KR101684022B1 - System and method for controlling generator torque in hybrid vehicle - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and method for controlling generator torque of a hybrid vehicle, and more particularly, to a system and method for controlling a generator torque of a hybrid vehicle to prevent an explosion shock from being transmitted to a vehicle body during an initial explosion .
Accordingly, the present invention includes a vehicle controller (HCU) that controls a torque of the generator when the engine is started with a generator, the vehicle controller (HCU) includes a speed controller for calculating a primary engine target torque for engine starting; And a disturbance observer for calculating a disturbance canceling torque for removing a disturbance component included in the primary engine target torque, wherein a value obtained by adding the primary engine target torque and the disturbance canceling torque is converted to calculate a disturbance component And determines the removed generator target torque based on the output torque of the generator.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a system and method for controlling a generator torque of a hybrid vehicle,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system and method for controlling generator torque of a hybrid vehicle, and more particularly, to a system and method for controlling a generator torque of a hybrid vehicle to prevent an explosion shock from being transmitted to a vehicle body during an initial explosion .

Hybrid vehicle systems include two planetary gear systems, a TMED (Transmission Mounted Electric Device) system and a FMED (Flywheel Mounted Electric Device) system.

In the TMED system, the engine clutch configured between the transmission and the engine is released when the engine is started, so that the engine explosion impact is not transmitted to the drive shaft. In the case of the FMED system, the torque converter is mounted so that the torque converter attenuates the engine's explosion impact, so that the engine explosion impact is not transmitted to the drive shaft. In other words, the FMED system and the TMED system did not cause a problem without considering the explosion impact of the engine at engine start-up.

In the case of a system using two planetary gears, the engine and the transmission are directly connected, but the output shaft and the engine are connected to different planetary gears.

Recently, the power split-parallel system of a hybrid vehicle is capable of implementing an electric vehicle (EV) mode, a power split mode, and an overdrive mode (or parallel mode) .

In the power split mode, the output of the engine is distributed to the sun gear and the ring gear of the planetary gear, the engine output transmitted to the sun gear is absorbed by the generator, the absorbed energy is transmitted to the battery or the motor, This mode is used for driving a vehicle. At this time, the motor also generates an output for driving to assist the engine output transmitted to the ring gear.

The power split mode and the parallel mode are hybrid vehicle (HEV) modes in which an engine and a motor run. The difference between the power split mode and the parallel mode is classified according to the fixed state of the sun gear. In the power split mode, the three elements of the planetary gear are controlled by the engine, the generator, and the motor. In the parallel mode, however, the sun gear is fixed to the brake and the operation of the generator is not necessary. At this time, since the sun gear connected to the generator is fixed at 0 rpm, the carrier and the ring gear, to which the engine and the motor are connected, have a fixed gear ratio and are called a parallel mode.

4, the drive shaft is connected to the generator 2, the motor 3 and the engine 4 via one planetary gear 1, and a ring gear ring gear is connected to the wheel by an external gear so that the explosion impact is transmitted to the wheels on the drive shaft when the engine is started.

On the other hand, when the engine is cranking with a hybrid starter generator (HSG), when the rotational speed of the engine becomes equal to or higher than a predetermined rotational speed, the hybrid vehicle injects and explodes the fuel to start the engine.

Generally, in a hybrid vehicle (HEV), a torque (a torque command) calculated by a speed controller inside a vehicle controller (HCU) is transmitted to a generator (HSG) through a motor controller to start the engine.

5, the speed controller in the HCU is generally constituted by a PI controller 6 and a feedforward controller 7. The speed controller in the vehicle controller HCU includes a PI controller 6 and a feedforward controller 7, The torque command is calculated based on the difference between the target engine speed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power split parallel system of a hybrid vehicle capable of preventing an explosion impact from being transmitted to a vehicle body by reducing an explosion impact upon an initial explosion during engine starting, And an object of the present invention is to provide a system and method for controlling generator torque of a hybrid vehicle.

Accordingly, the present invention includes a vehicle controller (HCU) that controls a torque of the generator when the engine is started with a generator, the vehicle controller (HCU) includes a speed controller for calculating a primary engine target torque for engine starting; And a disturbance observer for calculating a disturbance canceling torque for removing a disturbance component included in the primary engine target torque, wherein a value obtained by adding the primary engine target torque and the disturbance canceling torque is converted to calculate a disturbance component And determines the removed generator target torque based on the output torque of the generator.

