JP2014011826A - Battery state of charge controller for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery state of charge controller for a vehicle capable of accurately determining a state of charge of a battery on the basis of a current value of charge/discharge current of the battery, even when the battery has been deteriorated.SOLUTION: A battery state of charge controller for a vehicle comprises: a power generator which is driven by an engine and supplies power to an electric apparatus for the vehicle while charging a battery; and a current sensor for detecting a current value of charge/discharge current of the battery. The controller determines that the charge of the battery is completed, when the current value of the battery decreases to equal to or lower than a predetermined charge threshold C1. The controller detects the degree of deterioration of the battery, and corrects the charge threshold depending on the degree of deterioration of the battery so that the charge threshold is lower (C2 and C3) as the degree of deterioration of the battery increases.

Description

  The present invention relates to a technique for controlling a state of charge (SOC) of a battery mounted on a vehicle.

  In a vehicle equipped with a battery, when the vehicle decelerates, the generator output voltage (power generation voltage) is increased to generate regenerative power to charge the battery, and then the electric power stored in the battery by regenerative power generation consumes in-vehicle electrical equipment. By covering the electric power, the energy required for driving the generator is reduced and the fuel consumption is improved (see Patent Document 1).

  In order to keep the fuel consumption reduction effect and deceleration acceleration performance, etc., by the deceleration regeneration control of this generator constant, the charge state of the battery, that is, the ratio of the charge amount actually charged to the chargeable capacity of the battery (%) Needs to be controlled within a predetermined setting range (for example, 80 to 85%) that can be charged.

  Therefore, as a method for detecting the state of charge (SOC) of the battery, for example, the method described in Patent Document 1 uses the characteristic that the current value of the charge / discharge current of the battery decreases as the state of charge of the battery increases. Then, the completion of charging of the battery is determined using the current value of the battery.

On the other hand, it is known that when the battery is repeatedly charged and discharged, the battery inevitably deteriorates and the chargeable capacity of the battery decreases (see Patent Document 2).
JP 2007-318888 A JP 2004-180478 A

  Since the relationship between the battery current value and the battery charge state changes as the battery deteriorates, if the battery charge state is determined based on the battery current value without considering the battery deterioration, There is a risk of erroneously determining the state of charge. For this reason, for example, when it is erroneously determined that the charging is completed even though the charging is not actually completed, the battery is in the discharge mode in a state where the charging is not sufficiently performed, and the charging state of the battery may be excessively lowered. There is.

  The present invention has been made in view of such circumstances, and a battery for a novel vehicle that can accurately determine the state of charge of the battery based on the current value of the charge / discharge current of the battery even if the battery deteriorates. It aims at providing a charge condition control apparatus.

  A battery charge state control device for a vehicle according to the present invention is mounted on a vehicle and is capable of charging and discharging electric power, and is driven by an engine to supply electric power to an electric device for the vehicle. And a generator that charges the vehicle, suppresses the power generation of the generator according to the state of charge of the battery, and can supply electric power to the electric device for the vehicle by discharging from the battery. Then, the current value detecting means for detecting the current value of the charging / discharging current of the battery, and the charging of the battery is completed when the charging current value that rises with engine start and then falls below a predetermined charging threshold value Battery charge completion determination means for determining, battery deterioration detection means for detecting the battery deterioration degree, and threshold correction means for correcting the charging threshold according to the battery deterioration degree. It is said.

  According to the present invention, by correcting the charging threshold according to the degree of deterioration of the battery, even if the battery is deteriorated, the battery is determined based on the charging current value of the battery in a form that takes into account the degree of deterioration of the battery. Can be accurately determined. Therefore, it is possible to control the state of charge of the battery within a predetermined setting range, improving the charge / discharge performance and suppressing the overdischarge and overcharge of the battery.

1 is a system configuration diagram showing a vehicle battery charge state control device according to an embodiment of the present invention. The flowchart which shows the flow of control concerning a present Example. The timing chart which shows changes, such as a battery charge state at the time of applying a present Example. Explanatory drawing for demonstrating correction | amendment of the charge threshold value according to the battery deterioration degree in the charge state immediately after engine starting which concerns on a present Example. Explanatory drawing for demonstrating correction | amendment of the charge threshold value according to the battery degradation degree in the charge state immediately after engine starting which concerns on a present Example. Explanatory drawing for demonstrating correction | amendment of the charge threshold value according to the deterioration degree of the battery in the regeneration control state which concerns on a present Example.

