JP2004229354A - Controller for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the state of charge SOC of a battery from sharply dropping even if such operation that the generated power of a generator exceeds the drive power of a motor is performed frequently. <P>SOLUTION: This controller hourly integrates differences between the generated power of the generator and the drive power of the motor, and when the integrated value is smaller than a minus specified value (1), the desired value of the state of charge SOC is increased. On the other hand, when the above integrated value is larger than a plus specified value (2), the desired value of the state of charge SOC is decreased. Furthermore, if the integrated value is above the minus specified value and besides not more than the plus specified value (2), the desired value of the state of charge SOC is kept as it is as a reference value. Then, the generated power of the generator is fed back so that the actual state of charge accords with the desired value. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a hybrid vehicle that controls a charge amount of a battery that supplies power to a motor.
[0002]
[Prior art]
BACKGROUND ART Conventionally, a hybrid vehicle including an engine and a motor as power sources has been known (for example, see Patent Literature 1 and Non-Patent Literature 1).
[0003]
The hybrid vehicle includes a battery that supplies power to a motor, and a generator that is driven by an engine and supplies charging power to the battery. Here, it is known that maintaining the state of charge SOC of the battery (for example, the ratio of the remaining current amount to the full charge current amount) within a certain range always extends the life of the battery. In addition, the power generation of the generator is controlled by detecting the charge amount SOC.
[0004]
[Patent Document 1]
JP-A-10-288028 [Non-Patent Document 1]
Edited by Masayuki Okazawa, "Automotive Engineering June 1997", Railway Japan Co., Ltd., June 1, 1997, p38-p52
[0005]
[Problems to be solved by the invention]
By the way, when the drive power of the motor exceeds the power generated by the generator, the torque required for the motor is generated by the power supply from the battery. However, there is a problem that the battery life tends to be lower and the life of the battery and the motor output may be reduced.
[0006]
The present invention has been made in view of the above problems, and it is possible to suppress a decrease in the charge amount of a battery even when a state in which the drive power of a motor exceeds the power generated by a generator frequently occurs. An object of the present invention is to provide a control device for a hybrid vehicle that can avoid a reduction in life and a reduction in motor output.
[0007]
[Means for Solving the Problems]
Therefore, according to the first aspect of the present invention, the target value of the charge amount of the battery is changed according to the difference between the generated power of the generator and the driving power of the motor.
[0008]
According to this configuration, it is determined from the difference between the power generated by the generator and the drive power of the motor whether or not the power generated by the generator tends to be insufficient, and the target value of the charged amount is changed.
[0009]
Therefore, by changing the target value of the charge amount based on the determination as to whether or not the generated power of the generator tends to be insufficient, it is possible to secure a necessary and sufficient charge amount in advance.
[0010]
According to the second aspect of the present invention, when the driving power of the motor tends to exceed the power generated by the generator, the target value of the charged amount is changed to be larger.
According to such a configuration, when the drive power of the motor exceeds the power generated by the generator and the power generated tends to be insufficient, by increasing the target of the charge amount, the power generation of the generator is further promoted, and a large amount of power is generated in advance. The amount of charge can be secured.
[0011]
According to the third aspect of the invention, the target value of the charge amount is changed according to the integrated value of the difference between the power generated by the generator and the drive power of the motor.
According to this configuration, by integrating the difference between the generated power of the generator and the driving power of the motor, it is possible to determine whether the generated power of the generator is short or excessive based on the plus or minus of the integrated value. Then, the target of the charge amount is changed based on the determination result.
[0012]
Therefore, it is possible to easily and accurately determine whether the power generated by the generator tends to be insufficient or excessive.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a system schematic diagram of a hybrid vehicle according to the present embodiment.
[0014]
In FIG. 1, the driving force of a spark ignition gasoline engine 1 is divided by a power split mechanism 2 into a driving force of driving wheels 3 and a driving force of a generator 4.
As the power split mechanism 2, a planetary gear device as shown in FIG. 2 is used, and the power of the engine 1 is transmitted to a directly connected planetary carrier, and is distributed to a ring gear and a sun gear through a pinion gear.
[0015]
The rotating shaft of the ring gear is directly connected to the motor 5, and the driving force is transmitted to the driving wheels 3 through the speed reducer 8, while the rotating shaft of the sun gear is directly connected to the generator 4.
[0016]
That is, the power of the engine 1 is input to the power split mechanism 2 which is directly connected, one of the output shafts of the power split mechanism 2 is connected to the motor 5 and the drive wheels 3, and the other is connected to the generator 4. .
