JP6627402B2 - Deterioration degree estimation device and degradation degree estimation method - Google Patents

Description

  The present invention relates to a deterioration degree estimation device and a deterioration degree estimation method.

  A control system for a lithium ion secondary battery mounted on a hybrid vehicle is known. This control system detects the charge / discharge current of the battery and the voltage of the battery using a sensor, calculates the internal resistance from the detected current and the detected voltage, and estimates the degree of deterioration of the battery based on the calculated internal resistance. (Patent Document 1).

JP 2011-257314 A

  However, when the deterioration degree estimating system for estimating the deterioration degree as in the above control system is not mounted on the vehicle, the information on the vehicle battery must be transmitted to a system outside the vehicle. Therefore, it is necessary to separately provide a communication device for transmitting the battery information in the vehicle.

  An object of the present invention is to provide a deterioration degree estimating apparatus and a deterioration degree estimating method capable of estimating a deterioration degree of a battery without acquiring battery information from a vehicle by communication.

  The present invention stores the amount of charging power per one time of a battery, calculates the frequency distribution of the number of times of charging with respect to the amount of charging power based on the stored information on the amount of charging power for a plurality of times, and determines the deterioration of the battery based on the frequency distribution. The above problem is solved by estimating the degree.

  According to the present invention, the degree of deterioration is estimated while grasping the frequency distribution of the number of times of charging with respect to the amount of charging power from information obtained at the time of charging with an external power supply, and the current current of the battery is estimated when estimating the degree of deterioration. Alternatively, the voltage does not have to be obtained from outside. Therefore, the present invention can estimate the degree of deterioration of the battery without acquiring battery information through communication with the vehicle.

FIG. 1 is a block diagram of the deterioration degree estimation system according to the present embodiment. FIG. 2 is a block diagram of the wattmeter. FIG. 3 is a flowchart showing a control flow of the controller. FIG. 4 is a graph showing the characteristics of the frequency distribution in the area A. FIG. 5 is a graph showing characteristics of the frequency distribution in the area A.

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

  FIG. 1 is a block diagram of a deterioration degree estimation system including a deterioration estimation device according to an embodiment of the present invention. The deterioration estimation device according to the present embodiment is mounted on a power supply line that supplies power from an external power supply to a vehicle-mounted battery.

  The deterioration degree estimating system includes a power meter 10, an electric vehicle 20, and a charging cable 30. The wattmeter 10 has an outlet for supplying power to the outside of the house through the charging cable 30. The power source of the wattmeter 10 is a household AC power supply. When the plug of the charging cable 30 is connected to the insertion port of the wattmeter 10, an electric conduction line from the AC power supply to the charging cable 30 is formed. The power meter 10 has a display 11. The display 11 displays the amount of power output to the electric vehicle 20 and the like.

  The electric vehicle 20 is an electric vehicle or a hybrid vehicle including the battery 21. The battery 21 is a battery group in which a plurality of secondary batteries are connected in parallel or in series. The battery 21 is a battery that can be charged with electric power from an external power supply. The electric vehicle 20 has a charger for charging the battery 21 with electric power from an external power supply. The charger has a conversion circuit, a rectifier circuit, and the like. The charger converts AC power input from charging cable 30 into charging power suitable for charging battery 21, and outputs the charging power to battery 21.

  The charging cable 30 electrically connects the power meter 10 and the electric vehicle 20 when charging the battery 21 with the power of the external power supply. Plugs are provided at both ends of the charging cable 30, respectively. One plug is a plug for connecting to an insertion port of the wattmeter 10, and the other plug is a plug for connecting to a charging port of the electric vehicle 20. The charging cable 30 has a controller box 31. The controller box 31 has a safety function.

  Next, the configuration of the power meter 10 will be described with reference to FIG. The power meter 10 has a controller 12, a sensor 13, and a memory 14 in addition to the display 11. The controller 12 manages the entire power meter 10 and has a CPU and the like. The controller 12 includes a function of detecting a charging power, a function of calculating a frequency distribution of the number of times of charging, and a function of estimating a degree of deterioration of the battery 21. And a deterioration degree estimating unit 123.