  Hereinafter, the present invention will be described with reference to illustrated embodiments. FIG. 1 is a system configuration diagram showing an embodiment of a battery charge state control device for a vehicle according to the present invention. This vehicle is operated by a generator 3 that is driven by the engine 1 through the timing belt 2 to generate power, a battery 4 that charges and generates power, and power supplied from the battery 4 and the generator 3. And an electric device 5 such as an air conditioner compressor. A current sensor 6 is attached to the negative cable of the battery 4, detects a charge / discharge current of the battery 4, and transmits a voltage signal corresponding to the current value to an ECM (engine control module) 7 as a control unit.

  The ECM 7 can store and execute various engine control processes. As will be described later, the ECM 7 determines the state of charge SOC of the battery 4 based on the (charge) current value of the battery 4 detected by the current sensor 6. Depending on the state of charge SOC of the battery 4, the power generation voltage variable control of the generator 3 is performed to control charging / discharging of the battery 4.

  That is, the ECM 7 calculates a target generated voltage according to the state of charge of the battery 4 and transmits the calculated value to the electrical system controller 8 as a power generation command value. The electrical system controller 8 converts the received power generation command DUTY value into a power generation command signal and transmits it to the regulator 9. Based on the received power generation command signal, the regulator 9 performs control so that the output voltage (power generation voltage) of the generator 3 becomes the target power generation voltage. The electrical system controller 8 may be omitted, and the power generation command signal may be directly transmitted from the ECM 7 to the regulator 9.

  The ECM 7 determines the state of charge SOC of the battery 4, that is, the proportion (%) of the battery 4 that is actually charged with respect to the chargeable capacity, and the state of charge SOC is within a predetermined control range (for example, 80%). The output voltage (target power generation voltage) of the generator 3 is controlled in accordance with the state of charge SOC of the battery 4 so as to be (˜85%).

  FIG. 2 is a flowchart showing a flow of control of the output voltage of the generator 3 according to the state of charge SOC of the battery 4. In step S11, it is determined whether or not the engine 1 has been started for the first time and the suspension engine has just been started. If it is immediately after engine starting, it will progress to step S15 and will set the output voltage of the generator 3 to a value (for example, 14-15V) higher than a battery voltage (for example, about 13V). Thereby, it will be in the charge mode in which the battery 4 is charged by the power generation of the generator 3.

  If not immediately after the engine is started, the process proceeds from step S11 to step S12, and whether or not the state of charge SOC of the battery 4 is equal to or lower than a predetermined upper limit value α1 (for example, 85%), that is, whether or not the charging of the battery 4 is completed. Is determined. Here, since the current value of the battery 4 decreases as the battery charge state SOC increases, this battery charge completion determination is performed using the current value of the battery 4. That is, when the current value of the battery 4 falls below a predetermined charging threshold C1 (C1 '), it is determined that the battery charge state SOC has reached the upper limit value α1.

  If the battery charge state exceeds the upper limit α1, the process proceeds from step S12 to step S17, and the output voltage of the generator 3 is set to a value (for example, 11 to 12V) lower than the battery voltage (about 13V). As a result, the discharge mode in which electric power is supplied from the battery 4 to the electric device 5 by discharging the battery 4 can be reduced, the engine load due to power generation by the generator 3 can be reduced, and the fuel consumption can be reduced.

  If the battery charge state SOC is not more than the upper limit value α1, it is determined that the battery 4 is in a chargeable state, and the process proceeds from step S12 to step S13. In step S13, it is determined whether the vehicle accompanying the fuel cut of the engine 1 is being decelerated. If it is decelerating, it will progress to step S15 and regeneration control which regenerates vehicle driving energy and charges the battery 4 will be performed. Specifically, in step S <b> 15, the output voltage of the generator 3 is set to a value (for example, 14 to 15 V) higher than the battery voltage, and the battery 4 is charged by the power generation of the generator 3.

  On the other hand, if the vehicle is not decelerating, the process proceeds from step S13 to step S14, and it is determined whether or not the battery charge state SOC is equal to or lower than a predetermined lower limit value α2 (for example, 80%) that is a value lower than the upper limit value α1. judge. For example, the integrated value of the charging current of the battery 4 is obtained using the current value of the battery 4 detected by the current sensor 6, and it is determined whether the battery charge state SOC is equal to or lower than the lower limit value α2 using this integrated value. be able to.

