Device for ascertaining charging rate of vehicle-mounted rechargeable batteries

Abstract

The present invention makes it possible to ascertain the charging rate of an electric vehicle in accordance with the actual situation. When a vehicle (10) is started, a voltage-estimated SOC value is obtained by estimating the charging rate using the voltage of a large-scale battery (12), and after traveling begins, a change in the charging rate is estimated on the basis of inputs and outputs of current to and from the large-scale battery (12) to obtain a current-integrated SOC calculated value that has changed from the voltage-estimated SOC value, the advisability of reacquisition is determined on the basis of at least one of a continuous traveling history, a charge / discharge history, and a temperature history, and the charging rate is estimated using the voltage of the large-scale battery (12) even if the vehicle (10) is in the P range and reacquisition is permitted, and if the inputs and outputs of current to and from the large-scale battery (12) are less than a first predetermined value.

Description

Device for determining the charging rate of vehicle-mounted rechargeable batteries

[0001] The present invention relates to determining the charging rate of a rechargeable battery when operating an electric vehicle.

[0002] Currently, automobiles equipped with large-capacity lithium-ion batteries that run on these batteries are becoming more common. Hybrid vehicles, which are equipped with large-capacity lithium-ion batteries along with power generation mechanisms such as engines and fuel cells, have taken the lead, and fully electric vehicles that can be charged externally are also becoming more common.

[0003] These electric vehicles primarily use power stored in large-capacity lithium-ion batteries, so it is extremely important to understand the current state of charge (SOC). In particular, fully electric vehicles cannot even travel if the state of charge drops. Even if this is not the case, if a sufficient state of charge is not maintained, it becomes difficult to travel long distances. On the other hand, if the state of charge is too high, the battery may be overvoltaged, making it impossible to use regenerative current.

[0004] In the case of a fuel tank for an engine vehicle, the amount of remaining fuel can be physically measured using a float installed inside the tank, but it is extremely difficult to directly observe the current state of charge of a lithium-ion battery. Strictly speaking, the current situation is that the remaining charge of the battery cannot be determined until it is completely discharged. However, since this is not possible to operate the battery in this way, it is common practice to obtain data in advance based on the battery's design and capacity, and based on that data, estimate the state of charge when a certain voltage is displayed, display this to the driver, and control the battery internally.

[0005] However, the voltage of a battery increases or decreases depending on the amount of current during charging or discharging. Therefore, there are limitations to estimating the state of charge based solely on the voltage. Therefore, a method is proposed in which the current flowing in and out of the battery is measured and the sum of this current is also used to estimate the state of charge. For example, this is proposed in Patent Document 1.

[0006] International Publication No. 2017 / 056732

[0007] However, as pointed out in Patent Document 1, it is known that estimation by integrating current gradually leads to errors. Through investigations by the present inventors, the main causes of errors were found to be as follows. Figure 5 shows an example of a system configuration diagram of an electric vehicle 60 equipped with a battery pack 61 using a large-capacity lithium-ion battery. The battery pack 61 is equipped with a battery control unit 62 (BMU: Battery Management Unit) that controls appropriate charging and discharging. To collect data necessary for this control, a current sensor 64, a voltage sensor 65, a temperature sensor 66, and other sensors 67 are attached. The battery control unit 62 collects data such as current, temperature, and voltage to estimate the state of charge. The data is then transmitted to a control unit 71, which is a vehicle ECU, and the control unit 71 displays this state of charge data on a meter 72.

[0008] The battery control unit 62 does not calculate the charging rate in real time, but rather calculates it at its own calculation cycle and transmits it to the control unit 71. Data transmission from the current sensor 64 to the battery control unit 62 occurs at transmission cycles determined by CAN (Controller Area Network) communication. To synchronize with these cycles, a time delay of approximately several tens of milliseconds occurs between each transmission. First, the resulting time error becomes a significant factor when accumulated. Furthermore, the current sensor 64 may not be able to capture instantaneous changes in current, and the transmitted current value may not accurately capture the peak. In this case, a current value smaller than the actual current value is transmitted with a delay, resulting in a delayed response and incomplete detection of the discharge current.

[0009] Furthermore, due to individual differences between individual lithium-ion battery cells, the amount of current that can flow even at the same potential varies to some extent, which can have a significant impact in some cases. In addition, the discharge characteristics of lithium-ion batteries are significantly affected by ambient temperature, and the amount of electricity that can actually be charged / discharged can decrease due to the influence of temperature. Furthermore, due to the characteristics of the current sensor 64 itself, if the current value is too high or too low, a certain amount of correction can be made to address the issue, but the impact of differences in sensitivity is likely to remain.

