KR102237064B1 - Hybrid electric vehicle and controlling method thereof - Google Patents

Abstract

The hybrid vehicle includes: a hybrid controller configured to determine an absolute value of a motor torque gradient and an engine torque gradient such that an absolute value of a motor torque gradient and an engine torque gradient are minimized based on a driver's required torque and an available motor torque, in a mode conversion section that is converted from an EV mode to an HEV mode; A motor controller controlling a motor to change a motor torque according to the motor torque slope; And an engine controller that controls the engine so that the engine torque changes according to the engine torque slope.

Description

Hybrid vehicle and its control method {HYBRID ELECTRIC VEHICLE AND CONTROLLING METHOD THEREOF}

The present invention relates to a hybrid vehicle and a control method thereof.

Hybrid vehicles are driven by efficiently combining two or more different power sources. The power source may include an engine and a motor.

Hybrid vehicles are driven in the EV mode (Electric Vehicle mode), which uses a motor with relatively good low-speed torque characteristics as the main power source at low speed, and the HEV mode (Hybrid Mode), which uses an engine with relatively good high-speed torque characteristics as the main power source at high speed. Electric Vehicle mode).

In the mode conversion section from EV mode to HEV mode, the motor torque gradually decreases and the engine torque gradually increases. Existing hybrid vehicles rapidly increase the engine torque so that the engine torque follows the optimum engine operating point as quickly as possible. In order to rapidly increase the engine torque in a short period of time, there is a problem in that fuel efficiency is deteriorated because an excess amount of fuel is consumed and the ignition angle is perceived.

The technical problem to be solved by the present invention is to provide a hybrid vehicle capable of efficiently controlling engine torque and motor torque compared to fuel economy in a mode conversion section that is converted from EV mode to HEV mode, and a control method thereof.

In the hybrid vehicle according to an embodiment of the present invention, in the mode conversion section in which the EV mode is converted to the HEV mode, the absolute value of the motor torque slope and the engine torque slope are determined to be minimum based on the driver's requested torque and the available motor torque. A hybrid controller; A motor controller controlling a motor to change a motor torque according to the motor torque slope; And an engine controller that controls the engine so that the engine torque changes according to the engine torque slope.

The hybrid controller may calculate the available motor torque based on at least one of the number of motors and the available power of a battery.

The hybrid controller may calculate the driver's requested torque based on at least one of an accelerator pedal operation state, a brake pedal operation state, a vehicle speed, and a gear stage state.

The larger the available motor torque is, the smaller the absolute value of the allowable motor torque gradient is, and the hybrid controller may determine the absolute value of the motor torque gradient to be greater than the absolute value of the allowable motor torque gradient.

The smaller the driver's required torque is, the smaller the first allowable engine torque gradient, and the hybrid controller may determine the engine torque gradient to be greater than the first allowable engine torque gradient.

The second allowable engine torque slope is determined based on an optimum fuel amount required for the engine torque to follow the engine optimum operating point and a corresponding optimum ignition angle, and the hybrid controller converts the second allowable engine torque slope to the engine torque slope. You can decide.

The optimum fuel amount and the optimum ignition angle may be recorded in a lookup table (LUT) corresponding to the engine torque and the required torque.

The second allowable engine torque gradient is plural, and the hybrid controller may determine the largest second allowable engine torque gradient among the plurality of second allowable engine torque gradients as the engine torque gradient.

The hybrid controller may determine the motor torque slope and the engine torque slope so that the sum of the motor torque and the engine torque becomes a required torque.

A method for controlling a hybrid vehicle according to an embodiment of the present invention includes: calculating a driver's required torque and an available motor torque in a mode conversion section in which an EV mode is converted to an HEV mode; Determining an absolute value of a motor torque slope and an engine torque slope to be minimum based on the driver's requested torque and the available motor torque; Controlling the motor to change the motor torque according to the motor torque slope; And controlling the engine so that the engine torque changes according to the engine torque slope.

