JP2019170136A - Charge control device - Google Patents

Abstract

To specify a factor of difficulty of charge if there is possibility of the difficulty of charge when charging lithium ion secondary battery.SOLUTION: A charge control device 10 includes: a calculation section 13 for calculating a first charging rate Ci on the basis of a current integration value of a lithium ion secondary battery; a determination section 14 when the first charging rate Ci during charging of the battery is less than full charging determination value Cf, for determining whether charging is to be continued or not on the basis of a chargeable rate Cp indicating a rate of chargeable capacity to the current capacity of the battery; and a control section 15 for controlling a charging state of the battery on the basis of the determined result of the determination section 14. The chargeable rate Cp is previously set and has characteristics that when a battery temperature T is lowered, the chargeable rate is lowered.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a charging control device that performs appropriate control by identifying the cause of charging when there is a possibility that charging is difficult when charging a lithium ion secondary battery (hereinafter simply referred to as “battery”). It is suitable for use during normal charging of a vehicle-mounted battery.

  Conventionally, in electric vehicles such as electric vehicles and hybrid vehicles, various methods have been developed for accurately calculating the state of charge (SOC) of a battery for driving the vehicle. For example, there is a method of calculating the charging rate by accumulating the charging / discharging current of the battery and tracking the change in the battery capacity. In addition, the relationship between the battery open voltage (OCV, Open Circuit Voltage) and the charge rate is defined in advance in the form of a function, map, or table, and the charge rate is calculated from the measured value or estimated value of the open voltage. There is also a method for calculating.

  The former method is called current integration method or current integration method, and the latter method is called voltage estimation method or OCV method. These methods are selectively used according to the running state of the vehicle and the state of the battery, or are used in combination (see Patent Document 1). For example, since the OCV method can be accurately calculated when the open-circuit voltage value is stable, the current integration method is used during energization, and the OCV method is used only when the open-circuit voltage value is stable. It is possible to use it.

JP 2017-223537 A

  However, the calculation accuracy of the charging rate by the current integration method is characterized in that it depends on the detection accuracy of the current value. Therefore, when charging the battery using the charging rate calculated by this method, if calculated as a value lower than the true charging rate (that is, if there is an error in the calculated charging rate), it is based on the calculated charging rate. If the charging current is controlled in this way, there is a problem that the battery is not fully charged indefinitely. In other words, in this case, there is a problem that due to this problem, the control device misidentifies that “the charging is difficult”, and the charging completion timing is delayed.

  In addition to the above problems, the battery has a characteristic that the internal resistance of the battery increases and the charging current decreases in a low temperature state. Therefore, charging becomes difficult in a low temperature state. Furthermore, the battery also has a characteristic that the chargeable capacity (charge capacity) decreases in a low temperature state. For this reason, when charging in a low temperature state, even if it is determined that the control device has reached full charge and further charging is difficult (ie, charging is completed), the battery temperature rises. When the charging capacity increases (recovers), a phenomenon occurs in which the charging rate decreases even though the battery is not used. In this case, since the display part (for example, segment display) which shows the charge condition of a battery changes from the display which shows a full charge state, there exists a subject of giving a user discomfort.

  The charging control device of the present invention has been devised in view of such problems, and when charging a lithium ion secondary battery, if there is a possibility that charging is difficult, the cause is identified and appropriate control is performed. One of the purposes is to do. The present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiment for carrying out the invention described later, and has another function and effect that cannot be obtained by conventional techniques. is there.

  (1) A charging control device disclosed herein includes a calculating unit that calculates a first charging rate based on a current integrated value of a lithium ion secondary battery, and the first charging rate during charging of the battery is a full charge determination. A determination unit that determines whether or not to continue the charging based on a possible charge rate that indicates a ratio of a chargeable capacity to a current capacity of the battery, and a determination result by the determination unit when the value is less than the value And a control unit that controls the state of charge of the battery, wherein the possible charge rate is set in advance and has a characteristic of becoming lower as the temperature of the battery is lower.

(2) When the voltage value of the battery is stable, the calculation unit calculates a second charging rate based on the voltage value, and the control unit determines that the charging is not continued by the determination unit. Preferably, the charging is temporarily stopped and the second charging rate calculated by the calculating unit is acquired.
(3) Preferably, when the determination unit determines that the charging is not continued, the control unit temporarily stops the charging after the voltage value of the battery is stabilized.

  (4) If the second charging rate is less than the full charge determination value, the control unit sets a target charging current according to the second charging rate and restarts the charging, and the second charging rate. Is preferably equal to or greater than the full charge determination value, the charging is preferably terminated.

  (5) It is preferable that the battery is provided with a heater that is electrically connected to the battery via a circuit breaker and operates according to the temperature of the battery to heat the battery. . In this case, when the determination unit determines that the charging is not continued and the heater is operating, the control unit temporarily stops the charging by setting the breaker in a disconnected state. However, it is preferable to acquire the second charging rate after the operating state of the heater is maintained and the voltage value of the battery is stabilized.