According to the embodiment of the present invention, the speed controller calculates the primary engine target torque based on the difference between the actual engine speed at engine startup and the target engine speed at engine startup.

According to an embodiment of the present invention, the disturbance observer calculates a disturbance canceling torque based on a difference value between a first engine target torque and an actual engine torque at the time of starting the engine, wherein the disturbance observer calculates an actual engine speed A value obtained by multiplying the engine acceleration obtained from the input actual engine speed value by the predetermined engine inertia is used as the actual engine torque at the time of engine startup.

Preferably, the disturbance observer includes a first band-pass filter for removing an offset of a first engine target torque and a second band-pass filter for removing an offset of an actual engine torque at the time of starting the engine.

Further, in the present invention, for the generator torque control of the hybrid vehicle that starts the engine with the generator, the primary engine target torque is computed based on the difference between the actual engine speed at engine startup and the engine target speed at engine startup Process; Calculating a disturbance canceling torque for removing a disturbance component included in the primary engine target torque based on a difference value between the primary engine target torque and the actual engine torque at engine startup; And a step of calculating a target generator torque by removing a disturbance component by converting a value obtained by summing the primary engine target torque and a disturbance canceling torque.

Here, the actual engine torque is calculated by multiplying the engine acceleration obtained from the actual engine speed value at the time of engine startup by a predetermined engine inertia, and in the process of calculating the disturbance canceling torque, the offset component And the difference between the actual engine torque obtained by removing the offset component through the second band-pass filter is determined as the disturbance canceling torque.

According to the system and method for controlling the generator torque of the hybrid vehicle according to the present invention, when the engine of the hybrid vehicle is started, particularly when the engine of the hybrid vehicle equipped with the power split parallel system is started, Therefore, it is possible to prevent the explosion impact at the time of starting the engine from being transmitted to the vehicle body, and also to detect the disturbance other than the initial explosion impact at all times, thereby performing robust engine speed control.

1 is a view showing a generator torque control system of a hybrid vehicle according to the present invention;
2 is a diagram showing an outline of generator torque control for preventing an impact when an engine is started in a hybrid vehicle according to the present invention
3 is a flowchart showing a generator torque control method of a hybrid vehicle according to the present invention.
4 is a configuration diagram showing a power split parallel system of a conventional hybrid vehicle
5 is a configuration diagram showing a speed controller configured in a vehicle controller of a conventional hybrid vehicle

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

In the present invention, the control of a hybrid control unit (HCU) that controls a torque command of a motor and an engine and a hybrid starter generator (HSG) in a power split parallel system of a hybrid vehicle So that the shock is prevented from being transmitted to the vehicle body by attenuating the shock.

In the hybrid vehicle, when the vehicle controller (HCU) starts the engine through the generator, it switches from EV mode to EVT (Electric Variable Transmission) mode. At this time, the HCU determines the engine operating point (the torque and the rotation speed to be output by the engine) in the EVT mode and determines the torque of the generator according to the engine operating point (EMS) and the MCU Communicate command.

The torque (or torque command) of the generator which is calculated by the vehicle controller HCU is composed of a reaction torque for the engine at the time of operation at a specific operating point and a speed control torque for varying the engine to the target rotation speed.

The engine startup of the hybrid vehicle occurs in the process of the generator raising the engine to the target rotation speed. At this time, the generator outputs a torque for sending the engine at the target rotation speed, and the engine performs fuel injection at a specific rotation speed while being pulled up to the target speed by the generator, The explosion is caused by the procedure, and the engine is able to output the command torque transmitted from the vehicle controller (HCU).

Therefore, the torque of the generator is determined as a torque for raising the engine to the target rotation speed (or target speed).

In the present invention, in order to attenuate the initial explosion impact of the engine in designing the speed controller in the HCU that determines the torque of the generator, the engine initial explosion shock at engine startup is referred to as a disturbance of the speed controller Disturbance Observer to detect disturbance is additionally constructed.

Here, the controlled object is the engine and the controlling subject is the generator. In other words, the vehicle controller (HCU) controls the torque of the generator, and the torque of the generator is determined so as to control the engine at the target rotation speed without shock or vibration during start-up.

