JP2014131412A - Electric vehicle control device and electric vehicle control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress degradation of an onboard battery of an electric vehicle during parking.SOLUTION: Control means 26 for controlling power exchange between an onboard battery 24 of an electric vehicle and an external battery 20 installed outside the vehicle calculates a first degradation level change that is a change in the level of degradation of the onboard battery 24 in a predetermined period after the connection of the onboard battery 24 to the external battery 20 within which predetermined electrical energy is transferred from the onboard battery 24 to the external battery 20 and the predetermined power transferred is returned from the external battery 20 to the onboard battery 24. The control means 26 also calculates a second degradation level change that is a change in the level of degradation of the onboard battery 24 in a predetermined period within which such predetermined power is not transferred from the onboard battery 24 to the external battery 20. If the first degradation level change is smaller than the second degradation level change, the control means 26 transfers the predetermined electrical energy from the onboard battery 24 to the external battery 20.

Description

  The present invention relates to power control of an in-vehicle battery mounted on an electric vehicle.

  Even if the vehicle-mounted battery of an electric vehicle is not used, it deteriorates due to so-called storage deterioration. In particular, the storage deterioration progresses as the SOC (State Of Charge) increases.

  In Patent Document 1, if the in-vehicle battery has a high SOC when the electric vehicle is parked, for example, the battery is moved to a battery installed outside the vehicle like a household storage battery, and the battery outside the vehicle is used by the next vehicle use. By returning power from the vehicle to the vehicle battery, storage degradation of the vehicle battery during parking is suppressed.

JP 2010-148283 A

  However, the control described in the above document may lead to deterioration of the battery.

  Then, it aims at providing the control apparatus which can suppress deterioration of the vehicle-mounted battery in parking and can improve the lifetime of a vehicle-mounted battery.

  According to an aspect of the present invention, there is provided an electric vehicle control device including a control unit that controls power transfer between an in-vehicle battery mounted on an electric vehicle and an external battery installed outside the vehicle.

  In this electric vehicle control device, the control means moves a predetermined amount of power from the in-vehicle battery to the out-of-vehicle battery during a predetermined period after the in-vehicle battery and the out-of-vehicle battery are connected, and the transferred predetermined power is transferred from the out-of-vehicle battery to the in-vehicle battery. A first deterioration degree change amount, which is a change in the deterioration degree of the in-vehicle battery, when the retraction control for returning the predetermined power amount is executed is calculated. In addition, a second deterioration degree change amount that is a change in the deterioration degree of the in-vehicle battery when power is not transferred from the in-vehicle battery to the external battery for a predetermined period is also calculated. If the first deterioration degree change amount is smaller than the second deterioration degree change amount, the predetermined power amount is moved from the in-vehicle battery to the outside battery.

  The deterioration of the battery proceeds by storage deterioration that is deterioration with time and cycle deterioration due to charge and discharge. Therefore, if power is transferred (discharged) from the in-vehicle battery to a battery installed outside the vehicle simply considering only storage deterioration, the in-vehicle battery may be deteriorated due to cycle deterioration caused by the power transfer.

  According to the above aspect, when the first deterioration degree change amount is smaller than the second deterioration degree change amount, the predetermined power amount is moved from the in-vehicle battery to the external battery, so that the power does not move due to the cycle deterioration accompanying the power movement. When deterioration progresses, there is no power transfer. That is, the case where the power is moved is compared with the case where the power is not moved, and the one having the smaller deterioration degree is selected. As a result, the in-vehicle battery is not deteriorated by the exchange of power, and the life of the in-vehicle battery can be reliably improved.

FIG. 1 is a configuration diagram of a system to which an embodiment of the present invention is applied. FIG. 2 is a diagram showing characteristics of cycle deterioration and storage deterioration. FIG. 3 is a time chart of the evacuation control. FIG. 4 is a flowchart showing the power control routine of the first embodiment. FIG. 5 is a flowchart showing a power control routine of the second embodiment. FIG. 6 is a flowchart showing a power control routine of the third embodiment.