  If the battery charge state SOC is larger than the lower limit value α2 (α2 <SOC <α1), the process proceeds from step S14 to step S17, the output voltage is set to a value lower than the battery voltage, and the above discharge mode is set. On the other hand, if the battery state of charge SOC has dropped below the lower limit value α2, the process proceeds from step S14 to step S16, and the output voltage of the generator 3 is set to an intermediate value (for example, about 13V) substantially equal to the battery voltage. Set. As a result, the battery 4 is neither charged nor discharged, the opportunity for the battery 4 to be charged or discharged is reduced, and the progress of deterioration of the battery 4 can be suppressed.

  FIG. 3 is a timing chart showing changes in the battery charge state SOC or the like when the present embodiment is applied. Immediately after the start of the engine 1 where the state of charge SOC of the battery 4 is low (t1 to t), as described above, the output voltage of the generator 3 is set to a high value to enter the charge mode, and the battery 4 is charged. When the current value of the battery 4 decreases to the predetermined charging threshold C1 (t2), the charging state SOC of the battery 4 reaches the upper limit value α1, it is determined that the charging is completed, and the output voltage is reduced to a low value. Transition to mode.

  When the vehicle is decelerated with fuel cut while the vehicle is running (t3, t5), regenerative control is performed. That is, the output voltage of the generator 3 is set to a value higher than the battery voltage, the mode is shifted to the charging mode, and the battery 4 is charged. Thus, by charging the battery 4 when the vehicle is decelerated, the vehicle deceleration energy can be recovered to improve fuel efficiency.

  During the regenerative control in such a vehicle deceleration state, when the battery current value decreases to a predetermined charging threshold C1 ′ (t4, t6), it is determined that the state of charge SOC of the battery 4 has reached the upper limit value α1, Again, the output voltage is set to a low value and the mode is changed to the discharge mode.

  Here, in the regenerative control state, the current value of the battery 4 with respect to the state of charge SOC of the battery 4 is lower than in the battery charge state immediately after the engine is started. C1 ′ is set to a value higher than the charging threshold C1 used for determining the completion of charging in the charging state immediately after engine startup (C1 ′> C1).

  Next, with reference to FIGS. 4 to 6, correction of the charging threshold C <b> 1 (C <b> 1 ′) that is a main part of the present embodiment will be described. 4 and 5 are explanatory diagrams for explaining the correction of the charging threshold C1 in the battery charging state immediately after the engine is started. When the battery 4 deteriorates with time due to repeated charging and discharging, the chargeable capacity of the battery 4 decreases and the current value of the battery 4 also decreases. For this reason, as shown in the comparative examples of FIGS. 4 and 5, the charging of the battery 4 is completed when the current value of the battery 4 decreases to a predetermined charging threshold C <b> 1 without considering the degree of deterioration of the battery 4. When it is determined that the battery 4 has been charged, the state of charge of the battery 4 reaches a predetermined upper limit value α1 in the middle deterioration stage L2 or the late deterioration stage L3 in which the degree of deterioration of the battery 4 has advanced as compared to the initial deterioration stage L1, as shown in FIG. Since it is erroneously determined that the charging is completed before reaching the battery 4 and the battery 4 is discharged, the state of charge SOC of the battery 4 may be excessively lowered.

  Therefore, in this embodiment, the degree of deterioration of the battery 4 is obtained based on the integrated amount of discharge of the battery 4, and charging is performed according to the degree of deterioration of the battery 4 so that the charging threshold C1 becomes lower as the degree of deterioration of the battery 4 increases. The threshold value C1 is corrected. The accumulated discharge amount of the battery 4 can be obtained by integrating the current value of the discharge current of the battery 4 detected by the current sensor 6.

  Specifically, as shown in FIG. 4 and FIG. 5, charging is performed in the deterioration middle period L2 where the integrated discharge amount is A1 or more and A2 or less with respect to the charging threshold C1 in the deterioration initial stage L1 where the integrated discharge amount is A1 or less. The threshold value C2 is corrected to be lower than the charging threshold value C1 in the initial deterioration stage L1 (C2 <C1), and the charging threshold value C3 is further set to be lower than the charging threshold value C2 in the middle deterioration period L2 in the late deterioration stage L3 in which the integrated discharge amount exceeds A2. It is corrected to a low value (C3 <C2).

