Anti-jerk control apparatus and method for hybrid electric vehicle

Abstract

The present invention relates to an anti-jerk control apparatus and method for an Hybrid Electric Vehicle (HEV). The anti-jerk control apparatus includes a model speed calculation unit for calculating a model speed of the motor in a state in which a vibration of a drive shaft is not considered. A vibration occurrence determination unit detects a speed vibration component while calculating a reference speed difference and an average speed difference from differences between the model speed and an actual speed of the motor, thus determining whether a vibration occurs on the drive shaft. A torque correction value calculation unit calculates a motor torque correction value for anti-jerk required to damp the vibration of the drive shaft, and controls torque of the motor if the vibration occurrence determination unit determines that the vibration occurs on the drive shaft.

Claims

1. An anti-jerk control method for a Hybrid Electric Vehicle (HEV), comprising: calculating a model speed of a motor in a state in which a vibration of a drive shaft is not considered; calculating an actual speed of the motor; obtaining differences between the model speed and the actual speed of the motor, thus calculating a reference speed difference and an average speed difference; comparing the reference speed difference with the average speed difference, and determining that a vibration of the drive shaft has occurred when a speed vibration component, obtained when the reference speed difference is greater or less than the average speed difference, is detected; determining a motor torque correction value for anti-jerk required to damp the vibration of the drive shaft; and controlling torque of the motor using negative feedback control allowing the motor torque correction value for anti-jerk to be applied so that the difference between the model speed and the actual speed of the motor becomes 0.

2. The anti-jerk control method of claim 1, wherein the motor torque correction value for anti-jerk is determined by an equation of [torque correction value=gain*((model speedactual speed)average speed difference)].

3. The anti-jerk control method of claim 2, wherein the gain is set to different values for cases requiring anti-jerk control, such as clutch releasing, gear changing, tip-in/out, and braking.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments thereof illustrated the accompanying drawings which are given hereinbelow by way of illustration only, and thus are not limitative of the present invention, and wherein:

(2) FIG. 1 is a control diagram showing an exemplary anti-jerk control apparatus for an HEV according to the present invention;

(3) FIGS. 2A to 2C are graphs showing an exemplary anti-jerk control operation for an HEV according to the present invention;

(4) FIG. 3 is a flowchart showing an exemplary anti-jerk control method for an HEV according to the present invention; and

(5) FIG. 4 is a diagram showing an exemplary power train system for an HEV.

(6) It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

(7) In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

(8) As described herein, the present invention features an anti-jerk control apparatus for a Hybrid Electric Vehicle (HEV) in which an engine, a motor and an automatic transmission are disposed in a collinear fashion on one shaft and a clutch is disposed between the engine and the motor, comprising a model speed calculation unit for calculating a model speed of the motor in a state in which a vibration of a drive shaft is not considered, a vibration occurrence determination unit, and a torque correction value calculation unit.

(9) In one embodiment, the vibration occurrence determination unit is used for detecting a speed vibration component while calculating a reference speed difference and an average speed difference from differences between the model speed and an actual speed of the motor, thus determining whether a vibration occurs on the drive shaft.

(10) In another embodiment, the vibration occurrence determination unit determines that the vibration occurs on the drive shaft, the torque correction value calculation unit calculates a motor torque correction value for anti-jerk required to damp the vibration of the drive shaft, and controls the torque of the motor.

(11) In another aspect, the present invention also features an anti-jerk control method for a Hybrid Electric Vehicle (HEV), comprising calculating a model speed of a motor in a state in which a vibration of a drive shaft is not considered, calculating an actual speed of the motor, obtaining differences between the model speed and the actual speed of the motor, thus calculating a reference speed difference and an average speed difference, comparing the reference speed difference with the average speed difference, and determining that a vibration of the drive shaft has occurred when a speed vibration component, obtained when the reference speed difference is greater or less than the average speed difference, is detected, determining a motor torque correction value for anti-jerk required to damp the vibration of the drive shaft, and controlling torque of the motor using negative feedback control allowing the motor torque correction value for anti-jerk to be applied so that the difference between the model speed and the actual speed of the motor becomes 0.

(12) Hereinafter reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

(13) Hereinafter, embodiments of the present invention will be described in detail with the attached drawings.

