JP2017028874A - Secondary battery, electric automobile and arithmetic unit for secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery which can suppress lowering of a travel possible distance of an electric automobile which is driven by the secondary battery even if the secondary battery is deteriorated.SOLUTION: A secondary battery 10 comprises: a battery part 11 of which charging/discharging can be repeatedly performed; and a battery control part 16 which adjusts a lower limit value within a use possible range of electric power charged in the battery part 11 on the basis of electric energy which can be charged in the battery part 11, and a request electric energy required for that a vehicle 1, which is driven by use of electric power charged in the battery part 11, travels by a prescribed distance.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a secondary battery, an electric vehicle, and an arithmetic device for a secondary battery.

  A secondary battery is a battery that can be repeatedly charged and discharged, and is used in various applications such as information equipment and electric vehicles. Such secondary batteries are known to deteriorate over time, and the degree of deterioration varies depending on usage conditions, and various methods have been proposed to suppress the deterioration of secondary batteries. Yes.

  In order to suppress deterioration of a secondary battery mounted on a vehicle such as an electric vehicle, Patent Document 1 limits the upper limit value of the charge amount when charging a secondary battery mounted on a parked vehicle. Techniques to do this are disclosed. If the battery is left for a long time with a high charge, the secondary battery will deteriorate significantly. For this reason, in a state where the vehicle is parked, the deterioration of the secondary battery can be suppressed by discharging to a limited upper limit value and reducing the charge amount.

JP 2013-74706 A

  However, with the technique disclosed in Patent Document 1, it is possible to delay the deterioration of the secondary battery and improve the life, but still deteriorate over time. For this reason, even if it is the same secondary battery, the electric energy stored when it charges to a full charge state will fall gradually. Therefore, when such a secondary battery is used for driving an electric vehicle, the travelable distance, which is the distance that the electric vehicle can travel when fully charged, gradually decreases, and the battery is fully charged. Nevertheless, there was a problem that it was not possible to maintain a certain driving distance.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to maintain a constant travelable distance of an electric vehicle driven by the secondary battery even when the secondary battery is deteriorated. And

The secondary battery according to the present invention is
A battery part that can be repeatedly charged and discharged;
Based on the amount of power that can be charged in the battery unit and the required amount of power that is the amount of power required for a vehicle driven using the power charged in the battery unit to travel a predetermined distance, A battery control unit that adjusts a lower limit value of a usable range of power charged in the battery unit.

The electric vehicle according to the present invention is
An electric vehicle driven by using electric power stored in a secondary battery, comprising a vehicle control unit for controlling the electric vehicle,
The secondary battery is
A battery part that can be repeatedly charged and discharged;
Based on the amount of power that can be charged in the battery unit and the required amount of power that is the amount of power required for a vehicle driven using the power charged in the battery unit to travel a predetermined distance, The lower limit value of the usable range of power charged in the battery unit is adjusted, and the lower limit value of the usable range is subtracted from the remaining power amount of the battery unit as the remaining power amount of the vehicle to the vehicle control unit. A battery control unit for transmitting the value,
The vehicle control unit calculates a travel distance of the vehicle based on the remaining power amount of the vehicle transmitted from the battery control unit.

Moreover, the arithmetic device for a secondary battery according to the present invention is:
Means for measuring the amount of power that can be charged in a rechargeable battery unit; and
Means for obtaining a required power amount that is a power amount necessary for a vehicle driven using the power charged in the battery unit to travel a predetermined distance;
A battery control unit that adjusts a lower limit value of a usable range of power charged in the battery unit based on the chargeable power amount and the required power amount.

  According to the present invention, even when the secondary battery is deteriorated, it is possible to maintain a certain travelable distance of the electric vehicle driven by the secondary battery.

It is a figure which shows roughly the hardware constitutions of the electric vehicle 1 carrying the secondary battery 10 which concerns on one Embodiment of this invention. It is a figure for demonstrating the outline | summary of this invention. It is a flowchart for demonstrating the operation | movement which adjusts the discharge end electric energy in the secondary battery which concerns on this invention. It is a sequence diagram for demonstrating the display operation | movement of the travelable distance which concerns on the 1st Embodiment of this invention. An example of a screen display including the remaining travelable distance output by the display unit 60 is shown. It is a figure which shows the relationship between the electric energy consumption of a battery, and a no-load battery voltage. It is a sequence diagram for demonstrating the display operation | movement of the travelable distance which concerns on the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in this specification and drawing, the description which overlaps may be abbreviate | omitted by attaching | subjecting the same code | symbol about the component which has the same function.