(6) It is preferable that the control unit notifies the user that it is difficult to charge when the determination unit determines that the charging is continued.
(7) When the determination unit determines that the charging is to be continued, the control unit notifies the user by turning on an indicator indicating that charging is difficult, and the charging duration time is a timeout period. It is preferable to end the charging while the indicator is turned on.

  (8) The charging control device includes a storage unit that stores a three-dimensional map in which a relationship among the temperature of the battery, the degree of deterioration of the battery, and the possible charge rate is defined, and the temperature and the It is preferable to provide an acquisition unit that applies the degree of deterioration to acquire the possible charge rate.

  According to the disclosed charging control device, the battery temperature and the charging state can be determined at the same time by using a possible charging rate having a characteristic that the lower the battery temperature, which is the temperature of the lithium ion secondary battery, the battery is charged. In this case, if there is a possibility that charging is difficult, the cause can be identified and appropriate control can be performed.

It is a schematic diagram which illustrates the vehicle provided with the charge control apparatus which concerns on embodiment. It is a block diagram which shows the structure of the charge control apparatus and vehicle which concern on 1st embodiment. It is an example of the map memorize | stored in the memory | storage part of the charge control apparatus of FIG. It is a modification of the map memorize | stored in the memory | storage part of a charge control apparatus. It is a flowchart which illustrates the control content implemented with the charge control apparatus of FIG. It is a block diagram which shows the structure of the charge control apparatus and vehicle which concern on 2nd embodiment. It is a block diagram which shows the structure of the vehicle of FIG. 6, (a) shows during normal charge, (b) shows the charge rate estimation time immediately after completion | finish of charge. It is a flowchart which illustrates the control content implemented with the charge control apparatus of FIG. FIG. 9 is a sub-flowchart of FIG. 8.

  A charge control device as an embodiment will be described with reference to the drawings. The embodiment described below is merely an example, and there is no intention of excluding various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit thereof. Further, they can be selected as necessary, or can be appropriately combined.

[1. Device configuration]
A vehicle 1 to which the charge control device 10 of the present embodiment is applied is illustrated in FIG. This vehicle 1 is an electric vehicle (an electric vehicle or a plug-in hybrid vehicle) equipped with at least a motor 2 for traveling and a driving lithium ion secondary battery 3 (hereinafter referred to as “battery 3”) capable of external charging. It is. The motor 2 is a motor generator (motor / generator) having both a function as an electric motor and a function as a generator.

  A motor control unit 4 (hereinafter referred to as “MCU 4”) is interposed between the motor 2 and the battery 3. The MCU 4 is an electronic control device that incorporates an inverter that is a converter that mutually converts DC power on the battery 3 side and AC power on the motor 2 side. For example, when the motor 2 is powered, alternating drive power is supplied from the battery 3 side to the motor 2 side. On the other hand, during regeneration of the motor 2, DC regenerative power is supplied from the motor 2 side to the battery 3 side.

  The battery 3 is a high-voltage power source configured to be able to charge regenerative power by the motor 2 and external charging by a power source outside the vehicle. The battery 3 can be charged with a household AC power supply (normal charging) or charged with a high-voltage DC power supply (rapid charging). In the case of a plug-in hybrid vehicle, charging of electric power generated by an engine-driven generator is also possible. A charging port (not shown) for connecting the vehicle 1 to an external power supply facility is provided on the side surface of the vehicle 1.

  The vehicle 1 is provided with an in-vehicle charger 5 and an air conditioner 6 as devices that operate with the power of the battery 3. The in-vehicle charger 5 is a high voltage device that charges the battery 3 by converting electric power input from an external power supply facility during normal charging. Here, AC power supplied from the outside of the vehicle 1 is converted to DC power having a predetermined charging voltage corresponding to the battery voltage, and the battery 3 is charged. The operating state of the on-vehicle charger 5 is controlled by the charge control device 10. The air conditioner 6 includes a compressor for pumping a refrigerant used during cooling and heating in the vehicle interior and a heater used during heating, and operates according to the temperature in the vehicle interior.

  On the high voltage circuit between the battery 3 and the MCU 4, a current sensor 17 that detects the input / output current of the battery 3 and a voltage sensor 18 that detects the voltage of the battery 3 are provided. The current sensor 17 outputs a detection signal corresponding to each of the current discharged from the battery 3 and the current charged in the battery 3. The voltage sensor 18 outputs a detection signal corresponding to the voltage between the conductive wire connected to the positive electrode of the battery 3 and the conductive wire connected to the negative electrode. Detection signals output from the current sensor 17 and the voltage sensor 18 are transmitted to the charge control device 10.