[0010] For these reasons, it has been found that there are cases where the charging rate value obtained according to the integrated amount of current value obtained via the BMU inevitably deviates from the actual situation.

[0011] Therefore, an object of the present invention is to suppress the influence of errors that occur when estimating the state of charge using the integrated current capacity in an electric vehicle, thereby enabling a state of charge that more closely reflects the actual situation to be grasped.

[0012] The present invention solves the above problem by a first solving means which is a vehicle charging rate grasping device, which comprises: a voltage reference estimation means which, when the vehicle is started, estimates the charging rate using the voltage of the large-scale battery to obtain a voltage estimated SOC value; after driving has started, a current reference estimation means which estimates changes in the charging rate based on the current input and output of the large-scale battery to obtain a current integrated SOC calculation value which has changed from the voltage estimated SOC value; a reacquisition determination means which determines whether or not reacquisition is possible based on at least one of continuous driving history, charge and discharge history, and temperature history; and a voltage acquisition correction means which estimates the charging rate using the voltage of the large-scale battery even when the vehicle range is in P range and the reacquisition is possible, or when the current input and output of the large-scale battery is less than a first predetermined value.

[0013] Furthermore, in addition to the first solution means, the vehicle charging rate grasping device of the present invention can employ a second solution means that is capable of executing a notification means to a pre-registered user terminal, and that executes an incompletion notification means to notify the user terminal of the fact that the vehicle has become non-operating before the execution of the voltage acquisition correction means is completed.

[0014] Furthermore, in addition to the first solution means, the vehicle charging rate grasping device according to the present invention can employ a third solution means, which executes the voltage acquisition correction means when the range of the vehicle is other than the P range and the difference between the current integrated SOC calculation value estimated by the current reference estimation means and the charging rate estimated using the voltage immediately before becomes equal to or greater than a second predetermined value.

[0015] Furthermore, in addition to the third solution, the vehicle charging rate determination device of the present invention can employ a fourth solution, which executes a frequency adjustment means to set the second predetermined value smaller the lower the battery temperature of the large-scale battery or the lower the charging rate determined by the vehicle charging rate determination device.

[0016] Furthermore, in addition to the first to fourth solutions, the vehicle charging rate grasping device of the present invention can employ a fifth solution, in which, when the temperature history or the charge / discharge history satisfies a predetermined condition and the measured voltage of the large-scale battery reaches a third predetermined value, the next time the input / output of current of the large-scale battery falls below the first predetermined value, the voltage acquisition correction means is executed.

[0017] The vehicle charging rate grasping device of the present invention can suppress the discrepancy between the grasped charging rate and the actual charging rate by first calculating a voltage estimated SOC value using a voltage acquisition correction means and treating this as the latest charging rate grasped by the vehicle charging rate grasping device, even in situations where a small current amount and a small voltage drop are expected, such as when the vehicle is parked in P range, and in situations where it is determined from history that re-acquisition is necessary.

[0018] A functional block diagram showing an embodiment of a vehicle charging rate determination device according to the present invention. An example of a graph showing different discharge processes depending on temperature in the embodiment and corresponding responses. An example of a flow for re-acquiring the charging rate value based on multiple histories. An example of a condition diagram for the driving history of FIG. 3. An example of a condition diagram for the charge / discharge history of FIG. 3. An example of a condition diagram for the temperature history of FIG. 3. A functional block diagram of a conventional vehicle equipped with a large-scale battery.

[0019] An embodiment of the vehicle charging rate determination device 11 according to the present invention will be described below with reference to the functional block diagram shown in Figure 1. Note that each means executed in the present invention may be primarily executed by either the battery control unit 13 or the control unit 21 of the entire vehicle 10, and there are no particular limitations on the part where it is executed as long as it can acquire the necessary data and calculate the necessary results. The allocation of each means is one example in the embodiment.

[0020] The vehicle charging rate monitoring device 11 according to the present invention is mounted on the vehicle 10, which is an electric vehicle. Here, the electric vehicle may not only be an electric vehicle that runs only on an external power supply, but also a hybrid vehicle having an engine or a fuel cell. In the case of a hybrid vehicle, the vehicle may not only be charged by power generated by an engine, but may also be a plug-in hybrid vehicle (PHEV) that is equipped with an external charger that allows power to be charged from an external source or an external power supply that allows power to be supplied to an external source. In other words, the type of electric vehicle is not limited as long as the vehicle 10 uses electricity from the large-scale battery 12 as driving force for traveling.

