JP4670831B2 - Battery capacity detection method and apparatus for electric vehicle and electric vehicle maintenance method - Google Patents

Description

  The present invention relates to a technique for detecting the degree of deterioration of a battery that stores electric power for driving an electric vehicle, and relates to a battery capacity detection method and apparatus for an electric vehicle for detecting the actual capacity of the battery, and an electric vehicle maintenance method using the same. About.

As a matter of course, a vehicle that travels by the driving force of the electric motor (that is, an electric vehicle) is equipped with a battery as a power supply source to the electric motor.
The batteries mounted on these electric vehicles are those in which a plurality of battery cells each consisting of a secondary battery having an electromotive force of several volts are connected in series, or by using an assembled battery in which series connection and parallel connection are used in combination. It is configured to obtain a voltage (usually about several hundred volts) required for running the vehicle.

Electric vehicles are classified into those that are equipped with a power generation source, such as hybrid electric vehicles (HEV) and fuel cell vehicles (FCV), and those that are driven by precharged battery power (EV). Can do.
By the way, in an electric vehicle not equipped with a power generation source (hereinafter referred to as “EV” when simply referred to as an electric vehicle), naturally, the vehicle depends on the remaining capacity of the battery (the amount of electric power remaining in the battery). The travelable distance is limited.

For this reason, in an electric vehicle, it is particularly important to accurately detect the remaining capacity of the battery as much as possible and to accurately transmit information related to the travelable distance of the vehicle to the driver.
Conventionally, as a technique for detecting the remaining capacity of the battery of an electric vehicle, the battery voltage (open circuit voltage) at the time of no load is detected, the battery charge rate (SOC) is calculated from the detected open circuit voltage, and the vehicle A technique for obtaining and displaying a travelable distance is known.

Here, the battery charging rate can be defined as the ratio (percentage) of the current charging capacity (remaining capacity) to the capacity when the battery is fully charged.
Therefore, by detecting the battery charge rate, it is possible to detect the remaining battery capacity and the travelable distance from the rated charge capacity of the battery and the battery charge rate.
However, with the above-described technology, while the battery is nearly new, the remaining capacity of the battery can be detected with relatively high accuracy. However, when the battery is repeatedly charged and discharged, the capacity of each battery cell in the battery deteriorates. When this occurs, the accuracy of the detection result of the remaining capacity of the battery gradually decreases according to the degree of the capacity deterioration.

This is because the battery charge rate is only the ratio of the remaining capacity to the actual capacity in the fully charged state of the battery, so as the difference between the rated charge capacity of the battery and the actual capacity in the fully charged state increases, This is because even if the charging rate is the same, the detection result of the remaining capacity of the battery is larger than the actual remaining capacity.
In order to solve such a problem, Patent Document 1 calculates the battery capacity deterioration (deterioration degree) based on the time change of the current value and voltage value of the battery, and according to the calculated battery deterioration degree. A technique for correcting the battery charge rate is disclosed.

And in the technique of patent document 1, since a battery charging rate is correct | amended according to the capacity deterioration of a battery, the remaining capacity of a battery can be detected more accurately.
JP-A-8-106928

However, the value of the internal resistance of each battery cell in the battery (that is, the internal resistance value of the entire battery) varies depending on various usage conditions such as the running mode of the electric vehicle and the temperature of each battery cell.
However, in the technique of Patent Document 1, since the deterioration degree of the battery is calculated based on the time change of the current value and the voltage value of the battery, the fluctuation of the internal resistance value of each battery cell affects the calculation result of the deterioration degree. As a result, the calculation accuracy of the deterioration degree of the battery is lowered.

For this reason, in the technique of Patent Document 1, an error between the detection result of the remaining capacity of the battery and the actual remaining capacity still occurs, and the travelable distance of the vehicle cannot be accurately displayed.
The present invention has been devised in view of such a problem, and enables an actual charge capacity (actual capacity) of a battery mounted on an electric vehicle to be detected with higher accuracy and to determine a travelable distance with higher accuracy. An object of the present invention is to provide a battery capacity detection method and a battery capacity detection device for an electric vehicle, and a maintenance method for an electric vehicle using the same.