  A temperature sensor 19 that detects the temperature of the battery 3 is provided inside or around the battery 3. The temperature sensor 19 of the present embodiment detects each temperature (cell temperature) of a plurality of cells built in the battery 3 and outputs the representative value or average value to the charge control device 10 as the battery temperature T. Further, as shown in FIGS. 1 and 2, a display device 7 that displays the state of charge of the battery 3 is provided in the passenger compartment of the vehicle 1. The display device 7 of the present embodiment is disposed at a position that can be easily seen by the driver, an indicator 7A indicating that charging is difficult during normal charging of the vehicle 1, and a segment 7B indicating the charging rate. Including. The indicator 7A is turned on when charging is difficult. The segment 7B is composed of a plurality of lighting sections, and the number of lighting increases as the charging rate increases, and all the lighting sections are lit when fully charged. The display device 7 (lighting and extinguishing of the indicator 7A and the segment 7B) is controlled by the charging control device 10.

  The charging control device 10 is an electronic control device (computer) that performs various controls related to charging of the battery 3 (hereinafter referred to as “charging control”). Inside the charging control device 10, a processor, a memory, an interface device, etc. (all not shown) connected to each other via a bus are built in and connected to a communication line of an in-vehicle network provided in the vehicle 1. . The sensors 17 to 19 are connected to the input side of the charge control device 10, and the in-vehicle charger 5 and the display device 7 are connected to the output side of the charge control device 10.

  The processor is a processing device including, for example, a control unit (control circuit), an arithmetic unit (arithmetic circuit), a cache memory (register), and the like. The memory is a storage device that stores programs and data during work, and includes ROM, RAM, nonvolatile memory, and the like. The contents of the control executed by the control device 30 are recorded and stored in the memory as firmware or an application program. When the program is executed, the contents of the program are expanded in the memory space and executed by the processor. In addition to the charging control device 10, the vehicle 1 is also equipped with a control device (not shown) that integrally controls in-vehicle devices such as the motor 2 and the MCU 4. This control device is also connected to the communication line of the in-vehicle network and can communicate with the charging control device 10.

[2. Control overview]
If there is a possibility of a situation where it is difficult to charge the battery 3 during normal charging of the battery 3, the charging control device 10 identifies the cause and performs appropriate control. As a situation where charging is difficult, there is a case where normal charging is performed in a state where the temperature of the battery 3 is low. In this case, since the internal resistance of the battery 3 is increased and the charging current is reduced as compared with normal charging at normal temperature or high temperature, the charging does not easily proceed (situation where charging is difficult).

  Further, the battery 3 has a characteristic that the charge capacity is lowered at a low temperature. For this reason, even if the battery 3 is fully charged in a low temperature state, if the temperature of the battery 3 rises and the charge capacity rises (recovers), the phenomenon that the charging rate decreases even though the battery 3 is not used. appear. That is, in a state where the battery 3 is at a low temperature and close to full charge, the charging capacity is reduced and the charging does not easily proceed (situation where charging is difficult).

  In contrast to the above, there is a case where the charging time is prolonged due to a false determination that the charging is difficult even though the charging is substantially completed. This is a case where the charging current is controlled using the charging rate calculated to a value lower than the true charging rate. That is, although it is supposed to be determined that “charging is complete”, it is erroneously determined as “a situation where it is difficult to charge” due to the influence of the calculation error of the charging rate.

  The charge control device 10 of the present embodiment determines whether or not the state is close to full charge based on the charge current Ac. Further, based on a charging rate Ci calculated by the current integration method (hereinafter referred to as “first charging rate Ci”) and a parameter called a possible charging rate Cp, which will be described later, it is determined whether or not it is a “charge difficult situation”. Then, it is determined (determined) whether or not to continue charging. The charging current Ac is a value detected by the current sensor 17 during charging of the battery 3.

The possible charging rate Cp is a value indicating the ratio of the chargeable capacity to the current capacity of the battery 3 as shown in the following equation 1, and for example, as the battery temperature T decreases as shown in FIGS. It has the characteristic that it becomes low. The “chargeable capacity” of the numerator in Equation 1 means the full charge capacity (the maximum capacity that can be charged in the battery state at that time) at the battery temperature T and the degree of deterioration of the battery 3. On the other hand, the “current capacity” of the denominator in Equation 1 means a full charge capacity (maximum capacity when the battery 3 is new and charged at normal temperature) in a good condition in a new condition.
Possible charge rate Cp = (capacitable capacity [Ah] / current capacity [Ah]) × 100 [%] Equation 1

  Note that the possible charging rate Cp can also be said to be a charging rate at which charging is possible until the charging current Ac reaches the suppression current As. The suppression current As is a current value that is small enough to stabilize the voltage during normal charging (energization) of the battery 3, and is, for example, 0.1 [A] to 1.0 [A]. As shown in FIGS. 3 and 4, the possible charge rate Cp is 100 [%] when the battery temperature T is high, and decreases as the battery temperature T goes from room temperature to low temperature. Note that the map of FIG. 3 defines the relationship between the battery temperature T and the possible charge rate Cp, and the map of FIG. 4 further considers the degree of deterioration (SOH, State Of Health) of the battery 3.