[0021] The large-scale battery 12 is basically a secondary battery, such as a lithium-ion battery or a sodium battery, that has a high voltage and large capacity and supplies power for driving. In other words, it is basically a battery that is installed separately from the lead-acid battery.

[0022] The large-scale battery 12 has a battery control unit 13 that controls the battery so that it can be appropriately charged and discharged. This battery control unit 13 does not require the addition of a new arithmetic unit or the like to the large-scale battery 12 for the purpose of this invention, and may be realized by updating the program of a conventionally used BMU or the like. In other words, the operation of the battery control unit 13 may be achieved by executing the various means described below by executing a stored program.

[0023] The vehicle 10 also has a control unit 21 for controlling parts other than the battery and for performing higher-level management of the battery control unit 13. The control unit 21 also realizes functions realized by executing stored programs and each of the means described below as functions using dedicated circuits. There is no need to provide a separate control unit 21 specifically for the present invention; it is easy to introduce the control unit 21 by installing and executing a program that realizes each of the means constituting the present invention as an additional function in an ECU (Electronic Control Unit) mounted on the vehicle 10 for driving control, etc.

[0024] Both the battery control unit 13 and the control unit 21 may have a necessary storage unit along with a calculation device, and may store data and programs and use them for calculations as appropriate.

[0025] The vehicle charging rate monitoring device 11 according to the present invention preferably includes a wireless interface 22 for wireless network communication. Specifically, wireless communication functions such as a mobile communication network and Wi-Fi (registered trademark) can be used. The control unit 21 may be capable of executing a notification means 41 for sending a notification to a user terminal 51 held by the driver via the wireless interface 22 having these functions. At least one of the telephone number or other identification number of the user terminal 51, a corresponding ID in a web service managed by the automobile company, and information that can reference these numbers or IDs is stored in the storage unit, and a notification is displayed or played on the user terminal 51 by specifying and transmitting the number or ID.

[0026] The large-scale battery 12 is also equipped with various sensors that monitor the battery status and transmit the information to the battery control unit 13. At least a current sensor 14 and a voltage sensor 15 are required, and a temperature sensor 16 is preferable. The current sensor 14 is a sensor that detects the current input and output to the battery. The voltage sensor 15 is a sensor that detects the battery voltage. The temperature sensor 16 is a sensor that detects the battery temperature. Each sensor may be for the entire large-scale battery 12 or for each individual cell, and it is more preferable to have both. The battery control unit 13 periodically receives data from these sensors and performs appropriate control according to the program. By executing the various means described below, the battery can more accurately monitor the charging rate.

[0027] The battery control unit 13 or control unit 21 of the vehicle state of charge determination device 11 according to the present invention executes a voltage reference estimation means 31 that estimates the state of charge using the voltage of the large-scale battery 12 and calculates a voltage-estimated SOC value when the vehicle 10 is started. Startup basically refers to when the ignition is turned on, and is the timing when the state in which the large-scale battery 12 has been discharging no current or a nearly negligible amount of current until then changes to a state in which it is now able to output current. In other words, at this stage, the amount of current can be considered nearly zero, the voltage drop of the large-scale battery 12 can be nearly negligible, and the state in which the state in which the state of charge is estimated using the voltage is highly accurate. The estimation method here involves referencing a correspondence table or correspondence function between voltage and charging rate, an SOC-OCV (-Open Current Voltage) curve, etc. (hereinafter referred to as "correspondence table, etc.") that are stored in advance in a storage unit (not shown) of the control unit 21 or the battery control unit 13 as the physical properties of the large-scale battery 12 of the vehicle 10, and determining the charging rate that corresponds to the voltage value sent from the voltage sensor 15, thereby determining the voltage estimated SOC value. The voltage estimated SOC value determined in this way becomes the initial value of the charging rate estimated during driving.

[0028] After starting to drive, the battery control unit 13 or control unit 21 of the vehicle state of charge determination device 11 according to the present invention executes a current reference estimation means 32 that estimates changes in the state of charge using the input and output current values ​​of the large-scale battery 12 and calculates a current integrated SOC calculation value that has changed from the voltage estimated SOC value. The input and output currents can be obtained by integrating the current values ​​sent from the current sensor 14 over time. The current integrated SOC calculation value, which is basically obtained by subtracting the amount of electricity equivalent to the integrated amount of current discharged from the initial state of charge, becomes the state of charge estimated at that time. The current reference estimation means 32 is executed periodically to obtain the value of the state of charge estimated at that time.

