KR101693947B1 - Method for controlling operation point in regenerative brake of HEV - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a control method of an operating point during regenerative braking of a hybrid vehicle, and more particularly, The object of the present invention is to provide a method of controlling an operating point during braking.
Therefore, in the present invention, in a hybrid vehicle that generates regenerative braking when the vehicle is stopped and generates a motor charging torque, determining whether the braking state is for a vehicle stop; And a step of performing a shift to a target shift stage corresponding to an opening amount of the brake pedal while allowing a skip shift to perform shifting of two or more stages at a time in a braking state for stopping the vehicle, Provides a method for controlling the starting point.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of controlling a regenerative brake of a hybrid vehicle,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a control method of an operating point during regenerative braking of a hybrid vehicle, and more particularly, The present invention relates to a method of controlling an operating point during braking.

In the case of a hybrid vehicle (HEV) equipped with a multi-stage transmission, a difference in regenerative energy occurs due to the speed change stage and the shift control. In particular, if the torque intervention is performed to reduce the charge torque of the motor for the shift control, the absolute value of the motor torque is reduced by the intervention and the regenerative power is eventually reduced.

If continuous shifting occurs during braking, there is a disadvantage in that the motor charging torque is reduced in each shifting state.

Also, in the case of an automatic transmission vehicle, when the transmission is driven by an electric oil pump (EOP), the operating energy of the electric oil pump increases for maximum line pressure control in each shift.

It is effective in terms of fuel economy to perform two or more shifts that can reduce the number of shifts in succession. However, after the braking, a small APS (accelerator pedal system) (Shift Quality) and acceleration may be disadvantageous in terms of fuel economy.

1 is a view for explaining a control method in regenerative braking of a conventional hybrid vehicle.

Referring to Fig. 1, the brake controller calculates the total braking amount required by the driver and distributes the frictional brake braking force with reference to the regenerative braking (regenerative braking execution amount) of the vehicle controller HCU. Then, the vehicle controller HCU determines the regenerative braking command in consideration of the regeneration prohibition situation and estimates the regenerative braking (execution) amount in consideration of the state of the motor and the transmission. Then, the motor controller (MCU) controls the motor output in accordance with the regenerative braking command, and the shift controller (TCU) performs the transmission shift control according to the shift state. At this time, the transmission is a multi-speed transmission such as an automatic transmission (AT) / a double clutch transmission (DCT), and the electric oil pump (EOP) may be a single drive type in the case of an automatic transmission.

The hybrid vehicle that uses the control method in the conventional regenerative braking performs the downshift during the regenerative braking. At this time, the hybrid vehicle sequentially performs the shifting by one step in accordance with the decrease of the vehicle speed. Thereby performing a torque intervention to reduce the absolute value (magnitude value) of the charging torque (negative torque) of the motor torque which interferes with the transmission input speed (or motor speed) rise at each shifting. Accordingly, in a situation where the number of shifts is large, the motor charging torque is reduced by the torque intervention, resulting in a reduction in the charging power, resulting in a loss of the amount of energy recovered during regenerative braking (see FIG.

In addition, in the case of a vehicle that drives a transmission only by an electric oil pump (EOP), loss of EOP drive energy due to maximum line pressure control occurs at each shift, and a skip shift is aimed at. However, (Rpm), which may cause a loss in terms of fuel economy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of controlling a starting point of regenerative braking of a hybrid vehicle which monitors the behavior of a forward vehicle to determine whether or not braking is required for stopping the vehicle, The purpose is to provide.

Therefore, in the present invention, in a hybrid vehicle that generates regenerative braking when the vehicle is stopped and generates a motor charging torque, determining whether the braking state is for a vehicle stop; And a step of performing a shift to a target shift stage corresponding to an opening amount of the brake pedal while allowing a skip shift to perform shifting of two or more stages at a time in a braking state for stopping the vehicle, Provides a method for controlling the starting point.