  That is, these maps indicate that when the temperature during charging of the battery 3 is high, the charging rate when charging until the charging current Ac reaches the suppression current As is 100 [%]. The lower the temperature during charging, the faster the charging current Ac reaches the suppression current As, indicating that sufficient charging cannot be performed (the charging rate does not reach 100 [%]). The map of FIG. 4 further indicates that the possible charge rate Cp in the low temperature state decreases as the deterioration of the battery 3 progresses (the deterioration degree is lower). These maps are stored in the charging control device 10 in advance. In the present embodiment, a case where the map of FIG. 3 is used will be described.

  When the charge control device 10 determines that the state is close to full charge based on the charge current Ac, the first charge rate Ci is a determination value indicating substantially full charge (for example, 96 [%], hereinafter “full charge determination value”). If it is less than “Cf”), it is determined that there is a possibility of the above-mentioned “difficult situation to charge”. That is, if the charge rate is checked in a situation where it can be determined that the battery is fully charged based on only the current value, if the determination results are inconsistent (less than the charge rate determined to be fully charged), there is some abnormality. Probability is high. In this case, the charge control device 10 compares the possible charge rate Cp with a predetermined threshold Cd (for example, 96 [%]), is it really difficult to charge, or is difficult to charge? Distinguish whether or not there is only a misjudgment.

  The threshold value Cd is a determination value for determining whether or not charging is difficult (charge difficulty determination value), and is set in advance to a value equal to or greater than the full charge determination value Cf (Cd ≧ Cf). . If the possible charging rate Cp does not reach the threshold value Cd, it is determined that charging is difficult because the battery 3 is in a low temperature state and the charging capacity is reduced. On the other hand, if the possible charge rate Cp is equal to or greater than the threshold value Cd, it is determined that the charge is only affected by the calculation error of the first charge rate Ci and is not difficult to charge. In the former case, charging is continued, and in the latter case, charging is not continued, but is temporarily stopped or terminated.

[3. Control configuration]
As shown in FIG. 2, the charge control device 10 is provided with a storage unit 11, an acquisition unit 12, a calculation unit 13, a determination unit 14, and a control unit 15 as functional elements for performing the above charge control. These elements may be realized by an electronic circuit (hardware), or may be programmed as software, or some of these functions may be provided as hardware, and other parts may be software. It may be what you did.

The storage unit 11 has a two-dimensional map (for example, a map shown in FIG. 3) in which the relationship between the battery temperature T and the possible charge rate Cp is defined, or the relationship between the battery temperature T and the degree of deterioration of the battery 3 and the possible charge rate Cp. A defined three-dimensional map (for example, the map shown in FIG. 4) is stored.
The acquisition unit 12 acquires various types of information used for the above control. The acquisition unit 12 of the present embodiment includes a charge / discharge current (charge current Ac, discharge current) of the battery 3 and a voltage (closed circuit voltage, open circuit voltage) of the battery 3 from the current sensor 17, the voltage sensor 18, and the temperature sensor 19. The battery temperature T is acquired. Further, the acquisition unit 12 acquires the possible charging rate Cp by applying the battery temperature T to the map shown in FIG.

  The calculation unit 13 calculates the first charging rate Ci of the battery 3 using a known current integration method. That is, the first charging rate Ci is calculated based on the integrated current value while the battery 3 is energized. In addition, the calculation unit 13 of the present embodiment calculates the charging rate Co (hereinafter referred to as “second charging rate Co”) of the battery 3 using a known voltage estimation method (OCV method). That is, the second charging rate Co is calculated based on the voltage value when the voltage value of the battery 3 is stable.

  The calculation unit 13 of the present embodiment calculates the first charging rate Ci while the battery 3 is being charged, and when the state where the charging current Ac is less than the suppression current As immediately before the completion of charging continues for a predetermined specified time ts, It is determined that the voltage is stable, and the second charging rate Co is calculated. The specified time ts is a time expected to be necessary for the voltage to stabilize, and is set to, for example, 30 [minutes] to 60 [minutes]. The calculation unit 13 does not calculate the second charge rate Co when receiving an instruction to stop calculating the second charge rate Co from the control unit 15 described later.

  The determination unit 14 performs determination for correctly determining “a situation where charging is difficult”. First, the determination unit 14 determines whether or not the normal charging of the battery 3 is about to be completed based on the charging current Ac. If it is just before the completion of charging, it is next determined whether or not the first charging rate Ci calculated by the calculation unit 13 is less than the full charge determination value Cf. At this time, if Ci ≧ Cf, the determination unit 14 determines that the battery 3 is fully charged because there is no contradiction between the determination result based on the current value and the determination result based on the charging rate.

  On the other hand, if Ci <Cf, the determination result based on the current value and the determination result based on the charging rate contradict each other, so the determination unit 14 determines whether to continue charging based on the possible charging rate Cp. . Specifically, the possible charging rate Cp is compared with the above threshold Cd, and if Cp <Cd, it is determined that charging is difficult, and it is determined that charging is continued. On the other hand, if Cp ≧ Cd, it is determined that charging is not difficult and it is determined that charging is not continued.