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

(First embodiment)
FIG. 1 is a configuration diagram of a system to which the first embodiment is applied. An electric vehicle is installed in an electric power system of a house including a storage battery (hereinafter referred to as an external battery 20) as a power source for supplying electric power to an electrical load in the house. Indicates the state where the power system is connected. In the following description, the vehicle battery 20 and the vehicle battery 24 will be described as lithium ion batteries.

  The control device 26, the in-vehicle battery 24, and the DCDC converter 22 are devices mounted on the electric vehicle, and the others are devices installed on the house side.

  The control device 26 reads the temperature and SOC of the in-vehicle battery 24 and outputs a power command value to the DCDC converter 22 based on these. The temperature of the in-vehicle battery 24 is detected by a sensor (not shown), and the SOC is estimated based on the input / output current of the in-vehicle battery 24 and the like. The control device 26 is composed of a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The control device 26 can be composed of a plurality of microcomputers.

  The control device 26 also reads the power usage history of the electric vehicle, the vehicle usage history, vehicle information, and weather data, and if the user manually sets the next use time, that time is also read. The vehicle use history includes, for example, a day of the week when the vehicle is used, a departure time, a return time, and the like, and is used for controlling the in-vehicle battery 24 described later. The vehicle information includes, for example, whether or not the vehicle is on the way home and how much time is required until the vehicle returns, and is used for controlling the vehicle battery 24 to be described later, similarly to the vehicle use history. As the weather forecast data, for example, existing weather forecast data is read via the Internet and used for prediction of vehicle use time. For example, it is possible to predict with high accuracy the weather forecast data using the weather forecast data such that the electric vehicle is used for commuting in rainy weather but not used in fine weather. The weather forecast data can also be used to predict the amount of power generated by the solar cell 10.

  The vehicle exterior battery 20 is connected to the solar battery 10 via the DCDC converter 18 and the DCDC converter 12, and is connected to the grid 16 and the power load via the DCDC converter 18 and the DCAC inverter 14.

  When the electric vehicle power system is connected to the house power system, the control device 26 also reads the temperature and SOC of the vehicle battery 20 and outputs a power command to the DCDC converter 18.

  As a result, the electric power generated by the solar cell 10 is charged to the vehicle battery 20 via the DCDC converter 12 and the DCDC converter 18, and the electric power of the vehicle battery 20 is loaded via the DCDC converter 18 and the DCAC inverter 14. Or to the grid 16.

  In addition, in a state where the power system of the electric vehicle is connected to the power system of the house, the power generated by the solar battery 10 or the power of the vehicle battery 20 can be supplied to the vehicle battery 24 to charge the vehicle battery 24. . Furthermore, it is possible to supply power from the in-vehicle battery 24 to the external battery 20 or the power load of the house. That is, power can be exchanged between the in-vehicle battery 24 and the external battery 20.

  Note that the solar cell 10 is not an essential configuration, and electric power from a general power supply line may be used for charging the vehicle battery 20 and the vehicle battery 24.

  Here, the deterioration of the in-vehicle battery 24 will be described.

  FIG. 2 is a diagram showing storage deterioration and cycle deterioration.

  The maintenance deterioration indicates the degree of deterioration when storing for a certain time per day with the SOC indicated on the horizontal axis for one year, and it can be seen that the deterioration progresses as the SOC during storage increases.

  On the other hand, as shown in FIG. 3, the cycle deterioration is performed once a day, in which power is saved to another battery from SOC 100% to SOC shown on the horizontal axis and charged to SOC 100% again. Indicates the degree of deterioration when 1 is repeated for one year.

  As shown in FIG. 2, when the SOC after evacuation is 10 to 90%, cycle deterioration can be suppressed compared to when the evacuation is not performed at all, that is, when the SOC after evacuation is 100%. Further, in the above experiment, it can be seen that when the SOC after evacuation becomes 0%, that is, when the entire power is evacuated, the cycle deterioration is advanced as compared with the case where the evacuation is not performed at all.

  In this embodiment, a lithium ion battery is used instead of an in-vehicle battery and an out-of-vehicle battery. However, if the battery material or the battery capacity is changed, there is a possibility that the change in the degree of deterioration becomes larger. For example, a nickel metal hydride battery has a self-discharge characteristic in which the capacity gradually decreases when left unattended, so that the effect of saving power to another battery is increased.

