JP3285638B2 - Control device for hybrid vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a hybrid vehicle using both an engine and an electric motor as drive sources.

[0002]

2. Description of the Related Art For example, as disclosed in Japanese Patent Application Laid-Open No. 58-198104, a hybrid vehicle using an engine and an electric motor together as a drive source is known.

In this hybrid vehicle, as shown in FIG. 28, an engine (internal combustion engine) and an electric motor (hereinafter referred to as "motor") are connected in parallel to an output shaft, and the throttle opening of the engine and the electric power of the motor are connected. This is to control while maintaining a predetermined relationship with the slave voltage.

[0004]

In general, in a vehicle engine, CO, HC, N contained in exhaust gas
The harmful components of O _X or the like in order to Kiyoshika, is provided with the catalytic converter comprised of the three-way catalyst in an exhaust passage, to obtain CO, HC, simultaneously high Kiyoshika rate to three components of the NO _X in the three-way catalyst For this purpose, it is necessary to accurately control the air-fuel ratio within a narrow region near the stoichiometric air-fuel ratio. For this reason, an air-fuel ratio sensor (O ₂ sensor) provided in the exhaust passage of the engine detects the oxygen concentration in the exhaust gas, and a controller including a microcomputer controls the fuel injection valve so that the air-fuel ratio becomes the stoichiometric air-fuel ratio. Is feedback-controlled.

[0005] However, even the engine that performs such air-fuel ratio control has the following problems.

(1) The air-fuel ratio in the engine cylinder deviates from a predetermined value (the stoichiometric air-fuel ratio or the lean air-fuel ratio) due to a delay in fuel transport in the engine intake system during acceleration / deceleration, and the exhaust gas purification rate of the catalyst decreases to reduce the exhaust gas. HC and CO in the gas increase.

(2) The air-fuel ratio deviates from a predetermined value due to variations in the characteristics of the engine (for example, fuel transport delay characteristics of the intake system, etc.), the exhaust gas purification rate of the catalyst decreases, and H in the exhaust gas decreases.
C and CO increase, and exercise performance decreases.

(3) When performing traction control for suppressing wheel slip on a low μ road such as a snowy road, if the torque of the engine changes suddenly, HC and CO in the exhaust gas increase for the same reason as described above .

[0009] In view of the above circumstances, purpose of the present invention, in a hybrid vehicle using both the engine and the motor as a power source, FIG reduction of harmful components in the exhaust gas to prevent sudden change in the engine torque Rutotomoni is to provide a control apparatus for a hybrid vehicle with good response without overshoot.

[0010]

Control apparatus for a hybrid vehicle according to the present invention SUMMARY OF THE INVENTION, as described in claim 1, in the control apparatus for a hybrid vehicle using both the engine and the electric motor as the dynamic power source, the operation Based on the target torque value determined according to the operation amount of the output control means operated by the user, when performing feedback control of the combined torque of the engine torque and the motor torque, the engine and motor models are set in advance. estimates the internal state quantity of the engine and the motor by the state observer, a control means for performing the determined feedback control the amount of feedback based on the estimated, to a value smaller than the feedback gain of the feedback gain of the engine motor It is characterized by being set.

[0011] The present invention as described in claim 2, identified in the configuration described in claim 1, wherein the control means, the engine and the motor model from the target value and the measured value in the control The internal state quantities of the engine and the motor are estimated using the model.

According to a third aspect of the present invention, in a control apparatus for a hybrid vehicle using both an engine and an electric motor as power sources, an engine torque and a motor torque are adjusted based on a target vehicle speed. When the vehicle speed is feedback-controlled, the engine and motor models are set in advance, and the state observer estimates the internal state quantities of the engine and motor, determines the feedback quantity based on the estimation, and performs feedback control. comprising means, in which the feedback gain of the engine, characterized by comprising been set to a value smaller than the feedback gain of the motor.

