KR20060024157A - Method of excessively controlling regenerating braking torque for hybrid electric vehicle - Google Patents

Abstract

Disclosed is a transient control method of regenerative braking torque of a hybrid electric vehicle. The transient control method of regenerative braking torque of the disclosed hybrid electric vehicle includes: (a) detecting a state of a vehicle by receiving signals from a TPS, a brake, a vehicle speed, an engine speed, and each gear in a hybrid electric vehicle; (b) determining a driving mode according to the state of the vehicle and outputting a regenerative braking torque map; (c) adjusting regenerative braking torque according to the driving mode change; (d) adjusting the regenerative braking torque according to the vehicle speed, engine RPM, and SOC to output a final regenerative braking torque.

According to the present invention, by applying a transient control algorithm for minimizing the heterogeneity caused by the change of the regenerative braking amount under a given regenerative braking torque map, there is an advantage of minimizing the sense of heterogeneity transmitted to the driver as the regenerative braking torque is added.

Hybrid electric vehicle, regenerative braking torque, SOC

Description

TECHNICAL OF EXCESSIVELY CONTROLLING REGENERATING BRAKING TORQUE FOR HYBRID ELECTRIC VEHICLE}

1 is a schematic flowchart sequentially showing a transient control method of regenerative braking torque of a hybrid electric vehicle according to the present invention.

Figure 2 is a schematic diagram showing the configuration of a vehicle to which the transient control method of regenerative braking torque of a hybrid electric vehicle according to the present invention is applied.

3 to 9 are schematic signal diagrams shown for explaining the transient control method of the regenerative braking torque of the hybrid electric vehicle according to the present invention, respectively.

The present invention relates to a transient control method of regenerative braking torque of a hybrid electric vehicle, and more particularly, to a transient control method of regenerative braking torque of a hybrid electric vehicle for minimizing heterogeneity transmitted to a driver due to the addition of the regenerative braking torque. will be.

In a hybrid electric vehicle (HEV), regenerative braking is one of the main technologies for improving fuel efficiency, and is a major factor in determining the amount of power assistance of a motor. Maximizing the amount of braking is very important for HEVs.

In relation to the braking mechanism, in case of the existing vehicle, the braking is designed to correspond only to the input value of the driver's braking pedal because the braking acts directly on the driving wheel of the vehicle.

However, in the case of a 1-axis HEV in which a motor is directly connected to the engine, the braking force of the motor basically acts on the engine shaft, and a sensor for linearly measuring a driver's brake pedal input value, for example, a brake position sensor none.

Therefore, the braking situation should be determined from the input values of the vehicle speed, engine speed, shift stage, brake switch, clutch sensor, and the like.

Here, if the braking situation changes rapidly, for example, when braking during inertia driving or when regenerative braking torque is not added at high SOC in connection with control of the battery SOC Smooth transient control of regenerative braking is essential to ensure no change.

Therefore, the development of an algorithm that controls regenerative braking without heterogeneous braking only with sensors attached to the existing vehicle is very important, and many related technologies have appeared in Honda, which is already mass-producing hybrid electric vehicles.

However, Honda's patent has many disadvantages because it is related to the cylinder idle technology of the engine, which is Honda's own technology, and it is difficult to apply independently, and it requires a lot of calculations for transient control of regenerative braking torque.

The present invention has been made to solve the above problems, the brake switch and the vehicle speed / engine sensor, which is a sensor mounted on the vehicle, the shift stage information through the minimum calculation through the braking without heterogeneous braking feeling in each of the regenerative braking mode transition situation The purpose of the present invention is to provide a transient control method of regenerative braking torque of a hybrid electric vehicle that minimizes the heterogeneity transmitted to the driver.

The transient control method of the regenerative braking torque of the hybrid electric vehicle of the present invention for achieving the above object is (a) in a hybrid electric vehicle, receiving a signal from the TPS, brake, vehicle speed, engine speed and each gear of the vehicle Detecting a state; (b) determining a driving mode according to the state of the vehicle and outputting a regenerative braking torque map; (c) adjusting regenerative braking torque according to the driving mode change; (d) adjusting the regenerative braking torque according to the vehicle speed, engine RPM, and SOC to output a final regenerative braking torque.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic flowchart showing a transient control method of regenerative braking torque of a hybrid electric vehicle according to the present invention in sequence.