  Next, power control of the in-vehicle battery 24 will be described.

  FIG. 4 is a flowchart showing a power control routine of the in-vehicle battery 24 executed by the control device 26 while the vehicle is parked. This routine is for suppressing the deterioration of the in-vehicle battery 24 until the next vehicle use, and is executed when the vehicle is parked and the in-vehicle battery 24 is connected to the power system of the house. For example, the case where the vehicle returns home and is connected to a power system of a house equipped with a storage battery is assumed.

  In step S1010, the control device 26 detects the temperature of the in-vehicle battery 24 using a battery temperature sensor or the like. The detected temperature is used to determine an output at the time of retraction described later. In addition, you may make it detect the surrounding temperature of the vehicle-mounted battery 24 instead of the temperature of the vehicle-mounted battery 24. FIG.

  Further, since the battery temperature has increased after the vehicle travels, it may be detected and updated again several hours later. Thereby, the output at the time of recharging from the vehicle exterior battery 20 mentioned later to the vehicle-mounted battery 24 can be set more appropriately.

  In step S1020, the control device 26 calculates the charged amount Pa1 of the in-vehicle battery 24. Specifically, first, the internal resistance R = V / I is calculated from the current I and voltage V during the most recent charge / discharge using the power usage history. Then, the current full charge capacity is calculated based on the current degree of deterioration obtained from the internal resistance R with respect to the internal resistance when new. Further, the SOC is calculated from the open circuit voltage, which is the current voltage that is not charged / discharged, and the current full charge capacity is multiplied by the SOC, thereby calculating the current charged amount Pa1.

  In step S1030, the control device 26 calculates an acceptable power amount P ′ of the vehicle battery 20. Specifically, how much power can be charged is calculated from the full charge capacity of the vehicle battery 20 and the current SOC. The full charge capacity of the battery 20 outside the vehicle and the current SOC are read from a control device (not shown) for the power system of the house. Note that an acceptable power amount P ′ may be calculated and read by the power system of the house. At this time, the temperature of the battery 20 outside the vehicle is also read.

  In step S1040, the control device 26 calculates a saved power amount P. More specifically, in addition to the saved power amount P, the output at the time of saving and the recharge time are also calculated.

  From the viewpoint of suppressing storage deterioration, the lower the SOC, the better. Therefore, it is desirable to make the saved power amount P equal to the acceptable power amount P ′.

  However, there are cases where the evacuated power amount P has to be smaller than the acceptable power amount P ′. For example, because the temperature of the in-vehicle battery 24 is low, the output is limited during retraction, or because the temperature of the external battery 20 is low, the output is limited when receiving, and recharging until the next vehicle use described later is performed. Is expected to be unable to complete. In such a case, the maximum electric energy is set as the evacuated electric energy P within a range in which recharging can be completed before the next vehicle use.

  The next time the vehicle is used, it is estimated based on the vehicle usage history. For example, if it is used for commuting, the next sunrise working hours can be estimated from the vehicle usage history, and an appropriate next vehicle usage time can be set. Furthermore, if the weather forecast data is used together, it is possible to cope with the case where the working hours differ depending on the weather. In addition, when the user inputs the use time, that time is set. Thereby, it is possible to cope with a use time that cannot be estimated from the vehicle use history.

  In consideration of the deterioration of the in-vehicle battery 24 and the external battery 20, the output value is preferably small as long as it does not hinder retraction and recharging. By setting the output value, the slope from timing T1 to timing T2 in FIG. 3 is determined. The timing T2 is determined from the saved power amount P and the output value.

  The recharge time is set so that the recharge is completed when the vehicle is next used (timing T4 in FIG. 3) based on the evacuated power amount P and the output. Thereby, the timing T3 is determined. As a result of calculating the recharge time, if the recharge cannot be completed by the next use of the vehicle, the output or the saved power amount P is reviewed. Note that the temperature of the in-vehicle battery 24 and the external battery 20 may be detected again after the start of retraction, the output value at the time of recharging is calculated, and the recharging time may be set based on this.

