KR101000405B1 - Driving force control method for parallel HEV - Google Patents

Abstract

The present invention relates to a drive control method for a parallel hybrid vehicle, and more particularly, a stabilization time for stably changing the engine torque command and the motor torque command to the optimum engine torque and the optimum motor torque for a predetermined time after the lock-up. The present invention relates to a drive control method for a parallel hybrid vehicle capable of improving driving performance and stably controlling a power train.

To this end, the present invention includes the steps of determining whether to receive a request to switch from the EV mode to the HEV mode, the clutch lockup request; Determining whether a difference between a predetermined optimum engine torque and an engine torque command is within a predetermined range when the conversion to the HEV mode and a clutch lockup request are received; If the difference between the optimum engine torque and the engine torque command is within a certain range, input the optimum engine torque to the engine torque command, and if the difference between the optimum engine torque and the engine torque command is not within a certain range, the optimum engine until it comes within a certain range. It provides a drive control method for a parallel hybrid vehicle comprising the step of controlling the engine torque command to rise by a constant slope by applying a rate limiter to the torque.

Clutch, Lockup, Engine Torque, Motor Torque, Rate Limiter

Description

Driving control method for parallel hybrid vehicle {Driving force control method for parallel HEV}

The present invention relates to a drive control method for a parallel hybrid vehicle, and more particularly, to a drive control method for a parallel hybrid vehicle for determining engine torque and motor torque at the time when a clutch is engaged in mode conversion from EV mode to HEV mode. It is about.

Typically, hybrid electric vehicles using two or more power sources can be configured with a variety of power transmission schemes using engines and motors as power sources, and most hybrid vehicles now employ either parallel or series power transmission configurations. Doing.

In series type, the engine and motor are directly connected, and the structure is simpler and the control logic is simpler than the parallel type. However, the mechanical energy from the engine is stored in the battery and the motor must be driven again. This is disadvantageous in terms of efficiency when converting energy. On the other hand, the parallel structure is relatively more complicated than the serial type and the control logic is more complicated. However, the mechanical energy of the engine and the electrical energy of the battery can be used simultaneously. Therefore, there is a tendency that is adopted in passenger cars because it has the advantage of using energy efficiently.

A system configuration of a parallel hybrid electric vehicle is one example. As shown in FIG. 1, the engine 10 and the motor 13 are connected by an engine clutch 12, and the engine 10 and the motor 13 are connected to each other. ), The automatic transmission 14 is connected to the shaft of the motor, and a battery for charging is connected to the motor 13, and an integrated start generator (ISG 11) is attached to the engine 10. It is.

The main driving mode for the hybrid electric vehicle is an electric vehicle (EV) mode, which is a pure electric vehicle mode using only the power of the motor 13, and the rotational force of the engine 10 as the main power, as is well known. HEV (hybrid electric vehicle) mode, which is an auxiliary mode that uses rotational power as an auxiliary power, and regenerative braking which recovers the vehicle's braking and inertia energy through generation of electric power from the motor 13 and charges the battery when driving by braking or inertia of the vehicle. (RB: Regenerative Braking) mode.

The conversion between the EV mode and the HEV mode is one of the main functions of the hybrid vehicle, and is a factor that affects the driving performance, fuel economy, and power performance of the hybrid vehicle.

In particular, the engine 10 and the motor 13 power is transmitted to the drive shaft through the coupling of the clutch 12 during the conversion from the EV mode to the HEV mode. Until the clutch 12 becomes lock-up (engagement of the engine 10 and the motor 13), the total demand torque is satisfied by the motor 13, and immediately after the lock-up, the optimum fuel economy is considered in consideration of system efficiency. Through the torque command to the engine 10 and the motor 13 to be distributed to the optimum engine torque, the optimum motor torque.

However, if the torque distribution is applied immediately after the lockup, the total required torque may not be satisfied depending on the responsiveness of the powertrain unit, and the sudden change in torque may affect the operability.

The present invention has been made in view of the above, by providing a stabilization time so that the clutch can be stably changed to the optimum engine torque and the optimum motor torque for a predetermined time after the lock-up, operability The purpose of the present invention is to provide a drive control method for a parallel hybrid vehicle that can improve the powertrain and control the power train stably.

The above object is a drive control method of a parallel hybrid vehicle,

Determining whether to receive a request for a change from the EV mode to the HEV mode and to receive the clutch lockup request; Determining whether a difference between a predetermined optimum engine torque and an engine torque command is within a predetermined range when the conversion to the HEV mode and a clutch lockup request are received; If the difference between the optimum engine torque and the engine torque command is within a certain range, input the optimum engine torque to the engine torque command, and if the difference between the optimum engine torque and the engine torque command is not within a certain range, the optimum engine until it comes within a certain range. And applying the rate limiter to the torque to control the engine torque command to rise at a constant inclination.

Preferably, when the difference between the optimum engine torque and the engine torque command is within a predetermined range, the optimum motor torque is input to the motor torque command, and when the difference between the optimum engine torque and the engine torque command is not within the predetermined range, the motor may come within a certain range. And controlling the motor torque command to fall to a value obtained by subtracting the engine torque command from the total required torque.

