JP2008255913A - Power generation control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration of a battery due to overcharging during deceleration fuel cut and improve fuel economy by lengthening no-power generation time of a generator after completion of fuel cut. <P>SOLUTION: Alternator power generation voltage is controlled to voltage making the battery not charge and discharge to prevent deterioration of the battery when battery overcharge is judged in regeneration power generation control during deceleration fuel cut of an engine. Alternator power generation voltage is lowered and no-power generation control is started to forcibly discharge the battery. Consequently, no-power generation time after restart of fuel supply is lengthened and electric power is supplied from the battery to improve fuel economy during idling or the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power generation control device for a vehicle that forcibly charges a battery by regenerative power generation control when an engine decelerates fuel is cut, and particularly relates to a countermeasure technique when the battery is overcharged during regenerative power generation control.

Conventionally, as a vehicle power generation control device, when the engine decelerating fuel is cut, the power generation voltage of the engine-driven generator is raised to perform regenerative power generation to forcibly charge the battery and improve fuel efficiency by collecting power, while reducing fuel cut After completion, for a predetermined time according to the amount of charge during forced charging, the generator load is reduced to reduce power generation by reducing the engine load and suppressing a sudden drop in engine rotation. (See, for example, Patent Document 1).
JP 2003-244998 A

  By the way, in this type of power generation control device, when the battery is forcibly charged by regenerative power generation during deceleration fuel cut, if the battery charge state (SOC) exceeds a predetermined value and the battery is overcharged, Therefore, regenerative power generation is prohibited by lowering the generator voltage. However, if the battery is forcibly discharged by immediately reducing the generator's power generation voltage to the voltage at which the battery is discharged when an overcharged state occurs during deceleration fuel cut, no power generation time at idle, etc. after deceleration fuel cut ends There is a problem that there will be less.

  The present invention has been made paying attention to the above-mentioned problems, and provides a vehicle power generation control device that can suppress deterioration due to overcharging of a battery without reducing the generator's no power generation time after the end of deceleration fuel cut. For the purpose.

  For this reason, the present invention provides a vehicle power generation control device for forcibly charging a battery by increasing a power generation voltage of a generator driven by the engine when the engine is decelerating fuel cut. When the determination is made, the power generation voltage of the generator is controlled to be lowered to a voltage at which the battery is not charged / discharged during the deceleration fuel cut.

  According to the present invention, when it is determined that the battery is overcharged during forced charging during deceleration fuel cut, the power generation voltage of the generator is controlled to a voltage at which the battery is not charged and discharged without immediately discharging the battery by non-power generation control. And, the non-power generation control time after the end of fuel cut can be lengthened. Therefore, the deterioration of the battery due to the battery overcharge state during regenerative power generation can be prevented, and the fuel consumption can be improved by extending the power supply time from the battery during idling.

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

  FIG. 1 is a system configuration diagram showing an embodiment of a vehicle power generation control device according to the present invention.

  In FIG. 1, an alternator 2 as a generator that is driven by an engine 1 through a fan belt to generate electric power receives a power generation voltage command from an ECM (engine control module) 6 that incorporates a microcomputer to be described later. The generated voltage is controlled. The battery 4 is connected to the alternator 2 so as to be chargeable / dischargeable according to the generated voltage of the alternator 2. The current sensor 5 detects the charging / discharging current of the battery 4 and inputs the detection output to the ECM 6.

  The ECM 6 includes, for example, a computer and is driven by power supply from the battery 4, and controls the operating state of the engine 1 by signals from various sensors. In addition, the ECM 6 uses a signal from the rotational speed sensor 7 and the throttle sensor 8 to detect the fuel from the fuel injection valve when the throttle valve for controlling the intake air amount is in an idle state in which the intake air amount is substantially fully closed and the engine rotational speed is reduced more than a predetermined value. The fuel cut control for stopping the injection is performed, and then the recovery control for restarting the fuel injection when the engine speed becomes the recovery value or less is performed.

  In addition, normal control for controlling the power generation voltage of the alternator 2 to a set voltage is performed so as to maintain the charge amount of the battery 4 at an appropriate amount, while a high power generation voltage command is issued to the regulator 3 of the alternator 2 during fuel cut. A regenerative power generation control is performed in which a value (for example, 14.5 V) is output and regenerative power generation is performed to charge the battery 4. During this regenerative power generation control, the state of charge (SOC) of the battery 4 is monitored and the battery overcharge is monitored. When it is determined that the battery is charged, the power generation voltage of the alternator 2 is controlled so as to inhibit the regenerative power generation control by lowering the power generation voltage of the alternator 2 to a voltage value (for example, 13V) that the battery 4 does not charge / discharge until the fuel cut control is completed. 4 is suppressed.

  Next, alternator power generation control by the ECM 6 of this embodiment will be described with reference to the flowchart of FIG. 2 and the timing chart of FIG.

  In step 1 (indicated by S1 in the figure, the same shall apply hereinafter), it is determined whether or not the fuel cut control is being performed.

  In step 2, as shown in FIG. 3, the power generation voltage of the alternator 2 is raised to a voltage (for example, 14.5 V) higher than the battery voltage, and the battery 4 is forcibly charged.

  In step 3, the charge amount at the time of forced charge is integrated and the battery charge state SOC is calculated. Regarding the charge amount integration during forced charging, specifically, the battery charge current vCHAI [A / h] detected by the current sensor 5 is converted into a charge current value vCHAI / 360000 per sampling time [10 ms] and integrated. Thus, the integrated charge amount vCHADD from the start of forced charging is calculated as follows.

vCHADD = vCHADDz + vCHAI / 360000
However, vCHADDz is the previous value of vCHADD.

