KR-102962188-B1 - Control method for virtual gear shift feeling generation of electric vehicle

KR102962188B1KR 102962188 B1KR102962188 B1KR 102962188B1KR-102962188-B1

Abstract

The present invention relates to a control method for an electric vehicle, and its primary objective is to provide a control method for an electric vehicle capable of generating and implementing a shifting sensation similar to that of a vehicle equipped with a multi-stage transmission in an electric vehicle that lacks a multi-stage transmission. To achieve the above objective, a control method for an electric vehicle is disclosed, which implements a virtual multi-stage shifting sensation by determining a virtual shift intervention torque and a limit torque for each virtual gear stage from input variables through a virtual shift model that takes vehicle driving information collected from the vehicle during driving as input, and by controlling a motor using the determined virtual shift intervention torque, the limit torque for each virtual gear stage, and a motor torque command.

Inventors

오지원
어정수

Assignees

현대자동차주식회사
기아 주식회사

Dates

Publication Date: 20260507
Application Date: 20200610

Claims (20)

A step in which, during the driving of an electric vehicle, a basic torque command is determined in real time by a controller based on vehicle driving information collected from the vehicle; A step in which a virtual target gear ratio is determined by a controller based on vehicle driving information collected from the vehicle; A step in which a transmission class is determined by a controller from a virtual current transmission gear and a determined virtual target transmission gear, and a virtual transmission intervention torque profile corresponding to the determined current transmission class is selected from among preset virtual transmission intervention torque profiles for each transmission class; A step in which a virtual shift intervention torque for generating a virtual shift feel is determined in real time by a controller according to the selected virtual shift intervention torque profile, and a final motor torque command is generated using the determined basic torque command and the virtual shift intervention torque; and The method includes a step in which the operation of a motor for vehicle driving is controlled by a controller according to the final motor torque command generated above, and In the step where the virtual target gear ratio is determined, a virtual vehicle speed, which is a reference speed, is determined based on the vehicle driving information, and The virtual vehicle speed, which is the above reference speed, is a virtual vehicle speed for upshifting, and During upshifting, a virtual target gear is determined by a preset shift schedule map using the virtual vehicle speed for upshifting, and A control method for generating a virtual shifting sensation in an electric vehicle, characterized in that, during downshifting, a virtual target gear position is determined by the shifting schedule map using a virtual vehicle speed for downshifting calculated by applying a scale factor and an offset value to the virtual vehicle speed for upshifting.
In claim 1, A control method for generating a virtual gear shift sensation in an electric vehicle, characterized in that the electric vehicle is a motor-driven vehicle equipped with a reduction gear and driven solely by a motor.
In claim 1, A control method for generating a virtual gear shift sensation of an electric vehicle, characterized in that, in the step of determining the virtual target gear shift, the virtual target gear shift is determined from the virtual vehicle speed and vehicle load value determined by the preset gear shift schedule map.
In claim 3, A control method for generating a virtual gear shift feel of an electric vehicle, characterized in that the above vehicle load value is one of an accelerator pedal input value by a driver, a brake pedal input value, or a basic torque command.
In claim 3, A control method for generating a virtual gear shift feel of an electric vehicle, characterized in that the above-mentioned virtual vehicle speed is determined from the actual motor speed detected by the motor speed detection unit and the preset virtual final reduction gear ratio.
In claim 3, The above transmission schedule map is, A shift schedule map for upshifting used during upshifting; and A control method for generating a virtual shifting sensation in an electric vehicle, characterized by including a downshifting shift schedule map used during downshifting.
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In claim 1, The virtual vehicle speed for the downshift mentioned above is, A control method for generating a virtual shift sensation of an electric vehicle, characterized by being determined by adding a positive offset value to a value obtained by multiplying the virtual vehicle speed for the upshift by a scale factor greater than 1.
In claim 1, In the step where the above virtual target gear ratio is determined, The vehicle driving information used to determine the above virtual target gear ratio is, Paddle shift input information by the driver; and Includes shift lever input information by the driver, A control method for generating a virtual gear shift sensation in an electric vehicle, characterized in that when there is a paddle shift input or shift lever input by the driver, the controller determines the manual transmission mode and determines a virtual target gear based on the paddle shift input information or shift lever input information.
In claim 1, The controller further includes a step of calculating the limit torque of the current gear by multiplying a virtual gear ratio corresponding to the virtual current gear, a preset virtual final drive gear ratio, and a limit torque setting parameter. A control method for generating a virtual shift sensation of an electric vehicle, characterized in that, in the step of generating the final motor torque command, if the basic torque command is greater than or equal to the calculated limit torque value, the basic torque command with a value limited by the limit torque is used to generate the final motor torque command.
In claim 10, The above limit torque is, A limit torque for the driving direction to limit the basic torque command of the driving direction; and Includes a limit torque for the regenerative direction to limit the basic torque command for the regenerative direction, and A control method for generating a virtual shift sensation of an electric vehicle, characterized in that, in the step of generating the final motor torque command, a basic torque command limited by one of the driving direction limit torque and the regenerative direction limit torque is used.