In order to achieve the above-described object, a battery capacity detection method for an electric vehicle according to the present invention (Claim 1) is provided in an electric vehicle that runs using electric power supplied from a precharged battery as a main drive source. A battery capacity detection method for detecting an actual charge capacity of the battery, wherein a discharge step for discharging the electric power remaining in the battery to a fully discharged state in which the charging rate of the battery is approximately 0%, and the fully discharged state A charging step of supplying a charging current to the battery and charging the battery to a fully charged state in which the charging rate of the battery is approximately 100%; and a current amount of the charging current flowing into the battery in the charging step the by integrating and a real capacity calculation step of calculating the actual charge capacity of the battery, the charging step, the electric power discharged in the discharge step And a first charging step for supplying the charging current to the battery, and after the first charging step is completed, the charging current is supplied until the battery reaches the fully charged state using only power from a power source. It is characterized in Rukoto a and a second charging step.

The battery includes a plurality of battery cells that are secondary batteries, and the charging rate of the battery is based on the voltage of the battery cell having the lowest voltage among the plurality of battery cells. It is preferable to include a determination step for determining that the fully discharged state is about 0%, and in the discharging step, the discharge is performed until the fully discharged state is determined by the determining step. ).
In addition, the battery capacity detection device for an electric vehicle according to the present invention (Claim 3) detects an actual charge capacity of the battery in an electric vehicle that runs using electric power supplied from a battery charged in advance as a main drive source. A battery capacity detecting device for discharging electric power remaining in the battery to a fully discharged state where the charging rate of the battery is approximately 0%; and a charging current for the fully discharged battery. A charging means for charging the battery to a fully charged state in which the charging rate of the battery is approximately 100%, and integrating the amount of current flowing into the battery by the charging means to obtain an actual charging capacity of the battery. and a real capacity calculation means for calculating includes a temporary energy storage battery for temporarily charging the electric power discharged from the battery, the charging means, electrodeposition of the temporary energy storage battery The charging current is supplied to the battery until the power of the temporary storage battery is consumed, and the charging current is used until the battery is fully charged using only power from a power source. It is characterized that you provided to the battery.

The battery comprises a plurality of battery cells that are secondary batteries, and the discharging means is based on the voltage of the battery cell having the lowest voltage among the plurality of battery cells. It is preferable to perform the discharge until it is determined that the battery is in a fully discharged state in which the charging rate of the battery is approximately 0% (Claim 4).

  An electric vehicle maintenance method according to the present invention (Claim 5) is a method for maintaining an electric vehicle having a function of displaying a travelable distance based on a battery charging rate. Correction for correcting the travelable distance based on the actual capacity detection step for executing the battery capacity detection method for the vehicle, the actual charge capacity of the battery detected in the actual capacity detection step, and the rated charge capacity of the battery And a step.

A cell voltage detecting step for detecting the voltage of each of the plurality of battery cells after execution of the actual capacity detecting step; and a plurality of the plurality of battery cells based on the voltages of the plurality of battery cells detected in the cell voltage detecting step. It is preferable to have a battery cell recombination step of rearranging the arrangement position of the battery cell in the battery.

  In general, since the battery capacity deterioration is relatively gradual, the battery capacity detection for an electric vehicle or the maintenance of the electric car according to the present invention should be carried out at the time of periodic inspection of the electric car. do it.

According to the electric battery capacity detection side Ho及 Beauty battery capacity detection equipment for vehicle according to the present invention, in the fully discharged state to a fully charged state, the actual battery by accumulating the amount of current actually flowing to the battery Therefore, the actual charging of the battery is not affected by fluctuations in the internal resistance value of each battery cell in the battery due to various usage conditions such as the driving mode of the electric vehicle and the temperature of each battery cell. The capacity (actual capacity) can be detected with higher accuracy.

Further, according to the electric battery capacity detection side Ho及 Beauty battery capacity detection equipment for vehicle according to the present invention, a power that was originally in the battery can be used without waste.
Further, according to the maintenance how the electric vehicle of the present invention, the actual capacity detecting step, the actual charge capacity of the battery (actual capacity) can be accurately detected, the sensed battery actual capacity and the battery rated Since the travelable distance is corrected based on the charge capacity, it is possible to display the travelable distance with higher accuracy.

Further, according to the maintenance how the electric vehicle of the present invention, after executing the actual capacity detecting step (i.e., the battery is fully charged state) at, by detecting the voltage of each battery cell, the degree of deterioration of each battery cell Can be detected.
The variation in the degree of deterioration for each battery cell is considered to be mainly related to the temperature condition, and by rearranging the arrangement position of the battery cell in the battery based on the degree of deterioration for each battery cell, The variation in the degree of deterioration can be flattened, and as a result, the life of the battery can be increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 6 are for explaining a maintenance method for an electric vehicle according to an embodiment of the present invention. FIG. 1 is a flowchart showing a procedure for battery capacity detection and electric vehicle maintenance. 2 is a schematic diagram showing a schematic configuration of an electric vehicle and a battery charging device, FIG. 3 is a diagram schematically showing a structure of the battery and the battery charging device, and FIG. 4 is a voltage (battery cell voltage with respect to a charging rate of the battery cell). 5 is a graph showing the current value of the charging current with respect to the charging rate of the battery, and FIG. 6 is a graph showing the current value of the charging current with respect to the charging time of the battery.