  The control unit 15 controls the state of charge of the battery 3 based on the determination result by the determination unit 14. Specifically, when it is determined that the battery is fully charged, the charging is terminated, and when it is determined that the charging is continued, the charged state is maintained (charging is continued). When the determination unit 14 determines to continue charging, the control unit 15 of the present embodiment instructs the calculation unit 13 to stop calculating the second charging rate Co and makes it difficult for the user to charge. Notify that. The former is for omitting unnecessary arithmetic processing, and the latter is for allowing the user to recognize the current state of charge. Examples of the notification method include lighting the indicator 7A, displaying on a liquid crystal screen, and sounding a sound, a buzzer, a melody, or the like.

  The control part 15 of this embodiment shall alert | report to a user by lighting of the indicator 7A. In addition, the control part 15 of this embodiment lights the segment 7B according to the 1st charging rate Ci. In addition, when the time during which charging is continued by turning on the indicator 7A reaches a predetermined timeout time th, the control unit 15 ends the charging with the indicator 7A being turned on. The time-out time th is a maximum value of the time for which charging is continued in a situation where charging is difficult, and is set in advance, for example, from 18 [hours] to 20 [hours].

  That is, the control unit 15 determines whether or not the continuation time (implementation continuation time) reaches the timeout time th when the charging is continuously performed while the situation where the charging is difficult continues. In this case, it is also determined whether or not the charging gun is connected to the charging port. Then, if the duration exceeds the timeout time without removing the charging gun from the charging port, the control unit 15 ends the charging without turning off the indicator 7A, so that the user uses the vehicle 1 next. Sometimes, it is possible to recognize from the display of the indicator 7A that the situation was difficult at the time of the previous charging.

  On the other hand, when the determination unit 14 determines that the charging is not continued, the control unit 15 temporarily stops the charging after the voltage value of the battery 3 is stabilized, and the second charging calculated by the calculation unit 13 The rate Co is acquired, and the value Co is compared with the full charge determination value Cf. As described above, whether or not the voltage is stable can be determined by the fact that the state where the charging current Ac is less than the suppression current As has continued for a specified time ts or longer. That is, when it is determined that charging is not continued, the control unit 15 temporarily stops charging after waiting for the voltage value to stabilize so that the calculation unit 13 calculates the second charging rate Co. .

  If Co ≧ Cf, the control unit 15 ends the charging at that time, and if Co <Cf, sets the target charging current At corresponding to the second charging rate Co and restarts the charging. The target charging current At set here is a target of a current value necessary to bring the battery 3 into a fully charged state. That is, when there is a possibility that the first charging rate Ci is calculated to be lower than the true charging rate, the control unit 15 temporarily stops charging and determines whether or not the fully charged state is present. If the battery 3 is not fully charged, the charging is resumed with the target charging current At corresponding to the second charging rate Co, so that the battery 3 is surely fully charged. If charging is resumed and the determination unit 14 determines that Ci ≧ Cf, the control unit 15 ends the charging.

[4. flowchart]
FIG. 5 is a flowchart illustrating a control procedure performed by the charge control device 10 described above. This flowchart is performed at a predetermined calculation cycle when a charging gun is connected to the charging port of the vehicle 1 and normal charging is started. In parallel with the flowchart of FIG. 5, the calculation unit 13 calculates the first charging rate Ci during energization, and calculates the second charging rate Co when the voltage is stable.

  In step X1, the charging current Ac and the battery temperature T are acquired from the current sensor 17 and the temperature sensor 19, and in step X3, it is determined whether or not the charging current Ac is less than the suppression current As. If Ac.gtoreq.As, it is not just before the completion of charging, the process proceeds to step X40, the indicator 7A is turned off, charging is continued (step X41), and this flow is returned. On the other hand, if Ac <As, the timer is turned on. That is, when the process proceeds to step X4 for the first time, the timer count is started at that time. When the process returns to step X4 after returning from the flow, the timer count is continued. This timer measures the time during which the state of charge under the suppression current As is continued.

  In step X5, the first charging rate Ci at this time is acquired, and in step X6, it is determined whether or not the first charging rate Ci is less than the full charge determination value Cf. If Ci ≧ Cf, since the battery 3 is fully charged, the process proceeds to step X36 and the charging is terminated (step X36). Then, the indicator 7A is turned off (step X37), the timer is turned off (timer count is stopped) and reset (step X39), and this flow is finished.

  On the other hand, if Ci <Cf in Step X6, the possible charge rate Cp corresponding to the battery temperature T is acquired from the map (Step X7), and it is determined whether or not the possible charge rate Cp is equal to or greater than the threshold Cd ( Step X8). If Cp ≧ Cd, it is determined that charging is not continued, so the process proceeds to step X9, the indicator 7A is turned off, and whether the charging state with the charging current Ac less than the suppression current As has continued for a specified time ts or more. Is determined (step X11). In step X11, it is determined whether or not the voltage value is stable. Here, it is determined whether or not the timer count value started in step X4 is equal to or longer than the specified time ts. This determination is repeatedly performed until the condition of step X11 is satisfied.