  In step S1050, the control device 26 calculates the deterioration degree D1 (first deterioration degree change amount) of the in-vehicle battery 24 when the saved power amount P is saved and recharged until the next vehicle use. The degree of deterioration D1 corresponds to the degree of deterioration between timing T1 and timing T4 in FIG. That is, it is the sum of cycle deterioration due to discharge for power saving from timing T1 to timing T2 and recharging from timing T3 to timing T4 and storage deterioration from timing T3 to timing T4.

  Since the cycle deterioration is mainly determined according to the charge / discharge amount, the relationship between the charge / discharge amount and the degree of deterioration is measured and mapped in advance, and a map search is performed using the discharge amount from timing T1 to timing T2. The amount of discharge may be obtained, for example, by integrating the amount of discharge of the in-vehicle battery 24 from timing T1 to timing T2, or as the product of the amount of discharge between timing T1 and timing T2 and the time from timing T1 to timing T2. May be. The same applies to the degree of deterioration from timing T3 to timing T4.

  In step S1060, the control device 26 changes the deterioration degree D2 (second deterioration degree change amount) that is the maintenance deterioration from the timing T1 to the timing T4 when the evacuated power amount P is zero to the deterioration characteristic shown in FIG. Calculate based on

  In step S1070, the control device 26 determines whether or not the deterioration degree D1 is smaller than the deterioration degree D2, and if it is smaller, executes the process of step S1080, and if not, executes the process of step S1090.

  In step S1080, the control device 26 performs power control (save control) of the in-vehicle battery 24 based on the saved power amount P, the output, and the recharge time obtained in step S1040. That is, in FIG. 3, the power saving from the in-vehicle battery 24 to the external battery 20 is started at the timing T1, the SOC of the in-vehicle battery 24 is kept constant from the timing T2 to the timing T3, and from the timing T3 to the timing T4. Recharge.

  In step S1090, the control device 26 ends this routine without executing the evacuation control.

  As described above, when the in-vehicle battery 24 is connected to the power system of the house, the control device 26 determines the deterioration degree D1 when power is saved from the in-vehicle battery 24 to the vehicle battery 20 and the deterioration degree D2 when not saved. In comparison, if the degree of deterioration D1 is smaller, evacuation is executed. As a result, it is possible to avoid a situation in which the deterioration progresses by evacuation.

  If there is a power request signal from the vehicle side between timing T1 and timing T4, power is immediately returned from the vehicle battery 20 to the vehicle battery 24. The case where there is a power request signal is, for example, a case where a key ON signal is input or a case where a remote air conditioner function for performing air conditioning control is activated before traveling. As a result, it is possible to cope with a case where the prediction at the next vehicle use is off. Furthermore, when the in-vehicle battery 24 has a temperature adjustment function, the temperature adjustment can be started quickly, so that the battery output can be prevented from being limited due to the battery temperature.

  Further, since the control device 26 predicts the next use time of the vehicle based on the use history of the vehicle, the power amount can be controlled without any special operation by the user. Furthermore, when the user sets the next time the vehicle is used, the set value is used, so that it is possible to cope with a use schedule that cannot be predicted from the use history.

(Second Embodiment)
The present embodiment is different from the first embodiment in that when the power is saved from the in-vehicle battery 24 to the outside battery 20, the saved power amount P is calculated such that the degree of deterioration becomes smaller.

  FIG. 5 is a flowchart showing a power control routine of the present embodiment.

  Steps S2010 to S2030 are the same as steps S1010 to S1030 in FIG.

  In step S2040, the control device 26 sets a plurality of patterns for the evacuation power amount P and the output and recharge time for evacuation, and the degradation degrees Dc1, Dc2,. The number of patterns) is calculated. The number of patterns may be set in advance, or may be increased as the acceptable power amount P ′ increases.

  In step S2050, the control device 26 calculates degradation degrees Ds1, Ds2,... Dsn due to storage deterioration during saving for each of a plurality of patterns.

  In step S2060, the control device 26 calculates a deterioration degree D2 due to storage deterioration when the save control is not executed.