  In this way, by correcting the charging threshold in consideration of the degree of deterioration of the battery 4, it becomes possible to charge the battery 4 up to the vicinity of the upper limit α1 of the charging completion regardless of the degree of deterioration of the battery 4. Even when the battery is deteriorated, the charge capacity of the battery 4 can be fully used, and the charge / discharge performance is improved. Further, as in the comparative example, it is possible to suppress erroneous determination that the charging is completed before the charging state of the battery 4 reaches the upper limit value α1, and to prevent overcharging and overdischarging of the battery 4 due to the erroneous determination. Can be suppressed.

  In this embodiment, the charging threshold is corrected by dividing the deterioration degree of the battery 4 into three stages, but the deterioration degree of the battery 4 may be divided into more stages, or in this way Instead of dividing the degree in stages, the charging threshold may be gradually (continuously) lowered as the degree of deterioration of the battery 4 increases.

  4 and 5, the correction of the charging threshold C1 used in the charging state immediately after engine startup has been described. However, the same applies to the charging threshold C1 ′ used in the regeneration control state (regeneration scene) as shown in FIG. In addition, the charging threshold is corrected according to the degree of deterioration of the battery 4 so that the charging threshold becomes lower as the degree of deterioration of the battery 4 increases. Specifically, as shown in FIG. 6, in the middle deterioration period L2, the charging threshold C2 ′ is corrected to be lower than the charging threshold C1 ′ in the deterioration initial stage L1 (C2 ′ <C1 ′). The charging threshold C3 ′ is corrected to be lower than the charging threshold C2 ′ in the middle deterioration period L2 (C3 ′ <C2 ′).

  Note that the current value of the battery 4 also depends on the temperature of the battery 4, and the current value increases as the battery temperature increases. Therefore, the temperature of the battery 4 is detected or estimated using a temperature sensor or the like. The current value of the battery 4 may be corrected based on the temperature.

  As a result, in the regenerative control state as well as in the charging state immediately after the engine is started, the charging threshold value is corrected in consideration of the deterioration level of the battery 4, so that the charging is performed regardless of the deterioration level of the battery 4. It becomes possible to charge the battery 4 to near the upper limit α1 of completion, and even when the battery 4 is deteriorated, the charge capacity of the battery 4 can be fully used, and the charge / discharge performance is improved. Overcharge and overdischarge can be suppressed.

  As described above, the present invention has been described based on the specific embodiments. However, the present invention is not limited to the above-described embodiments, and includes various modifications and changes. For example, the present invention can also be applied to a hybrid vehicle that uses both an engine and a motor.

DESCRIPTION OF SYMBOLS 1 ... Engine 3 ... Generator 4 ... Battery 6 ... Current sensor (Current value detection means)
7 ... ECM
8 ... Electrical controller

Claims (5)

A battery mounted on a vehicle and capable of charging and discharging power;
A power generator that is driven by an engine to supply power to an electric device for a vehicle and that charges the battery, and suppresses power generation of the power generator according to the state of charge of the battery, and discharges from the battery In a vehicle charge state control device capable of supplying electric power to an electric device for a vehicle,
Current value detection means for detecting the current value of the charge / discharge current of the battery;
Battery charge completion determination means for determining that the charging of the battery is completed when a charging current value that increases with engine startup and then decreases is equal to or less than a predetermined charging threshold;
Battery deterioration degree detecting means for detecting the deterioration degree of the battery;
Threshold correction means for correcting the charging threshold according to the degree of deterioration of the battery;
A battery state-of-charge control device for a vehicle, comprising:   2. The vehicle battery charge state control device according to claim 1, wherein the threshold correction unit corrects the charging threshold to a lower side as the degree of deterioration of the battery increases.   3. The battery deterioration degree detecting means calculates an accumulated discharge amount of the battery based on the current value, and obtains a deterioration degree of the battery based on the accumulated discharge amount. The battery state-of-charge control device for a vehicle according to claim 1. According to the state of charge of the battery, by controlling the output voltage of the generator, it has power generation voltage control means for controlling charging and discharging of the battery,
At the time of vehicle deceleration, regenerative control for charging the battery is performed by making the output voltage of the generator higher than the voltage of the battery by the generated voltage control means.
The battery charge completion determination means determines whether or not the battery has been completely charged in the charge state immediately after the engine is started based on the charge threshold value corrected by the threshold value correction means, and determines whether or not the battery has been fully charged in the regenerative control state. The battery state-of-charge control device for a vehicle according to any one of claims 1 to 3, wherein:   5. The vehicle battery charge state according to claim 4, wherein in the regenerative control state, a value of the charge threshold value corrected by the threshold value correction unit is set higher than that in the charge state immediately after the engine is started. Control device.

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