  The charging power detection unit 121 detects the charging power of the battery 21 per one time using the sensor 13. The charging power detection unit 121 stores the detected charging power in the memory 14. The frequency distribution calculation unit 122 calculates a frequency distribution of the number of times of charging based on information on charging power for a plurality of times stored in the memory (hereinafter, also simply referred to as charging information). The frequency distribution is a distribution of the frequency of the number of times of charging with respect to the amount of charging power. The frequency distribution represents a range in which the number of times that the battery 21 is charged with the divided charging power amount after the charging power amount is divided by a predetermined amount is indicated by a relative relationship between the charging power amount and the charging count. In the present embodiment, the number of times of charging is represented by frequency, and the frequency is a ratio of the number of times of charging to the divided amount of charging power to the total number of times of charging in a predetermined period. The predetermined period may be from the time when the count of the number of times of charging is started, or may be a period from the present to a predetermined time before.

  The deterioration degree estimating unit 123 estimates the deterioration degree of the battery 21 based on the frequency distribution calculated by the frequency distribution calculating unit 122.

  The sensor 13 detects a current or a voltage output from the wattmeter 10 to the charging cable 30. The memory 14 stores information on the charging power detected by the charging power detection unit 121. The memory 14 stores information on the frequency distribution calculated by the frequency distribution calculation unit 122.

  Next, a control flow of the controller 12 will be described with reference to FIG. FIG. 3 is a flowchart showing a control flow of the controller 12.

  In step S1, controller 12 determines whether charging cable 30 has been connected to the outlet. If the charging cable 30 is connected to the outlet, the process proceeds to the control flow of step S2. If the charging cable 30 is not connected to the outlet, the process waits in the control flow of step S1.

  In step S2, controller 12 determines whether charging has started. With the charging cable 30 connected between the wattmeter 10 and the electric vehicle 20, charging starts under the control of the electric vehicle 20. The controller 12 determines whether charging has been started by detecting an output current or an output voltage from the power meter 10 using the sensor 13.

  If the charging has started, the process proceeds to the control flow of step S3. If charging has not started, the process waits in the control flow of step S2.

  In step S3, charging power detection section 121 detects the amount of power using sensor 13. The charging power detection unit 121 detects an output current and an output voltage from the wattmeter at a predetermined sampling cycle. The charging power detection unit 121 detects the output power of the wattmeter 10 when charging the battery 21 as the charging power of the battery 21.

  In step S4, controller 12 determines whether or not charging has been completed. The controller 12 determines completion of charging by detecting that the output current or output voltage from the power meter 10 becomes zero using the sensor 13. When the charging is completed, the process proceeds to the control flow of step S4. If the charging has not been completed, the process waits in the control flow of step S3.

  In step S5, charging power detection section 121 detects the charging power of battery 21 by calculating the power from the start of charging to the end of charging. The charging power amount is the power amount consumed for charging the battery 21 per one charge of the battery 21. In addition, the charging power detection unit 121 stores the detected charging power amount in the memory 14. The memory 14 stores a charging power amount and a charging start time in association with each other. The time information associated with the charging power amount is not limited to the charging start time, but may be a charging end time or a time stored in a memory.

  In step S6, the controller 12 determines whether or not the total storage period is equal to or longer than six months. The total storage period is an elapsed time from the time when the charging power amount is first stored in the memory 14. If the total storage period is less than six months, the control flow ends. If the total storage period is less than six months, the amount of information stored in the memory 14 may not reach the amount of information necessary for estimating the degree of deterioration. Therefore, when the total storage period is less than six months, the controller 12 ends the control flow without performing the estimation control of the deterioration degree.

  In step S <b> 7, frequency distribution calculation section 122 calculates the frequency distribution of the charging power amount using the charging information stored in memory 14. While dividing the charging power amount by a predetermined power amount, the total number of times of charging corresponding to the divided charging power amount corresponds to the frequency. For example, it is assumed that the charging power amount is divided from 0 to 20 kWh by 2 kWh. The frequency distribution calculation unit 122 allocates the charging information stored in the memory 14 for each divided charging power amount. For example, when the charge information for one charge stored in the memory 14 indicates that charging is started at a certain time and the charging power from the start to the end of the charge is 9 kWh, the frequency distribution calculation unit 122 determines , 8 kWh to 10 kWh, the number of times of one charge is counted.

  Further, the frequency distribution calculation unit 122 calculates the latest frequency distribution and the reference frequency distribution. The latest frequency distribution is calculated from the charging information included from the latest charging start time to a predetermined time before. The reference frequency distribution is an initial frequency distribution, and is calculated from charging information included from a first charging start time to a predetermined time later. Note that the reference frequency distribution is not limited to the initial frequency distribution, and may be any time before the time indicated by the charging information used in the latest frequency distribution.

  In step S8, the deterioration degree estimating unit 123 compares the latest frequency distribution with the initial frequency distribution.