[0029] The battery control unit 13 or the control unit 21 of the vehicle state of charge determination device 11 according to the present invention executes a reacquisition determination means 33 that determines whether or not to reacquire the state of charge based on at least one of the continuous driving history, the charge / discharge history, and the temperature history. Here, "reacquisition" refers to reacquiring a state of charge value estimated using a new voltage value (using a voltage acquisition correction means 34, described later), rather than continuing to use the state of charge calculated based on the current-integrated SOC value. In a given environment, as the integrated amount of current increases, the error from the actual state becomes significant. Therefore, if a given condition is met, reacquisition allows the vehicle 10 to operate by obtaining a state of charge value closer to the actual state.

[0030] An example flow for re-acquiring the value of the state of charge based on these histories is shown in Figure 3. After starting (IG-ON), the driving history of the vehicle 10 itself, the charge / discharge history of the large-scale battery 12, the temperature history, etc. are recorded in parallel, and once any one of these conditions, or a combination of these conditions, is met, the voltage acquisition correction means 34 is executed the next time the amount of current decreases (gear P or coast state).

[0031] Here, an example of a continuous driving history is re-acquisition every five hours of driving time since startup. Alternatively, re-acquisition every 20 km of driving distance may be performed. However, the driving distance does not have to be constant. For example, the driving distance may be set according to the driving time, such as every 80 km when the driving time is short, or every 20 km when the driving time is long. In either case, it is considered that the error becomes unacceptable as driving continues for a long period of time. The graph in FIG. 4A shows an example of a condition used to determine whether or not to enable re-acquisition based on these combined conditions of driving distance and usage time. The bold line in the figure represents the condition line for whether or not re-acquisition is possible, and the area above and to the right of the condition line is valid, i.e., "Yes." In the example of high-speed driving shown in the figure, the condition line is crossed and valid when the driving distance exceeds 60 km in about one hour. In the example of medium-speed driving shown in the figure, the condition line is crossed and valid when the driving distance exceeds 40 km in about three hours. In the example of low-speed driving shown in the figure, the diagonal driving distance line is not crossed until five hours have passed, so the data is valid when five hours have passed.

[0032] Examples of charge / discharge history include re-acquiring the counted integrated current capacity each time 30% or more of the estimated total capacity of the large-scale battery 12 is consumed (the consumption here is determined by current accumulation), re-acquiring the count each time the most recently acquired value of the known charging rate falls below a predetermined threshold, or counting the frequency of high current usage and re-acquiring the count every predetermined number of times. An example of a condition using this frequency of high current usage is shown in the graph of FIG. 4B . The frequency of current values, both positive and negative, i.e., both charging and discharging current, is continuously counted per unit time. When the current amount, either positive or negative, falls within a valid range that exceeds a predetermined invalid range, it is treated as a high current and counted as a "high current usage frequency." When the frequency of high current usage reaches a predetermined number of times, re-acquisition is performed, and the frequency is reset, and the "high current usage frequency" continues to be counted.

[0033] For example, temperature history may be obtained by counting the time used in an extremely low temperature state and re-obtaining the data each time the count reaches a predetermined number, or by re-obtaining the data each time the deviation of the actual temperature of the large-scale battery 12 from the set standard temperature, accumulated over time, exceeds a predetermined value. The graph in FIG. 4C shows an example of conditions for counting the time used in a low temperature state. The temperature of the large-scale battery being used is counted every predetermined unit of time during operation, and the number of times this is done is counted for each temperature range. In practice, the graph will be a line graph showing the counts for each temperature range. Re-obtaining the data is performed when the total count for the valid range of temperatures below 0°C reaches a predetermined number. Alternatively, the valid range of temperatures may be limited to even colder temperatures below -20°C or -30°C.

[0034] The determination procedure using these histories is merely an example, and the use of the present invention is not limited to the above-mentioned form. If all data on these charge / discharge histories and temperature histories were recorded, the amount of data would be enormous, placing a heavy burden on memory. For this reason, it is possible to reduce the amount of data by not recording the history in the invalid area and recording only the history in the valid area. This allows for faster and lighter determination processing.

[0035] The battery control unit 13 or the control unit 21 of the vehicle charging rate determination device 11 according to the present invention executes the voltage acquisition and correction means 34 that estimates the charging rate using the voltage of the large-scale battery 12 when at least one of the following conditions (1) and (2) is met. That is, by correcting the determined charging rate using the voltage acquired in the situations (1) and (2), various errors that occur during current integration are corrected to obtain a charging rate value that is closer to the actual situation, and the vehicle 10 can run in accordance with that value.