As shown in FIG. 2, a vehicle (electric vehicle) 1 to which the present invention is applied has a battery 2 and a travel drive motor (electric motor) 3. The vehicle 1 is a so-called EV (Electric Vehicle) that travels using the power of the battery 2 charged in advance as a main drive source.
The travel drive motor 3 is provided on the rear axle of the vehicle 1 in the present embodiment, and is electrically connected to the battery 2 via the lead cable 4 and a motor control unit (not shown).

When the vehicle 1 travels, electric power corresponding to the travel request torque is supplied from the battery 2, whereby the travel drive motor 3 is driven, and the vehicle 1 travels by this driving force. Further, at the time of regenerative braking of the vehicle 1, regenerative electric power is generated by the travel drive motor 3, and the battery 2 can be charged with this regenerative electric power.
An instrument panel (hereinafter abbreviated as instrument panel) 8 as a display device is disposed in a driver's seat (not shown) of the vehicle 1. The instrument panel 8 displays the charging rate (SOC) of the battery 2 based on an input from an electronic control unit (ECU) 40 constituted by a computer, and can transmit it to the driver. The instrument panel 8 displays a distance that can be traveled with the current remaining capacity based on the charging rate of the battery 2.

Further, a battery charging device (discharging means, charging means) 6 is installed outside the vehicle 1, and battery charging is performed by connecting the battery charging device 6 and a connection terminal (not shown) of the battery 2 with a lead cable 7. The device 6 and the battery 2 are electrically connected.
Next, detailed configurations of the battery 2 and the battery charger 6 will be described with reference to FIG.

As shown in FIG. 3, the battery 2 includes a plurality of battery cells 21, a plurality of cell voltmeters 22, and a battery control device 23.
In FIG. 3, the number of the battery cells 21 and the cell voltmeter 22 is greatly reduced to simplify the drawing, but actually, the battery cell 21 and the cell voltmeter 22 are the same as those of the battery 2. About 100 pieces are arranged inside.

As the secondary battery constituting each battery cell 21, a lithium ion battery is used because the battery capacity per unit mass is excellent. In the present embodiment, each battery cell 21 is connected in series. ing.
That is, it is configured to obtain a battery voltage (usually about several hundred volts) necessary for suitably running the vehicle 1 by connecting about one hundred battery cells 21 in series.

Further, the battery 2 and the battery charging device 6 are connected by a conducting cable 7 so that a series circuit for charging is formed. In FIG. 3, the series circuit portion (the conducting wire through which the charging current is conducted) is shown by a bold line for easy understanding.
Each cell voltmeter 22 detects a voltage for each battery cell 21 (potential difference between the positive electrode and the negative electrode), and is connected in parallel to the battery cell 21 for each battery cell 21.

The battery control device 23 is configured by a computer or the like, and the detection value Vc of each cell voltmeter 22 is input thereto.
The battery control device 23 calculates a charging rate (SOC) that is a ratio of the remaining capacity to the actual capacity of the battery 2 in the fully charged state based on the detection value Vc of the cell voltmeter 22.

The calculation of the charging rate (SOC) of the battery 2 will be described more specifically.
First, the battery control device 23 sets the voltage of the battery cell 21 having the lowest voltage (hereinafter referred to as the lowest cell) 21 among the plurality of battery cells 21 (that is, the detection value Vc having the smallest value among the input detection values Vc). ) Is detected.
Then, the charging rate is calculated from the relationship between the voltage of the lowest cell and the charging rate of the battery 2.

The relationship between the charging rate of the battery 2 and the voltage (cell voltage) of each lowest cell 21 is as shown in FIG. 4, and if the cell voltage is found, the battery control device 23 is based on the map of FIG. Thus, the charging rate (SOC) of the battery 2 can be uniquely determined.
Therefore, when determining whether or not the battery 2 is in a fully discharged state in which the charging rate is 0% (zero percent), the battery control device 23 corresponds to the lowest cell among the battery cells 21. When the detection value Vc of the cell voltmeter 22 reaches V _min corresponding to a charging rate of 0% from the map of FIG. 4, it is determined to determine that the charging rate of the battery 2 is in a fully discharged state of 0%. ing.

