JP3843934B2 - 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]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a hybrid vehicle.
[0002]
[Prior art]
In a hybrid vehicle having an engine and a motor using a battery as a drive source for driving the vehicle, in order to improve fuel efficiency, the engine is automatically stopped and restarted (so-called idle) according to the driving conditions of the vehicle. What performs stop control) is widely known.
[0003]
In such a hybrid vehicle that automatically stops and restarts the engine, it is difficult to automatically restart the engine if the engine is automatically stopped when the battery is insufficiently charged. In an insufficiency state, automatic engine stop is prohibited.
[0004]
In addition, the battery charge amount is normally calculated by integrating the charge / discharge current to the battery over time, but in order to correct the integration error, the battery is forcibly discharged at the start or after a predetermined time has elapsed after the start, A battery charge amount is calculated and updated from the voltage and current at the time of forced battery 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 amount is updated from a large current flowing through the motor at the engine start, and after a predetermined time has passed, the battery charge amount is updated by flowing a large current through the forced discharge resistor.
[0006]
[Problems to be solved by the invention]
However, since the battery charge amount update timing is at the start of the engine and after a predetermined time has elapsed since the start, the battery charge amount is updated at a timing that originally needs to be updated, such as after battery charging where the integration accuracy deteriorates. There is a problem that can not be.
[0007]
In addition, when the battery charge is updated after a lapse of a predetermined time after starting, a forced discharge resistor is required, and the battery consumes power by passing a current through the forced discharge resistor. There is a problem of end.
[0008]
[Means for Solving the Problems]
The control device for a hybrid vehicle according to the present invention performs automatic stop / restart of the engine according to a predetermined driving condition, and the charge amount of the battery is less than a predetermined first determination value during the automatic stop of the engine. Then, the control device for a hybrid vehicle that automatically restarts the engine by driving the engine with the electric motor, the first charge amount calculating the battery charge amount by integrating the charge / discharge current of the battery over time. Battery charging based on the calculation means, the charge amount update request determination means for determining whether or not the update condition for the charge amount of the battery is satisfied, and the output current and output voltage of the battery when powering the motor A second charge amount calculation means for calculating the amount, and when the engine is automatically stopped and the update condition is satisfied, the battery charge amount is determined from the first determination value. When it becomes less than a large predetermined second determination value, the engine is driven by the electric motor to automatically restart the engine, and the battery charge amount calculated by the first charge amount calculation means is set to the second charge amount. The battery charge amount calculated by the amount calculation means is updated. This makes it possible to change the conditions for automatic engine restart as necessary, and to quickly update the battery charge amount.
[0009]
【The invention's effect】
According to the present invention, since the battery charge amount can be updated as necessary, the battery charge amount can be always accurately grasped.
[0010]
DETAILED DESCRIPTION OF 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 the 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 (continuously continuously variable) connected to the engine 1 via the torque converter 4. Variable transmission) 5, crankshaft 3, forward clutch 6 provided between torque converter 4 and CVT 5, and the output side of CVT 5 is not shown in the same manner as 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 the front end of the engine 1. A belt 11 is wound around the crank pulley 7 and a motor pulley 9 attached to the output shaft 8a of the motor generator 8 as an electric motor.
[0015]
The motor generator 8 is controlled by the total control unit 13 via the inverter 12, and when the engine is started by the engine key and when the engine is automatically restarted (described later), power is supplied from the battery 14 to perform a power running operation. In addition to performing cranking, regenerative operation is performed during vehicle deceleration operation, and energy from the crankshaft 3 is regenerated as a generator to generate power and charge the battery 14. Here, an ammeter 15 for detecting the charge / discharge current of the battery 14 and a voltmeter 16 for detecting the charge / discharge voltage of the battery 14 are interposed between the inverter 12 and the battery 14 as shown in FIG. It is disguised.
[0016]
The total control unit 13 detects the amount of charge of the battery 14, and also includes an oil temperature sensor 17 that detects the oil temperature of the automatic transmission 2, a hydraulic sensor 18 that detects the operating oil pressure of the automatic transmission 2, and the engine 1. A signal from a water temperature sensor 19 for detecting the cooling water temperature is input.
[0017]
The total control unit 13 stops the fuel injection of the engine 1 and automatically stops the engine 1 (idle stop) when a predetermined condition (idle stop condition) is satisfied when the vehicle is temporarily stopped after the warm-up operation ends. The engine 1 is automatically restarted (idle stop release) when a predetermined condition (idle stop release condition) is satisfied during automatic engine stop, and so-called idle stop control is performed. Driving with 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 for 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 battery charge amount SOC is updated. Further, 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 shown in the following equation (1) to calculate the battery charge amount SOC (No. 1). 1 charge amount calculation means).
[0020]
[Expression 1]
SOC = SOC + IH · Δt (1)
Next, the control contents of the total control unit 13 will be described with reference to the flowcharts of FIGS.