Referring to the drawings, the transient control method of the regenerative braking torque of the hybrid electric vehicle according to the present invention, first, in the HEV, the vehicle's TPS (Throttle Position Sensor), brake, vehicle speed, engine speed (engine RPM) and each Receive a signal from the gear to detect the state of the vehicle (step 110).

Next, the driving modes N, C, and R are determined according to the detected state of the vehicle, and a regenerative braking torque map is output (steps 120 and 130).

Herein, N, C, and R represent Normal, Coasting, and Regen modes, respectively, as described later.

Then, the regenerative braking torque is adjusted according to the change of the driving mode of the vehicle (step 140).

In addition, by regulating the regenerative braking torque according to the vehicle speed, engine RPM (engine speed) and SOC, the final regenerative braking torque is output.

As described later, the transient control for the vehicle speed and the engine speed is to give the regenerative braking torque linearly within a certain speed range, respectively.

In addition, the transient control according to the SOC may linearly dissipate the regenerative braking torque with a time delay when the SOC enters high and linearly with a certain time delay when the SOC is released. It is supposed to increase the regenerative braking amount.

The transient control according to the change of the driving mode N → C or C → R or N → R of the vehicle is made to increase linearly to the target regenerative braking amount with a certain time delay from the moment when the mode is changed. On the other hand, the transient control according to the change of the driving mode R → C or C → N or R → N is given to the coasting torque or stops the torque application according to the changed mode as soon as the condition is satisfied.

In addition, the final regenerative braking torque is applied by multiplying the gain and the torque value calculated in each driving mode control.

The transient control method of the regenerative braking torque of the hybrid electric vehicle according to the present invention as described above will be described in more detail.

Prior to the full description, the vehicle to which the present invention is applied is, for example, a 4WD HEV vehicle as shown in FIG. 2, and unlike a general mechanical 4WD and 2WD HEV vehicle, the vehicle has a HEV power train on the front wheel and a rear wheel. It has a separate motor system driven independently. And the transmission is provided with a manual transmission.

In FIG. 2, reference numeral 11 is an engine, 12 is a transmission, for example, a manual transmission (MT), 13 is a clutch, 14 and 17 are motors, 15 and 18 are differential, 16 shows a planetary gear device.

And to detect the condition of the vehicle, the accelerator pedal stroke sensor (Accel Pedal Stroke Sensor), brake switch (Vehicle Velocity), engine speed (Engine Speed), clutch on / off sensor (Clutch On / Off Sensor) ) Is required.

In addition, it is possible to estimate the current shift stage from the two vehicle signals and the engine speed. If the present invention is applied to a vehicle equipped with an automatic transmission, shift stage information can be obtained from a TCU (shift controller).

The present invention minimizes the occurrence of heterogeneous braking feeling when the regenerative braking amount is changed, which is directly linked to the maximization of the actual regenerative braking amount.

The regenerative braking torque map is completed during braking and coasting to generate the maximum regenerative braking amount that can be applied considering the motor output performance of the target vehicle, the maximum charging power limit of the battery, and the mechanical brake amount. do.

The regenerative braking map can be set to maximize the regenerative braking amount as much as possible, but if it is applied to the vehicle as it is, it causes an excessive braking feeling or an unintended acceleration feeling to the driver due to the heterogeneous shock caused by the sudden torque change. There is a concern.

This heterogeneity can be alleviated to some extent by reducing the amount of regenerative braking in general, but this is a factor to weaken the advantages of the aforementioned HEV, and furthermore, there is a limit in mitigating the change of various regenerative braking torques only by changing the map. .

Therefore, the method according to the present invention is a torque transient control algorithm during regenerative braking which gives the maximum regenerative braking amount applicable and at the same time minimizes the heterogeneity resulting from the rapid change in the regenerative braking amount.

In addition, the method according to the present invention linearly increases or decreases the amount of regenerative braking torque that is changed according to changes in vehicle speed, engine rpm, SOC, and driving mode, thereby minimizing shock and heterogeneity caused by a sudden change in regenerative braking torque. .

Hereinafter, the method according to the present invention will be described in detail.

First, transient control (Velocity> = veh_low_spd_regen_lo) for the vehicle speed will be described with reference to FIG. 3.

This is the case when regenerative braking is allowed only when driving over a certain speed to prevent different braking feeling at low speed. Therefore, in case of controlling by step, frequent pedal operation of driver can be induced by sudden change of braking feeling. Therefore, regenerative braking torque is given linearly according to vehicle speed.