Specifically, the step of determining whether the vehicle is in a braking state for stopping the vehicle includes calculating a vehicle-to-vehicle distance that can be traveled by the other vehicle until the driver vehicle reaches the same speed as the vehicle ahead of the vehicle. Determining whether the vehicle speed of the preceding vehicle is less than a predetermined threshold value to determine whether or not the preceding vehicle has entered the low-speed driving state for stopping; If it is determined that the preceding vehicle has entered the low-speed running state for stopping, it is determined whether or not the skip-shift is permissible depending on the result of comparing the value obtained by adding the predetermined constant margin to the headway distance between the driver's vehicle and the head- And a step of judging whether or not there is a problem.

Here, the step of calculating the above-mentioned inter-vehicle distance may include the steps of: obtaining a distance of a driver's vehicle from a current vehicle speed to a preceding vehicle; A process in which the preceding vehicle acquires the traveling distance of the preceding vehicle capable of traveling from the present vehicle speed to the other vehicle; And calculating a headway distance by subtracting the headway distance of the headway vehicle from the headway distance of the driver vehicle.

In the process of determining whether or not the skip transmission is allowed, the skip transmission is allowed if the value obtained by adding the predetermined margin to the headway distance between the driver's vehicle and the headway vehicle is equal to or less than the headway distance, If the value obtained by adding the predetermined margin to the vehicle-to-vehicle distance is larger than the value of the preceding vehicle-to-vehicle distance, the skip transmission is prohibited.

The step of performing the shifting to the target speed change stage according to the brake pedal opening amount may be performed by comparing the transmission input speed corresponding to each gear range with a predetermined maximum input speed of the transmission, Selecting a speed change stage corresponding to the speed change stage candidate as a speed change stage candidate capable of entering the speed change; And a step of selecting a target shift stage among the shift stage candidates based on the opening amount of the brake pedal and performing a shift to the selected target shift stage.

In addition, in the process of performing the shift to the selected target speed change stage, a sequential shift that performs the shift at one stage at a time based on the difference in the number of steps between the current shift stage and the target shift stage, or a skip shift that performs the shift at two or more stages at a time do.

According to the method of controlling an operating point during regenerative braking of a hybrid vehicle according to the present invention, skip shift is limited and allowed to prevent loss in fuel economy when re-acceleration after braking, and the regenerative energy recovery rate can be increased by limited skip- It is possible to obtain an effect of improving the fuel economy and to prevent a side effect such as a busy shift.

1 is a view showing a control system for regenerative braking of a conventional hybrid vehicle
2 is a view showing a problem caused by sequential shifting during regenerative braking of a conventional hybrid vehicle
3 is a flowchart for explaining a process of determining whether or not a hybrid vehicle is skip-shifted according to the present invention.
FIG. 4 is a schematic diagram for explaining a method of calculating a distance between vehicles that can travel in a line-by-line until the driver's vehicle reaches the same speed as the preceding vehicle according to the present invention
5 is a flowchart for explaining a process of shifting to a target shift stage when skip shift of a hybrid vehicle is permitted according to the present invention.
FIG. 6 illustrates the advantages of the hybrid vehicle according to the present invention when regenerative braking is performed. In the regenerative braking mode, the sequential shifting in which the shifting is sequentially performed one by one in the 5-, (Single) two-speed shifting in one step, and comparing the results of the skipped transmission (single shift)

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

In the present invention, a skip shift is determined by determining a braking situation for a stop that can achieve a fuel economy gain by skipping (or skipping) a shift that performs two or more shifts at a time, thereby reducing the fuel consumption loss .

First, it is determined whether or not the braking state for stopping the vehicle is determined during braking of the hybrid vehicle. In other words, it is determined whether or not the braking state occurs in which the rear wheel braking is not occurring after the braking of the hybrid vehicle. Based on the information, the behavior of the front vehicle is monitored to determine whether it is necessary to stop the vehicle.