Hereinafter, with reference to FIG. 1, the control for preventing the initial explosion shock at the time of engine startup of the hybrid vehicle will be described in detail.

FIG. 1 is a block diagram of a generator torque control system for preventing an explosion shock when an engine is started in a hybrid vehicle according to the present invention. Herein, FIG. 1 is a block diagram showing the internal structure of a vehicle controller HCU for controlling the torque of the generator for starting the engine of the hybrid vehicle Show detailed structure.

1, a vehicle controller (HCU) for calculating a torque command of a generator includes a feed forward controller 12, a P controller 14 and an I controller 16 to determine and calculate a generator target torque And a disturbance observer 20 for eliminating disturbance components included in the target engine torque of the primary engine calculated by the speed controller 10. The disturbance observer 20 calculates the target engine torque do.

Since the vehicle controller also carries out the engine start control and the speed control for sending the operating point of the engine to an efficient (high) region, in order to speed up the initial response of the speed control, the feed forward controller 12 The speed controller 10 is used.

As is known, a speed controller (not shown) for computing an engine target torque corresponding to a generator target torque to determine a generator target torque (torque command) in a controller (HCU) of a hybrid vehicle, that is, Generally consists of a feed-forward controller, a P-controller and an I-controller.

Here, the feedforward controller 12 is configured to perform the same function as the feed forward controller of a general speed controller, which is configured in the HCU, to differentiate the initial responsiveness of the system according to the rotational speed of the engine, Is the same as the feed forward controller of the conventional speed controller, so a detailed description thereof will be omitted.

The P controller 14 is configured to perform the same function as the P controller of a general speed controller included in the HCU, and is also the same as the P controller of the conventional speed controller, so that a detailed description thereof will be omitted.

Here, the P controller 14 differentiates the P gain value by classifying the operation state of the system, for example, the case of the engine cranking control and the case of the engine speed (rotation speed) control after the engine start .

The I controller 16 is configured to perform the same function as the I controller of a general speed controller that is configured in the vehicle controller HCU.

Since the output of the vehicle controller HCU is the generator target torque (torque command), when the torque command out of the maximum and the reverse maximum torque of the predetermined generator in the system is outputted, the error of the I controller 16 is accumulated, Which may lead to an unstable situation of the controller (HCU).

Also, an error of the I-controller 16 may occur even when the speed controller 10 is in a steady state.

Thus, in order to prevent the unstable situation of the speed controller 10 due to the error accumulation of the I controller 16 and to reduce the error of the I controller 16 occurring in the steady state, the output of the speed controller 10 is forward and An anti wind-up controller 30 is connected to the front end (input side) of the I-controller 16 to receive a restriction of the reverse torque.

The anti-windup controller 30 adds the anti-windup gain to the value input to the I controller 16 (the difference between the engine target speed and the actual engine speed at the time of starting the engine) and outputs the input value of the I controller to the anti- Thereby causing the output of the speed controller 10 to be limited in the forward and reverse torque of the generator.

The forward and reverse limiting torques of the generator to limit the output of the speed controller 10 and the output of the vehicle controller HCU (i.e., the torque limit value of the generator) are determined according to the state of the hybrid vehicle (HEV) system. For example, when the charge / discharge limit value of a high-voltage battery in a vehicle is within a normal range (a predetermined normal range in the system or a normally known normal range), the torque limit value of the generator is a normal value , The torque limit value of the generator becomes smaller than the normal value when the charge / discharge limit value of the high voltage battery is below the normal range.

As described above, the disturbance observer (DOB) 20 is for detecting a shock caused by an initial engine explosion when the engine is started. The actual engine torque generated by the initial explosion of the engine (Primary engine target torque) of the speed controller 10, it is recognized as a disturbance and detected.

An engine model is used to detect a disturbance perceived as a difference between an actual engine torque generated by an engine initial explosion at engine startup and a primary engine target torque of the speed controller 10, And expressed using the engine inertia (Inertia). Specifically, the actual engine torque generated when the engine is started is expressed by a value obtained by multiplying (multiplied) by the engine inertia obtained from the actual engine speed (actual engine rotation speed) and the engine inertia, The difference between the target torque of the primary engine of the engine becomes a disturbance.

