JP2004166389A - Control device for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a hybrid vehicle capable of renewing battery charging amount as necessary. <P>SOLUTION: This control device for hybrid vehicle comprises a first charging amount calculating means for conducting automatic engine restart and time-calculating the charging/discharging current of the battery to calculate battery charging amount, a charging amount updating request determination means for determining whether or not the updating condition for battery charging amount is satisfied, and a second charging amount calculating means for calculating battery charging amount on the basis of the output current and output voltage of the battery at power running of a motor. If the battery charging amount is less than a prescribed second determination value larger than a first determination value during automatic engine stopping and with updating conditions satisfied, automatic engine restarting is conducted for the updating into the battery charging amount calculated by the second charging amount calculating means. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a hybrid vehicle.
[0002]
[Prior art]
In a hybrid vehicle including an engine as a driving source for driving the vehicle and a motor using a battery as a driving source, in order to improve fuel efficiency, an automatic engine stop / automatic restart (so-called idle Stop control) is widely known.
[0003]
In a hybrid vehicle that performs such automatic engine stop / restart, if the engine is automatically stopped in a state where the battery charge is insufficient, it becomes difficult to automatically restart the engine. In a state of shortage, the automatic stop of the engine is prohibited.
[0004]
Also, the battery charge amount is normally calculated by integrating the charge / discharge current to the battery with time, but in order to correct the integration error, the battery is forcibly discharged at the time of starting or after a lapse of a predetermined time after starting, A battery charge amount is calculated and updated based on a voltage and a current at the time of the battery forced discharge (see Patent Document 1).
[0005]
[Patent Document 1]
JP 2001-224103 A (page 4)
In the above document, at the time of starting, the battery charge is updated from a large current flowing to the motor when the engine is started, and after a predetermined time elapses, the battery charge is updated by flowing a large current through the forced discharge resistor.
[0006]
[Problems to be solved by the invention]
However, since the timing of updating the battery charge amount is at the time of starting the engine and after a lapse of a predetermined time after the engine is started, the update of the battery charge amount is performed at a timing that needs to be updated, such as after the battery charge, which deteriorates the integration accuracy. There is a problem that you can not.
[0007]
In addition, when the battery charge amount is updated after a lapse of a predetermined time from the start, a resistor for forced discharge is required, and the battery consumes power by flowing a current through the resistor for forced discharge. Problem.
[0008]
[Means for Solving the Problems]
The control device for a hybrid vehicle of the present invention automatically stops and restarts the engine in accordance with a predetermined operating condition, and when the engine is automatically stopped, the charge amount of the battery is less than a predetermined first determination value. And a control unit for a hybrid vehicle that automatically restarts the engine by driving the engine with the electric motor, and calculates a battery charge by integrating the charge / discharge current of the battery with time. Calculating means; charge amount update request determining means for determining whether or not an update condition of the charge amount of the battery is satisfied; and battery charging based on the output current and output voltage of the battery when the electric motor is in power running operation. And a second charge amount calculating means for calculating the amount of charge. When the engine is automatically stopped and the update condition is satisfied, the battery charge amount becomes smaller than the first determination value. When the value becomes less than the large second determination value, the engine is driven by the electric motor to automatically restart the engine, and the battery charge calculated by the first charge calculation means is reduced by the second charge. It is characterized by updating to the battery charge amount calculated by the amount calculation means. This makes it possible to change the conditions for the automatic restart of the engine as needed, and to promptly update the battery charge.
[0009]
【The invention's effect】
According to the present invention, the battery charge amount can be updated as needed, so that the battery charge amount can always be accurately grasped.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0011]
FIG. 1 is an explanatory diagram showing an overall configuration of a control device for a hybrid vehicle according to the invention, and FIG. 2 shows a system configuration of a power supply system of the control device for a hybrid vehicle.
[0012]
As shown in FIG. 1, an automatic transmission 2 is connected to a rear end of the engine 1.
[0013]
The automatic transmission 2 includes a torque converter 4 to which a driving force is transmitted from a crankshaft 3 serving as an output shaft of the engine 1, and a belt-driven CVT (continuous continuously variable) connected to the engine 1 via the torque converter 4. Variable transmission) 5, a crankshaft 3, and a forward clutch 6 provided between the torque converter 4 and the CVT 5. The output side of the CVT 5 is not shown, as in a general automobile. It is connected to drive wheels (not shown) via a final reduction gear.