For this control, as shown in Fig. 3, the regenerative braking torque is given linearly within a certain speed range.

spd1 = veh_low_spd_regen_lo -----> tune after test,

spd2 = veh_low_spd_regen_up -----> tune after test,

gain_veh_spd_regen = (spd―spd1) / (spd2―spd1) -----> limit: min0 / max1

Next, transient control (Engine Speed> = eng_low_rpm_regen_lo) with respect to engine speed is demonstrated with reference to FIG.

This is the case when regenerative braking is allowed only when running above a certain engine speed in order to prevent engine stall at low speed. Therefore, in case of controlling by step, the driver's frequent pedal operation can be induced by a sudden change of braking feeling, so it gives linear regenerative braking torque according to engine speed.

For this control, as shown in Fig. 4, the regenerative braking torque is applied linearly within a constant engine speed range.

spd1 = eng_low_rpm_regen_lo ----> tuning after test,

spd2 = eng_low_rpm_regen_up ----> tuning after test,

gain_eng_rpm_regen = (spd―spd1) / (spd2―spd1) -----> limit: min0 / max1

Next, transient control (SOC <= soc_hi_regen_low (soc_hi_regen_high, hysterisys)) according to SOC will be described with reference to FIGS. 5 and 6.

First, as shown in Fig. 5, when describing SOC high entry, this is when the battery is charged above a certain level (hysteresis). Therefore, stop regenerative braking for battery protection, but allow time for preventing sudden changes in braking feeling.

For this control, as shown in FIG. 5, the regenerative braking torque is linearly dissipated with a time delay.

time_delay_soc_regen = time2―time1 ----> tune after test,

gain_soc_regen = 1― (t―time1) / time_delay_soc_regen -----> limit: min0 / max1

In addition, when SOC is released, the SOC is lowered to the charge allowable level (hysteresis) due to discharge such as DC / DC. Therefore, the regenerative braking torque is given, but the regenerative braking torque is increased linearly with time margin to prevent sudden braking feeling change.

For this control, there is a time delay and a linear increase to the target regenerative braking amount.

time_delay_soc_regen = time2―time1 ----> tune after test,

gain_soc_regen = (t―time1) / time_delay_soc_regen -----> limit: min0 / max1

Next, the transient control according to the driving mode change (N ↔ C ↔ R) will be described.

Prior to the description, the driving mode is defined.

(1) Normal Mode: Excel On and Brake Off (hereinafter referred to as Mode N, 0),

(2) Coasting Mode: Excel Off and Brake Off (hereinafter referred to as Mode C, 1),

(3) Regen Mode: Excel Off and Brake On (hereinafter referred to as Mode R, 2),

(4) Abnormal Mode: Accel On and Brake On (recognized as previous mode)

The purpose of the transient control and the mode conversion situation will be described.

An object of the present invention is to perform a smooth transition so as not to feel a heterogeneity during mode switching (N ↔ C ↔ R) according to the Excell / Brake operation.

At this time, it is defined as follows according to the mode conversion situation.

(1) Normal → Coasting, (2) Coasting → Regen, (3) Normal → Regen, (4) Regen → Coasting, (5) Coasting → Normal, (6) Normal → Regen

In the situation where regenerative braking torque is increased (Normal → Coasting, Coasting → Regen, Normal → Regen), the transient control is performed over time and the regenerative braking torque decreases (Regen → Coasting, Coasting → Normal, Normal → Regen). ), The mode transition immediately removes the regenerative braking torque.

And transient control according to the mode change with reference to Figure 7 will be described in more detail.

First, when mode N → mode C (when regenerative braking torque becomes large), this is a case where the driver's acceleration will stop. Therefore, in order to avoid sudden deceleration, slowly increase the target regenerative braking amount.

For this control, as shown in Fig. 7, linearly increasing the target regenerative braking amount with a certain time delay from the moment the mode is changed.

time_delay_mode_transition_regen = (time2―time1) ----> tuning after test,

gain_mode_transition_regen = (t―time1) / time_delay_mode_transition_regen -----> limit: min0 / max1

Torque = gain_mode_transition_regen X Target Coasting Torque

Next, with reference to FIG. 8, the case where mode C-mode R, (mode N-mode R) (when regenerative braking torque becomes large) is demonstrated.