(Physical configuration of electric vehicle)
FIG. 1 is a diagram schematically showing a hardware configuration of an electric vehicle 1 equipped with a secondary battery 10 according to an embodiment of the present invention. The electric vehicle 1 mainly includes a secondary battery 10, an inverter 20, a charging unit 30, a DC (Direct Current) / DC converter 40, a vehicle control unit 50, and a display unit 60.

  The secondary battery 10 includes a battery unit 11, a connection detection unit 12, a voltmeter 13, a thermometer 14, an ammeter 15, and a battery control unit (BMS: Battery Management System) 16.

  The battery unit 11 can be repeatedly charged and discharged, and the battery control unit 16 controls charging and discharging of the battery unit 11. The connection detection unit 12 detects whether or not the secondary battery 10 is connected so that power can be supplied to each unit of the electric vehicle 1, and inputs the connection state to the battery control unit 16. The voltmeter 13 measures the cell voltage, which is the voltage of the battery unit 11, and inputs the measured cell voltage (inter-terminal voltage of the unit battery) to the battery control unit 16. The thermometer 14 measures the temperature of the battery unit 11 and inputs the measured battery temperature to the battery control unit 16. The ammeter 15 measures the current supplied to the outside by the secondary battery 10 and inputs the measured current value to the battery control unit 16.

  The battery control unit 16 controls the battery unit 11 based on input information such as a connection state, a cell voltage, a battery temperature, and a current value. The battery control unit 16 can be used to adjust the usable range of the power stored in the battery unit 11 by adjusting the discharge end power amount, which is the power amount for stopping the discharge of the power stored in the battery unit 11. It can function as a range adjustment means, and can maintain a certain travelable distance. Further, the battery control unit 16 can also function as remaining power amount calculation means for calculating a value obtained by subtracting the lower limit value of the usable range from the remaining power amount of the battery unit 11 as the remaining power amount of the electric vehicle 1. The battery control unit 16 can transmit the calculated remaining power amount to the vehicle control unit 50.

  The inverter 20 generates AC power from DC power and supplies it to an AC motor for driving an electric vehicle. The charging unit 30 supplies power supplied from an external power source such as a charging station or a system power source to the secondary battery 10. The DC / DC converter 40 converts a direct current voltage into a direct current voltage of another voltage value and supplies it to, for example, a 12V in-vehicle electrical equipment. The vehicle control unit 50 controls the movement of the electric vehicle 1. The vehicle control unit 50 is connected to the components of the electric vehicle 1 including the secondary battery 10 via an in-vehicle network such as a CAN (Controller Area Network). The display unit 60 is installed in the electric vehicle 1. The display unit 60 displays various types of information, such as the current speed of the electric vehicle 1 and the travelable distance, according to the control of the vehicle control unit 50.

(Outline of battery controller operation)
FIG. 2 is a diagram for explaining the outline of the present invention. As shown in FIG. 2, it is assumed that at the shipping stage of the secondary battery 10, SOH (State Of Health = deteriorated state) is 100% and the battery temperature is 25 degrees. If the chargeable power amount in this case is 20 kWh and the required power amount, which is the amount of power required for the electric vehicle 1 to travel a predetermined distance, is 15 kWh, the battery control section 16 Set quantity to 5 kWh. In this case, the usable range is 15 kWh between 5 kWh and 20 kWh. When the secondary battery 10 deteriorates over time, the SOH is 90%, the chargeable power amount is reduced to 19 kWh, and the battery temperature is 0 degrees, the battery control unit 16 sets the discharge end power amount. Reduce to 4 kWh. In this case, the usable range is 15 kWh between 4 kWh and 19 kWh. With this configuration, a change in the amount of power in the usable range of the secondary battery 10 is suppressed to be substantially constant, and the travelable distance of the electric vehicle 1 when the secondary battery 10 is fully charged is equal to that of the secondary battery 10. It is possible to suppress a change depending on the degree of deterioration.