  4 and 5 are graphs showing characteristics of the frequency distribution. 4 and 5 show characteristics when the electric vehicle 20 is used on a daily basis under another environment. The solid line represents the characteristics of the latest frequency distribution, and the dotted line represents the characteristics of the initial frequency distribution. As a general usage of the electric vehicle 20, the amount of electric power charged by one charging is concentrated at a predetermined amount according to the main parking position of the electric vehicle 20, daily usage of the vehicle, mileage, and the like. . For example, when the user uses the electric vehicle 20 for commuting and charges the battery at the charging facility at home when returning home, the traveling distance at the time of commuting is a fixed distance. It is repeatedly charged with electric energy. In such a case, the frequency of the number of times of charging with respect to the amount of charged power peaks at the amount of charged power corresponding to the travel distance of the commuting route.

  Further, as the deterioration of the battery 21 progresses, the amount of charging power to be charged at one time changes, and the charging frequency also changes. On the other hand, even if the battery 21 is deteriorated, the traveling distance of the commuting route does not change, so that a peak value appears in the frequency distribution. That is, a change in the characteristics of the frequency distribution of the battery 21 indicates the degree of deterioration of the battery 21. As described below, the deterioration degree estimating unit 123 estimates the deterioration degree of the electric vehicle 20 based on the peak value included in the frequency distribution.

  In step S9, deterioration degree estimating section 123 determines whether or not the peak value of the frequency distribution has changed based on the comparison result between the latest frequency distribution and the initial frequency distribution. The peak value of the frequency distribution is represented by coordinates in which the horizontal axis represents the amount of charging power and the vertical axis represents frequency (the number of times of charging). The deterioration degree estimating unit 123 observes a change in the peak value within a predetermined charge power amount range with respect to the charge power amount at the peak value of the initial frequency distribution. The predetermined range of the charging power is a range in which the width of 10% of the initial capacity of the battery 21 is extended to the plus side and the minus side with respect to the charging power at the peak value of the initial frequency distribution. Further, regarding the change in the vertical axis direction, when the difference between the number of times of charging at the peak value of the initial frequency distribution and the number of times of charging at the peak value of the latest frequency distribution is larger than a predetermined value, the deterioration degree estimating unit 123 sets the peak value Is determined to have changed.

  In the control flow of step S9, when the deterioration degree estimating unit 123 determines that there is no change in the peak value, the control flow ends.

  In the control flow of step S10, when it is determined that the peak value has changed, the deterioration degree estimating unit 123 determines whether or not a plurality of peak values have changed.

When a plurality of peak values have changed, in step S11, the deterioration degree estimating unit 123 specifies a rising peak value and a falling peak value. In the characteristics shown in FIG. 4, up-peak value ^'a elevated peak value from (point A), the peak value (point B peak value (point ^A)' is the peak value lowered from) (point B). Point A ^{'is _{(X 1', Y 1 '}} ) is represented by the coordinates of the point A is expressed by coordinates _{(X 1, Y} 1), point ^B' coordinates of _{^{(X 2 ', Y 2'}} ) And the point B is represented by coordinates of (X ₂ , Y ₂ ).

In step S12, deterioration degree estimating section 123 estimates the deterioration degree of battery 21 based on the specified change in the peak value and the specified change in the peak value. A rising change corresponds to a change from point A ^' to point A, and a falling change corresponds to a change from point B ^' to point B. As shown in FIG. 4, even when time elapses, the amount of change in the x coordinate from point A ^′ to point A is small, and the amount of change in the x coordinate from point B ^′ to point B is small. Then, the deterioration degree estimating unit 123 estimates the capacity maintenance ratio (W) using the following equation (1).

  Thereby, the deterioration degree estimating unit 123 estimates the deterioration degree based on the relative relationship between the rising change of the peak value and the falling change of the peak value. Then, the control flow proceeds to step S15.

In the control flow of step S10, when the plurality of peak values have not changed, in step S13, the deterioration degree estimating unit 123 specifies the charging power amount at the reference frequency. As shown in FIG. 5, when one peak value changes with the passage of time, the deterioration degree estimating unit 123 calculates a reference frequency based on the frequency (Y ₃ ) at the peak value of the latest frequency distribution. The reference frequency corresponds to a belly part in specifying the peak of the frequency distribution, and is a half value of the frequency (Y ₃ ). The deterioration degree estimating unit 123 specifies the charging power amount at the reference frequency on the characteristics of the latest frequency distribution and the characteristics of the initial frequency distribution, respectively.