[0021]
FIG. 3 is a flowchart (charge amount update request determination means) for determining whether or not an update condition for 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 expressed as S), the power generation amount (including regenerative power generation) of the motor generator 8 is not less than a predetermined value, that is, the charge amount to the battery 14 is not less than a predetermined value (first charge amount). If it is greater than or equal to a predetermined value (first charge amount), it is determined that the update condition for the battery charge amount SOC is satisfied, and the process proceeds to S15, where the update required flag fkosin is set to fkosin = 1. To do. This is because, when the battery 14 is charged, such as during power generation or regeneration, due to the effect of the charge / discharge efficiency of the battery 14, the accumulated accuracy of the battery charge SOC, that is, the accuracy of the battery charge SOC by the first charge amount calculation means described above. This is because it gets worse. In the determination in S11, a value (Ah or Wh) obtained by integrating the charging current or charging power may be compared with a predetermined determination value. Here, the calculation of the integrated value (Ah or Wh) to be compared with the predetermined determination 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 once set. 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 the charging / discharging current of the battery 14 is equal to or less than a predetermined value and a predetermined time has elapsed. If the charging / discharging 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, and the process proceeds to S15, where the update required flag fkosin is set to fkosin = 1. This is because the influence of the accuracy of the ammeter 15 is larger in the lower current region, 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 required flag fkosin is set to fkosin = 1. This is because the smaller the battery charge amount SOC, the greater the influence of the battery charge amount SOC on the idle stop control. More specifically, since the battery charge amount SOC is used for determining whether or not the engine can be restarted 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 an idle stop (automatic engine stop) is in effect. If the engine is not idle stopped, the process proceeds to S22, and if the engine is idle stopped, the process proceeds to S24.
[0027]
In S22, it is determined whether or not an idle stop condition (engine automatic stop condition) is satisfied. If the idle stop condition is satisfied, the process proceeds to S23 to perform an idle stop (engine automatic stop). Here, the idle stop includes the driver's operation state such as shift range, vehicle speed, accelerator opening, brake hydraulic pressure, engine water temperature, battery state, master back negative pressure, automatic transmission oil temperature (AT oil temperature), 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 If it is OFF, the brake is ON, and the charge amount of the battery 14 is equal to or greater than a predetermined value and the engine water temperature is equal to or greater than a predetermined value, it is determined that the idle stop condition is satisfied.
[0028]
In S24, the state of the update necessary 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 cancellation SOCX is set to a second determination value (80% here) higher than normal, and the process proceeds to S27. In S26, the idle stop cancellation SOCX is set to a 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 (engine automatic restart) determination is performed 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, where the idle stop release is performed and the discharge from the battery 14 due to the power running operation of the motor generator 8 when the engine is automatically restarted. The battery charge SOC is updated from the output current and output voltage.
[0031]
Here, a method (second charge amount calculation means) for calculating the battery charge amount SOC from the output current and output voltage due to the discharge from the battery 14 accompanying the power running operation of the motor generator 8 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 engine automatic restart, and from the discharge voltage Va during idle stop and the discharge voltage Vb during engine automatic restart. ΔV is calculated, and an internal resistance R (inclination of a straight line connecting points P and Q in FIG. 7) is obtained from ΔI and ΔV. Then, the open circuit voltage Eb is calculated from the internal resistance R, the discharge current Ib at the time of automatic engine restart, and the discharge current Vb by the following equation.
[0032]
[Expression 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 in S28 after the battery charge amount SOC is updated.
[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, where it is determined whether an idle stop release condition other than the battery charge amount SOC is satisfied, and other than the battery charge amount SOC. If the idle stop cancellation condition is satisfied, the process proceeds to S28.
[0035]
FIG. 5 is a flowchart showing the contents of control when the battery charge amount SOC is updated 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 engine is in an idling stop (automatic engine stop) state. If not, the process proceeds to S42.
[0037]
In S42, it is determined whether or not a predetermined time has passed since the update required flag fkosin = 1, and if the predetermined time or more has passed, the process proceeds to S43.
[0038]
In S43, a torque increase command (+ TRQX) is issued to the motor generator 8 to cause the motor generator 8 to perform a power running operation, and a torque decrease command (−TRQX) for decreasing the engine torque by the torque increment TRQX to the motor generator 8 for the engine 1. ).
[0039]
In S44, the battery charge SOC is updated in substantially the same manner as 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 in the torque increase command (+ TRQX), and the torque increase command (+ TRQX) is sent to the motor generator 8. ΔV is calculated from the discharge voltage before delivery and the discharge voltage in the torque increase command (+ TRQX), and the internal resistance R is obtained from these ΔI and ΔV (see FIG. 7 described above). Then, the open circuit voltage Eb is calculated from the internal resistance R, the discharge current in the torque increase command (+ TRQX) and the discharge voltage in the torque increase command (+ TRQX), and the battery charge SOC is calculated using the open voltage Eb. Then, the battery charge amount SOC is updated (see FIG. 8). The update required flag fkosin is set to fkosin = 0 in S44 after the battery charge amount SOC is updated.
[0040]
As described above, by changing the idle stop cancellation SOCX as necessary, it is ensured that the engine start by the motor generator 8 becomes impossible due to the deterioration of the accuracy of the battery charge amount SOC that is the idle stop cancellation condition. Can be avoided.