[0036] The above condition (1) is when the vehicle's range is P range and the possibility of re-acquisition is yes. The range refers to the gear state that can be changed by operating the shift lever, and P range refers to a state in which the gear is fixed or a state equivalent thereto. In the P range state, the vehicle 10 does not start moving, and no large current flows through the large-scale battery 12, so voltage drop in the large-scale battery 12 is suppressed.

[0037] The above condition (2) is when the input / output current of the large-scale battery 12 is less than a first predetermined value. This first predetermined value is a situation in which the input / output current is as small as possible and the voltage drop of the large-scale battery 12 is small. Regardless of the above range, the current value is set to be less than the first predetermined value only when the current amount is extremely small, such as when the vehicle speed is 0 km / h or when coasting. This first predetermined value is set at the time of shipment according to the characteristics of the vehicle 10 and the large-scale battery 12, and can be determined by the battery control unit 13 or the control unit 21 appropriately reading it from the memory unit.

[0038] In these conditions, the voltage value obtained from the voltage sensor 15 is used to obtain the value of the charging rate indicated by that voltage by referring to the correspondence table between the voltage and the charging rate, and this charging rate value can be used as is or a calculated value can be obtained by adding the previously known charging rate including weighting, thereby making it possible to estimate a highly accurate charging rate value, and the charging rate recognized by the vehicle charging rate recognition device 11 is corrected to this value, and subsequent operation is continued. However, it is not necessary to perform the voltage acquisition correction means 34 every time the gear shifts to the P range, and it is considered to be necessary only if the above-mentioned re-acquisition is possible.

[0039] Furthermore, the battery control unit 13 or 21 of the vehicle charging rate determination device 11 according to the present invention preferably executes the voltage acquisition correction means 34 when the vehicle 10 is in a range other than P range and the difference between the current integrated SOC calculation value estimated by the current reference estimation means 32 and the most recently calculated voltage estimated SOC value exceeds a second predetermined value. Even in a situation where the vehicle has been traveling for a long time and it took a long time for the vehicle to be shifted into P range, if the difference between the charging rate estimated by current integration and the most recently calculated voltage estimated SOC value exceeds the second predetermined value, it is highly likely that an error has accumulated and become unacceptable. This second predetermined value may be set to, for example, 5% of the total battery capacity. Note that this value may be adjusted appropriately for each vehicle type, such as a hybrid vehicle or an electric vehicle. For example, the second predetermined value may be set smaller for an electric vehicle than for a hybrid vehicle. Furthermore, when the voltage acquisition and correction means 34 is executed on the condition that the voltage has reached or exceeded the second predetermined value, it is more preferable to execute the process when the current value from the large-scale battery 12 has sufficiently decreased, such as when the vehicle 10 has stopped temporarily and the speed has reached 0 km / h, or when the vehicle is coasting (for example, when the accelerator pedal stroke in D range reaches 0% or the current value from the current sensor falls below a predetermined value). This is because, during normal driving, the current output is large and the voltage drop cannot be ignored, causing the measured voltage to decrease, and therefore, using that voltage to estimate the state of charge may result in the estimated state of charge becoming increasingly different from the actual situation.

[0040] Furthermore, the battery control unit 13 or the control unit 21 of the vehicle charging rate determination device 11 according to the present invention preferably executes a frequency adjustment means 35 that sets the second predetermined value smaller as the battery temperature of the large-scale battery 12 or the charging rate determined by the vehicle charging rate determination device 11 decreases. Adjusting the frequency adjustment means 35 appropriately increases or decreases the number of correction opportunities. In low battery temperature environments, errors due to the characteristics of the current sensor 14 itself tend to become significant. By correspondingly decreasing the second predetermined value and increasing the execution frequency of the voltage acquisition correction means 34, deviation from the actual situation can be adequately suppressed. Furthermore, whether based on voltage or current, the lower the charging rate determined by the vehicle charging rate determination device 11 at that time, the greater the deviation between the estimated charging rate and the actual situation. This is because the impact of deviations in the battery charge / discharge curve from the expected value cannot be ignored, particularly at low charging rates. Therefore, by correspondingly decreasing the second predetermined value and increasing the execution frequency of the voltage acquisition correction means 34, deviation from the actual situation can be adequately suppressed. Of course, it is more desirable to set the second predetermined value small in accordance with both the battery temperature and the charging rate, as this will more effectively prevent deviation from the actual situation.