(Adjustment of discharge end power)
A specific operation of the battery control unit 16 for realizing the technique of the present invention described in FIG. 2 will be described. FIG. 3 is a flowchart for explaining an operation of adjusting the discharge end power amount of the secondary battery according to the first embodiment of the present invention. The operation shown in FIG. 3 is executed, for example, before the electric vehicle 1 is connected to an external power source and charging is started.

First, the battery control unit 16 estimates SOH that is the deterioration degree A of the battery unit 11 (step S101). The battery control unit 16 measures the battery capacity C1 when the SOH value is charged from the discharge end voltage to the full charge voltage based on the current value I input from the ammeter 15, for example, Is obtained by dividing the battery capacity C1 by the battery capacity C0 at the time of product shipment.
Subsequently, the battery control unit 16 measures the current battery temperature T using the thermometer 14 (step S102). The battery control unit 16 estimates the chargeable electric energy B from the estimated deterioration degree A and the measured battery temperature T (step S103). The chargeable electric energy B decreases as the deterioration degree A increases. Further, the rechargeable power amount B tends to decrease as the battery temperature T decreases. Specifically, when a deterioration degree A and a temperature T are input, a map that outputs a chargeable power amount B is created in advance, and the battery control unit 16 estimates the chargeable power amount B using this map. can do.

  The battery control unit 16 determines whether or not the estimated chargeable power amount B is larger than the required power amount D (step S104). The required power amount D is the amount of power necessary for the electric vehicle 1 to travel a predetermined distance. Although the required power amount D actually varies depending on the power consumption J of the electric vehicle 1, in this embodiment, for the sake of simplicity, it is assumed that the power cost J is the reference value J1 in a standard use state. D is a predetermined value D1 determined at the shipping stage.

  When the chargeable power amount B is greater than the required power amount D1, the battery control unit 16 sets the discharge end power amount E to a value of “chargeable power amount B−required power amount D1” (step S105). On the other hand, when the chargeable power amount B is equal to or less than the required power amount D1, the battery control unit 16 sets the discharge end power amount E to “0 kWh” (step S106).

  When the end-of-discharge power amount E described with reference to FIG. 3 is adjusted, the usable range (the range from the rechargeable power amount B to the end-of-discharge power amount E) of the power stored in the battery unit 11 is adjusted. The In the electric vehicle 1, a travelable distance corresponding to the adjusted usable range is displayed. FIG. 4 is a sequence diagram for explaining the display operation of the travelable distance in the electric vehicle 1.

  First, the battery control unit 16 performs a process for adjusting the discharge end power amount (step S100). The adjustment of the discharge end power amount E is specifically the processing shown in steps S101 to S106 in FIG.

  When the discharge end power amount E is adjusted, the battery control unit 16 calculates the remaining power amount F of the vehicle (step S110). The remaining power F of the vehicle is determined by the end of discharge from the remaining power G of the battery (obtained by subtracting the power consumption calculated from the integrated value of the battery voltage and current during use from the power when fully charged). It is obtained by subtracting the electric energy E. When calculating the remaining power amount F of the vehicle, the battery control unit 16 transmits the calculated remaining power amount F of the vehicle to the vehicle control unit 50 (step S120).

  When receiving the remaining power amount F of the vehicle transmitted by the battery control unit 16, the vehicle control unit 50 calculates the remaining travelable distance H of the vehicle using the received remaining power amount F of the vehicle (step S130). . Specifically, the vehicle control unit 50 can calculate the remaining travelable distance H (km) by dividing the remaining power amount F (Wh) of the vehicle by the power consumption J1 (Wh / km). After calculating the remaining travelable distance H, the vehicle control unit 50 inputs the calculated remaining travelable distance H to the display unit 60 using CAN communication (step S140).

  Display unit 60 displays the remaining travelable distance input from vehicle control unit 50 on the screen (step S150). FIG. 5 shows an example of a screen display including the remaining travelable distance output by the display unit 60. As shown in FIG. 5, the display unit 60 can display the remaining travelable distance by numbers. The symbol on the upper right of the remaining travelable distance (numerical value) includes an SOC display area 61 that displays the SOC state and an SOH display area 62 that displays the SOH state. The SOC display area 61 indicates the charge amount ratio from the lower right to the upper left by using the color to be displayed. The charge amount becomes empty as it goes to the lower right, and the upper left is a full charge state. The SOH display area 62 indicates the degree of deterioration from the lower right to the upper left using the color to be displayed. The degree of deterioration increases as it goes to the lower right, and the upper left is a new state.