[0014]
A crank pulley 7 that rotates integrally with the crankshaft 3 is disposed at a front end of the engine 1. A belt 11 is wound around the crank pulley 7 and a motor pulley 9 attached to an output shaft 8a of a motor generator 8 as an electric motor.
[0015]
The motor generator 8 is controlled by a total control unit 13 via an inverter 12. When the engine is started by an engine key and when the engine is automatically restarted (described later), electric power is supplied from a battery 14 to perform a power running operation and the engine 1 In addition to performing cranking, regenerative operation is performed at the time of vehicle deceleration operation to regenerate energy from the crankshaft 3 as a generator to generate power and charge the battery 14. Here, between the inverter 12 and the battery 14, as shown in FIG. 2, an ammeter 15 for detecting a charging / discharging current of the battery 14 and a voltmeter 16 for detecting a charging / discharging voltage of the battery 14 are interposed. Is equipped.
[0016]
The total control unit 13 detects an amount of charge of the battery 14, an oil temperature sensor 17 for detecting an oil temperature of the automatic transmission 2, a hydraulic sensor 18 for detecting an operating oil pressure of the automatic transmission 2, and an engine 1. A signal from a water temperature sensor 19 or the like for detecting the cooling water temperature is input.
[0017]
When a predetermined condition (idle stop condition) is satisfied when the vehicle is temporarily stopped after the warm-up operation is completed, the total control unit 13 stops fuel injection of the engine 1 and automatically stops the engine 1 (idle stop). When a predetermined condition (idle stop release condition) is satisfied during automatic stop of the engine, the engine 1 is automatically restarted (idle stop release), that is, so-called idle stop control is performed. The machine is running under torque control.
[0018]
The total control unit 13 performs calculation of a battery charge amount SOC (described later) and determination of a charge amount update request of the battery 14 (details will be described later).
[0019]
Here, the battery charge amount SOC written and stored in the backup memory when the power is turned off is calculated from the discharge current and the discharge voltage discharged from the battery 14 by powering the motor generator 8 when the engine is started by the engine key. The updated battery charge amount SOC is updated. Also, during vehicle operation, the charge / discharge current IH of the battery 14 is calculated every predetermined time Δt, and this is integrated over time as in the following equation (1) to calculate the battery charge amount SOC (No. (1 charge amount calculating means).
[0020]
(Equation 1)
SOC = SOC + IH ・ Δt (1)
Next, control contents of the total control unit 13 will be described with reference to flowcharts of FIGS.
[0021]
FIG. 3 is a flowchart (charge amount update request determination means) for determining whether or not the update condition of the battery charge amount SOC is satisfied, and is executed at predetermined time intervals (for example, every 10 ms).
[0022]
In step 11 (hereinafter, step is simply referred to as S), the amount of power generation (including regenerative power generation) of motor generator 8 is equal to or more than a predetermined value, that is, the amount of charge to battery 14 is equal to or more than a predetermined value (first amount of charge). It is determined whether or not there is, and if it is equal to or more than a predetermined value (first charge amount), it is determined that the update condition of the battery charge amount SOC is satisfied, and the process proceeds to S15. I do. This is because, when the battery 14 is charged for power generation, regeneration, and the like, the integration accuracy of the battery charge amount SOC, that is, the accuracy of the battery charge amount SOC by the first charge amount calculation unit described above is affected by the charging and discharging efficiency of the battery 14. Is worse. The determination in S11 may be made by comparing a value obtained by integrating the charging current or the charging power (Ah or Wh) with a predetermined determination value. Here, the calculation of the integrated value (Ah or Wh) to be compared with the determination predetermined value is started by turning on the key, and once the battery charge amount is updated (see S28 and S44 described later), the integrated value is calculated once. Is cleared, and the calculation of the integrated value is started again from the state where the integrated value is zero.
[0023]
In S12, it is determined whether or not the charge / discharge current of the battery 14 is equal to or less than a predetermined value and a predetermined time has elapsed. If the charge / discharge current of the battery 14 is equal to or less than the predetermined value and the predetermined time has elapsed, the battery charge amount SOC is updated. It is determined that the condition is satisfied, the process proceeds to S15, and the update necessary flag fkosin is set to fkosin = 1. This is because the influence of the accuracy of the ammeter 15 is larger in a lower current range, and the integration accuracy of the battery charge SOC is deteriorated.