In the step of calculating the available motor torque, the available motor torque may be calculated based on at least one of the number of motors and the available power of the battery.

In the step of calculating the driver's requested torque, the driver's requested torque may be calculated based on at least one of an accelerator pedal operation state, a brake pedal operation state, a vehicle speed, and a gear stage state.

Determining that the absolute value of the allowable motor torque slope is smaller as the available motor torque increases; And determining the absolute value of the motor torque slope to be greater than the absolute value of the allowable motor torque slope.

Determining that the first allowable engine torque slope is smaller as the driver's requested torque is smaller; And determining the engine torque slope to be greater than the first allowable engine torque slope.

Determining a second allowable engine torque slope based on an optimum fuel quantity and a corresponding optimum ignition angle required for the engine torque to follow the engine optimum operating point; And determining the second allowable engine torque slope as the engine torque slope.

The optimum fuel amount and the optimum ignition angle may be recorded in the LUT corresponding to the engine torque and the required torque.

In the step of determining the second allowable engine torque gradient, the second allowable engine torque gradient is plural, and the largest second allowable engine torque gradient among the plurality of second allowable engine torque gradients may be determined as the engine torque gradient. have.

It may further include determining the motor torque slope and the engine torque slope so that the sum of the motor torque and the engine torque becomes a required torque.

According to an embodiment of the present invention, it is possible to provide a hybrid vehicle capable of efficiently controlling engine torque and motor torque compared to fuel economy in a mode conversion section in which an EV mode is converted to an HEV mode, and a control method thereof.

1 is a diagram illustrating a hybrid vehicle according to an embodiment of the present invention.
2 is a diagram illustrating a conventional method for controlling a mode conversion section.
3 is a diagram illustrating a method of controlling a mode conversion section according to an embodiment of the present invention.
4 is a diagram illustrating an LUT according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art may easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

In order to clearly describe the embodiments of the present invention, parts irrelevant to the description are omitted, and the same reference numerals are attached to the same or similar components throughout the specification.

Throughout the specification, when a part is said to be "connected" with another part, this includes not only "directly connected" but also "electrically connected" with another element interposed therebetween. .

1 is a diagram illustrating a hybrid vehicle according to an embodiment of the present invention.

Referring to FIG. 1, a hybrid vehicle according to an embodiment of the present invention includes an engine 10, a motor 20, an engine clutch 30, a transmission 40, an inverter 50, a battery 60, and a starter generator ( 70) and the wheel 80.

The engine 10 generates power by burning fuel under the control of the engine controller 110.

The motor 20 assists the power of the engine 10 under the control of the motor controller 120 and may generate power by operating as a generator during braking. Power generated by the motor 20 may be stored in the battery 60.

The engine clutch 30 is connected between the engine 10 and the motor 20 and regulates power transmission between the engine 10 and the motor 20.

The transmission 40 is connected in series with the motor 20, and converts the power generated from the engine 10 into a rotational force required according to the speed and transmits it to the wheels 80. The transmission 40 may be implemented as an automatic transmission (AT) or a dual clutch transmission (DCT). The driving force shifted by the transmission 40 may be transmitted to the wheel 80 to drive the wheel 80.

The inverter 50 converts the DC voltage output from the battery 60 into an AC voltage and transmits it to the motor 20 or the starter generator 70.

The battery 60 may provide driving power of the motor 20 and starting power of the starter generator 70 through the inverter 50.

The starter generator 70 may start the engine 10 or perform power generation by the rotational force of the engine 10. On the other hand, in FIG. 1, a case where the starter generator 70 is referred to as a hybrid starter & generator (HSG) is illustrated as an example, but the starter generator 70 is also referred to as an integrated starter & generator (ISG).