However, before the disturbance observer 20 determines that the difference between the actual engine torque and the torque command of the speed controller 10 (primary engine target torque) is disturbance, the Q filter is used to minimize the uncertainty of the engine model It must go through.

Generally, a Q filter is designed by using a filter having a relative degree of 1 of a denominator and a numerator in the form of a low-pass filter.

In this case, since the engine model is represented as one inertia type, it is assumed that the engine inertia and the engine which are generated when the actual engine is started are one force, and the difference between the engine inertia set through the result of the experiment using the engine model .

In addition, there is an experimental error because the engine inertia set through the result of the experiment using the engine model is the value obtained through the experiment. In order to minimize the error, a bandpass filter capable of passing only a desired frequency domain is used as a Q filter.

For example, when the engine inertia obtained through the experiment is different from the engine inertia occurring when the engine is actually started, the disturbance measured by the disturbance observer 20 is observed as a value having a specific offset.

Therefore, the disturbance observer 20 uses a Q filter to remove an offset to observe pure disturbance having no offset.

The offset component included in the disturbance is a low-frequency component having a degree of 0 through a Fourier transform. The filter for removing the component is a high-pass filter. Since all sensor signals include noise, a low pass filter is used as a filter to remove the noise.

Therefore, by using the band-pass filter that combines the two types of filters as a Q filter, the user can pass only the desired frequency band signal (that is, the torque with the removed offset and noise).

By using the band pass filter as a Q filter, it is possible to remove the error included in the disturbance measured by the disturbance observer and extract the actual disturbance.

In the vehicle controller HCU, the torque (the input value of the secondary engine target torque, that is, the input value of the generator torque calculator) for starting / operating the engine by summing the outputs of the speed controller 10 and the disturbance observer 20 described above is obtained , Converts it into a generator target torque (generator torque command) in consideration of a predetermined planetary gear relationship and a gear ratio in the system, and transmits the converted torque to a motor controller (not shown).

2, when the disturbance due to the difference between the actual engine speed and the target engine speed (engine target speed) occurs, the controller (HCU) of the hybrid vehicle removes the disturbance from its output value (generator target torque) (Secondary engine target torque) obtained by adding the disturbance canceling torque to the output of the speed controller 10 (the primary engine target torque) so as to output the generator target torque that has removed the disturbance do.

Hereinafter, a process of calculating the torque command of the generator in the vehicle controller HCU will be described in detail with reference to FIGS. 1 and 3. FIG.

First, the vehicle controller (HCU) grasps the vehicle mode to determine whether it is a hybrid vehicle (HEV) mode or a power split mode.

The power split mode is one of the modes of a hybrid vehicle equipped with a power split parallel system. The power split mode distributes the output of the engine to the sun gear and the ring gear of the planetary gear, absorbs the engine output transmitted to the sun gear to the generator, Battery or motor, and the engine output transmitted to the ring gear is a mode used for driving the vehicle. At this time, the motor also generates an output for driving to assist the engine output transmitted to the ring gear.

When it is determined that the vehicle mode is the hybrid vehicle mode and the power split mode state, the vehicle controller HCU determines that the conditions for engine startup are satisfied, and the actual engine speed at engine startup The target engine torque is calculated based on the difference between the target engine speed for engine startup (the engine speed before completion) and the engine target speed for engine startup (the target engine speed at engine startup).

At this time, the speed controller 10 uses the input of the anti-windup gain outputted from the anti-windup controller 30 to prevent the error accumulation of the I controller 16 using the input of the I controller 16 and outputs the output torque of the HCU Generator target torque) to within the torque limit value set in the system.

The primary engine target torque output from the speed controller 10 is used to calculate a generator target torque for engine starting in the generator torque computing unit 40 in addition to the disturbance canceling torque output from the disturbance observer 20.

The disturbance observer 20 calculates disturbance canceling torque based on the difference between the target engine torque outputted from the speed controller 10 and the actual engine torque at the time of starting the engine.

When the actual engine speed value at the time of engine startup is input (or recognized), the disturbance observer 20 multiplies the engine acceleration obtained from the input actual engine speed value by the predetermined engine inertia value to the actual engine torque at engine startup .