The inter-vehicle distance sensor senses the inter-vehicle distance between the driver's vehicle and the preceding vehicle, and the inter-vehicle distance sensor controller calculates the relative speed of the driver vehicle with respect to the preceding vehicle based on the inter-vehicle distance information received from the inter- vehicle distance sensor.

Here, the headway distance sensor controller is a controller in a vehicle (driver's vehicle) capable of receiving the headway distance information from the headway distance sensor and calculating the relative speed between the driver's vehicle and the headway vehicle based on the received headway distance information, (HCU) which determines whether skip-shift is permitted based on the inter-vehicle distance information and the relative speed information of the driver's vehicle.

The vehicle controller (HCU) determines the speed (vehicle speed) of the preceding vehicle on the basis of the received information, and specifically calculates a value obtained by subtracting the relative speed of the driver vehicle from the speed of the driver vehicle (vehicle speed) do.

After recognizing and recognizing the vehicle speed of the preceding vehicle and the vehicle speed of the driver vehicle, the vehicle controller HCU computes a distance C that allows the driver vehicle to travel in the other direction until the speed of the driver vehicle reaches the same speed as the preceding vehicle 3).

3 is a flowchart for explaining a process of determining whether or not a skip shift is allowed in braking a hybrid vehicle, and FIG. 4 is a view for explaining a process for determining whether or not a skip- (C).

3 and 4, in order to calculate the vehicle-to-vehicle distance C that can be traveled in a line-by-line until the driver's vehicle reaches the same speed as the preceding vehicle, in the vehicle controller HCU, (B, a preceding vehicle traveling distance) in which the preceding vehicle is able to travel in the current traveling speed in the current vehicle speed, and a second traveling distance (A, second traveling distance of the preceding vehicle) (AB) obtained by subtracting the preceding vehicle distance (B) from the preceding vehicle distance A is calculated as the above-mentioned vehicle-to-vehicle distance C (AB).

Here, the another traveling distance A of the driver's vehicle can be obtained from a pre-configured map by mapping the different traveling distance values depending on the vehicle speed of the driver's vehicle and the running resistance (slope) And this map is stored in the vehicle controller (HCU).

Further, the other vehicle distance (B) of the preceding vehicle can also be obtained from a pre-configured map by mapping the different vehicle distance values depending on the vehicle speed and running resistance (inclination) of the preceding vehicle as values derived through testing in actual vehicle conditions, The map is stored in the vehicle controller (HCU).

The traveling distance of the driver's vehicle and the traveling distance of the preceding vehicle are functions that are interlocked with general vehicle resistance such as rolling resistance, slope resistance, and air resistance of the vehicle and can usually be calculated by the equation. Here, And the same data (for example, running resistance) is used in the case of the preceding vehicle assuming the same driving conditions as those of the driver's vehicle.

In the vehicle controller HCU, the front vehicle enters a low-speed running state (vehicle speed close to zero) for stopping, and at this time, the vehicle-to-vehicle distance C is equal to a predetermined constant margin C2), it is determined that the skip shift (skip shift) can be permitted.

Here, the predetermined margin C2 is a value derived through testing and evaluation in an actual vehicle condition.

More specifically, when it is determined in the vehicle controller HCU that the vehicle speed of the preceding vehicle has entered a low speed region (low speed running state) of less than a predetermined threshold value C1, it is determined that the preceding vehicle is in a low speed running state for stopping, A value obtained by adding a certain margin (C2) to the headway distance between the driver's vehicle and the headway vehicle is compared with the value of the headway distance C in a situation where the headway vehicle enters a low speed running state for stopping, ) Is greater than a value obtained by adding a certain margin (C2) to the headway distance between the front vehicle and the driver's vehicle, the skip shift is permitted, and the headway distance C provides a certain margin (C2) to the headway distance between the front vehicle and the driver's vehicle If the sum is less than the sum, skip shifting is prohibited.

Also, in the vehicle controller HCU, even when it is determined that the forward vehicle has not entered the low-speed running state for stopping, the skip-shifting is prohibited.