In addition, the hybrid vehicle according to the embodiment of the present invention, a hybrid controller (Hybrid Control Unit, HCU) 200, an engine controller (Engine Control Unit, ECU) 110, a motor controller (Motor Control Unit, MCU) 120 ), a transmission control unit (TCU) 140, a battery management system (BMS) 160, and the like.

The hybrid controller 200 is a top-level controller, and can control the overall operation of the hybrid vehicle by collectively controlling lower controllers connected to the network and collecting and analyzing information of each lower controller. In addition, the hybrid controller 200 controls the fastening pressure of the engine clutch 30 to engage and disengage the engine clutch 30, thereby controlling power transmission of the engine 10.

The hybrid controller 200 determines the absolute value of the motor torque slope and the engine torque slope to be minimum based on the driver's required torque and the available motor torque in the mode conversion section in which the EV mode is converted to the HEV mode according to the required torque.

The engine controller 110 controls the engine 10 to change the engine torque according to the engine torque slope instructed from the hybrid controller 200.

The motor controller 120 controls the motor 20 to change the motor torque according to the motor torque slope instructed from the hybrid controller 200. In addition, the motor controller 120 may control the overall operation of the starter generator 70.

The shift controller 140 may control an actuator provided in the transmission 40 according to the control of the hybrid controller 200 to control gear engagement of a target shift stage.

The battery controller 160 manages and controls the state of charge (SOC) by comprehensively detecting information such as voltage, current, and temperature of the battery 60, and controls the amount of charge/discharge current of the battery 60 to limit Do not overdischarge below the voltage or overcharge above the limit voltage.

In the hybrid vehicle of the above-described structure, the electric vehicle mode (EV mode), which is a pure electric vehicle mode using only the power of the motor 20, uses the rotational power of the engine 10 as the main power and the rotational power of the motor 20 as an auxiliary power. HEV mode (Hybrid Electric Vehicle mode) used, a regenerative braking mode in which braking and inertial energy is recovered through power generation of the motor 20 and charged to the battery 60 when driving by braking or inertia of the vehicle (regenerative braking mode) ( RB mode).

2 is a diagram illustrating a conventional method for controlling a mode conversion section.

Referring to FIG. 2, a change in torque over time is shown in a graph at the top, a change in fuel amount over time is shown in a graph in a middle portion, and a change in ignition angle over time is shown in a graph at the bottom.

When the hybrid vehicle is running in the EV mode, the engine torque is zero and the motor torque is equal to the required torque. Therefore, the hybrid vehicle is traveling by using the power generated from the motor, and the amount of fuel and the ignition angle are each zero.

In the mode conversion section that is converted from the EV mode to the HEV mode, the engine torque gradually increases according to the _{engine torque slope θ 1} , and the motor torque gradually decreases according to the _{motor torque slope θ 2.} As described above, the conventional hybrid vehicle rapidly increases the engine torque so that the engine torque follows the engine optimum operating point EE as quickly as possible. Also, the motor torque is reduced to follow the motor optimum operating point ME. The sum of the engine torque and the motor torque is controlled to become the required torque.

In the mode change section, an excessive amount of fuel is required to support a rapid increase in engine torque, and the ignition angle is retarded for complete combustion of the increased amount of fuel. Accordingly, there is a problem in that the power generated by the engine is small compared to the amount of fuel consumed, and fuel efficiency is low.

3 is a diagram illustrating a method of controlling a mode conversion section according to an embodiment of the present invention.

Referring to FIG. 3, a change in torque over time is shown in a graph at the top, a change in fuel amount over time is shown in a graph in a middle portion, and a change in ignition angle over time is shown in a graph at the bottom.

When the hybrid vehicle is running in the EV mode, the engine torque is zero and the motor torque is equal to the required torque. Accordingly, the hybrid vehicle is traveling using power generated from the motor 20, and the amount of fuel and the ignition angle are each zero.