  Further, regarding the calculation of the battery charge state SOC, specifically, the charge state SOC based on the initial value of the battery open-end voltage when the relay connecting the battery 4 and the power supply circuit is OFF when the vehicle is stopped for a long time. Then, the current charge state of the battery is calculated by integrating the charge / discharge current value detected by the current sensor 5 as + when charging and as-when discharging. Therefore, the battery charge state SOC during forced charging is obtained by adding the integrated charge amount vCHADD to the battery charge state SOC immediately before regenerative power generation.

  In step 4, it is determined whether or not the battery charge state is overcharge. For example, the overcharge determination threshold SOCth is set in advance, and the latest battery charge state SOC calculated in step 3 is compared with the determination threshold SOCth. If SOC ≧ SOCth, it is determined that overcharge occurs, and the process proceeds to step 5.

  In step 5, as shown in FIG. 3, the power generation voltage of the alternator 2 is lowered to a voltage (for example, 13 V) at which the battery 4 is not charged / discharged, regenerative power generation control is prohibited, and charging of the battery 4 is stopped.

  In step 6, it is determined whether or not the fuel cut control is finished. If the fuel cut is in progress, the power generation voltage of the alternator 2 is maintained at a voltage (for example, 13V) at which the battery 4 is not charged / discharged. Proceed to 7.

  In step 7, as shown in FIG. 3, the power generation voltage of the alternator 2 is lowered to a voltage (for example, 12.5 V) lower than the voltage (for example, 13 V) at which the battery 4 is not charged / discharged, and the non-power generation control is started. Thereby, the battery 4 is forcibly discharged by the amount of charge by the regenerative power generation control.

  In step 8, the current accumulated charge amount vCHADD of the battery 4 is calculated by subtracting the discharge amount during non-power generation control from the accumulated charge amount vCHADD charged to the battery 4 by regenerative power generation control. Specifically, the cumulative charge amount vCHADD from the start of forced discharge is calculated by subtracting the cumulative charge amount vCHADD during forced charge from the discharge current value vCHAI / 360,000 per sampling time [10 ms] as shown in the following equation. To calculate.

vCHADD = vCHADDz-vCHAI / 360000
In step 9, it is determined whether or not the accumulated charge amount vCHADD calculated in step 8 has become zero. As shown in FIG. 3, normal control is started by increasing the charge amount of the battery 4 to a set voltage (for example, 13 V) for maintaining the charge amount at an appropriate amount.

  If it is determined in step 4 that the battery overcharge is not overcharge (SOC <SOCth), the process proceeds to step 11 to determine whether or not the fuel cut is completed. Return and continue accumulating the amount of charge. On the other hand, when it is determined that the fuel cut has ended, the process proceeds to step 12.

  In step 12, it is determined whether or not the battery charge state SOC is equal to or less than a predetermined value. If it is determined that the battery charge state SOC is greater than a predetermined value and the battery charge state SOC is insufficient to affect the electric load control even if the non-power generation control is performed, the process proceeds to step 7 and there is nothing as described above. Perform power generation control. Further, when it is determined that the battery charge state SOC is equal to or less than a predetermined value and there is a possibility that the battery charge state SOC is insufficient to affect the electric load control when the non-power generation control is performed, the non-power generation control is performed. Instead, the process proceeds to step 10 and normal control is started immediately.

  According to the power generation control device of this embodiment, when it is determined that the battery is overcharged during regenerative power generation control, the alternator power generation voltage is controlled to a voltage at which the battery is not charged / discharged, and the battery discharge voltage is lowered after the fuel cut ends. Since the non-power generation control is performed, the non-power generation control time Tn (shown in FIG. 3) after the end of the fuel cut according to the present embodiment is started immediately after the overcharge determination as shown by a two-dot chain line in FIG. In this case, it can be longer than the non-power generation control time To (shown in FIG. 3). Therefore, deterioration of the battery 4 due to the battery overcharge state during regenerative power generation can be prevented, and fuel consumption can be improved by extending the power supply time from the battery 4 by non-power generation control during idling or the like.

The system block diagram which shows one Embodiment of the electric power generation control apparatus of the vehicle which concerns on this invention. Flow chart for explaining the power generation control operation of this embodiment Time chart explaining power generation control operation of this embodiment

Explanation of symbols

1 Engine 2 Alternator 3 Regulator 4 Battery 5 Current Sensor 6 ECM (Engine Control Module)
7 Rotational speed sensor 8 Throttle sensor

Claims (4)

In the vehicle power generation control device for forcibly charging the battery by raising the power generation voltage of the generator driven by the engine when the engine decelerates fuel cut,
When it is determined that the battery is overcharged during the forced charge during deceleration fuel cut, the power generation voltage of the generator is controlled to be lowered to a voltage at which the battery is not charged / discharged during the deceleration fuel cut. Vehicle power generation control device.   2. The vehicle according to claim 1, wherein after the deceleration fuel cut is finished, the power generation voltage of the generator is controlled to a voltage lower than the voltage at which the battery is not charged / discharged to generate no power and the battery is discharged. Power generation control device.   The power generation control device for a vehicle according to claim 2, wherein the time of the non-power generation control is configured to be a time for discharging from the battery by a charge amount during the forced charging.   4. The vehicle power generation control device according to claim 2, wherein when the battery charge amount after the end of forced charging is equal to or lower than a predetermined level, the power generation control of the generator is prohibited. 5.

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