In this way, when it is determined that the braking state is for braking the vehicle, the vehicle controller HCU permits the skip-shifting to perform at least two shifts at a time, do.

In a hybrid vehicle that performs regenerative braking when a vehicle is at a standstill and generates a motor charging torque, when a skip shift of two or more stages is performed during braking of the vehicle, when the driver releases braking, Busy shifts where shifts occur can occur frequently.

For example, if the speed change stage corresponding to the current vehicle speed is 5 according to the shift pattern, the skip shift is performed by the braking in the third stage, and then the 3-, 4-, It can occur frequently.

In this case, in order to minimize this phenomenon, it is necessary to perform sequential shifting or two or more skip shifting according to the magnitude of the driver's braking demand (that is, driver's braking demand) It is necessary to judge whether it is possible.

In addition, to protect the system, the shift must be performed only for the shift within the transmission maximum input speed range.

In the case of a vehicle equipped with a multi-speed transmission such as an automatic transmission and a double clutch transmission (DCT), it is possible to consider a shiftable speed range and a shiftable range that can not be shifted in consideration of system characteristics.

5 is a flowchart for explaining a process of shifting to a target shift stage when skip shift of the hybrid vehicle is permitted.

Referring to FIG. 5, when the shift controller (TCU) recognizes that the hybrid vehicle is allowed to perform a skip shift in braking by the vehicle controller (HCU), first, (Motor speed) corresponding to the transmission speed of the transmission. In order to protect the system, the transmission control unit (TCU) permits shifting only when the transmission input speed corresponding to each gear range is within the range of the transmission maximum input speed.

At this time, the shift controller (TCU) calculates and recognizes the transmission input speed corresponding to each gear range based on the gear ratio of each gear stage based on the current wheel speed.

The transmission controller (TCU) compares the transmission input speed corresponding to each of the gear positions detected to the maximum input speed of the transmission, and selects the transmission end corresponding to the input speed of the transmission below the maximum input speed of the transmission as a speed change end candidate And excludes the gear stage corresponding to the transmission input speed exceeding the maximum input speed of the transmission from the gear stage candidate capable of entering the shift.

Here, the maximum transmission input speed is a limit range of the transmission input speed for system protection when the hybrid vehicle permits a skip shift in braking, and is set according to the allowable range of the hardware.

The shift controller (TCU) recognizes the driver's braking demand based on the opening amount of the brake pedal, and selects and determines a target speed change stage corresponding to the driver's braking demand amount (opening amount of the brake pedal) from the speed change stage candidates.

At this time, in the shift control unit (TCU), the step difference (the difference between the present speed change stage and the target speed change stage to be changed) according to the braking demand of the driver is determined through a pre-configured table, And the gear position is selected from among the gear position candidates. The table is configured by preliminary derivation and determination through experiments and evaluations in actual vehicle conditions, and is stored in the transmission control unit (TCU).

When the speed change stage corresponding to the step difference determined through the table is not included in the speed change stage candidate, the shift controller (TCU) selects and selects a lower speed shift stage candidate as the target speed change stage.

The shift controller (TCU) selects and decides sequential shifting (performing shifting in one step) or skipped (performing shifting in two or more steps at a time) based on the determined difference between the target shift speed and the current shift speed, (Sequential shift or skipped shift) is performed. That is, sequential shifting is determined when the difference between the target speed change stage and the current speed change stage is one, and skip transmission is determined when the difference between the target speed change stage and the present speed change stage is two or more stages.

For example, when the current speed change stage is 5 and the target speed change stage is 3, the skip transmission is selected and performed because the step difference is 2, and when the current speed change stage is 4 and the target speed change stage is 3, So that sequential shifting is selected and performed.

Here, the present speed change stage is a current speed change stage before shifting, and the target speed change stage is a shifting stage to be shifted to shift the gear to shift.