In step S14, deterioration degree estimating section 123 estimates the deterioration degree of battery 21 based on the change in the amount of charging power with respect to the reference frequency. As shown in FIG. 5, with the passage of time, the charging electric energy with respect to the reference frequency is changed from X ₃ ^'to X _3. Then, the deterioration degree estimating unit 123 estimates the capacity maintenance ratio (W) using the following equation (2).

  As a result, the deterioration degree estimating unit 123 estimates the deterioration degree based on the change in the charging power amount with respect to the reference frequency. Then, the control flow proceeds to step S15.

  In step S15, the controller 12 displays the estimated degree of deterioration (capacity maintenance rate) on the display 11. In step S16, the controller 12 transmits information on the degree of deterioration (capacity maintenance rate) to the server. The server may transmit the information on the degree of deterioration received from the controller 12 to the user by e-mail or the like. Then, the control flow ends.

  As described above, in the present embodiment, the charging power amount per one charge of the battery 21 is stored in the memory 14, and the number of times of charging with respect to the charging power amount is determined based on the information on the charging power amount for a plurality of times stored in the memory 14. A frequency distribution is calculated, and the degree of battery deterioration is estimated based on the frequency distribution. Thus, the deterioration degree can be estimated without obtaining the current or voltage of the battery 21 from the outside when estimating the deterioration degree.

  In the present embodiment, the degree of deterioration is estimated based on a change in the peak value included in the frequency distribution. This makes it possible to estimate the degree of deterioration without depending on the battery deterioration determination device mounted on the vehicle, by grasping the deterioration tendency based on the temporal change of the frequency distribution.

In the present embodiment, the change in the first peak value included in the frequency distribution is specified as a first change (corresponding to a change from point A ^′ to point A in FIG. 4), and the second peak value included in the frequency distribution is specified. A change in the value is specified as a second change (corresponding to a change from point B ^′ to point B in FIG. 4), and the degree of deterioration is estimated based on the relative relationship between the first change and the second change. As a result, when there are a plurality of peaks in the frequency distribution, some peaks increase in frequency, while some peaks decrease in frequency. By grasping changes in these peak values, the estimation accuracy of the degree of deterioration can be improved. Can be enhanced. Further, the estimation accuracy can be improved as compared with the case where the degree of deterioration is estimated based on one peak value.

Also, in the present embodiment, a plurality of peak values included in the frequency distribution are specified, and the peak value at the second time that has increased with respect to the peak value at the first time (corresponding to the point A ^′ in FIG. 4) (see FIG. The peak value of the first time (corresponding to point B ^' in FIG. 4) and the peak value of the second time (corresponding to point B in FIG. 4) which are decreased with respect to the peak value at the first time are specified, and the peak value is determined. The degree of deterioration is estimated based on the relative relationship between the upward change and the downward change of the peak value. A causal relationship can be expected between the peak at which the frequency increases and the peak at which the frequency decreases, and it is considered that the frequency has shifted from a distribution having a reduced frequency to a distribution having an increased frequency as the deterioration of the battery 21 progresses. Therefore, by grasping the relative relationship between the rising change of the peak value and the falling change of the peak value, highly accurate estimation of the degree of deterioration can be realized.

In the present embodiment, the peak value at the first time (corresponding to the point A ^′ or the point B ^′ in FIG. 4) included in the frequency distribution and the peak value at the second time changed from the peak value at the first time (Corresponding to the point A or the point B in FIG. 4), and the degree of deterioration is estimated based on the peak value at the first time and the peak value at the second time. At this time, the first time is a time earlier than the second time, and the charging power amount at the peak value of the first time and the charging power amount at the peak value of the second time are within a predetermined range. The profile of the frequency distribution mainly depends on the battery capacity of the battery 21 and the environment of the charging spot, and the X coordinate of the peak value of the frequency distribution is fixed unless the battery capacity and the environment are significantly changed. Therefore, it is possible to specify a peak having a fixed X coordinate and grasp a change in the frequency of the Y coordinate, thereby realizing highly accurate estimation of the degree of deterioration.

In the first embodiment, (5, values represented by Y _3/2) predetermined charge times to estimate the deterioration degree based on a change in the charging electric energy for. This makes it possible to estimate the degree of deterioration even when the frequency distribution includes only one peak value.

  In the control flow of step S6, the controller 12 sets the threshold value of the total storage period to six months. However, the threshold value does not necessarily need to be six months, and may be, for example, five months. Further, the controller 12 does not need to compare the total storage period with the time threshold, and may determine whether or not to execute the deterioration degree estimation control according to the amount of information in the memory 14, for example.