The value of V _min is set in advance to be a value obtained by multiplying the lower limit value and lower limit value of the appropriate voltage of the battery cell 21 by a predetermined safety factor, and the value of V _min is used as a battery cell. The lower limit value of the appropriate voltage range of the battery cell 21 is set according to the type of the secondary battery to be performed.
This is because when the lowest cell detection value Vc drops to _Vmin , it is determined that the battery 2 is fully discharged, and further discharge from the battery 2 is prohibited, so that the lowest cell is overdischarged. This is to prevent this. For example, if the discharge from the battery 2 continues even though the lowest cell is in a fully discharged state, the voltage of the lowest cell is excessively lowered and the battery cell 21 may be damaged.

Moreover, it is also possible to obtain | require the charging rate for each battery cell 21 using the map of detection value Vc and charging rate for each battery cell 21. FIG.
In addition, the battery control device 23 detects the voltage Vc of the battery cell 21 having the highest voltage (hereinafter referred to as the highest cell) among the battery cells 21 (that is, the detection value Vc having the highest value among the input detection values Vc). ) _Reaches V _max , the detection value Vc of the cell voltmeter 22 corresponding to the highest cell 21 is transmitted to the charging device controller 34.

Note that the value of V _max is set in advance so as to be a value obtained by multiplying the upper limit value and the upper limit value of the appropriate voltage of the battery cell 21 by a predetermined safety factor, and the value of V _{max is} the value of V _min Similarly to the value, the voltage of the battery cell 21 is set as the upper limit value of the appropriate voltage range according to the type of secondary battery used as the battery cell.
The battery charging device 6 includes a power supply device (power source) 31, a current sensor 33, and a charging device control device 34. A temporary battery (temporary storage battery) 32 is housed in the power supply device 31.

The battery control device 23, the charging device control device 34, and the electronic control device 40 are electrically connected so that signals can be exchanged with each other.
The current sensor 33 is configured to detect a current value that conducts the conducting cable 7, and a current value Ir detected by the current sensor 33 (this is a current value of a charging current output from the power supply device 31. Therefore, the charging current value Ir) is input to the charging device control device 34.

  The power supply device 31 is a power supply device that supplies power to the battery 2 after discharging the battery 2 to a fully discharged state when the battery 2 is charged, and charges the battery 2 from an external power source and a temporary battery 32 (not shown). It is comprised so that the electric current for charging for performing can be output. The power supply device 31 is controlled by the charging device control device 34.

As shown in FIG. 5, the power supply device 31 performs charging by supplying a charging current to the battery 2 at a constant current (initial current value Im) at the initial stage of charging (constant current charging).
When the voltage of the highest cell 21 reaches V _max and the detected value Vc of the highest cell 21 is input from the battery control device 23 to the charging device control device 34, the detected value Vc of the highest cell 21 is V _The battery 2 is set to gradually decrease the charging current so as to maintain the vicinity of _max (constant voltage charging).

Hereinafter, the time from the start of charging until the detection value Vc of the voltage of the highest cell 21 is input is referred to as a predetermined time T.
Here, the constant voltage charging will be described in more detail. The charging device controller 34 gradually decreases (gradually decreases) the charging current value Ir as shown in FIG. 5 after a predetermined time T has elapsed from the start of charging.

The reason for this will be described. When the charging current is conducted to the battery cell 21, a potential difference is generated between the terminals of each battery cell 21 according to Ohm's law from the relationship between the internal resistance of the battery cell 21 and the charging current.
That is, the detected value Vc detected by the cell voltage sensor 22 at the time of charging is obtained by adding an apparent voltage due to the conduction of the charging current to the cell voltage at the time of no load. Even if the detected value Vc of V reaches V _max , the cell voltage drops below V _max when the charging is stopped. That is, the highest cell 21 is still in a state with a sufficient capacity.

However, since that may cause breakage of the battery cell 21 when the voltage of the battery cell 21 as described above is excessively increased, the charging device controller 34, a substantially detected value Vc of the voltage of the highest cell 21 is at V _max vicinity It is set to perform charging control (that is, constant voltage charging) that gradually decreases (gradually decreases) the charging current value Ir so as to be constant.
The temporary battery 32 in the power supply device 31 has a function of supplying the stored power to the battery 2 when the battery 2 is charged in the discharging prior to the charging of the battery 2 described above.