When entering the mode conversion section that is converted from the EV mode to the HEV mode, the hybrid controller 200 _{determines the absolute value of the motor torque slope (θ M} ) and the engine torque slope (θ _E ) based on the driver's required torque and the available motor torque. Decide to be minimal. The motor torque slope θ _M is the slope versus time required for the motor torque to follow the motor optimum operating point ME from the current motor torque. The engine torque slope θ _E is the slope versus time required for the engine torque to follow the engine optimum operating point EE from the current engine torque. Therefore, that the absolute value of the motor torque slope (θ _M ) and the engine torque slope (θ _E ) become minimum, compared to the case of FIG. 2, the engine torque increases more slowly, and the mode conversion section becomes longer. Means.

The engine optimum operating point EE means an optimum engine torque required for the engine 10 with respect to the required torque. The motor optimum operating point ME means the motor torque required of the motor 20 to compensate for the difference between the engine optimum operating point EE and the required torque. In FIG. 3, since the engine optimum operating point EE is higher than the required torque, excess torque is generated, and the hybrid controller 200 sets the motor optimum operating point ME to a negative value, and sets the extra torque to 20) can be used for power generation.

The available motor torque means the maximum motor torque that the motor 20 can generate at the present time. The hybrid controller 200 may calculate the available motor torque based on at least one of the number of motors 20 and the available power of the battery 60.

The greater the available motor torque, the greater the power that can be produced from the motor 20, and the absolute value of the _{allowable motor torque slope θ M may decrease.} That is, even if the engine torque is increased more slowly as the available motor torque increases, the motor 20 may assist this. The allowable motor torque slope is _{shown in FIG. 3 as the allowable motor torque slope (θ AM} ), and the hybrid controller 200 is _{the motor torque slope (θ M} ) to be greater than the absolute value _{of the allowable motor torque slope (θ AM ).} The absolute value of can be determined. If the absolute value of the motor torque slope (θ _M ) is less than the absolute value of the allowable motor torque slope (θ _AM ), it is not preferable because the motor 20 may not be able to handle the required motor torque or inefficiently. .

The driver's required torque means the torque required by the driver's operation. The hybrid controller 200 may calculate the driver's requested torque based on at least one of an accelerator pedal operation state, a brake pedal operation state, a vehicle speed, and a gear stage state. The driver's required torque can be reflected in the required torque.

The smaller the driver's required torque is, the smaller the first allowable engine torque gradient θ _AE1 is, and the hybrid controller 200 may determine the engine torque gradient θ _{E to be greater than the first allowable engine torque gradient θ AE1} .

On the other hand, if the driver's required torque is large, the first allowable engine torque slope θ _AE1 is also set large. That is, if there is a need to rapidly increase the engine torque according to the driver's request, the first allowable engine torque slope θ _AE1 is set to be large in order to meet the driver's demand, even if fuel efficiency is low. Accordingly, since the hybrid controller 200 controls the engine torque slope θ _E to be greater than the first allowable engine torque slope θ _AE1 , it may respond to a user's request.

According to the description so far, the hybrid controller 200 controls _{the absolute value of the motor torque slope (θ M} ) and the engine torque slope (θ _E ) to be minimum, respectively, the absolute value of the _{allowable motor torque slope (θ AM)} And a first allowable engine torque slope (θ _AE1 ) with a lower limit thereof.

Therefore, the absolute value of the motor torque slope (θ _M ) and the engine torque slope (θ _E ) are not randomly minimized, and unlike the case of FIG. 2, the engine torque slowly increases so that an excessive amount of fuel is not required, and ignition The angle can be advanced. Therefore, fuel consumption efficiency is high because unnecessary fuel is minimized.

The hybrid vehicle according to an embodiment of the present invention may further control the engine torque slope θ _{E by introducing the second allowable engine torque slope θ AE2.}

The second allowable engine torque slope θ _AE2 may be determined based on an optimal amount of fuel required for the engine torque to follow the engine optimal operating point EE and a corresponding optimal ignition angle. The hybrid controller 200 may use the determined second allowable engine torque slope θ _AE2 as the engine torque slope θ _E.