In the present embodiment, the deterioration degree estimating unit 123 uses Expression (1) to estimate the deterioration degree of the battery 21 based on the specified change in the peak value and the specified change in the peak value. Although the degree of deterioration was calculated by using, the difference may be used instead of the ratio (Y ₂ ^′ / Y ₁ ^′ ) and the ratio (Y ₂ / Y ₁ ).

  Note that the deterioration degree estimation device according to the present embodiment is not limited to a contact type charging system using a charging cable, and may be applied to a non-contact power supply system using a coil. When applied to a non-contact power supply system, the deterioration degree estimation device is mounted on a ground-side charging device.

DESCRIPTION OF SYMBOLS 10 ... Wattmeter 11 ... Display 12 ... Controller 13 ... Sensor 14 ... Memory 20 ... Electric vehicle 21 ... Battery 30 ... Charging cable 31 ... Controller box 121 ... Charging power detection unit 122 ... Frequency distribution calculation unit 123 ... Deterioration degree estimation unit

Claims (2)

In a deterioration degree estimating device for estimating the deterioration degree of a battery
A charging power amount detection unit mounted on a power supply line that supplies power from an external power supply to a battery provided in the vehicle, and detecting a charging power amount per one time of the battery;
A storage unit for storing the charging power amount,
A frequency distribution calculation unit that calculates a frequency distribution of the number of times of charging with respect to the charging power amount, based on the information on the charging power amount for a plurality of times stored in the storage unit;
And a deterioration degree estimation portion for estimating the degree of deterioration based on the frequency distribution,
The frequency distribution calculation unit,
The latest frequency distribution calculated from the charging information included up to a predetermined time before the latest charging start time,
The charging information included from the first charging start time to after a predetermined time, or the reference frequency distribution calculated from the charging information included in the predetermined time before the time indicated by the charging information used in the latest frequency distribution. And are calculated respectively,
The deterioration degree estimating unit,
When it is determined that the peak value of the latest frequency distribution has changed with respect to the peak value of the reference frequency distribution, when there are a plurality of changed peak values, the capacity maintenance ratio is determined based on the following equation (1). Presumed,
When the changed peak value is one, the deterioration degree is estimated by estimating the capacity retention rate based on the following equation (2),
The deterioration degree estimating device , wherein the peak value is a value at which the frequency of the number of times of charging in the frequency distribution has a peak .

Here, W is the capacity retention ratio, a and b are correction coefficients, Y1 'and Y2' are the number of charging times at the peak value of the reference frequency distribution, and Y1 is the frequency of the latest frequency distribution rising from Y1 '. The number of times of charging at the peak value, Y2 is the number of times of charging at the peak value of the latest frequency distribution falling from Y2 ′, and X3 is the half value of the peak value of the latest frequency distribution on the characteristics of the latest frequency distribution. The charging power amount at the frequency of the frequency, X3 ', is the charging power amount at the charging frequency of half the peak value of the reference frequency distribution on the characteristics of the frequency distribution for the reference.   A charging power amount detection unit mounted on a power supply line that supplies power from an external power supply to a battery provided in the vehicle, detects a charging power amount per time of the battery,
  Storing the charging power amount;
  Based on the stored information of the charging power amount for a plurality of times, as a frequency distribution of the number of times of charging with respect to the charging power amount, the latest frequency distribution calculated from the charging information included a predetermined time before the latest charging start time, The charging information included from the first charging start time to a predetermined time later, or the reference frequency distribution calculated from the charging information included in the predetermined time before the time indicated by the charging information used in the latest frequency distribution. And calculate
  When it is determined that the peak value of the latest frequency distribution has changed with respect to the peak value of the reference frequency distribution, when there are a plurality of changed peak values, the capacity maintenance ratio is determined based on the following equation (1). Presumed,
  When the number of the changed peak values is one, the degree of deterioration of the battery is estimated by estimating a capacity retention rate based on the following equation (2).
  The deterioration degree estimating method, wherein the peak value is a value at which the frequency of the number of times of charging in the frequency distribution has a peak.

Here, W is the capacity retention ratio, a and b are correction coefficients, Y1 'and Y2' are the number of charging times at the peak value of the reference frequency distribution, and Y1 is the frequency of the latest frequency distribution rising from Y1 '. The number of times of charging at the peak value, Y2 is the number of times of charging at the peak value of the latest frequency distribution falling from Y2 ', and X3 is the half value of the peak value of the latest frequency distribution on the characteristic of the latest frequency distribution. The charging power amount at the frequency of the number of times, X3 ', is the charging power amount at the frequency of the number of times of charging at half the peak value of the reference frequency distribution on the characteristics of the reference frequency distribution.

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