This is the case when the driver's deceleration will be input. Therefore, in order not to give a sudden sense of deceleration, slowly increase the target regenerative braking amount with time allowance until the friction brake is sufficiently formed.

For this control, as shown in Fig. 8, a linear increase to the target regenerative braking amount with a certain time delay from the moment the mode is converted.

time_delay_mode_transition_regen = (time2―time1) ----> tuning after test,

gain_mode_transition_regen = (t―time1) / time_delay_mode_transition_regen -----> limit: min0 / max1,

Final Torque Before ------> Final regenerative braking torque at time1,

Torque = gain_mode_transition_regen X (Target Regen Torque-Final Torque Before) + Final Torque Before

Next, a description will be given with reference to FIG. 9 in the case of mode R-mode C, mode C-mode N, (mode R-mode N) (when regenerative braking torque becomes small).

This is the case when the driver's deceleration will stop or acceleration will be input. Therefore, the coasting torque is immediately applied or the torque application is stopped according to the changed mode.

For this control, as shown in Fig. 9, the coasting torque is applied or the torque application is stopped according to the changed mode as soon as the condition is satisfied.

Torque = Target Coasting Torque (in Mode C) = 0 (in Mode N)

Finally, the final regenerative braking torque is applied.

This is the regenerative braking torque by applying the regenerative braking torque by multiplying the torque value calculated in the equation described with reference to FIGS. 7 to 9 by the torque value calculated in the transient control according to the above-described driving mode change (N ↔ C ↔ R). Do not convey excessive heterogeneity to the driver even if there is a drastic change.

As described above, the present invention is intended to alleviate the heterogeneous shock to the driver by suppressing the occurrence of the heterogeneous braking feeling while maintaining the regenerative braking amount efficiently set to the maximum.

That is, a regenerative braking torque map is generated in consideration of the characteristics of the target vehicle, and the regenerative braking torque is linearly dissipated or applied according to the vehicle speed, engine rpm, and SOC state. In addition, the regenerative braking torque applied linearly increases or decreases according to the change of the driving mode of the vehicle, thereby reducing the heterogeneity caused by the sudden change of the regenerative braking torque.

Without changing the regenerative braking torque map provided by the above process, it is possible to secure the maximum possible regenerative braking amount and to perform regenerative braking to minimize the heterogeneity caused by the change in the regenerative braking amount.

As described above, the transient control method of the regenerative braking torque of the hybrid electric vehicle according to the present invention has the following effects.

By applying a transient control algorithm that minimizes the heterogeneity caused by the change of the regenerative braking amount under the given regenerative braking torque map, it is possible to minimize the heterogeneity transmitted to the driver as the regenerative braking torque is added.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (6)

A hybrid electric vehicle, comprising: detecting a state of a vehicle by receiving signals from a TPS, a brake, a vehicle speed, an engine speed, and each gear; (b) determining a driving mode according to the state of the vehicle and outputting a regenerative braking torque map; (c) adjusting regenerative braking torque according to the driving mode change; and outputting the final regenerative braking torque by adjusting the regenerative braking torque according to the vehicle speed, the engine RPM, and the SOC. The method of claim 1, The transient control of the vehicle speed and the engine speed is a transient control method of the regenerative braking torque of the hybrid electric vehicle, characterized in that the regenerative braking torque is linearly provided within a predetermined speed range. The method of claim 1, The transient control according to the SOC, When the SOC enters high, the regenerative braking torque is linearly dissipated with a time delay. The method of controlling transient regenerative braking torque of a hybrid electric vehicle, wherein the SOC is linearly increased to a target regenerative braking amount with a predetermined time delay when the SOC is released. The method of claim 1, Transition control according to the driving mode N → C or C → R or N → R change, Transient control method of regenerative braking torque of a hybrid electric vehicle, characterized by increasing linearly to the target regenerative braking amount with a predetermined time delay from the moment the mode is converted. The method of claim 1, Transition control according to the driving mode R → C or C → N or R → N change, 12. A transient control method for regenerative braking torque of a hybrid electric vehicle, wherein the coasting torque is given or the torque is stopped in accordance with the changed mode immediately after the condition is satisfied. The method of claim 1, The final regenerative braking torque is, And applying torque multiplied by a torque value calculated in each driving mode control to apply the multiplicity of gain to the regenerative braking torque of the hybrid electric vehicle.

Images