[0041] Furthermore, when the battery control unit 13 or 21 of the vehicle charging rate determination device 11 according to the present invention acquires a voltage value during execution of the voltage acquisition correction means 34, it may not only use the voltage value obtained by referencing the correspondence table or the like as the charging rate thereafter, but may also weight and sum the current-integrated SOC calculation value and the voltage value obtained by referencing the correspondence table or the like, and set the sum as the charging rate. Voltage values ​​during or immediately after driving are not completely reliable, and although the value estimated by integrating the current values ​​up to that point contains errors, it still reflects the actual situation to some extent. Therefore, by adding these values ​​together with weighting, it is possible to obtain a charging rate value with even smaller errors. A simple weighting method is to take a simple average, but adjusting the weighting depending on the situation is more preferable.

[0042] An example of the weighting is shown in Table 1. When the voltage acquisition correction means 34, which acquires the voltage value during normal driving, is executed, the newly estimated value of the charging rate is obtained by multiplying the charging rate obtained from the voltage using a correspondence table or the like by 0.6, adding the value obtained by multiplying the current integrated SOC calculated up to that point by 0.4, and determining the new value of the charging rate. This is because it is fully possible that the voltage may not be stable depending on the timing during normal driving. Next, as Case 1, when the voltage acquisition correction means 34, which acquires the voltage value, is executed in a situation where high current is frequently present or in an extremely low temperature environment, the newly estimated value of the charging rate is obtained by multiplying the charging rate obtained from the voltage using a correspondence table or the like by 0.8, adding the value obtained by multiplying the current integrated SOC calculated up to that point by 0.2, and determining the new value of the charging rate. This is because the current value cannot be tracked in a situation where a high current is flowing or in an extremely low temperature environment. Furthermore, as Case 2, for example, when the voltage acquisition correction means 34 that acquires the voltage value is executed in a low temperature environment where the current value cannot be tracked, but is not a situation where the frequency of high current is high or a low temperature environment, the newly estimated value of the charging rate is obtained by multiplying the charging rate obtained from the voltage using a correspondence table or the like by 0.7, and adding the result obtained by multiplying the current integrated SOC calculated value up to that point by 0.3. This is because the current value cannot be tracked, although not as frequently as in a situation where the frequency of high current is high or a low temperature environment. Alternatively, Case 2 may be a situation where the frequency of high voltage is higher than the predetermined condition, but not as frequently as in Case 1.

[0043]

[0044] These multiplication weight ratios are merely examples, and optimal values ​​should be set appropriately at the time of shipment depending on the characteristics of the vehicle 10 and the characteristics of the large-scale battery 12, and in some cases, they may be adjustable via the control unit 21 by the driver's operation.

[0045] The vehicle charging rate determination device 11 according to the present invention preferably displays the determined charging rate on a display unit 23 located in a position visible from the driver's seat of the vehicle 10. The display method may be an analog meter or a digital meter, and is not particularly limited. However, a digital meter makes it easier to realize the effect of the correction according to the present invention.

[0046] Furthermore, the control unit 21 of the vehicle charging rate monitoring device 11 according to the present invention is preferably capable of communicating with a user terminal 51 using the wireless interface 22 of the vehicle 10. The user terminal 51 is preferably a wireless-enabled terminal carried by the driver, and a typical smartphone is preferably used. Alternatively, the user terminal 51 may be a terminal such as a tablet connected to a home computer installed in the driver's home. Regardless of the form, it is sufficient that the notification by the notification means 41 from the vehicle charging rate monitoring device 11 can be received and displayed on a screen or audibly notified so that the driver can confirm the notification. For example, the user terminal 51 may be installed with a dedicated application that can execute these functions. Although not shown, notification may be enabled via a control server between the wireless interface 22 and the user terminal 51.

[0047] If the vehicle 10 enters a non-operating state before the voltage acquisition correction means 34 is fully executed, the control unit 21 preferably executes the incompletion notification means 42, which notifies the user terminal 51 of this. Generally, the voltage acquisition correction means 34 is executed at some stage before the vehicle is stopped and parked, and the driver ends the drive by shifting the gear to P. However, if the ignition is turned off immediately after shifting the gear to P, the voltage acquisition correction means 34 may not be executed in time to determine the new state of charge and update the display accordingly. In this case, the last state of charge value checked by the driver is likely to be different from the actual state, and this value is communicated to the driver without being corrected. This can lead to the driver starting the next drive with a misunderstanding of the current state of charge of the vehicle 10. For this reason, if the vehicle enters a non-operating state before the voltage acquisition correction means 34 is fully executed, it is preferable to notify the driver of this, i.e., that the last state of charge displayed by the driver is likely to be a value that has not been re-obtained by the voltage acquisition correction means 34 and contains a large error, or a summary of this information.