[0017]
In the power split device 2, the rotation speed of the engine 1 (carrier) can be changed by controlling the rotation of the generator 4 (sun gear) by the inverter 6 (see FIG. 3).
[0018]
At the same time, a part of the engine output is transmitted to the motor 5 via the generator 4 and converted into the driving force of the vehicle, thereby having a function as a continuously variable transmission.
[0019]
The electric power generated by the generator 4 is directly used for driving the motor 5, is converted into direct current by the inverter 6, and is stored in the battery 7.
Information such as engine speed, accelerator pedal depression amount, vehicle speed, battery voltage, shift position, and the like is input to the control unit 9 incorporating a microcomputer, and based on these information, the opening of the electronic throttle provided in the engine 1 is performed. In addition to controlling the fuel injection by the fuel injection valve and the ignition by the spark plug, the rotation speed of the generator 4 and the torque of the motor 5 are controlled.
[0020]
Specifically, when the vehicle is stopped, the engine 1, the generator 4, and the motor 5 are both stopped (see FIG. 3A), and the fuel supply to the engine 1 is stopped when the engine 1 is started at a low efficiency or when the engine 1 is lightly loaded. Then, the vehicle is driven only by the motor 5.
[0021]
The fuel supply of the engine 1 is started after the start (see FIG. 3B), and the engine 1 is mainly driven by the output of the engine 1 during steady running.
Therefore, during steady running, power generation by the generator 4 becomes almost unnecessary (see FIG. 3C).
[0022]
When accelerating from steady running, the engine 1 is rotated at a higher speed, the generator 4 is caused to generate power, and the motor driving force is added to the direct driving force of the engine 1 to accelerate (see FIG. 3D).
[0023]
At the time of deceleration, the drive wheels 3 drive the motor 5 so that the motor 5 functions as a generator, regenerative power is generated, and the regenerated energy is stored in the battery 7.
The control unit 9 detects the state of charge SOC of the battery 7 (for example, the ratio of the remaining current amount to the full charge current amount), and controls the power generated by the generator 4 based on the detection result. It has a feedback control function of maintaining the state of charge SOC of the battery 7 within a specific range.
[0024]
That is, as shown in FIG. 4, an upper limit value (Upper) and a lower limit value (Lower) are set before and after the target value of the charge amount SOC, and when the charge amount SOC reaches the upper limit value, the electric power generated by the generator 4 And the driving power is supplied to the motor 5 by discharging from the battery 7. Conversely, when the charging amount SOC reaches the lower limit value, the power generated by the generator 4 is increased to increase the charging amount to the battery 7. .
[0025]
The flowchart of FIG. 5 shows the control of the power generated by the generator 4 by the control unit 9.
First, in step S1, the charge amount SOC of the battery 7 is estimated by integrating the charge / discharge current of the battery 7 with time.
[0026]
In step S2, a target value of the charge amount SOC is set according to a flowchart of FIG.
In step S3, a power generation correction amount (feedback correction amount) for causing the actual charge amount SOC to converge around the target value from the actual charge amount SOC estimated in step S1 and the target value set in step S2. Is calculated.
[0027]
In step S4, a basic power generation amount is calculated from the driving torque required for the motor 5 and the torque for driving the auxiliary devices.
In step S5, the final power generation amount is obtained by adding the power generation correction amount to the basic power generation amount.
[0028]
The power generation amount is converted into an engine speed with characteristics as shown in FIG. 7, and the engine load and the motor torque are controlled so as to become the engine speed.
The flowchart of FIG. 6 shows the process of setting the target charge amount in step S2 in detail.
[0029]
In the flowchart of FIG. 6, first, in step S21, a reference target value is set.
The reference target value is stored in advance as a fixed value.
[0030]
In the next step S22, a time integrated value (= Σ (generated power of generator 4−driving power of motor 5)) of the difference between the generated power of generator 4 and the driving power of motor 5 is calculated.
[0031]
The integrated value indicates a negative value when the power generated by the generator 4 tends to be smaller than the drive power of the motor 5, and the power generated by the generator 4 tends to be larger than the drive power of the motor 5. At some point, it will show a positive value.
[0032]
In step S23, it is determined whether or not the integrated value of the power difference is smaller than a negative predetermined value (1).
When the integrated value of the power difference is smaller than the negative predetermined value (1), the process proceeds to step S24, and the result obtained by adding a predetermined correction amount (> 0) to the reference target value is determined as the final charge amount SOC. The target value is set, and a target value larger than the reference target value is set.