That is, if the absolute value of the allowable motor torque slope (θ _AM ) and the first allowable engine torque slope (θ _AE1 ) set the absolute value of the motor torque slope (θ _M ) and the lower limit of the _{engine torque slope (θ E ),} 2 The allowable engine torque slope θ _AE2 may be _{a desirable engine torque slope θ E} corresponding to the optimum amount of fuel and the optimum ignition angle above its lower limit. The second allowable engine torque slope θ _AE2 may be greater than or equal to the first allowable engine torque slope θ _AE1.

How much is the optimum fuel amount and the optimum ignition angle may vary depending on the specific configuration such as the manufacturer, vehicle, engine, and motor. For example, a general driver may want the engine torque to rapidly increase to the engine optimum operating point (EE) according to the operation of the accelerator pedal, and the degree to which the driver's request is reflected may vary depending on the manufacturer. As an example, the optimum ignition angle may be an ignition angle that advances without being perceived at least in the mode conversion section, and an optimum fuel amount may be determined corresponding thereto.

The optimum fuel quantity and the corresponding optimum ignition angle may be recorded in advance in a LUT (LookUp Table) at the vehicle manufacturing stage. This will be described in more detail with reference to FIG. 4.

As another embodiment, the optimum fuel amount and the corresponding optimum ignition angle may be calculated by the hybrid controller 200 based on the engine torque and the required torque. The equation for outputting the optimum fuel amount and the optimum ignition angle by inputting the engine torque and the required torque as inputs may be determined differently according to a specific configuration such as a manufacturer, vehicle, engine, and motor.

Second allowable engine torque gradient (θ _AE2) has a plurality clear up can, hybrid controller 200 is the largest second allowable engine torque gradient (θ _AE2) of the plurality of the second allowable engine torque gradient (θ _AE2) engine torque It can be determined by the slope (θ _{E ).} Therefore, the hybrid vehicle can quickly increase the engine torque without inefficiency of fuel economy.

4 is a diagram illustrating an LUT according to an embodiment of the present invention.

Referring to FIG. 4, the LUT 400 includes an optimum fuel amount (FE00, FE01, ... FE0n, FE10) based on the engine torque (ET0, ET1, ... ETn) and the required torque (RT0, RT1, ... RTn). , FE11, ... FE1n, FEn0, FEn1, ... FEnn) and corresponding optimal firing angles (IE00, IE01, ... IE0n, IE10, IE11, ... IE1n, IEn0, IEn1, ... IEnn) can be recorded.

Therefore, the hybrid controller 200 uses the engine torque (ET0, ET1, ... ETn) and the requested torque (RT0, RT1, ... RTn) as inputs of the LUT 400, which is the output of the LUT 400. Optimal fuel quantity (FE00, FE01, ... FE0n, FE10, FE11, ... FE1n, FEn0, FEn1, ... FEnn) and corresponding optimal ignition angles (IE00, IE01, ... IE0n, IE10, IE11) , ... IE1n, IEn0, IEn1, ... IEnn) can be used to determine the second allowable engine torque slope (θ _AE2 ). The engine torque generated according to the amount of fuel and the ignition angle is a well-known technology, so it will not be described separately.

The drawings referenced so far and the detailed description of the invention described are merely illustrative of the present invention, which are used only for the purpose of describing the present invention, but are used to limit the meaning or the scope of the invention described in the claims It is not. Therefore, those of ordinary skill in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

10: engine
20: motor
30: engine clutch
40: transmission
50: inverter
60: battery
70: starting generator
80: wheel
110: engine controller
120: motor controller
140: shift controller
160: battery controller
200: hybrid controller

Claims (18)