(Effect of the invention)
As described above, according to the first embodiment of the present invention, the amount of power that can be charged in the battery unit 11 and the required amount of power that is the amount of power required for the electric vehicle 1 to travel a predetermined distance. Based on the above, the lower limit value of the usable range of the power charged in the battery unit 11 is adjusted. With this configuration, the amount of power stored in the usable range is adjusted according to the required amount of power. For this reason, even if the battery unit 11 is deteriorated, the travelable distance of the electric vehicle 1 driven by the battery unit 11 can be maintained constant.

  Further, the battery control unit 16 may estimate the amount of power that can be charged based on the temperature of the battery unit 11. Since the amount of power that can be charged in the battery unit 11 varies depending on the temperature of the battery unit 11, the accuracy of the estimated value of the amount of power that can be charged can be improved by using the temperature of the battery unit 11. For example, the lower the temperature, the smaller the amount of power that can be charged. Therefore, even when the battery unit 11 is deteriorated, the travelable distance of the electric vehicle 1 can be maintained more accurately.

  Further, when the chargeable power amount is larger than the required power amount, the battery control unit 16 sets the lower limit value of the usable range to a value obtained by subtracting the required power amount from the chargeable power amount, and the chargeable power amount is requested. When it is less than the amount of electric power, the lower limit value of the usable range is set to 0. With this configuration, the travelable distance of the electric vehicle 1 can be kept constant until the battery unit 11 is further deteriorated and the chargeable power amount becomes equal to the required power amount.

  In addition, the battery control unit 16 transmits a value obtained by subtracting the lower limit value of the usable range from the remaining power amount of the battery unit 11 to the vehicle control unit 50 that controls the electric vehicle 1 as the remaining power amount of the vehicle. With this configuration, the vehicle control unit 50 is notified of the amount of power charged in the set usable range, not the amount of remaining power actually charged in the battery unit 11. Therefore, the vehicle control unit 50 can control the electric vehicle 1 according to the limited usable range.

  Further, the vehicle control unit 50 calculates the travelable distance of the electric vehicle 1 based on the remaining power amount of the vehicle. With this configuration, even when the battery unit 11 is deteriorated and the amount of power that can be charged is reduced, it is possible to maintain a constant travelable distance of the electric vehicle 1.

  In addition, the vehicle control unit 50 causes the display unit 60 to display the travelable distance calculated according to the adjusted usable range. With this configuration, even when the battery unit 11 is deteriorated, a certain travelable distance is notified to the user.

  In the present embodiment, the use range of the battery is controlled not by voltage but by electric energy. As a method of controlling the use range of the battery, it is conceivable to use a voltage. However, in the present embodiment, in order to keep the travelable distance constant, it is necessary to calculate the electric energy (Wh). There is a non-linear relationship between power consumption and battery voltage. FIG. 6 is a diagram showing the relationship between the battery power consumption and the no-load battery voltage. If the value of the no-load battery voltage can be measured, the amount of power consumption can be known, but the no-load battery voltage cannot be measured while the electric vehicle 1 is traveling. For this reason, in this invention, it decided to use the control by electric energy.

<Second Embodiment>
Since the configuration of the electric vehicle 1 according to the second embodiment of the present invention is the same as that of the first embodiment, the description thereof is omitted here.
FIG. 7 is a sequence diagram for explaining the display operation of the travelable distance according to the second embodiment of the present invention. This embodiment is different from the first embodiment in that the required power amount is corrected according to the power consumption J2. Vehicle control unit 50 transmits power consumption J2 (Wh / km) to battery control unit 16 (step S200). The power consumption J2 is obtained by measuring the power consumption and travel distance of the battery during use, and dividing the power consumption by the travel distance.

  When the battery control unit 16 receives the power consumption J2 transmitted by the vehicle control unit 50, the battery control unit 16 corrects the required power amount D1 using the received power consumption J2 to obtain a corrected required power amount D2 (step S210). Specifically, the battery control unit 16 calculates a correction coefficient obtained by dividing the current power consumption J2 received from the vehicle control unit 50 by the reference power consumption (set on the vehicle side), and uses the calculated correction coefficient as the required power. The required power amount D1 is corrected by integrating the amount D1. If an auxiliary device such as an air conditioner is used or if the power consumption increases due to the driving of the driver, the travelable distance of the electric vehicle 1 will decrease. For this reason, in this embodiment, by correcting the required power amount according to the power consumption, it is possible to maintain a constant travelable distance even if the power consumption changes.