[0033]
On the other hand, when the integrated value of the power difference is equal to or more than the negative predetermined value (1), the process proceeds to step S25, and it is determined whether the integrated value of the power difference is larger than the positive predetermined value (2). .
[0034]
When the integrated value of the power difference is larger than the plus predetermined value (2), the process proceeds to step S26, and the result obtained by subtracting a predetermined correction (> 0) from the reference target value is used as the final charge amount SOC. A target value is set, and a target value smaller than the reference target value is set.
[0035]
Further, when it is determined that the integrated value of the power difference is equal to or less than a plus predetermined value (2), that is, the integrated value of the power difference is equal to or more than a minus predetermined value (1), and When the power balance is substantially equal to or less than the predetermined value (2), the process proceeds to step S27, and the reference target value is directly set to the target value of the state of charge SOC.
[0036]
As described above, when the generated power of the generator 4 tends to be smaller than the drive power of the motor 5, if the target value of the charge amount SOC is changed to be increased, the battery 7 can be charged more than usual when charge is possible. To charge more.
[0037]
Therefore, even when the full-open acceleration that requires the supply of the driving power from the battery 7 is frequently performed, it is possible to prevent the charge amount in the battery 7 from being significantly reduced, and to reduce the life of the battery due to the decrease in the charge amount. It is possible to avoid a drop or a decrease in the motor output.
[0038]
Further, when the generated power of the generator 4 tends to be larger than the drive power of the motor 5, the target value of the charge amount SOC is changed to be reduced, so that the power generation of the generator 4 is performed excessively and the fuel consumption performance is reduced. I won't let you.
[0039]
Note that, when the generated power of the generator 4 continues to be smaller (larger) than the drive power of the motor 5, the target value of the state of charge SOC may be gradually changed to be larger (smaller).
[0040]
Further, the larger the absolute value of the integrated value of the power difference is, the more the target value of the state of charge SOC may be increased or decreased.
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described below together with their effects.
(A) In the control device for a hybrid vehicle according to claim 3,
When the integrated value of the difference between the power generated by the generator and the drive power of the motor is smaller than a predetermined negative value, the target value of the charge amount is increased and changed. A control device for a hybrid vehicle, wherein a target value of an amount is reduced and changed.
[0041]
According to this configuration, when the integrated value of the power difference tends to be short of a power generation amount smaller than a minus predetermined value, the target value of the charged amount is changed to be increased, and the integrated value of the power difference is set to be larger than the predetermined value. When there is also a tendency to generate too much power, the target value of the charged amount is reduced and changed, and the power balance is such that the integrated value of the power difference is equal to or more than a negative predetermined value and equal to or less than a positive predetermined value. When substantially balanced, the target value is kept at the reference value.
[0042]
Therefore, by appropriately changing the amount of power generation in response to the excess or deficiency of the amount of power generation, it is possible to stably control the charge and discharge of the battery while avoiding a large change in the charge amount of the battery.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a hybrid vehicle according to an embodiment.
FIG. 2 is a diagram showing a planetary gear device constituting the power split device according to the embodiment.
FIG. 3 is a collinear chart showing a correlation between shaft rotation speeds of planetary gears constituting a power split mechanism in the embodiment.
FIG. 4 is a time chart showing the behavior of the state of charge SOC of the battery in the embodiment.
FIG. 5 is a flowchart illustrating a state of battery charge control in the embodiment.
FIG. 6 is a flowchart showing how to set a target value of the state of charge SOC in the embodiment.
FIG. 7 is a diagram showing a correlation between a power generation amount and an engine rotation speed in the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Power distribution mechanism, 3 ... Drive wheel, 4 ... Generator, 5 ... Motor, 6 ... Inverter, 7 ... Battery, 8 ... Reduction gear, 9 ... Control unit

Claims (3)

An engine and a motor as power sources, a battery that supplies power to the motor, and a generator that is driven by the engine and supplies charging power to the battery,
In the control device of the hybrid vehicle that controls the generated power of the generator according to the charge amount of the battery,
A control device for a hybrid vehicle, wherein a target value of the charged amount of the battery is changed in accordance with a difference between a generated power of the generator and a driving power of the motor. 2. The control device for a hybrid vehicle according to claim 1, wherein when the drive power of the motor tends to exceed the power generated by the generator, the target value of the charge amount is changed to a larger value. 3. The control device for a hybrid vehicle according to claim 1, wherein the target value of the charge amount is changed according to an integrated value of a difference between a power generated by the generator and a drive power of the motor.

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