In claim 10, In the step where the above basic torque command is calculated in real time, the basic torque command is calculated by summing the regenerative torque command, the coasting torque command, and the driving torque command, and A control method for generating a virtual shifting sensation of an electric vehicle, characterized in that, in the step of generating the final motor torque command, the summed basic torque command is limited to a limit torque value for the driving direction during driving, and the summed basic torque command is limited to a limit torque value for the regenerative direction during coasting and regeneration.
In claim 1, When the virtual target gear ratio is determined, the method further includes the step of, during the gear shifting process, the controller counting time from the point in time when the virtual target gear ratio is determined and determining a virtual gear shift progress rate using the counted time. The above virtual shift progress rate is determined as a percentage (%) value of the above-mentioned counted time relative to the set total shift time, and A control method for generating a virtual shift feel of an electric vehicle, characterized in that, in the step of generating the final motor torque command, the controller determines a virtual shift intervention torque value corresponding to the current virtual shift progress rate from a virtual shift intervention torque profile.
In claim 1, When the virtual target gear stage is determined, the method further includes the step of, during the gear shifting process, the controller counting time from the point in time when a set delay time has elapsed after the virtual target gear stage is determined, and determining a virtual gear shift progress rate using the counted time. The above virtual shift progress rate is determined as a percentage (%) of the above-mentioned counted time relative to the total shift time set, and A control method for generating a virtual shift feel of an electric vehicle, characterized in that, in the step of generating the final motor torque command, the controller determines a virtual shift intervention torque value corresponding to the current virtual shift progress rate from a virtual shift intervention torque profile.
In claim 1, A step in which the controller determines a virtual vehicle speed from the actual motor speed detected by the motor speed detection unit and a preset virtual final reduction gear ratio; A step in which a controller determines the virtual engine speed of the virtual current gear using the virtual vehicle speed at the time when the virtual target gear is determined and the virtual gear ratio information of the virtual current gear; A step in which a controller determines a virtual engine speed of a virtual target gear using virtual vehicle speed at the time when the virtual target gear is determined and virtual gear ratio information of the virtual target gear; and After the virtual target gear stage is determined, during the gear shifting process, the controller further includes the step of determining a virtual gear shift progress rate from the virtual engine speed of the determined virtual current gear stage, the virtual engine speed of the virtual target gear stage, and the current virtual engine speed obtained during the gear shifting process. A control method for generating a virtual shift feel of an electric vehicle, characterized in that, in the step of generating the final motor torque command, the controller determines a virtual shift intervention torque value corresponding to the current virtual shift progress rate from a virtual shift intervention torque profile.
In claim 15, A control method for generating a virtual shifting sensation in an electric vehicle, characterized in that, in the step of determining the virtual shifting progress rate, the virtual shifting progress rate is determined as a percentage (%) value of the speed difference between the current virtual engine speed and the virtual engine speed of the virtual current gear, with respect to the speed difference between the virtual engine speed of the virtual target gear and the virtual engine speed of the virtual current gear.
In claim 1, At the point where the virtual target gear ratio is determined, the controller determines a virtual vehicle speed from the actual motor speed detected by the motor speed detection unit and a preset virtual final reduction gear ratio; At the point when the virtual target gear ratio is determined, a step in which a controller determines the virtual engine speed of the virtual current gear ratio using the determined virtual vehicle speed and virtual gear ratio information of the virtual current gear ratio; At the point when the virtual target gear is determined, a step in which a controller determines the virtual engine speed of the virtual target gear using the determined virtual vehicle speed and virtual gear ratio information of the virtual target gear; and A control method for generating a virtual gear shift sensation of an electric vehicle, characterized by further including, when the virtual target gear shift is determined, a step during the gear shifting process in which the controller determines the virtual engine speed by applying a predetermined rate limit to the virtual engine speed of the determined virtual current gear shift.
In claim 1, A step in which a virtual vehicle speed is determined from the actual motor speed detected by the motor speed detection unit in the controller and a preset virtual final reduction gear ratio; A step in which a virtual engine speed is determined using the virtual vehicle speed and virtual gear ratio information of the virtual current gear stage determined in the controller; and A control method for generating a virtual gear shift sensation of an electric vehicle, characterized by further including the step of controlling the controller to display the determined virtual engine speed on the cluster.
In claim 1, A control method for generating a virtual gear shift sensation of an electric vehicle, characterized by further including the step of controlling the controller to display the virtual current gear and the determined virtual target gear on the cluster.
In claim 1, A step in which a virtual vehicle speed is determined from the actual motor speed detected by the motor speed detection unit in the controller and a preset virtual final reduction gear ratio; A step in which a virtual engine speed is determined using the virtual vehicle speed and virtual gear ratio information of the virtual current gear stage determined above in the controller; A step of comparing the determined virtual engine speed with a set threshold speed in the controller, and determining that the virtual engine speed has entered a virtual red zone if it is greater than or equal to the threshold speed; and A control method for generating a virtual shift sensation in an electric vehicle, characterized by further including the step of performing virtual fuel-cut control, wherein, upon determining entry into a virtual red zone, the controller generates a torque command to reduce the virtual engine speed with the critical speed as a target and controls the motor operation.