At this time, in the disturbance observer 20, the engine acceleration is calculated through a differentiator using an actual engine speed value as an input, and the engine inertia uses a predetermined value through experiment.

The disturbance observer 20 eliminates the offset between the primary engine target torque and the actual engine torque and the noise component by using the band pass filters 22 and 24 that pass only the constant frequency region of the input signal and output it.

That is, the disturbance observer 20 includes a first band-pass filter 22 for eliminating the offset of the primary engine target torque and a noise component, a second band for eliminating the offset of the actual engine torque at the time of starting the engine, Pass filter 24 to remove offset and noise components that may be included in the disturbance canceling torque.

The disturbance observer 20 detects a difference between the first engine target torque at which the offset and the noise components are removed from the first band pass filter 22 and the actual engine torque at which the offset and the noise components are removed from the second band pass filter 24 (Actual engine torque-first engine target torque) to determine the disturbance canceling torque.

A value obtained by adding the disturbance canceling torque determined by the disturbance observer 20 and the primary engine target torque determined by the speed controller 10 is input to the generator torque computing unit 40 and the generator torque computation unit 40 And converted into a generator target torque in consideration of the gear relation and the gear ratio.

The generator target torque is transmitted as an output value of the vehicle controller HCU to the motor controller through the supelerator 42. The motor controller controls the torque of the generator based on the generator target torque to start the engine at the target rotation speed .

At this time, the output value of the generator torque computing unit 40 is compared with the torque limit value of the predetermined system in the transmitter 42.

When the generator target torque output from the generator torque computing unit 40 exceeds the torque limit value of the system set in the synthesizer 42, the vehicle controller HCU lowers the calculated generator target torque, And sends a difference value (a synthesizer output value) obtained by subtracting the torque limit value from the generator target torque to the anti-windup controller 30.

In order to prevent the generator target torque from exceeding the torque limit value of the system in the anti-windup controller 30 and prevent the error accumulation of the I controller 16, the anti-windup controller 30 sends the output of the stabilizer to the I controller 16 side Determine the anti-windup gain.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. Modifications are also included in the scope of the present invention.

10: Speed controller
20: disturbance observer
30: Anti-windup controller
40: Generator torque calculator

Claims (8)

And a vehicle controller (HCU) for controlling the torque of the generator when the engine is started with the generator,
A speed controller for calculating a primary engine target torque for starting the engine;
And a disturbance observer for calculating a disturbance canceling torque for removing a disturbance component included in the primary engine target torque,
A value obtained by adding the primary engine target torque and the disturbance canceling torque is converted to determine a generator target torque from which the disturbance component is removed,
Wherein the disturbance observer calculates an actual engine torque at engine startup by multiplying an engine acceleration obtained from an actual engine speed value at the time of engine startup by a set engine inertia to calculate a difference between an actual engine torque at the time of starting the engine And the disturbance canceling torque is calculated based on the disturbance canceling torque.
The method according to claim 1,
Wherein the speed controller calculates a primary engine target torque based on a difference between an actual engine speed at engine startup and an engine target speed at engine startup.
delete delete The method according to claim 1,
Wherein the disturbance observer includes a first band-pass filter for removing an offset of a first engine target torque and a second band-pass filter for removing an offset of an actual engine torque at the time of starting the engine. .
In order to control the generator torque of the hybrid vehicle that starts the engine with the generator,
Calculating a first engine target torque based on a difference between an actual engine speed at engine startup and an engine target speed at engine startup;
Calculating a disturbance canceling torque for removing a disturbance component included in the primary engine target torque based on a difference value between the primary engine target torque and the actual engine torque at engine startup;
And a step of calculating a target generator torque by removing a disturbance component by converting a value obtained by adding the primary engine target torque and the disturbance canceling torque,
Wherein the actual engine torque is a value obtained by multiplying an engine acceleration obtained from an actual engine speed value at the time of engine startup by a set engine inertia.
delete The method of claim 6,
In the process of calculating the disturbance canceling torque,
And a difference between an actual engine torque obtained by subtracting an offset component from a first engine target torque obtained by removing an offset component through a first band-pass filter and an actual engine torque obtained by removing an offset component through a second band-pass filter is determined as a disturbance canceling torque Control method.

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