  When the voltage value is stabilized, the process proceeds from step X11 to step X12, charging is temporarily stopped, and the second charging rate Co at this point is acquired (step X13). In step X14, it is determined whether or not the second charge rate Co is equal to or greater than the full charge determination value Cf. If Co ≧ Cf, charging is terminated (step X15), the timer count is stopped and reset (step X15). X16), this flow is terminated.

  On the other hand, if Co <Cf in step X14, the target charging current At corresponding to the second charging rate Co is set and charging is resumed (step X17), and this flow is returned. In this case, in the calculation cycle after the next time, for example, if the target charging current At set in step X17 is equal to or greater than the suppression current As, the process proceeds from step X3 to step X40. Further, when At <As, if the first charging rate Ci becomes equal to or higher than the full charge determination value Cf, the process proceeds from step X6 to step X36, and if the second charging rate Co becomes equal to or higher than the full charge determination value Cf, then from step X14. Proceed to step X15.

  Further, if Cp <Cd in step X8, it is determined that charging is to be continued, so the process proceeds to step X30, the indicator 7A is turned on, and an instruction to stop the calculation of the second charging rate Co in the calculation unit 13 is instructed. (Step X31). In step X32, it is determined whether or not the charging time (implementation continuation time) performed in a situation where charging is difficult has reached the timeout time th. Here, it is determined whether or not the timer count value started in step X4 is greater than or equal to the timeout time th.

  If it is not timed out, the process proceeds to step X33 to determine whether or not a charging gun is connected. If this condition is satisfied, this flow is returned. In this case, in the calculation cycle after the next time, for example, if the first charging rate Ci is equal to or greater than the full charge determination value Cf, the process proceeds from step X6 to step X36. Further, if the battery temperature T rises and the possible charge rate Cp becomes equal to or higher than the threshold Cd, the process proceeds from step X8 to step X9. In cases other than these, the process proceeds to step X32 again.

  On the other hand, if it is determined in step X32 that a time-out has occurred, or if it is determined in step X33 that the charging gun has been removed, the process proceeds to step X34, charging is terminated, the timer count is stopped and reset. (Step X35), this flow is finished. In this case, the lighting state of the indicator 7A is maintained until the next flow is started and the process proceeds to Step X9, X37 or X40.

[5. Action, effect]
(1) According to the charge control device 10 described above, the battery temperature T and the state of charge can be determined at the same time by using the possible charging rate Cp having the characteristic that the lower the battery temperature T, the lower the battery temperature T, and the battery 3 is charged. At this time, if there is a possibility that charging is difficult, the cause can be identified and appropriate control can be performed.

  For example, if the possible charge rate Cp is less than a predetermined threshold value Cd, it is determined that the charge capacity has decreased even when the battery is close to a fully charged state, and the charging is continued, thereby displaying the charging state of the battery 3. 7 segment 7B can be prevented from changing from a display indicating a fully charged state (so-called segment missing), and the user does not feel uncomfortable. On the other hand, if the possible charging rate Cp is equal to or greater than the threshold Cd, it is possible to prevent the charging time from being prolonged by determining that charging is not continued. Thus, appropriate charge control can be implemented by determining whether or not to continue charging based on the possible charge rate Cp.

(2) According to the charge control device 10 described above, when it is determined that the continuation of the charge is unnecessary based on the possible charge rate Cp, the charge is temporarily stopped and calculated by another method (OCV method). Since the second charge rate Co is acquired, the second charge rate Co can be used for determination and control together with the first charge rate Ci calculated by the current integration method, and the accuracy of the charge control can be improved. it can.
(3) When the determination unit 14 determines that the charging is not continued, the control unit 15 temporarily stops charging after the voltage value of the battery 3 is stabilized. Therefore, the second charging rate Co according to the OCV method is used. The calculation accuracy can be improved, and the accuracy of charge control can be further improved.

  (4) According to the charge control device 10 described above, if the second charge rate Co has not reached the full charge determination value Cf, the target charge current At is set and charging is resumed, while the second charge rate Co is Since charging is terminated if it is equal to or greater than the full charge determination value Cf, the battery 3 can be appropriately brought into a fully charged state, and an increase in charging time can be prevented.

  (5) According to the charge control device 10 described above, the user is informed that it is difficult to charge, so that it is difficult to charge due to a decrease in the charge capacity of the battery 3 due to low temperature. User can recognize. Thereby, for example, since the user can leave the charging gun connected or take measures to increase the charging environment temperature, the battery 3 is easily brought close to the fully charged state. Moreover, convenience can be improved without giving a sense of incongruity by notifying a user.

  (6) In the charging control device 10 described above, the user is notified by turning on the indicator 7A indicating that charging is difficult, so that the user can easily recognize the situation. Further, when the time for which the charging is continued in a situation where it is difficult to charge reaches the timeout time th, the charging is terminated while the indicator 7A is lit, so that it can be as close to a fully charged state as possible and the user has difficulty in charging. The situation can be recognized at the next use, and convenience can be improved.