In the mode conversion section from EV mode to HEV mode,
A hybrid controller that determines the absolute value of the motor torque slope and the engine torque slope to be minimum based on the driver's required torque and the available motor torque;
A motor controller controlling a motor to change a motor torque according to the motor torque slope; And
Including an engine controller for controlling the engine to change the engine torque according to the engine torque slope,
The larger the available motor torque, the smaller the absolute value of the allowable motor torque gradient, and the hybrid controller determines the absolute value of the motor torque gradient so that it is greater than the absolute value of the allowable motor torque gradient,
Hybrid vehicle. The method of claim 1,
The hybrid controller calculates the available motor torque based on at least one of the number of motors and available power of the battery,
Hybrid vehicle. The method of claim 2,
The hybrid controller calculates the driver's requested torque based on at least one of an accelerator pedal operation state, a brake pedal operation state, a vehicle speed and a gear stage state,
Hybrid vehicle. delete The method of claim 1,
The smaller the driver's required torque, the smaller the first allowable engine torque slope,
The hybrid controller determines the engine torque slope to be greater than the first allowable engine torque slope,
Hybrid vehicle. The method of claim 5,
The second allowable engine torque slope is determined based on the optimum fuel amount required for the engine torque to follow the engine optimum operating point and the corresponding optimum ignition angle,
The hybrid controller determines the second allowable engine torque slope as the engine torque slope,
Hybrid vehicle. The method of claim 6,
The optimum fuel amount and the optimum ignition angle are recorded in a lookup table (LUT) corresponding to the engine torque and required torque,
Hybrid vehicle. The method of claim 6,
The second allowable engine torque slope is plural,
The hybrid controller determines the largest second allowable engine torque gradient among the plurality of second allowable engine torque gradients as the engine torque gradient.
Hybrid vehicle. The method of claim 6,
The hybrid controller determines the motor torque slope and the engine torque slope such that the sum of the motor torque and the engine torque becomes a required torque,
Hybrid vehicle. In the mode conversion section from EV mode to HEV mode,
Calculating a driver's required torque and an available motor torque;
Determining an absolute value of a motor torque slope and an engine torque slope to be minimum based on the driver's requested torque and the available motor torque;
Controlling the motor to change the motor torque according to the motor torque slope;
Controlling the engine so that the engine torque changes according to the engine torque slope;
Determining that the absolute value of the allowable motor torque slope is smaller as the available motor torque increases; And
Including the step of determining the absolute value of the motor torque slope to be greater than the absolute value of the allowable motor torque slope
Hybrid vehicle control method. The method of claim 10,
In the step of calculating the available motor torque,
The available motor torque is calculated based on at least one of the number of motors and the available power of the battery,
Hybrid vehicle control method. The method of claim 11,
In the step of calculating the driver's required torque,
The driver's requested torque is calculated based on at least one of an accelerator pedal operation state, a brake pedal operation state, a vehicle speed and a gear stage state,
Hybrid vehicle control method. delete The method of claim 10,
Determining that the first allowable engine torque slope is smaller as the driver's requested torque is smaller; And
Further comprising the step of determining the engine torque slope to be greater than the first allowable engine torque slope
Hybrid vehicle control method. The method of claim 14,
Determining a second allowable engine torque slope based on an optimum fuel quantity and a corresponding optimum ignition angle required for the engine torque to follow the engine optimum operating point; And
Further comprising the step of determining the second allowable engine torque slope as the engine torque slope
Hybrid vehicle control method. The method of claim 15,
The optimum fuel amount and the optimum ignition angle are recorded in the LUT corresponding to the engine torque and the required torque,
Hybrid vehicle control method. The method of claim 15,
In the step of determining the second allowable engine torque slope,
The second allowable engine torque gradient is plural, and the largest second allowable engine torque gradient among the plurality of second allowable engine torque gradients is determined as the engine torque gradient,
Hybrid vehicle control method. The method of claim 16,
Further comprising the step of determining the motor torque slope and the engine torque slope such that the sum of the motor torque and the engine torque becomes a required torque
Hybrid vehicle control method.

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