[0048] An example of a specific implementation of the vehicle charging rate grasping device 11 according to the present invention is shown in the graph of FIG. 2, and its contents will be described below.

[0049] This vehicle is equipped with a large-scale battery designed to have a voltage of 4.10 V at 100% charge and 2.80 V at 0% charge. At vehicle startup, which is indicated by starting point A in the figure, the voltage value acquired by the voltage sensor was 4.00 V. The battery control unit holds an SOC-OCV curve showing the characteristics of this large-scale battery, and the voltage reference estimation means 31 references this SOC-OCV curve to acquire a charge rate of 90% at startup. Thereafter, the current reference estimation means 32 continues to integrate the current value acquired by the current sensor, thereby estimating the charge rate. The change in charge rate at room temperature is shown by a thick solid line, and the change in charge rate at low temperatures is shown by a thin solid line. An excerpt of the SOC-OCV curve values ​​at room temperature is shown on the left side of Figure 2.

[0050] If the temperature history remains at room temperature, the reacquisition determination means determines that there is little error, and leaves the decision as to whether or not reacquisition is possible as "no," and continues to acquire the charging rate using the current reference estimation means 32, and uses the value as it is without executing the voltage acquisition correction means 34 as the charging rate.

[0051] On the other hand, when the temperature history is low (assuming temperatures are below 0°C), the voltage drop is more significant than at room temperature. In this example, the large-scale battery exhibits a characteristic of a 70% state of charge at 3.85 V on the SOC-OCV curve at room temperature. However, at low temperatures, the battery's internal resistance increases, resulting in a corresponding large voltage drop. Therefore, the voltage of the large-scale battery measured in real time reaches 3.85 V before the actual state of charge drops to 70%. A voltage corresponding to a predetermined state of charge, which is used as a criterion for determining a certain drop in state of charge, is set as a third predetermined value. Here, this voltage of 3.85 V, which would normally indicate a state of charge of 70%, is set as the first control threshold, which serves as a dividing line. When the voltage measured in real time in this low-temperature environment reaches this first control threshold (third predetermined value), the voltage acquisition and correction means 34 is executed the next time the vehicle speed reaches 0 km / h and the input / output current falls below the first predetermined value.

[0052] Although only the temperature history is used as an example here, if the charging / discharging history includes a large voltage drop, such as when a large current is instantaneously discharged due to sudden acceleration, the first control threshold may be reached quickly in an instant. Even under such conditions, the voltage acquisition and correction means 34 is operated.

[0053] In either case, when the shift shifts to P range or the vehicle speed reaches 0 km / h, the voltage acquisition and correction means 34 is executed to first acquire a voltage value from the voltage sensor. This voltage value is used as the reference value for the state of charge obtained by referring to the SOC-OCV curve, but is not used as is for the reference value for the state of charge to be calculated thereafter. Instead, it is weighted and added to the voltage of the first control threshold. The state of charge value obtained by referring to the SOC-OCV curve using the voltage value is multiplied by 0.8, and the latest value of the current-integrated SOC calculation value estimated up to that point is multiplied by 0.2, and these values ​​are summed. This sum is recognized as the state of charge value estimated at this stage (starting point B). Thereafter, the current-reference estimation means is executed using starting point B as a reference to determine the current-integrated SOC calculation value.

[0054] Although this embodiment uses a low-temperature environment as an example, if the battery itself has deteriorated due to its charge / discharge history or continuous driving history, the internal resistance of the battery may increase and the voltage drop may become large.

[0055] The subsequent estimation of the state of charge (area 2) is performed at room temperature by using the state of charge at starting point A as the basis, executing the current-based estimation means to obtain a current-integrated SOC calculation value, and continuing to estimate the state of charge. Meanwhile, in a low-temperature environment, the state of charge at starting point B, which was estimated using the voltage by the voltage acquisition and correction means, is used as the basis, and then the current-based estimation means is executed to obtain a current-integrated SOC calculation value, and continuing to estimate the state of charge. Furthermore, in a low-temperature environment, when the voltage reaches the next set second control threshold of 3.0 V, the voltage value is acquired again, and the voltage acquisition and correction means is executed, just as when the first control threshold is reached. This second control threshold of 3.0 V is the line indicating a state of charge of 20% according to the SOC-OCV curve. This is taken as the newly estimated value of the state of charge (starting point C).

