharged from the battery exceeds a predetermined current value.   The control means calculates an output possible current value that the battery can output continuously for a predetermined time based on the calculated current square integrated value, and based on the output possible current value, the battery The current control device according to claim 1, wherein control is performed to limit a current discharged from the battery.   The control means has current value data that predetermines an outputable current value in accordance with a current square integrated value, and collates the calculated current square integrated value with the current value data, thereby enabling the output possible current. The current control device according to claim 8, which calculates a value.   The control means calculates an output possible power value at which the battery can output continuously for a predetermined time based on the calculated output possible current value, and based on the output possible power value, The current control device according to claim 8 or 9, wherein control is performed to limit the output of the battery.   The control means calculates a subtracted value obtained by subtracting a predetermined integrated value from the calculated current square integrated value, recalculates the outputtable current value based on the subtracted value, and based on the outputable current value The current control device according to claim 8, wherein control for changing a limit of a current discharged from the battery is performed.   The current control device according to claim 11, wherein the control unit starts calculating the subtraction value when a current actually discharged from the battery becomes less than the outputtable current value.   The current control device according to claim 11 or 12, wherein the control means performs control to stop limiting a current discharged from the battery when the subtracted value is equal to or less than an actual current square integrated value. A current control method for controlling a current discharged from a battery,
A detection step of detecting a current discharged from the battery;
A square value calculation step of calculating a current square value by squaring the current value detected in the detection step;
An integrated value calculating step of repeating the detection step and the square value calculating step, calculating the current square integrated value by integrating the current square values calculated in the square value calculating steps according to a time series, and
A current control method comprising: a limiting step of performing control to limit a current discharged from the battery based on the current square integrated value calculated in the integrated value calculating step. In the limiting step,
The current square integrated value calculated in the integrated value calculating step is compared with a predetermined threshold value, and when the current square integrated value is larger than the threshold value, control is performed to limit the current discharged from the battery. Item 15. The current control method according to Item 14.   The current control method according to claim 15, wherein in the limiting step, the threshold is determined based on a temperature of the battery.   The current control method according to claim 15 or 16, wherein, in the limiting step, the threshold is determined based on a state of charge (SOC) of the battery.   The current control method according to claim 15, wherein, in the limiting step, the threshold is determined based on a battery capacity of the battery. In the square value calculation step,
The current control method according to claim 14, wherein the calculation of the current square value is started simultaneously with the start of discharging of the battery. In the square value calculation step,
The current control method according to claim 14, wherein when the current discharged from the battery exceeds a predetermined current value, calculation of the current square value is started. Based on the current square integrated value calculated in the integrated value calculating step, the battery further comprises a current value calculating step for calculating an outputable current value that the battery can output continuously for a predetermined time.
In the limiting step,
21. The current control method according to claim 14, wherein control is performed to limit a current discharged from the battery based on the outputable current value calculated in the current value calculation step. In the current value calculating step,
The outputable current value is calculated by collating the current square integrated value calculated in the integrated value calculating step against current value data in which the outputable current value is predetermined according to the current square integrated value. The current control method according to claim 21. Based on the output possible current value calculated in the current value calculation step, the battery further includes a power value calculation step for calculating an output possible power value at which the battery can continuously output for a predetermined time.
In the limiting step,
The current control method according to claim 21 or 22, wherein control is performed to limit the output of the battery based on the outputable power value calculated in the power value calculation step.   A subtracted value obtained by subtracting a predetermined integrated value from the current square integrated value calculated in the integrated value calculating step is calculated, the outputable current value is recalculated based on the subtracted value, and the outputable current value is calculated. The current control method according to any one of claims 21 to 23, further comprising a change step of performing control to change a limit of a current discharged from the battery based on the control.   25. The current control method according to claim 24, wherein calculation of the subtraction value is started in the changing step when the current actually discharged from the battery in the limiting step becomes less than the outputable current. 26. The current according to claim 24 or 25, further comprising an output limit stop step for performing control so as to stop control of the current discharged from the battery when the subtracted value is less than or equal to an actual current square integrated value. Control method.

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