[0013]

According to the first to third aspects of the present invention, when the target torque value changes, the motor torque greatly changes, but the engine torque changes slowly.
The deviation amount of the air-fuel ratio is reduced, and the emission amount of harmful components such as HC and CO can be reduced. In addition, control responsiveness can be improved.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. First, the basic configuration of the control device is described in the PI file.
About various reference examples to which the feedback control system is applied.
And then state feedback control and adaptive control
An embodiment of the present invention to which control is applied will be described.

FIG. 1 is a block diagram showing the configuration of a control device for a hybrid vehicle according to a first embodiment of the present invention, and FIG. 2 is a block diagram showing the PI feedback control system.

[0016] In the present embodiment, the engine torque Te
Torque Tp is fed back in order to smoothly control the combined torque Tp of the motor and the motor Tm, and a target torque value a represented by an operation amount of an accelerator pedal, which is output control means operated by a driver, that is, an accelerator opening degree. By adjusting the input t (throttle opening) of the engine and the input v (electron voltage) of the motor,
Feedback control is performed so that the resultant torque Tp follows the target torque value.

In FIG. 2, Kie and Kpe respectively represent an integral term and a proportional term of an engine feedback gain (feedback constant) in PI feedback control, and Kim and Kpm respectively represent a motor feedback gain in PI feedback control. These are the integral term and the proportional term.

The present reference example, the fuel transfer delay of the engine intake system during acceleration and deceleration, the air-fuel ratio in the engine cylinder is a control system for preventing the shift from a predetermined value, and it is characterized The point is that the feedback gains Kie and Kpe of the engine are set lower than the feedback gains Kim and Kpm of the motor. Thus, instead of increasing the change in the motor torque Tm as shown in FIG. Abrupt changes can be suppressed, thereby suppressing an increase in HC and CO in the exhaust gas.

[0019] The flow of the control routine executed by a controller in the present embodiment shown in FIG.

In the flowchart of FIG. 4, first, the output I of the integrator is initialized, and the target torque value a and the resultant torque Tp represented by the accelerator opening are detected. Then a
The difference e between Tp and Tp is obtained, and integration is performed to calculate the value of I. Next, the engine input t and the motor input v are calculated,
Output t and v. Then, the determination in the next step is “YE
The next control cycle is executed after waiting for "S".

Next, FIGS. 5 and 6 show the second embodiment of the present invention.
It is a block diagram illustrating a block diagram and PI feedback control system showing the arrangement of a control apparatus for a hybrid vehicle according to considered example.

The present reference example, which according to the amount of deviation from the target air-fuel ratio of the actual air-fuel ratio obtained from the air-fuel ratio sensor provided in an exhaust system and adapted to correct the torque distribution characteristic of the engine and the motor This is a control system for preventing an increase in HC and CO and a decrease in kinetic performance due to variations in engine characteristics.

In FIG. 6, in addition to the control system shown in FIG. 2, the actual air-fuel ratio detected by the air-fuel ratio sensor is compared with the target air-fuel ratio to determine the absolute value s (abs) of the difference. Is larger than the predetermined constant g1, the constants g2 and g3 are subtracted from the feedback gains Kie and Kpe, respectively. That is, the larger the deviation of the actual air-fuel ratio from the target air-fuel ratio is, the more the feedback gain of the engine is reduced. As a result, as shown in FIG. 7, with respect to the change in the target torque value a represented by the accelerator opening, Thus, the degree of change in the engine torque Te is further reduced to prevent an increase in HC and CO, and the degree of change in the motor torque Tm is increased to prevent a decrease in exercise performance.

[0024] The flow of the control routine executed by a controller in the present embodiment shown in FIG.

In the flowchart of FIG. 8, the output I of the integrator is initialized, and the engine feedback gain Ki is initialized.
After initial values are set in e and Kpe, the actual air-fuel ratio is detected, and the absolute value s of the difference from the target air-fuel ratio is obtained. When the value of s is larger than the constant g1, the feedback gain Kie, Constants g2 and g3 are subtracted from Kpe.
The subsequent control flow is the same as the flow shown in FIG.