[6. Modified example]
As shown in FIG. 6, a heater 8 that operates according to the battery temperature T may be attached to the battery 3 described above. As shown in FIGS. 7A and 7B, the heater 8 is electrically connected to the battery 3 through the circuit breaker 9 and operates when the battery temperature T is low to heat the battery 3. To do. Thus, a structure and control content in case the heater 8 and the circuit breaker 9 are provided are demonstrated using FIGS.

  Note that FIG. 6 is a block diagram corresponding to the block diagram of FIG. 8 and 9 are flowcharts corresponding to the flowchart of FIG. 5, and only the steps indicated by thick frames are different from those in FIG. 5. In the following description, different elements and steps will be described in detail, and overlapping descriptions will be omitted.

  As shown in FIG. 6, a heater 8 and a circuit breaker 9 are connected to the output side of the charging control device 10 in addition to the in-vehicle charger 5 and the display device 7. As shown in FIGS. 7A and 7B, the circuit breaker 9 is a switch or contactor having a function of connecting / disconnecting the high voltage circuit, and its connection / disconnection state is controlled by the charge control device 10. When the circuit breaker 9 is in the connected state as shown in FIG. 7A, the battery 3 is connected to the high voltage circuit, and the air conditioner 6 and the heater 8 can use the power of the battery 3, and the power from the outside The battery 3 can be charged.

  On the other hand, as shown in FIG. 7B, when the circuit breaker 9 is disconnected, the battery 3 is disconnected from the high voltage circuit, and the current supply to the battery 3 is interrupted. In this case, the heater 8 or the like can be operated by external electric power during external charging. Here, it is assumed that the operating state of the heater 8 is controlled by an electronic control device other than the charging control device 10. For example, the heater 8 is turned on when the battery temperature T is in a low temperature state equal to or lower than the first predetermined value T1, and is turned off when the battery temperature T becomes higher than the second predetermined value T2 higher than the first predetermined value T1. Become.

  In this modification, the control unit 15 of the charge control device 10 acquires the state of the heater 8 that operates according to the battery temperature T (step Z2 in FIG. 8). Furthermore, the control unit 15 is a case where the determination unit 14 determines that charging is not continued (same as the Yes route of Step Z8 in FIG. 8 and the Yes route of Step X8 in FIG. 5), and the heater 8 is activated. If it is present (No route in step Z10 in FIG. 9), the circuit breaker 9 is disconnected (step Z18). In Step Z10, since it is determined whether or not the high-voltage equipment other than the on-vehicle charger 5 (MCU 4, air conditioner 6, heater 8 in the example of FIG. 6) is stopped, MCU 4 or air conditioner 6 Even in the operation, the process proceeds from step Z10 to step Z18, and the high voltage circuit is disconnected as shown in FIG. 7B (step Z18).

  Since the power supply to the battery 3 is physically cut off by cutting the high voltage circuit, the voltage value is likely to be stabilized. Further, if the heater 8 is operating, the heater 8 continues to operate with external power as shown in FIG. The control unit 15 acquires the battery temperature T (step Z19), and determines whether or not the temperature T is equal to or higher than a predetermined temperature threshold Td (step Z20). The temperature threshold value Td is set in advance to a temperature at which it can be considered that the charge capacity of the battery 3 has not decreased. The temperature threshold Td is set to a value higher than, for example, the temperature at which the heater 8 starts operating (the first predetermined value T1).

  When the heater 8 is operating, the condition of step Z20 is eventually satisfied, and the process proceeds to step Z21. If a high voltage device other than the heater 8 is operating, the condition of step Z20 is satisfied, and the process proceeds to step Z21. In step Z21, it is determined whether or not the time for the voltage of the battery 3 to stabilize has elapsed. If this condition is not satisfied, the process returns to step Z19, and the same processing and determination are repeated. On the other hand, if the time during which the voltage stabilizes elapses, the second charge rate Co is acquired (step Z23) and whether or not Co ≧ Cf is satisfied, as in steps X13 and X14 described above (step S23). Step Z24).

  If Co ≧ Cf, the process proceeds to step Z25 and charging is stopped. If the heater 8 is operating, it is stopped (step Z26), the timer count is stopped and reset (step Z27), and this flow is finished. To do. On the other hand, if Co <Cf, the circuit breaker 9 is connected (step Z28), and the charging is resumed after the target charging current At is set as in step X17 (step Z29). If the first charging rate Ci is equal to or greater than the full charge determination value Cf, the control unit 15 ends the charging (step Z36), controls the indicator 7 to be turned off, and the heater 8 is activated. If so, the operation is stopped (step Z38).

  As described above, in the charging control device 10 according to the present modification, when the control unit 15 determines that the charging is not continued by the determination unit 14 and the heater 8 is operating, the circuit breaker 9 is set. The operation state of the heater 8 is maintained while charging is temporarily stopped by setting the disconnected state, and the second charging rate So is acquired after the voltage value of the battery 3 is stabilized. When the heater 8 is attached as in the present modification, the possible charging rate Cp may be equal to or higher than the threshold Cd due to the operation of the heater 8. For this reason, the circuit breaker 9 is disconnected and charging is temporarily stopped, and the calculation of the second charging rate Co can be improved by waiting for the voltage to be stabilized while the heater 8 is operated. Accuracy can be further improved.