[0056] In area 3, where the voltage is even lower than the second control threshold, in a normal temperature environment, the current reference estimation means is executed to determine the current integrated SOC calculated value based on starting point A. On the other hand, in a low temperature environment, the current reference estimation means is executed to determine the current integrated SOC calculated value based on starting point C. As a result, even in a low temperature environment, by making appropriate corrections, it is possible to continue to grasp the state of charge with a small deviation from the actual situation.

[0057] REFERENCE SIGNS LIST 10 Vehicle 11 Vehicle charging rate grasping device 12 Large-scale battery 13, 62 Battery control unit 14, 64 Current sensor 15, 65 Voltage sensor 16, 66 Temperature sensor 17, 67 Other sensors 21, 71 Control unit 22 Wireless interface 23 Display unit 31 Voltage reference estimation means 32 Current reference estimation means 33 Reacquisition determination means 34 Voltage acquisition correction means 35 Frequency adjustment means 41 Notification means 42 Incompletion notification means 51 User terminal 60 Electric vehicle 61 Battery pack 72 Meter

Claims

1. A device for determining the charge level of a large battery installed in a vehicle, When the vehicle is started, a voltage reference estimation means is executed to estimate the charge rate using the voltage of the large battery and to obtain the estimated voltage SOC value. After the start of operation, the current reference estimation means is executed to estimate the change in the charge rate based on the input and output of the current of the large battery, and to calculate the current integrated SOC value that has changed from the voltage estimated SOC value. A reacquisition determination means is executed to determine whether or not reacquisition is possible based on at least one of the continuous driving history, charge / discharge history, and temperature history. When the input / output current of the large-scale battery is below a first predetermined value, a voltage acquisition correction means is executed to estimate the charge level using the voltage of the large-scale battery and correct the current integrated SOC calculation value. Vehicle charge level monitoring device.

2. A device for determining the charge level of a large battery installed in a vehicle, When the vehicle is started, a voltage reference estimation means is executed to estimate the charge rate using the voltage of the large battery and to obtain the estimated voltage SOC value. After the start of operation, the current reference estimation means is executed to estimate the change in the charge rate based on the input and output of the current of the large battery, and to calculate the current integrated SOC value that has changed from the voltage estimated SOC value. A reacquisition determination means is executed to determine whether or not reacquisition is possible based on at least one of the continuous driving history, charge / discharge history, and temperature history. Even when the vehicle's range is in the P range and the possibility of reacquisition is permitted, and when the input / output of the current of the large battery is less than a first predetermined value, the voltage acquisition correction means is executed to estimate the charge rate using the voltage of the large battery and correct the current integrated SOC calculation value. It is possible to implement a notification method to pre-registered user terminals, If the vehicle becomes inoperable before the execution of the voltage acquisition correction means is completed, an incomplete notification means is executed to notify the user terminal that there is a high probability that the displayed charge rate is a value that has not been reacquired. Vehicle charge level monitoring device.

3. A device for determining the charge level of a large battery installed in a vehicle, When the vehicle is started, a voltage reference estimation means is executed to estimate the charge rate using the voltage of the large battery and to obtain the estimated voltage SOC value. After the start of operation, the current reference estimation means is executed to estimate the change in the charge rate based on the input and output of the current of the large battery, and to calculate the current integrated SOC value that has changed from the voltage estimated SOC value. A reacquisition determination means is executed to determine whether or not reacquisition is possible based on at least one of the continuous driving history, charge / discharge history, and temperature history. When the vehicle's range is other than P range, and the difference between the current integrated SOC calculation value estimated by the current reference estimation means and the charge rate estimated using the voltage obtained immediately before is greater than or equal to a second predetermined value, the voltage acquisition correction means is executed to estimate the charge rate using the voltage obtained immediately before and correct the current integrated SOC calculation value. Vehicle charge level monitoring device.

4. The frequency adjustment means is executed to set the second predetermined value to a smaller value as the battery temperature of the large-scale battery decreases, or as the charge rate detected by the vehicle charge rate monitoring device decreases. The vehicle charge level determination device according to claim 3.

5. When the temperature history or the charge / discharge history satisfies predetermined conditions and the measured voltage of the large battery reaches a third predetermined value, the voltage acquisition correction means is executed when the input / output current of the large battery falls below a first predetermined value. A vehicle charge level determination device according to any one of claims 1 to 4.