In addition, when the charging current value Ir input from the current sensor 33 becomes smaller than a preset charging completion current value Ie (naturally Ie <Im), the charging device control device 34 performs charging from the power supply device 31. The power supply is set to be stopped.
That is, the charge completion current value Ie is a current value that serves as a threshold for determining whether or not the battery 2 has reached a fully charged state (that is, a charging rate of 100%), and can prevent overcharging of the battery 2. It is set as a value.

Further, the charging device control device 34 has a built-in timer that measures a charging time T _T from the start of charging to the completion of charging, and can measure the charging time T _T from the start of charging to the end of charging.
Then, the charging device controller 34, the integrated value total charge current of a (region indicated by hatching in FIG. 6) of the charging current value Ir which is provided to the battery 2 to charge time T _T (unit: A · h, ampere In other words, the actual charge capacity in the fully charged state is calculated.

By the way, as described in the background art section, the battery 2 deteriorates as it is repeatedly charged and discharged, and in the fully charged state, the charged capacity (rated charge capacity) in the fully charged state at the time of a new product is reduced. The actual charge capacity will decrease.
On the other hand, the electric vehicle 1 is configured to obtain and display the travelable distance based on the ratio of the current remaining capacity to the rated charge capacity, that is, the SOC.

Specifically, the ECU 40 stores a predetermined distance D that can be traveled at the rated charging capacity of the battery 2 in advance, and by multiplying the predetermined charging distance SOC (%) of the battery 2 by this predetermined distance D, The distance d that can be traveled with the current remaining capacity of the battery 2 is calculated.
However, when the capacity of the battery 2 is deteriorated as described above, the actual remaining capacity is lower than that when the battery is new, even if the charging rate is the same as when the battery is new. I can't do that.

Therefore, in the present embodiment, when the battery 2 is charged, all the remaining power remaining in the battery 2 is once discharged (full discharge state) prior to the charging, and then the battery 2 is supplied with power until the battery 2 is fully charged. In addition, the actual charge capacity (actual capacity) in the fully charged state is calculated by integrating the supply amount of the charging current until the fully charged state is reached.
When the actual capacity of the battery 2 is calculated, the actual capacity and the rated charge capacity of the battery 2 are compared to calculate the degree of battery deterioration (correction coefficient) k. The deterioration degree k is calculated by the following equation.

k = charge capacity at full charge (actual capacity) / rated charge capacity When the degree of deterioration of the battery 2 is calculated as the correction coefficient k, the travelable distance d is corrected using the correction coefficient k, and this correction The travelable distance d is displayed on the instrument panel 8.
The travelable distance d is corrected as follows.
d = k · D · SOC
On the other hand, the battery control device 23 monitors the variation of the voltage (that is, the detection value Vc) of each battery cell 21 in the fully charged state, and changes in the arrangement of the battery cells (cell recombination) according to the variation in voltage. Done.

That is, even when the battery 2 is in a fully charged state, the degree of capacity deterioration of each battery cell 21 in the battery 2 varies, so that the charging rate for each battery cell 21 has reached 100%. is not.
Therefore, when the battery 2 is fully charged, the battery cell 21 having a large detection value Vc of the cell voltage sensor 22 (that is, having a high cell voltage) is compared with the battery cell 21 having a smaller detection value Vc of the cell voltage sensor 22. Thus, it can be said that the battery cell 21 has a high charge rate (that is, there is no allowance for the charge rate), and the battery cell 21 can be considered to have further deteriorated capacity.

  Moreover, in the case of a lithium ion battery, it is known that capacity | capacitance deterioration will advance easily, so that the temperature at the time of use is high. Therefore, it is considered that the battery cell 21 disposed at a position closer to a heat source such as the travel driving motor 3 also has a higher degree of capacity deterioration in the battery 2. That is, it can be said that there is a correlation between the degree of progress of capacity deterioration of each battery cell 21 and the arrangement position of each battery cell 21 in the battery.

Therefore, the arrangement positions in the battery 2 of the battery cells 21 that are considered to have a high degree of progress in capacity deterioration and the battery cells 21 that are considered to have a low degree of progress in capacity deterioration according to the voltage of each battery cell 21 in the fully charged state By rearranging, the degree of progress of capacity deterioration of each battery cell 21 in the battery 2 is equalized.
Thereby, the deterioration degree for each battery cell 21 is made uniform, and the deterioration of the entire battery 2 is suppressed as much as possible.