[7. Others]
Although the case where the two-dimensional map shown in FIG. 3 is used has been described in the above embodiment, the three-dimensional map shown in FIG. 4 may be used. In this case, if the estimation part which estimates the deterioration degree of the battery 3 by a well-known method is provided and the acquisition part 12 applies the battery temperature T and the estimated deterioration degree to the three-dimensional map, the possible charging rate Cp is acquired. Good. Since the charge capacity of the battery 3 also changes depending on the degree of deterioration, the determination accuracy can be further improved if the degree of deterioration is taken into account when obtaining the possible charge rate Cp.

  The above flowchart is an example. For example, the order of steps X36, 37, and 39 in the flowchart of FIG. 5 may be changed, or the order of steps X15 and 16 and steps X34 and 35 may be changed. Similarly, the flowcharts illustrated in FIGS. 8 and 9 are also examples, and for example, the order of steps Z36 to 39 may be switched, or the order of steps Z25 to 27 may be switched. Further, when the notification to the user is performed by a method other than the lighting of the indicator 7A, it may be notified by voice, a buzzer or the like instead of the process of “turning the indicator 7 on” in step X30 and step Z30. . In this case, the process of “turning the indicator 7 off” such as step X9 may be omitted.

  In the above-described embodiment, the charging control device 10 that performs control related to charging of the battery 3 mounted on the vehicle 1 has been described. However, the control target of the charging control device 10 is not limited to the vehicle-mounted battery 3, for example, Similar control may be performed when a lithium-ion secondary battery built in an emergency power supply facility or electronic device is charged with a household power supply.

1 vehicle 2 motor 3 battery (lithium ion secondary battery)
4 MCU (Motor Control Unit)
DESCRIPTION OF SYMBOLS 5 Car-mounted charger 6 Air conditioning apparatus 7 Display apparatus 7A Indicator 7B Segment 8 Heater 9 Circuit breaker 10 Charge control apparatus 11 Memory | storage part 12 Acquisition part 13 Calculation part 14 Determination part 15 Control part 17 Current sensor 18 Voltage sensor 19 Temperature sensor Ac Charging current As suppression current At target charge current Cd threshold Cf full charge judgment value Ci first charge rate Co second charge rate Cp possible charge rate T battery temperature Td temperature threshold th time-out time ts specified time

Claims (8)

A calculation unit that calculates the first charging rate based on the integrated current value of the lithium ion secondary battery;
Whether or not to continue the charging based on a possible charging rate indicating a ratio of a chargeable capacity to a current capacity of the battery when the first charging rate during charging of the battery is less than a full charge determination value. A determination unit for determining
A control unit for controlling the state of charge of the battery based on a determination result by the determination unit,
The charge control device is characterized in that the possible charge rate is set in advance and has a characteristic of becoming lower as the temperature of the battery is lower. The calculation unit calculates a second charging rate based on the voltage value when the voltage value of the battery is stable,
2. The control unit according to claim 1, wherein when the determination unit determines that the charging is not continued, the control unit temporarily stops the charging and acquires the second charging rate calculated by the calculation unit. The charging control device described. 3. The charge control according to claim 2, wherein, when the determination unit determines that the charging is not continued, the control unit temporarily stops the charging after the voltage value of the battery is stabilized. apparatus. If the second charging rate is less than the full charge determination value, the control unit sets a target charging current according to the second charging rate and restarts the charging, and the second charging rate is set to the full charging rate. The charge control device according to claim 2 or 3, wherein the charge is terminated if the charge determination value is equal to or greater than the charge determination value. The battery is provided with a heater that is electrically connected to the battery via a circuit breaker and operates according to the temperature of the battery to heat the battery.
When the controller determines that the charging is not continued and the heater is in operation, the control unit temporarily stops the charging by setting the breaker to a disconnected state. The charge control device according to claim 4, wherein the second charging rate is acquired after the operating state of the heater is maintained and the voltage value of the battery is stabilized. The said control part alert | reports to a user that it is in the condition where charge is difficult, when it determines with the said charging part continuing the said charge, The any one of Claims 1-5 characterized by the above-mentioned. The charging control device described. When the determination unit determines that the charging is to be continued, the control unit notifies the user by turning on an indicator that indicates that charging is difficult, and when the charging duration time reaches a timeout time The charging control device according to claim 6, wherein the charging is terminated while the indicator is lit. A storage unit storing a three-dimensional map in which a relationship between the battery temperature, the battery deterioration degree, and the possible charge rate is defined;
The charging control according to claim 1, further comprising: an acquisition unit that acquires the possible charging rate by applying the temperature and the degree of deterioration to the three-dimensional map. apparatus.

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