  Since the operation from step S100 to step S150 is the same as that of the first embodiment described with reference to FIG. 4, the description thereof is omitted here. In step S100, the discharge end power amount is adjusted using the required power amount corrected in step S210. As a result, the remaining travelable distance displayed in step S150 is a value corrected according to the power consumption. Become.

  While the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  For example, in the above embodiment, the display unit 60 is installed in the electric vehicle 1, but the present invention is not limited to such an example. For example, the display unit 60 that displays the travelable distance may be installed at a charging stand connected to the electric vehicle 1.

  In the above embodiment, the secondary battery mounted on the electric vehicle has been described. However, the technology of the present invention can also be applied to a secondary battery mounted on a hybrid car having a plurality of drive sources. is there.

  Moreover, in the said embodiment, although the battery control part 16 of the secondary battery 10 decided to adjust the lower limit of the usable range of the battery part 11, this invention is not limited to this example. The process of adjusting the lower limit value of the usable range may be performed in a secondary battery arithmetic device separate from the secondary battery 10. In this case, the arithmetic unit for the secondary battery includes a unit that measures the amount of power that can be charged in the battery unit that can be repeatedly charged and discharged, and a vehicle that is driven using the power charged in the battery unit travels a predetermined distance. Battery control that adjusts the lower limit value of the usable range of the power charged in the battery unit based on the means for obtaining the required power amount, which is the amount of power required to perform, and the chargeable power amount and the required power amount A part.

DESCRIPTION OF SYMBOLS 1 Electric vehicle 10 Secondary battery 11 Battery part 16 Battery control part 50 Vehicle control part 60 Display part

Claims (7)

A battery part that can be repeatedly charged and discharged;
Based on the amount of power that can be charged in the battery unit and the required amount of power that is the amount of power required for a vehicle driven using the power charged in the battery unit to travel a predetermined distance, A secondary battery comprising: a battery control unit that adjusts a lower limit value of a usable range of power charged in the battery unit.   The secondary battery according to claim 1, wherein the battery control unit estimates the chargeable electric energy based on a temperature of the battery unit.   When the rechargeable power amount is larger than the required power amount, the battery control unit sets the lower limit value of the usable range as a value obtained by subtracting the required power amount from the rechargeable power amount, so that the charge can be performed. The secondary battery according to claim 1 or 2, wherein a lower limit value of the usable range is set to 0 when the electric energy is equal to or less than the required electric energy.   The battery control unit transmits a value obtained by subtracting a lower limit value of the usable range from a remaining power amount of the battery unit, as a remaining power amount of the vehicle, to a vehicle control unit that controls the vehicle. The secondary battery according to any one of items 1 to 3.   5. The battery control unit according to claim 1, wherein the battery control unit acquires current power consumption information of the vehicle from a vehicle control unit that controls the vehicle, and corrects the required power amount based on the power consumption information. Secondary battery described in 1. An electric vehicle that is driven using electric power stored in a secondary battery,
A battery part that can be repeatedly charged and discharged;
Based on the amount of power that can be charged in the battery unit and the required amount of power that is the amount of power required for a vehicle driven using the power charged in the battery unit to travel a predetermined distance, Usable range adjustment means for adjusting the lower limit of the usable range of the electric power charged in the battery unit;
A remaining power amount calculating means for calculating a value obtained by subtracting the lower limit value of the usable range from the remaining power amount of the battery unit as the remaining power amount of the vehicle;
A travel distance calculating means for calculating a travelable distance of the vehicle based on the remaining power amount of the vehicle;
An electric vehicle comprising display means for displaying the travelable distance. Means for measuring the amount of power that can be charged in a rechargeable battery unit; and
Means for obtaining a required power amount that is a power amount necessary for a vehicle driven using the power charged in the battery unit to travel a predetermined distance;
An arithmetic device for a secondary battery, comprising: a battery control unit that adjusts a lower limit value of a usable range of power charged in the battery unit based on the chargeable power amount and the required power amount.

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