When the shift controller (TCU) recognizes that the skip shift is inhibited by the vehicle controller (HCU), when the driver does not step on the accelerator pedal (step), the shift pattern map And controls the sequential shifting to be performed at the selected target speed change stage.

The shift pattern map is configured by mapping a map that is derived by mapping the speed change stages depending on the vehicle speed and the opening amount of the accelerator pedal through the test under actual vehicle conditions. Here, .

FIG. 6 shows sequential shifting in which the hybrid vehicle is shifted one by one in 5-, 4-, and 3 stages in the same regenerative braking state, and two-stage shifting is performed in a single (single) And the results of one skip transmission (single shift) are compared.

As shown in FIG. 6, in the case of the skipped transmission, the motor torque intervention event is also less in comparison with the sequential shift, and the step speed at the time of shifting is large, so that the motor speed rpm is also kept higher than the sequential shift speed. The recovery rate of the regenerative energy can be increased.

In addition, there is an advantage that the electric power consumption of the electric oil pump can be reduced in the case of an automatic transmission vehicle of an electric oil pump alone drive type.

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.

Claims (7)

1. A hybrid vehicle which performs regenerative braking when a vehicle is stopped and generates a motor charging torque,
Determining whether the vehicle is in a braking state for stopping the vehicle;
Performing a shift to a target shift stage according to an opening amount of a brake pedal, while allowing a skip shift to perform a shift of two or more stages at a time in a braking situation for a vehicle stop;
≪ / RTI >
Wherein the step of performing the shift to the target shift stage according to the brake pedal opening amount comprises:
Comparing the transmission input speed corresponding to each gear position with a predetermined maximum input speed of the transmission to select a gear position corresponding to a transmission input speed lower than the maximum input speed of the transmission as a gear position candidate capable of shifting into the gear position;
Selecting a target shift stage from among the shift stage candidates based on the opening amount of the brake pedal and performing a shift to a selected target shift stage;
And a control unit for controlling the operation of the hybrid vehicle.
The method according to claim 1,
Wherein the step of determining whether the vehicle is in a braking state for stopping the vehicle comprises the steps of:
A step of calculating an inter-vehicle distance that can be traveled by a third line until the driver vehicle reaches the same speed as the preceding vehicle;
Determining whether the vehicle speed of the preceding vehicle is less than a predetermined threshold value to determine whether or not the preceding vehicle has entered the low-speed driving state for stopping;
If it is determined that the preceding vehicle has entered the low-speed running state for stopping, it is determined whether or not the skip-shift is permissible depending on the result of comparing the value obtained by adding the predetermined constant margin to the headway distance between the driver's vehicle and the head- ;
And a control unit for controlling the operation of the hybrid vehicle.
The method of claim 2,
The step of calculating the inter-vehicle distance may include:
A process in which the driver vehicle obtains the distance of the driver vehicle from the current vehicle speed to the other vehicle;
A process in which the preceding vehicle acquires the traveling distance of the preceding vehicle capable of traveling from the present vehicle speed to the other vehicle;
Calculating a headway distance by subtracting the headway distance of the headway vehicle from the headway distance of the driver vehicle;
And a control unit for controlling the operation of the hybrid vehicle.
The method of claim 2,
In the process of determining whether or not the skip transmission is permitted,
Wherein when the value obtained by adding a certain margin to the headway distance between the driver's vehicle and the headway vehicle is equal to or less than the headway distance, the skip shift is allowed.
The method of claim 2,
In the process of determining whether or not the skip transmission is permitted,
When the value obtained by adding a certain margin to the vehicle-to-vehicle distance between the driver's vehicle and the preceding vehicle is larger than the value of the preceding vehicle-to-vehicle distance, the skip-shifting is prohibited.
delete The method according to claim 1,
In the process of performing the shifting to the selected target speed change stage, a sequential shift that performs the shifting at one step at a time based on the step difference between the current speed change stage and the target speed change stage, or a skip shift that performs the shifting by two or more steps at a time is selected A method of controlling an operating point during regenerative braking of a hybrid vehicle.

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