[0024]
In S13, it is determined whether or not the battery charge amount SOC after power generation (including regeneration) is equal to or less than a predetermined value (second charge amount). It is determined that the SOC update condition is satisfied, the process proceeds to S15, and the update necessary flag fkosin is set to fkosin = 1. This is because the smaller the battery charge SOC is, the greater the influence of the battery charge SOC on the idle stop control is. Specifically, since the battery charge amount SOC is used for determining whether or not to restart the engine after the idle stop, it is necessary to accurately detect a decrease in the battery charge amount SOC.
[0025]
FIG. 4 is a flowchart showing the contents of the idle stop control, which is executed at predetermined time intervals (for example, every 10 ms).
[0026]
In S21, it is determined whether or not idle stop (engine automatic stop) is in progress. If not idle stop, the process proceeds to S22, and if idle stop is performed, the process proceeds to S24.
[0027]
In S22, it is determined whether or not an idle stop condition (automatic engine stop condition) is satisfied. If the idle stop condition is satisfied, the process proceeds to S23 and idle stop (automatic engine stop) is performed. Here, the idle stop means the driver's operation state such as shift range, vehicle speed, accelerator opening, brake oil pressure, etc., engine water temperature, battery state, master back negative pressure, automatic transmission oil temperature (AT oil temperature), and outside air temperature. For example, when the select lever is in the D range, the brake pedal is depressed by the driver, the vehicle speed is 0 (km / h), and the engine is burning, the accelerator is depressed. If the OFF state, the brake ON state, the charge amount of the battery 14 is equal to or more than a predetermined value, and the engine water temperature is equal to or more than a predetermined value, it is determined that the idle stop condition is satisfied.
[0028]
In S24, the state of the update required flag fkosin is determined. If fkosin = 1, the process proceeds to S25, and if fkosin = 0, the process proceeds to S26.
[0029]
In S25, as shown in FIG. 6, the idle stop release SOCX is set to a second determination value higher than usual (here, 80%), and the process proceeds to S27. In S26, the idle stop release SOCX is set to the normal value (here, 70%), that is, the first determination value, and the process proceeds to S27. That is, when the update condition of the battery charge amount SOC is satisfied, the idle stop release SOCX is set to be larger than when the update condition of the battery charge amount SOC is not satisfied.
[0030]
In S27, an idle stop release (automatic engine restart) determination is made based on the idle stop release SOCX set in S25 or S26. When it is determined that the battery charge amount SOC is equal to or less than the idle stop release SOCX, the process proceeds to S28, in which the idle stop is released, and the battery 14 is discharged from the battery 14 due to the power running operation of the motor generator 8 when the engine is automatically restarted. The battery charge amount SOC is updated based on the output current and the output voltage.
[0031]
Here, a method of calculating the battery charge amount SOC from the output current and the output voltage due to the discharge from the battery 14 due to the power running operation of the motor generator 8 (second charge amount calculation means) will be described in detail. As shown in FIG. 7, ΔI is calculated from the discharge current Ia during idle stop and the discharge current Ib during automatic restart of the engine, and is calculated from the discharge voltage Va during idle stop and the discharge voltage Vb during automatic restart of the engine. ΔV is calculated, and the internal resistance R (the slope of the straight line connecting the points P and Q in FIG. 7) is determined from these ΔI and ΔV. Then, based on the internal resistance R and the discharge current Ib and the discharge current Vb at the time of automatic restart of the engine, an open circuit voltage Eb is calculated by the following equation.
[0032]
(Equation 2)
Eb = Vb + Ib × R (2)
Here, the open circuit voltage Eb is a voltage that can be generated by the battery 14 at the present time when the battery charge amount SOC is 100%.
[0033]
Then, using the open circuit voltage Eb calculated by the above equation (2), the battery charge amount SOC is calculated from FIG. 8, and the battery charge amount SOC is updated. The update required flag fkosin is set to fkosin = 0 at S28 after updating the battery charge amount SOC.
[0034]
On the other hand, if the battery charge amount SOC is not equal to or less than the idle stop release SOCX in S27, the process proceeds to S29, and it is determined whether or not idle stop release conditions other than the battery charge amount SOC are satisfied. If the idle stop release condition is satisfied, the process proceeds to S28.
[0035]
FIG. 5 is a flowchart showing the contents of control when updating the battery charge amount SOC other than when the engine is started, and is executed at predetermined time intervals (for example, every 10 ms).
[0036]
In S41, it is determined whether or not the vehicle is idle-stopped (the engine is automatically stopped). If not, the process proceeds to S42.