  In step S2070, the control device 26 determines whether or not there is a value smaller than the deterioration degree D2 in Dc1 + Ds1, Dc2 + Ds2,... Dcn + Dsn which is the sum of the deterioration degree Dcn and the deterioration degree Dsn when executing the evacuation control. Determine whether.

  If there is a deterioration degree Dcn + Dsn smaller than the deterioration degree D2, the process of step S2075 is executed, and if not, the process of step S2090 is executed.

  In step S2075, the control device 26 determines the power that minimizes the deterioration degree Dcn + Dsn as the saved power P.

  Steps S2080 and S2090 are the same as steps S1080 and S1090 in FIG.

  As described above, in this embodiment, the plurality of deterioration levels Dcn + Dsn are calculated by changing the evacuation power amount P, and the lowest one is used as the deterioration level when the evacuation is executed. The degree of deterioration when power is saved to can be further reduced.

(Third embodiment)
In the present embodiment, the evacuation power P is set before the in-vehicle battery 24 is connected to the battery 20 outside the vehicle, that is, before the electric vehicle returns, and when the evacuation power P is larger than the acceptable power amount P ′, The second embodiment is different from the second embodiment in that the battery 20 outside the vehicle is discharged.

  That is, in this embodiment, before the electric vehicle returns home, the storage amount Pa1 at the time of arrival is predicted, the deterioration degree Dcn + Dsc and the deterioration degree D2 are calculated based on the predicted values, and whether or not to evacuate, and The evacuation power amount P is determined. If the evacuated power amount P is larger than the acceptable power amount P ′, the vehicle battery 20 is subjected to discharge control via communication before the electric vehicle returns home, and is brought into an acceptable state.

  FIG. 6 is a flowchart showing a power control routine executed by the control device 26 in the present embodiment. This control routine is executed when the electric vehicle approaches a predetermined distance from the house based on vehicle position information such as GPS, or when the user selects a return route using the navigation system.

  In step S3005, the control device 26 predicts the SOC of the in-vehicle battery 24 when the electric vehicle returns home. For example, from the power usage history of the vehicle, it is possible to predict how much the SOC is when returning home. In addition, if the power usage amount from the current position to the house is predicted on the basis of the power usage history and the prediction value is taken into consideration, the prediction accuracy becomes higher.

  Steps S3010 and S3040 to S3070 are the same as steps S2010 and S2040 to S2070 in FIG.

  In step S3072, the control device 26 sets the evacuation power amount P as in step S2075 of FIG.

  In step S3074, the control device 26 calculates the acceptable power amount P ′ of the vehicle battery 20 and compares it with the evacuated power amount P in the same manner as in step S2030 of FIG. If the evacuated power amount P is larger, the SOC of the vehicle battery 20 at which the acceptable power amount P ′ is greater than or equal to the evacuated power amount P is determined. Note that by predicting the power consumption due to the electrical load of the house until the electric vehicle arrives, the calculation accuracy of the acceptable power amount P ′ when the electric vehicle arrives can be increased.

  In step S3076, the control device 26 determines the output (current value) of the external battery 20 and the discharge start timing for achieving the above acceptable SOC. Considering the deterioration of the battery 20 outside the vehicle, it is preferable that the output is small, but it is necessary to make the output acceptable until the vehicle arrives at the house or the evacuation control is started. Therefore, an output as small as possible is set within a range satisfying the above conditions. If the output is determined, the discharge start timing is also determined.

  In step S3078, control device 26 instructs a control device (not shown) of the power system of the house via communication such as the Internet to execute discharge control of vehicle battery 20. Thereby, the discharge control of the vehicle battery 20 is executed.

  In step S3074, if the vehicle battery 20 is in a state where it can accept the evacuated power P, steps S3076 and S3078 are not necessary.

  Steps S3080 and S3090 are the same as steps S2080 and S2090 in FIG.

  If it is found in steps S3074 and S3076 that the evacuated power P cannot be accepted before the electric vehicle arrives, the output and discharge are made as close as possible to the acceptable state before arrival. Set the start timing. In step S3080, when the control device 26 saves the amount of power that can be received by the external battery 20, the remaining power of the in-vehicle battery 24 is consumed by operating other devices.