(14) According to certain preferred embodiments, and as shown in FIGS. 1-3, for example, FIG. 1 is a control diagram showing an anti-jerk control apparatus for a Hybrid Electric Vehicle (HEV) according to a preferred embodiment of the present invention, FIGS. 2A to 2C are graphs showing an anti-jerk control operation for an HEV according to another preferred embodiment of the present invention, and FIG. 3 is a flowchart showing an anti-jerk control method for an HEV according to another preferred embodiment of the present invention.

(15) Preferably, anti-jerk control for an HEV according to the present invention is performed by a Motor Control Unit (MCU) and is suitably configured to perform control such that vibrations (jerks) are prevented from occurring on a drive shaft under various conditions such as a tip-in/out operation during the driving of the vehicle or a creep driving operation (refers to a driving operation when the vehicle is slowly moving after stopping in an EV mode) in an EV mode, and a gear changing operation or a clutch releasing operation in an HEV mode.

(16) According to preferred embodiments, for these operations, a model speed, which is the speed of the motor in the state in which vibration (jerk) of a drive shaft is not considered (a jerk-free state), is suitably calculated by a model speed calculation unit 100. Preferably, this model speed is calculated by subtracting drag torque from commanded motor torque, subtracting the total torque of the drive shaft from resulting torque, and integrating final resulting torque.

(17) Preferably, when the HEV is driving, a vibration phenomenon such as a shock & jerk occurs together with the vibration of the drive shaft, and thus the actual speed of the motor that may preferably include a vibration component is calculated.

(18) In another further preferred embodiment, the vibration occurrence determination unit 200 of the motor control unit calculates the differences between the model speed of the motor and the actual speed of the motor in real time, and suitably calculates the average speed difference thereof while setting a reference speed difference on the basis of the speed differences.

(19) Accordingly, when a predetermined difference between the model speed and the actual speed of the motor is suitably obtained, the difference is set to the reference speed difference. Preferably, the speed differences are filtered by a Low Pass Filter (LPF) 202, and thus the average speed difference is suitably obtained.

(20) Preferably, when the average speed difference is suitably obtained while the reference speed difference is set, the reference speed difference is compared with the average speed difference, as shown in FIG. 2B, and thus a speed vibration component is suitably detected.

(21) According to preferred exemplary embodiments, for example as shown in detail in FIG. 2C, the reference speed difference is compared with the average speed difference. Preferably, when the reference speed difference is greater or less than the average speed difference, a vibration component proportional to the difference therebetween is suitably detected as the speed vibration component.

(22) According to preferred exemplary embodiments, when the speed vibration component is detected in this way, the vibration occurrence determination unit 200 determines that a vibration has occurred on the drive shaft, and thus a torque correction value calculation unit 300 calculates a motor torque correction value for anti-jerk.

(23) In other words, when the vibration occurrence determination unit 200 suitably determines that the vibration has occurred on the drive shaft, the torque correction value calculation unit 300 calculates the motor torque correction value for anti-jerk required to damp the vibration of the drive shaft, and suitably controls the torque of the motor to damp the vibration of the drive shaft.

(24) Accordingly, in further preferred embodiments, after the speed vibration component has been suitably detected, the vibration of the drive shaft mainly occurs in various conditional modes such as a gear changing mode in which gears are changed, a braking mode in which a brake pedal is pressed after the clutch is released, a tip-in/out mode in which an accelerator pedal is repeatedly pressed or released after the clutch is released, and a creep mode in which low-speed driving is suitably performed using only the driving force of the motor while the accelerator pedal is not pressed after the clutch is released, as shown in FIG. 3. Accordingly, the motor torque correction value for anti-jerk required to damp the vibration of the drive shaft is calculated, so that the torque of the motor is suitably controlled to damp the vibration of the drive shaft.

(25) In certain preferred exemplary embodiments, the motor torque correction value for anti-jerk is suitably determined by an equation of [gain*((model speedactual speed)average speed difference)], and the gain is previously set to different values for various cases requiring anti-jerk control, such as clutch releasing, gear changing, tip-in/out, and braking.

(26) Accordingly, the torque correction value calculation unit 300 controls the torque of the motor using negative feedback control so that the difference between the model speed and the actual speed of the motor becomes 0.

(27) Accordingly, in certain preferred embodiments, the motor torque is suitably controlled by means of negative feedback control allowing the determined motor torque correction value for anti-jerk to be applied to the torque correction value calculation unit 300 until the difference between the model speed and the actual speed of the motor becomes 0, thus easily preventing vibrations (jerks) from occurring on the drive shaft under various conditions such as a gear changing operation and a tip-in/out operation, as well as a clutch releasing operation.

(28) The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.