[0037]
In S42, it is determined whether or not a predetermined time has elapsed since the update required flag fkosin = 1, and if the predetermined time has elapsed, the process proceeds to S43.
[0038]
In S43, a torque increase command (+ TRQX) is issued to the motor generator 8 in order to cause the motor generator 8 to perform the power running operation, and a torque reduction command (-TRQX) is issued to the engine 1 to reduce the engine torque by the torque increment TRQX to the motor generator 8. ).
[0039]
In S44, the battery charge amount SOC is updated in substantially the same manner as in S28 in FIG. 4 described above. That is, in S44, ΔI is calculated from the discharge current before issuing the torque increase command (+ TRQX) to the motor generator 8 and the discharge current during the torque increase command (+ TRQX), and the torque increase command (+ TRQX) is given to the motor generator 8. ΔV is calculated from the discharge voltage before output and the discharge voltage during the torque increase command (+ TRQX), and the internal resistance R is obtained from ΔI and ΔV (see FIG. 7 described above). The open circuit voltage Eb is calculated from the internal resistance R, the discharge current during the torque increase command (+ TRQX) and the discharge voltage during the torque increase command (+ TRQX), and the battery charge amount SOC is calculated using the open voltage Eb. , The battery charge amount SOC is updated (see FIG. 8). The update required flag fkosin is set to fkosin = 0 at S44 after the battery charge amount SOC is updated.
[0040]
As described above, by changing the idle stop release SOCX as necessary, it is ensured that the motor generator 8 cannot start the engine due to the deterioration of the accuracy of the battery charge amount SOC which is the idle stop release condition. Can be avoided.
[0041]
Further, since the battery charge amount SOC can be updated at the timing of releasing the idle stop, the battery charge amount SOC required for the idle stop control can always be grasped with high accuracy.
[0042]
When the accuracy of the battery charge amount SOC due to the time integration (first charge amount calculation means) deteriorates, that is, when the power generation amount (including regenerative power generation) of the motor generator 8 is equal to or more than a predetermined value, the charging and discharging of the battery 14 is performed. When the current is equal to or less than a predetermined value and a predetermined time has elapsed, or when the battery charge SOC after power generation (including regeneration) is equal to or less than a predetermined value, the battery charge SOC is updated to be used for idle stop control. The accuracy of the battery charge amount SOC can be improved, and the frequency of the idle stop can be prevented from being reduced by changing the condition of the idle stop release SOCX.
[0043]
Further, even when the engine is not started, that is, even during the rotation of the engine, the torque of the engine 1 is reduced by the torque increment TRQX for causing the motor generator 8 to perform the power running operation without affecting the driving of the vehicle. In addition, the battery charge amount SOC can be calculated and updated without causing a current to flow through a so-called forced discharge resistor.
[0044]
The technical ideas of the present invention that can be grasped from the above embodiments are listed together with their effects.
[0045]
(1) A control device for a hybrid vehicle including an electric motor driven by a battery as a driving source for driving the vehicle, and an engine, wherein the engine is automatically stopped and automatically restarted in accordance with predetermined driving conditions. When the vehicle is started and the charge amount of the battery becomes less than a predetermined first determination value during the automatic stop of the engine, control of the hybrid vehicle that drives the engine with the electric motor and automatically restarts the engine. A first charge amount calculating means for calculating a battery charge amount by time-integrating the charge / discharge current of the battery, and a charge amount update request for determining whether or not an update condition of the battery charge amount is satisfied; Determination means; and second charge amount calculation means for calculating a battery charge amount based on an output current and an output voltage of the battery when the electric motor is in power running operation. If the battery charge is less than a predetermined second determination value that is greater than the first determination value while the automatic stop is being performed and the update condition is satisfied, the engine is driven by the electric motor. Automatically restarts the engine, and updates the battery charge calculated by the first charge calculation means to the battery charge calculated by the second charge calculation means. As a result, it is possible to reliably prevent the engine from being unable to be started by the electric motor due to the deterioration in the accuracy of the battery charge amount SOC, which is the condition for canceling the idle stop.
[0046]
(2) In the configuration described in (1), the charge amount update request determination unit determines that the update condition is satisfied when the accuracy of the battery charge amount calculated by the first charge amount calculation unit decreases. I do.
[0047]
(3) In the configuration described in (2), the charge amount update request determination unit determines that the update condition is satisfied when the battery is charged to a predetermined first charge amount or more. .