Such recombination of each battery cell 21 may be performed manually by an operator or may be automated by a machine.
Next, with reference to the flowchart of FIG. 1, the procedure concerning the capacity | capacitance detection method of the battery 2 and the maintenance method of the vehicle 1 is demonstrated.
First, as a preparation before starting the capacity detection of the battery 2 of the battery 2, the lead wire cable 7 is connected to the connection terminal of the battery 2, and the battery charger 6 and the battery 2 are electrically connected.

At this time, each control device (battery control device 23, electronic control device 40) on the vehicle side and the charging device control device are also electrically connected so that signals can be transmitted and received.
Then, as step S <b> 100, the charging device control device 34 releases the power remaining in each battery cell 21 of the battery 2.
Next, in step S110, battery control unit 23 compares the detection value Vc and V _min of the cell voltmeter 22 for the lowest cell, whether the minimum cell reaches the fully discharged state of charge of 0% judge.

In step S110, if the detected value Vc of the lowest cell is larger than V _min (Vc ≧ V _min ), it is determined that the lowest cell has not reached 0% of the charging rate, and the process returns to step S100. Discharging continues.
On the other hand, when the detected value Vc of the lowest cell is equal to or lower than V _min (Vc <V _min ) in step S110, it is determined that the lowest cell has a charging rate of 0% (that is, the battery 2 is fully discharged). In step S120, discharging of the battery 2 is stopped. That is, the procedure from step S100 to S120 corresponds to a discharge step.

  Subsequently, as step S <b> 130, the charging device control device 34 controls the power supply device 31 to supply the battery 2 with a charging current Ir having a constant current (current value Im) to the battery 2 to charge the battery 2. To start. In the charging start stage, the electric power charged in the temporary battery 32 is used as a supply source of the charging current Ir. However, at this time, in the power supply device 31, in order to enable constant current and constant voltage charging, the power of the external power source is used together with the power of the temporary battery 32 to charge the battery 2 as the power source (first charging). Step). When the power of the temporary battery 32 is sufficient, it is not necessary to use the power of the external power source until the power of the temporary battery 32 is consumed.

When the power charged in the temporary battery 32 is consumed, charging is performed using only the power from the external power source as the power source (second charging step).
Thereafter, when a predetermined time T has elapsed from the start of charging, in step S140, the charging device controller 34 switches from constant current charging to constant voltage charging, and supplies a charging current to the battery 2 to perform constant voltage charging. .

That is, when switching from constant current charging to constant voltage charging in step S140, the charging current value Ir conducted to the battery 2 gradually decreases.
In step S150, the charging device control device 34 compares the magnitude relationship between the charging current value Ir and the charging completion current value Ie.
When the charging current value Ir is larger than the charging completion current value Ie (Ir> Ie), the process returns to step S140, and constant voltage charging is continued.

On the other hand, when the charging current value Ir is smaller than the charging completion current value Ie (Ir ≦ Ie), in step S160, the power supply control device 34 determines that the battery device 2 is fully charged and supplies power. The supply of the charging current from the device 31 is stopped. Thereby, charging of the battery 2 is completed. That is, steps S130 to S160 correspond to a charging step.
When the charging of the battery 2 is completed, in step S170, the charging device controller 34, the total charge amount of current is the time integral value of the charging time T _T of the charging current value Ir which flows in the battery 2 in step S130～S160 ( A · h) is calculated. The amount of current (A · h) calculated in this way is the maximum amount of current (actual charge capacity, actual capacity) that can be actually charged in the battery 2 (actual capacity calculation step). Steps S100 to S170 correspond to the actual capacity detection step.

  After the actual capacity detection step is executed, in step S180, the electronic control device 40 receives an input from the charging device control device 34, and compares the rated charging capacity of the battery 2 with the actual charging capacity in the fully charged state. Then, the correction coefficient k, which is the degree of capacity deterioration of the battery 2, is calculated. Then, the travelable distance output to the instrument panel 8 is corrected by multiplying the original travelable distance calculated by the electronic control unit 40 by the correction coefficient k (correction step).

On the other hand, the battery control device 23 detects the detection value Vc of each cell voltage sensor 22 immediately after the actual capacity detection step is completed, and each battery cell 21 and each cell corresponding thereto are detected from an output device (not shown). The detection value Vc of the voltage sensor 22 is output.
In step S190, the operator replaces the arrangement positions of the battery cells 21 in the battery 2 based on the output from the battery control device 23 (battery cell recombination step).