FIGS. 9 and 10 are a block diagram showing a configuration of a control device for a hybrid vehicle according to a third embodiment of the present invention and a block diagram showing a PI feedback control system.

The present embodiment is, when performing the suppressing traction control wheel slip, by suppressing the sudden change in the engine torque, a control system for preventing deterioration of exhaust gas purification performance of the catalyst.

That is, in the slip control, the combined torque Tp is sharply reduced by lowering the target torque value a based on a signal for detecting the wheel slip ratio. At this time, as shown in FIG. Most of the sudden drop in output torque is mainly due to motor torque T
The control is performed by reducing the value of m so that the engine torque Te is gradually reduced.

[0029] The flow of the control routine executed by a controller in the present embodiment shown in FIG. 12.

In the flowchart of FIG. 12, first, the slip ratio s of the wheel is detected. When the slip ratio s is larger than a predetermined constant g1, a value obtained by multiplying the slip ratio s by a predetermined constant g2 is subtracted from the target torque value a.

[0031] Also in this reference example, similarly to the first reference example,
By setting the engine feedback gains Kie and Kpe smaller than the motor feedback gains Kim and Kpm, a sudden change in the engine torque Te is prevented.

FIG. 13 is a block diagram showing a configuration of a control device for a hybrid vehicle according to a fourth embodiment of the present invention.

The present embodiment, at the time of cold start, the combustion energy is lost in the engine, a delay in the warm-up i.e. activation of the catalyst is arranged in an exhaust passage, HC, that CO is increased This is a control system for prevention, and the controller controls an ignition system and an injector of the engine.

[0034] In this reference example, at the time of cold start, without operating the injector is first, i.e., in a state of blocking the supply of fuel from the injector to the engine, as shown in FIG. 14, the engine rotation only by the motor torque Tm When the engine speed reaches a predetermined speed, fuel is supplied to the engine through an injector and the ignition system is controlled to adjust the ignition timing so that the rate of increase in the catalyst temperature is maximized. To adjust.

[0035] The flow of control executed by a controller in the present embodiment shown in FIG. 15.

In the flowchart of FIG. 15, the motor is rotated with the armature voltage v of the motor set to the predetermined voltage V0 in a state where the fuel supply to the engine is cut off, and the engine speed is increased. When the engine speed reaches the target engine speed N0, the fuel supply from the injector is disclosed. In conjunction with this, the catalyst temperature TC is detected, and the catalyst temperature increase rate dT
(TC ′ is the previous catalyst temperature). Next, fuel is injected from the injector while adjusting the ignition timing IG so that the catalyst temperature TC becomes maximum (IG 'is the previous ignition timing, dT' is the previous catalyst temperature rise rate, and g is a constant).

[0037] According to the present embodiment, at the time of cold start,
Since the catalyst can be warmed up efficiently, HC and CO in the exhaust gas can be reduced.

The first to third embodiments are all PI feedback control systems. However, the PID including the PI feedback control system
It is known that the feedback control system has some problems in terms of responsiveness, as is apparent from FIG. 3, for example. In addition, there is a problem that overshooting is likely to occur when trying to improve responsiveness.

In view of the above, in the following embodiment according to the present invention, a state feedback control system or an adaptive control system having much better controllability than the PID feedback control system is used. The responsiveness of control is improved while reducing harmful components emitted from the engine in various types of hybrid vehicles.

[0040] Figure 16 is a block diagram showing a feedback control system of the control apparatus for a hybrid vehicle according to a first embodiment of the present invention, in the configuration shown in FIG. 1 of the first reference example described above, as shown in FIG. 2 By using a state feedback control system in place of such a PI feedback control system, an object similar to that of the first embodiment can be achieved with higher responsiveness.