[0041]
In addition, since the battery charge amount SOC can be updated at the timing of releasing the idle stop, the battery charge amount SOC necessary for the idle stop control can always be grasped with high accuracy.
[0042]
When the accuracy of the battery charge amount SOC by 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 a predetermined value or more, charging / discharging of the battery 14 is performed. Used for idle stop control by updating the battery charge SOC when the current is less than a predetermined value and a predetermined time has elapsed or when the battery charge SOC after power generation (including regeneration) is less than a predetermined value The accuracy of the battery charge amount SOC can be improved, and it is possible to prevent the idle stop frequency from being reduced by changing the condition of the idle stop release SOCX.
[0043]
Further, even when the engine is not started, that is, while the engine is rotating, by reducing the torque of the engine 1 by the torque increment TRQX for causing the motor generator 8 to perform a power running without affecting the operation of the vehicle, In addition, the battery charge amount SOC can be calculated and updated without passing a current through the so-called forced discharge resistor.
[0044]
The technical idea of the present invention that can be grasped from the above embodiments will be listed together with the effects thereof.
[0045]
(1) A hybrid vehicle control device including a motor using a battery as a drive source for driving a vehicle and an engine, and automatically stopping / restarting the engine according to predetermined operating conditions. Control of the hybrid vehicle that starts and automatically restarts the engine by driving the engine with the electric motor when the charge amount of the battery becomes less than a predetermined first determination value while the engine is automatically stopped. In the apparatus, a first charge amount calculation means for calculating a battery charge amount by integrating the charge / discharge current of the battery over time, and a charge amount update request for determining whether or not an update condition for the charge amount of the battery 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 powered. If the battery charge amount is less than a predetermined second determination value that is larger than the first determination value, the engine is driven by the electric motor. The engine is automatically restarted, and the battery charge amount calculated by the first charge amount calculation unit is updated to the battery charge amount calculated by the second charge amount calculation unit. Thus, it is possible to reliably avoid the engine starting by the electric motor being disabled due to the deterioration of the accuracy of the battery charge amount SOC which is the idle stop cancellation condition.
[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. To 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 with a predetermined first charge amount or more. .
[0048]
(4) In the configuration described in (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 lower than a predetermined first current value. judge.
[0049]
(5) In the configuration according to any one of (2) to (4), when the charge amount update request determination unit is less than or equal to a predetermined second charge amount after completion of charging the battery, It is determined that the update condition is satisfied.
[0050]
(6) In the configuration according to any one of (1) to (5), when the update condition is satisfied and the engine is not automatically stopped for a predetermined time or more, the engine is operated. The power running operation of the electric motor is performed in a state in which the battery charge is maintained, and the battery charge amount calculated by the first charge amount calculation unit is updated to the battery charge amount calculated by the second charge amount calculation unit. As a result, even when the engine is not started, the battery charge amount SOC can be calculated and updated without passing a current through the so-called forced discharge resistor.
[0051]
(7) In the configuration described in (6) above, 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 the overall configuration of a control apparatus 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 a control device for a hybrid vehicle according to the present invention.
FIG. 3 is a flowchart showing a control flow of the control apparatus for a hybrid vehicle according to the present invention.
FIG. 4 is a flowchart showing a control flow of a control apparatus for a hybrid vehicle according to the present invention.
FIG. 5 is a flowchart showing a control flow of the control apparatus for a hybrid vehicle according to the present invention.
FIG. 6 is an explanatory diagram showing a change timing of idle stop cancellation SOCX.
FIG. 7 is an explanatory diagram showing a battery open voltage calculation method.
FIG. 8 is an explanatory diagram showing a relationship between a battery open voltage 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 comprising an electric motor using a battery as a drive source and an engine as a drive source for vehicle travel,
The engine is automatically stopped / restarted according to predetermined operating conditions, and 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 operated by the electric motor. In a hybrid vehicle control device that drives and automatically restarts the engine,
First charge amount calculating means for calculating a battery charge amount by integrating the charge / discharge current of the battery over time;
A charge amount update request determination means for determining whether or not an update condition for 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 powering the electric motor;
When the engine is automatically stopped and the update condition is satisfied, the engine is driven by the electric motor when the battery charge amount is less than a predetermined second determination value that is larger than the first determination value. The engine is automatically restarted, and the battery charge amount calculated by the first charge amount calculation means is updated to the battery charge amount calculated by the second charge amount 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. Vehicle control device. 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. 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 becomes equal to or less than a predetermined first current value. 5. Control device. The charge amount update request determination unit determines that the update condition is satisfied when the battery charge amount is equal to or lower than a predetermined second charge amount after the end of charging the battery. The control apparatus of the hybrid vehicle in any one. When the update condition is satisfied and the engine has not been automatically stopped for a predetermined time or longer, the electric motor is operated in a state where the operation of the engine is maintained, and the first charge amount calculation means 6. The hybrid vehicle control device according to claim 1, wherein the battery charge amount calculated in step 1 is updated to the battery charge amount calculated by the second charge amount calculation unit. The hybrid vehicle control device according to claim 6, wherein the torque of the engine is reduced in accordance with torque generated by powering operation of the electric motor.

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