As described above, according to the battery capacity detection method and apparatus for an electric vehicle and the maintenance method for an electric vehicle according to an embodiment of the present invention, the following effects can be obtained.
First, the conductor cable 7 is connected to the connection terminal of the battery 2, and the electric power remaining in each battery cell 21 of the battery 2 is discharged to the battery charging device 6 side, so that the lowest cell is fully discharged (charging rate 0%). Continue to discharge until it reaches.

Thereafter, a charging current (a constant current value Im) is supplied to the battery 2, and the battery 2 is charged by constant current charging. A part of the charging current at this time uses the power of the temporary battery 32. That is, the electric power originally remaining in the battery 2 is once charged in the temporary battery 32 and charged in the battery 2 again.
When the charging current value Ir reaches the charging completion current value Ie (Ir ≦ Ie), charging of the battery 2 is completed by stopping the supply of the charging current, and the battery 2 is changed from the fully discharged state to the fully charged state. The total amount of charging current provided from the battery charging device 6 (that is, the actual charging capacity) is calculated.

Further, the correction coefficient k is calculated from the actual charge capacity and the rated charge capacity, and the travelable distance displayed on the instrument panel 8 is corrected using the correction coefficient k. Further, based on the detection value Vc of each cell voltage sensor 22 immediately after the completion of battery charging, the arrangement position of the battery cell 21 in the battery 2 is switched.
Thus, according to the battery capacity detection method and apparatus for an electric vehicle and the maintenance method for an electric vehicle according to an embodiment of the present invention, the battery 2 is discharged once until the battery 2 is fully discharged, and then fully discharged. Since the actual charge capacity of the battery 2 is detected by integrating the amount of current flowing into the battery 2 from the state to the fully charged state, the travel mode of the vehicle 1 so far and the temperature of each battery cell 21 The actual charge capacity of the battery can be detected more accurately without being affected by fluctuations in the internal resistance value of the battery 2 due to variations in various usage conditions such as the above. Moreover, since the electric power originally charged in the battery 2 is once charged in the temporary battery 32 and then charged in the battery 2 again, the electric power can be used without waste.

Further, a correction coefficient k corresponding to the degree of capacity deterioration with respect to the rated charge capacity of the battery 2 is obtained based on the detected actual charge capacity of the battery 2, and the travelable distance of the vehicle 1 is more accurately determined by the electronic control unit 40. It can be calculated and displayed on the display means 8.
Further, by rearranging the arrangement position of the battery cell 21 in the battery 2 based on the progress degree of the capacity deterioration for each battery cell 21, the variation in the progress degree of the capacity deterioration for each battery cell 21 can be flattened. .

Thereby, the difference in the degree of progress of capacity deterioration between the lowest cell and the other battery cells 21 is reduced, and the individual battery cells 21 can be used more efficiently. As a result, the progress of capacity deterioration of the battery 2 is promoted. The life of the battery 2 can be increased by slowing down.
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, correction of the remaining capacity and recombination of the arrangement positions of the battery cells in the battery are performed based on the detection result of the actual charge capacity of the battery, but these are not necessarily performed and are omitted. Is possible. The detection result of the actual charge capacity of the battery can be widely applied to other maintenance of the electric vehicle. In the simplest case, the battery may be replaced based on the detection result of the actual charge capacity of the battery.

  Further, in the above-described embodiment, as the correction step, the battery deterioration degree (correction coefficient) k is calculated by comparing the actual charging capacity detection result of the battery with the rated charging capacity of the battery, and is set in advance. The travelable distance is corrected by multiplying the travelable distance calculated by the predetermined chargeable capacity of the battery 2 and the battery charge rate by the correction coefficient k, but instead of this, electronic control is performed. The apparatus may calculate the remaining battery capacity by multiplying the actual charging capacity of the battery by the battery charging rate, and obtain the travelable distance from the relationship between the calculated remaining capacity and the travelable distance.