Accordingly, according to the driving control method of the parallel hybrid vehicle according to the present invention, if the clutch lockup is determined during the conversion from the EV mode to the HEV mode, the engine torque command is set to increase by a constant slope by applying a rate limiter to the optimum engine torque value. By stabilizing time until the engine torque command reaches the optimum engine torque, it is possible to improve the operability for the engine and the torque control, and to control the power train stably.

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

The present invention relates to a method for determining the engine and motor torque at the time when the clutch is engaged in the conversion from the EV mode to the HEV mode.

The present invention provides a stabilization time so that the engine torque command and the motor torque command can be changed to the optimum engine torque and the optimum motor torque command for a certain time after the lockup of the clutch, thereby eliminating the factors that adversely affect the operability due to the sudden change in torque. can do.

2 is a graph illustrating a torque stabilization control method after clutch lock-up according to the present invention.

In HEV mode, the engine and the motor are coupled (clutch lock-up) by the clutch, so that the engine is used as the main power source and the motor as the auxiliary power source. Therefore, the total demand torque of the driver can be calculated as the sum of the engine torque and the motor torque.

However, as shown in FIG. 2, the optimum engine torque increases sharply after the clutch lockup and then gradually increases, and the optimum motor torque compensates for the insufficient torque after subtracting the optimum engine torque from the total required torque after the clutch lockup.

Herein, in the present invention, a stabilization time is provided to alleviate the increase and decrease of the torque that changes rapidly after the clutch lockup.

3 is an explanatory diagram for explaining a method for determining an engine torque command after clutch lockup.

When the clutch lockup is determined, a rate limiter is applied to the optimum engine torque value and the torque command is set to rise with a constant slope. In other words, the engine torque rises at a constant inclination until the optimum engine torque is reached at zero.

At this time, the application time of the rate limiter is performed until the difference between the optimum engine torque and the engine torque command value falls within a certain range. As the engine torque command value increases, the difference between the optimum engine torque and the engine torque command value decreases, and the rate limiter is applied until this value falls within a certain range.

Therefore, as shown in FIG. 2, the engine torque does not increase rapidly to the optimum engine torque but increases at a constant slope to reach the optimum engine torque.

4 is an explanatory diagram for explaining a method for determining an engine torque command after clutch lockup.

Until the difference between the optimum engine torque and the engine torque command is within a certain range, the motor torque command value is obtained by subtracting the engine torque command value from the total required torque, and commanding the optimum motor torque after the motor torque command value is within a certain range.

That is, as shown in FIG. 2, since the total demand torque is calculated as the sum of the engine torque and the motor torque, the motor torque command is decreased by the slope at which the engine torque command increases.

5 is a flowchart illustrating a driving control method of a hybrid vehicle according to an exemplary embodiment of the present invention.

It is determined whether the HCU is required to switch from EV mode to HEV mode and whether clutch lockup is required. When the conversion to the HEV mode and the clutch lockup request are received, it is determined whether the difference between the optimum engine torque and the engine torque command value is within a predetermined range C1.

If the difference between the optimum engine torque and the engine torque command value does not fall within a certain range, the rate limiter is applied to the optimum engine torque to increase the engine torque command value by a constant slope, and the motor torque command is a value obtained by subtracting the engine torque command from the total required torque. It is done.

Therefore, when the difference between the optimum engine torque and the engine torque command value is within a predetermined range, the optimum engine torque is input to the engine torque command, and the optimum motor torque is input to the motor torque command.

1 is a main configuration of a parallel hybrid vehicle,

2 is a graph for explaining torque stabilization control after clutch lock-up according to the present invention;

3 is an explanatory diagram for explaining a method for determining an engine torque command after clutch lockup;

4 is an explanatory diagram for explaining a method for determining a motor torque command after clutch lockup;

5 is a flowchart illustrating a driving control method of a hybrid vehicle according to an exemplary embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: engine 11: ISG

12: engine clutch 13: motor

14: transmission

Claims (2)

In the drive control method of a parallel hybrid vehicle, Determining whether to receive a request for a change from the EV mode to the HEV mode and to receive the clutch lockup request; Determining whether a difference between a predetermined optimum engine torque and an engine torque command is within a predetermined range when the conversion to the HEV mode and a clutch lockup request are received; If the difference between the optimum engine torque and the engine torque command is within a certain range, input the optimum engine torque to the engine torque command, and if the difference between the optimum engine torque and the engine torque command is not within a certain range, the optimum engine until it comes within a certain range. And applying the rate limiter to the torque so as to control the engine torque command to rise at a constant inclination. The method according to claim 1, If the difference between the optimum engine torque and the engine torque command is within a certain range, input the optimum motor torque to the motor torque command, and if the difference between the optimum engine torque and the engine torque command is not within a certain range, until the motor torque is within a certain range. And controlling the command to fall from the total demand torque to the value obtained by subtracting the engine torque command.

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