That is, in this embodiment, the dynamic characteristic models of the engine and the motor are set in advance, and the internal state quantities (filling efficiency, armature current, etc.) of the engine and the motor are measured by a state observer called an observer (or Kalman filter). Is estimated and multiplied by feedback gains Kce and Kcm (vector quantities) according to a plurality of state quantities (vector quantities) according to the order of the engine and motor models to determine the feedback quantity and perform feedback control. Has become.

By feeding back the internal state quantities of the engine and the motor in this way, as shown in FIG. 17, good responsiveness without overshoot to the accelerator opening can be obtained. Also, by setting the feedback gains Kim and Kcm to the motor to be larger than the feedback gains Kie and Kce to the engine, rapid acceleration and sudden deceleration of the engine are suppressed, thereby reducing emissions of harmful components from the engine. can do.

FIG. 18 shows the outline of the control flow in this embodiment.
Shown in Here, assuming that the number of state quantities of the engine and the motor is n, X: vector of state quantity of element n U: [tv] A: matrix of n × n B: matrix of n × 2 C: vector of element n Here, A, B, and C are constants representing models of the engine and the motor.

F: Gain of observer (or Kalman filter) (vector of element n) As a method of obtaining feedback gains Kie, Kce, Kim, and Kcm, there is a method based on a solution of a well-known Liccati equation. At this time, the weight v is applied to the motor input v (electron voltage) rather than the engine input t (throttle opening), so that K
Kim and Kcm can be set larger than ie and Kce.

FIGS. 19 and 20 show specific examples of the control flow.

FIG. 21 is a block diagram showing a feedback control system of a hybrid vehicle control device according to a second embodiment of the present invention, in which the state feedback control system is applied to vehicle speed control.

Also in the present embodiment, by controlling the output torques of the engine and the motor by feeding back the internal state quantities of the engine and the motor, as shown in FIG. The vehicle speed VSP can be controlled with high responsiveness.
And also in this case, the feedback gain K to the motor
im and Kcm are feedback gains to the engine Kie and K
By setting it to be larger than ce, sudden acceleration and sudden deceleration of the engine can be suppressed, thereby reducing the amount of emission of harmful components from the engine.

FIG. 23 shows a schematic control flow of this embodiment. The flowchart of FIG. 23 is obtained by replacing the target torque value a (throttle opening) and the resultant torque Tp in the control flow of FIG. 18 with the target vehicle speed and the vehicle speed VSP, respectively.

Next, a third embodiment of the control device for a hybrid vehicle according to the present invention will be described.

In the state feedback control systems according to the first and second embodiments, accurate dynamic characteristic models of the engine and the motor to be controlled are necessary for estimating the state quantity. Not only greatly changes the characteristics due to operating conditions and changes over time,
Since there is a variation for each control target, it may not be possible to determine a dynamic characteristic model in advance. Also, the gain at the time of setting the input from the state quantity may not be set to the optimum value because the dynamic characteristics cannot be determined.

Therefore, a model is identified during control, and the observer (or Kalman filter) is used by using the model.
Accordingly, an adaptive control system for estimating the internal state quantity (filling efficiency, armature current, etc.) of the engine and determining the feedback quantity becomes extremely effective as a power source control system in this kind of hybrid vehicle.

FIG. 24 is a block diagram showing an adaptive control system of the control device for a hybrid vehicle according to the third embodiment.
This achieves the same object as the first embodiment. With this adaptive control system, accurate state control can be performed irrespective of aging or product variations.

As a simple example of the above adaptive control system, an engine model and a motor model are respectively expressed as Te (K + 1) = ge1 · t (k) + ge2 · t (K−1) + ge3 · t (k−2) Tm (k + 1) = gm1 · v (k) + gm2 · v (K−1) + gm3 · t (k−2).

Here, k + 1, k,... Represent a time sequence.
Te and Tm are output torques of the engine and the motor, and it is assumed that Tp = Te + Tm.

The state space representation is as shown in the following equation 1. 25 to 27 show the control flow.