  As described above, in this embodiment, before the electric vehicle arrives at the house, it is determined whether or not the battery 20 outside the vehicle can accept the evacuated power P using the power usage history and the vehicle position information. Even if it is in an unacceptable state at the time of the determination, it can be in an acceptable state before arrival.

  Then, when the vehicle battery 20 cannot accept the evacuation power amount P, the vehicle battery 20 is discharged so that the vehicle battery 24 can be accepted. Deterioration can be suppressed by avoiding the situation of being unable to do so.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

20 Vehicle battery 24 Vehicle-mounted battery 26 Control device (control means)

Claims (9)

In an electric vehicle control device comprising a control means for controlling power transfer between an in-vehicle battery mounted on an electric vehicle and an external battery installed outside the vehicle,
The control means includes
When a predetermined amount of power is transferred from the in-vehicle battery to the out-of-vehicle battery within a predetermined period after the in-vehicle battery and the out-of-vehicle battery are connected, and the moved predetermined power is returned from the out-of-vehicle battery to the in-vehicle battery. A first deterioration degree change amount which is a change in the deterioration degree of the in-vehicle battery,
During the predetermined period, a second deterioration degree change amount that is a change in the deterioration degree of the in-vehicle battery when power is not transferred from the in-vehicle battery to the external battery;
Calculate and compare
An electric vehicle control device that moves a predetermined amount of power from the in-vehicle battery to the outside battery if the first deterioration degree change amount is smaller than the second deterioration degree change amount. In the electric vehicle control device according to claim 1,
The control means calculates the plurality of first deterioration degree change amounts by changing the predetermined power amount, and uses the value having the lowest deterioration degree as the first deterioration degree change amount among the calculated values. apparatus. In the electric vehicle control device according to claim 1 or 2,
The control means calculates the amount of electric power to be transferred from the in-vehicle battery to the external battery based on the charge state of the in-vehicle battery, and is acceptable when the external battery is in a charged state where the electric energy cannot be received. The electric vehicle control apparatus which discharges the said external battery so that it may become. In the electric vehicle control device according to claim 3,
The control means estimates a state of charge of the in-vehicle battery before the in-vehicle battery and the out-of-vehicle battery are connected based on a storage state history of the in-vehicle battery and vehicle position information, and the out-of-vehicle battery is in the in-vehicle battery. An electric vehicle control device that discharges the vehicle battery before the vehicle battery is connected to the vehicle battery so that the vehicle battery can be received when the battery is in a charged state where the amount of power from the vehicle cannot be received. In the electric vehicle control device according to any one of claims 1 to 4,
The said control means is an electric vehicle control apparatus which returns electric power from the said external battery to the said vehicle-mounted battery, when there exists an electric power request | requirement from the vehicle in the state which moved electric power to the said external battery. In the electric vehicle control device according to any one of claims 1 to 5,
The electric vehicle control device is a battery that is provided in a facility outside the vehicle and is used as a power source for driving an electrical load of the facility. In the electric vehicle control device according to any one of claims 1 to 6,
The electric vehicle control device, wherein the predetermined period is a period from when the in-vehicle battery and the external battery are connected to when the next vehicle is used, which is estimated by the control unit based on a vehicle use history. In the electric vehicle control device according to any one of claims 1 to 6,
The electric vehicle control device, wherein the predetermined period is a period from when the in-vehicle battery and the external battery are connected to when the vehicle is used next time set by a user. A predetermined amount of power is transferred from the in-vehicle battery to the out-of-vehicle battery within a predetermined period after the in-vehicle battery mounted on the electric vehicle and the out-of-vehicle battery installed outside the vehicle are connected. Calculating a first deterioration degree change amount that is a change in the deterioration degree of the in-vehicle battery within the predetermined period when the predetermined power amount is returned to the battery;
Calculating a second deterioration degree change amount that is a change in the deterioration degree of the in-vehicle battery in the predetermined period when the predetermined power is not transferred from the in-vehicle battery to the external battery in the predetermined period;
An electric vehicle control method for transferring a predetermined power amount from the in-vehicle battery to the external battery when the first deterioration degree change amount is smaller than the second deterioration degree change amount.

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