[0048]
(4) In the configuration according to (2) or (3), the charge amount update request determination unit determines that the update condition is satisfied when the charge / discharge current of the battery is equal to or less than a predetermined first current value. judge.
[0049]
(5) In the configuration according to any one of the above (2) to (4), the charge amount update request determination unit may determine that the battery charge amount becomes equal to or less than a predetermined second charge amount after charging of the battery is completed. It is determined that the above update condition is satisfied.
[0050]
(6) In the configuration according to any one of (1) to (5), when the automatic stop of the engine is not performed for a predetermined time or more in a state where the update condition is satisfied, the operation of the engine is performed. The power running operation of the electric motor is performed while maintaining the condition (1), and the battery charge calculated by the first charge calculation means is updated to the battery charge calculated by the second charge calculation means. As a result, even when the engine is not started, the battery charge amount SOC can be calculated and updated without causing a current to flow through a so-called forced discharge resistor.
[0051]
(7) In the configuration described in (6), the torque of the engine is reduced according to the torque generated by the power running operation of the electric motor. As a result, the battery charge amount SOC can be calculated and updated without affecting the driving of the vehicle.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an overall configuration of a control device for a hybrid vehicle according to the present invention.
FIG. 2 is an explanatory diagram showing a system configuration of a power supply system of the control device for a hybrid vehicle according to the present invention.
FIG. 3 is a flowchart showing a control flow of a hybrid vehicle control device according to the present invention.
FIG. 4 is a flowchart showing a control flow of a hybrid vehicle control device according to the present invention.
FIG. 5 is a flowchart showing a control flow of a control device for a hybrid vehicle according to the present invention.
FIG. 6 is an explanatory diagram showing a change timing of idle stop release SOCX.
FIG. 7 is an explanatory diagram showing a method of calculating an open circuit voltage of a battery.
FIG. 8 is an explanatory diagram showing a relationship between an open circuit voltage of a battery and a battery charge amount SOC.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Automatic transmission 7 ... Crank pulley 8 ... Motor generator 9 ... Motor pulley 12 ... Inverter 13 ... Total control unit 14 ... Battery 15 ... Ammeter 16 ... Voltmeter

Claims (7)

A control device for a hybrid vehicle including a motor as a driving source for driving the vehicle, an electric motor using a battery as a driving source, and an engine,
The engine is automatically stopped and restarted according to a predetermined operating condition. When the charge amount of the battery becomes less than a predetermined first determination value during the automatic stop of the engine, the engine is started by the electric motor. In a hybrid vehicle control device that drives to automatically restart the engine,
First charge amount calculation means for calculating the battery charge amount by integrating the charge / discharge current of the battery over time;
Charge amount update request determination means for determining whether or not the update condition of the charge amount of the battery is satisfied;
Second charge amount calculation means for calculating a battery charge amount based on an output current and an output voltage of the battery when the electric motor performs a power running operation,
When the engine is automatically stopped and the update condition is satisfied, the engine is driven by the electric motor when the battery charge becomes less than a predetermined second determination value larger than the first determination value. And automatically updating the engine, and updating the battery charge calculated by the first charge calculation means to the battery charge calculated by the second charge calculation means. Control device. 2. The hybrid according to claim 1, wherein the charge amount update request determination unit determines that the update condition is satisfied when the accuracy of the battery charge amount calculated by the first charge amount calculation unit decreases. 3. Vehicle control device. 3. The hybrid vehicle according to claim 2, wherein the charge amount update request determination unit determines that the update condition is satisfied when the battery is charged with a predetermined first charge amount or more. 4. Control device. 4. The hybrid vehicle according to claim 2, wherein the charge amount update request determination unit determines that the update condition is satisfied when a charge / discharge current of the battery is equal to or less than a predetermined first current value. 5. Control device. 5. The charge amount update request determining unit determines that the update condition is satisfied when the battery charge amount becomes equal to or less than a predetermined second charge amount after the charging of the battery is completed. A control device for a hybrid vehicle according to any one of the above. If the automatic stop of the engine has not been performed for a predetermined time or more in a state where the update condition is satisfied, the power running operation of the electric motor is performed while the operation of the engine is maintained, and the first charge amount calculating means The control device for a hybrid vehicle according to any one of claims 1 to 5, wherein the battery charge amount calculated in (1) is updated to the battery charge amount calculated by the second charge amount calculation means. The control device for a hybrid vehicle according to claim 6, wherein the torque of the engine is reduced according to a torque generated by the power running operation of the electric motor.

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