That is, if the rated charge capacity of the battery preset in the electronic control device is updated to the actual charge capacity of the battery 2 detected by the battery capacity detection method of the present invention, the travelable distance calculated as a result Therefore, more accurate information can be transmitted to the driver.
As another example, the display of the battery charge rate may be corrected to a smaller side based on the detection result of the actual charge capacity of the battery.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart for explaining a battery capacity detection method and apparatus for an electric vehicle and an electric vehicle maintenance method according to an embodiment of the present invention, and shows a procedure for battery capacity detection and electric vehicle maintenance. . BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating a schematic configuration of an electric vehicle and a battery charging device for explaining a battery capacity detection method and device for an electric vehicle and a maintenance method of the electric vehicle according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure for demonstrating the battery capacity detection method and apparatus for electric vehicles which concern on one Embodiment of this invention, and the maintenance method of an electric vehicle, Comprising: It is a figure which shows typically the structure of a battery and a battery charging device. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph for illustrating a battery capacity detection method and apparatus for an electric vehicle and a maintenance method for an electric vehicle according to an embodiment of the present invention, and showing a voltage (cell voltage) of a battery cell with respect to a charging rate of the battery cell. It is. It is a graph for demonstrating the battery capacity detection method and apparatus for electric vehicles which concern on one Embodiment of this invention, and the maintenance method of an electric vehicle, Comprising: It is a graph which shows the electric current value of the electric current for charging with respect to the charging rate of a battery. It is a graph for demonstrating the battery capacity detection method and apparatus for electric vehicles which concern on one Embodiment of this invention, and the maintenance method of an electric vehicle, Comprising: It is a graph which shows the electric current value of the electric current for charging with respect to the charging time of a battery.

Explanation of symbols

1 Vehicle (electric car)
2 Battery 3 Driving motor (electric motor)
4 Conductor cable 6 Battery charger (discharge means, charge means)
7 Conductor cable 8 Instrument panel (display device)
21 battery cell 22 cell voltmeter 23 battery control device 31 power supply device (power source)
32 Temporary battery (Battery for temporary storage)
33 Current sensor 34 Charging device controller 40 Electronic control means (ECU)

Claims (6)

In an electric vehicle that travels using power supplied from a precharged battery as a main drive source, a battery capacity detection method for detecting an actual charge capacity of the battery,
A discharging step of discharging the power remaining in the battery to a fully discharged state in which the charging rate of the battery is approximately 0%;
A charging step of supplying a charging current to the fully discharged battery and charging the battery to a fully charged state in which the charging rate of the battery is approximately 100%;
An actual capacity calculating step of calculating an actual charging capacity of the battery by integrating the amount of current of the charging current flowing into the battery in the charging step ;
The charging step includes
A first charging step of supplying the charging current to the battery using the electric power discharged in the discharging step;
After completion the first charging step, and wherein the Rukoto a and a second charging step of donating the charging current until the battery reaches a該満charged state by using only power from the power source for electric automobiles Battery capacity detection method.   The battery comprises a plurality of battery cells that are secondary batteries,
  A determination step for determining that the battery is fully discharged based on the voltage of the battery cell having the lowest voltage among the plurality of the battery cells, wherein the charging rate of the battery is approximately 0%;
  In the discharging step, the discharging is performed until the full discharge state is determined by the determining step.
The battery capacity detection method for an electric vehicle according to claim 1, wherein: In an electric vehicle that runs using electric power supplied from a precharged battery as a main drive source, a battery capacity detection device that detects an actual charge capacity of the battery,
Discharging means for discharging electric power remaining in the battery to a fully discharged state where the charging rate of the battery is approximately 0%;
Charging means for supplying a charging current to the fully discharged battery and charging the battery to a fully charged state in which the charging rate of the battery is approximately 100%;
An actual capacity calculating means for calculating the actual charge capacity of the battery by integrating the amount of current flowing into the battery by the charging means ;
A temporary storage battery for temporarily charging the electric power discharged from the battery;
The charging means supplies the charging current to the battery using the electric power of the temporary electric storage battery until the electric power of the temporary electric storage battery is consumed, and the battery uses only electric power from the power source. the the charging current until該満charge state characterized that you provided to the battery, an electric car battery capacity detecting unit.   The battery comprises a plurality of battery cells that are secondary batteries,
  The discharging means includes
  Based on the voltage of the battery cell having the lowest voltage among the plurality of battery cells, the discharge is performed until it is determined that the battery is in a fully discharged state in which the charging rate of the battery is approximately 0%.
The battery capacity detection device for an electric vehicle according to claim 3, wherein: An electric vehicle maintenance method having a function of displaying a travelable distance based on a battery charge rate,
An actual capacity detection step for executing the battery capacity detection method for an electric vehicle according to claim 1 or 2,
And a correction step of correcting the travelable distance based on the actual charge capacity of the battery detected in the actual capacity detection step and the rated charge capacity of the battery. Car maintenance method. A cell voltage detection step for detecting a voltage of each of the plurality of battery cells after execution of the actual capacity detection step;
A battery cell recombination step of rearranging the arrangement positions of the plurality of battery cells in the battery based on the voltages of the plurality of battery cells detected in the cell voltage detection step. An electric vehicle maintenance method according to claim 5.

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