[0056]

(Equation 1)

Here, G = [ge1 ge2 ge3 1 / ge1 1 / ge2 1 / ge3 gm1 gm2 gm3 1 / gm1 1 / gm2 1 / gm3] 'b1 to b8 are 12 element constant vectors h for identification. Gain.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first reference example of the present invention.

FIG. 2 is a block diagram showing the feedback control system.

FIG. 3 is a timing chart for explaining the same operation;

FIG. 4 is a flowchart showing the control routine.

FIG. 5 is a block diagram showing a configuration of a second reference example of the present invention.

FIG. 6 is a block diagram showing the feedback control system.

FIG. 7 is a timing chart for explaining the same operation;

FIG. 8 is a flowchart showing the control routine.

FIG. 9 is a block diagram showing a configuration of a third reference example of the present invention.

FIG. 10 is a block diagram showing the feedback control system.

FIG. 11 is a timing chart for explaining the same operation;

FIG. 12 is a flowchart showing the control routine.

FIG. 13 is a block diagram showing a configuration of a fourth reference example of the present invention.

FIG. 14 is a flowchart for explaining the same operation;

FIG. 15 is a flowchart showing the control routine.

FIG. 16 is a block diagram showing a feedback control system according to the first embodiment of the present invention.

FIG. 17 is a timing chart for explaining the same operation;

FIG. 18 is a flowchart schematically showing the control flow.

FIG. 19 is a flowchart showing the first half of the specific control flow;

FIG. 20 is a flowchart showing the latter half of the specific control flow;

FIG. 21 is a block diagram showing a feedback control system according to a second embodiment of the present invention.

FIG. 22 is a timing chart for explaining the same operation;

FIG. 23 is a flowchart schematically showing the control flow.

FIG. 24 is a block diagram showing a feedback control system according to a third embodiment of the present invention.

FIG. 25 is a flowchart showing the first half of the specific control flow;

FIG. 26 is a flowchart showing an intermediate part of the specific control flow;

FIG. 27 is a flowchart showing the latter half of the specific control flow;

FIG. 28 is a block diagram showing a configuration of a hybrid vehicle.

[Explanation of symbols]

 a Required torque value (accelerator opening) Te Engine torque Tm Motor torque Tp Synthetic torque t Throttle opening v Element voltage

Continuation of front page (56) References JP-A-49-67026 (JP, A) JP-A-61-191435 (JP, A) JP-A-64-22637 (JP, A) JP-A-63-18986 (JP) JP-A-62-233002 (JP, A) JP-A-1-150401 (JP, U) JP-A-60-103021 (JP, U) JP-B-61-57204 (JP, B1) JP-B-sho 52-12861 (JP, B1) Jiko 57-13387 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60L 11/14 B60K 9/00

Claims (3)

(57) [Claims] An engine and an electric motor are used as power sources.
In the control device of the hybrid vehicle to be used together , according to the operation amount of the output control means operated by the driver
Engine torque based on the target torque value
Feedback control of the combined torque of
The engine and motor models beforehand.
Engine and motor
Is estimated and the feedback is performed based on the estimation.
Control means for determining the amount and performing feedback control
The feedback gain of the above engine is
That it is set to a value smaller than the
A control device for a hybrid vehicle. 2. The control means according to claim 1, wherein said control means sets a target value during control.
Identify engine and motor models from measured and measured values
And the internal state of the engine and motor
2. The hybrid according to claim 1, wherein the amount is estimated.
Control device for padded vehicles. 3. An engine and an electric motor as power sources.
In the hybrid vehicle control device used together, the engine torque and the motor torque are determined based on the target vehicle speed.
When feedback control of vehicle speed by adjusting
Gin and motor models are set in advance,
The state of the engine and motor using the state observer.
Estimation, and the feedback amount is determined based on the estimation.
Control means for performing feedback control, wherein the feedback gain of the engine
That it is set to a value smaller than the
A control device for a hybrid vehicle.