Description

Control method for virtual gear shift feeling generation of electric vehicle The present invention relates to a control method for an electric vehicle, and more specifically, to a control method for an electric vehicle that can generate and implement a shifting sensation similar to that of a vehicle equipped with a multi-stage transmission in an electric vehicle without a multi-stage transmission. As is well known, an electric vehicle (EV) is a vehicle that drives using a motor as the source of driving force for vehicle operation. The drivetrain of an electric vehicle includes a battery that supplies power to drive a motor, an inverter connected to the battery to drive and control the motor, a motor connected to the battery via the inverter to enable charging and discharging as a driving source for the vehicle, and a reduction gear that reduces the rotational force of the motor and transmits it to the drive wheels. Here, the inverter converts the direct current (DC) supplied from the battery into alternating current (AC) when the motor is driven and applies it to the motor through the power cable, and during motor regeneration, it converts the alternating current generated by the motor operating as a generator into direct current and supplies it to the battery, thereby charging the battery. In addition, unlike conventional internal combustion engine vehicles, standard electric vehicles do not use multi-stage transmissions; instead, a reduction gear using a fixed gear ratio is placed between the motor and the drive wheels. This is because, unlike internal combustion engines which have a wide distribution range of energy efficiency depending on the operating point and can only provide high torque in the high-speed range, motors have a relatively small difference in efficiency with respect to the operating point, and high torque at low speeds can be achieved solely through the individual characteristics of the motor. While the absence of a transmission clearly has advantages in that it provides smooth driving without interruptions caused by gear changes, for drivers seeking driving enjoyment, the lack of a transmission and shifting feel can lead to boredom. Accordingly, there is a demand for technology that enables drivers of electric vehicles equipped with reduction gears but lacking multi-stage transmissions to experience the driving sensation, fun, excitement, and directness provided by vehicles equipped with multi-stage transmissions. FIG. 1 is a block diagram showing the configuration of a device for controlling an electric vehicle according to the present invention. FIG. 2 is a block diagram showing the input and output variables and virtual shift intermediate variables of a virtual shift model for implementing a virtual shift function in the present invention. FIG. 3 is a flowchart illustrating the process for implementing a virtual shift function in the present invention. FIG. 4 is a diagram illustrating a shift schedule map for determining a virtual target gear stage in the present invention. FIG. 5 is a diagram illustrating a single transmission schedule map that can be used for both upshifting and downshifting in the present invention. Figure 6 is a diagram illustrating the maximum motor torque curve according to motor speed and the limit torque for each virtual gear stage in the present invention. Figure 7 is a diagram showing an example of a virtual shift intervention torque profile in the present invention. FIG. 8 is a diagram illustrating the shifting state and vehicle behavior state in a virtual shifting process according to the present invention. Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. When a part of a specification is described as "including" a certain component, unless specifically stated otherwise, this means that it does not exclude other components but may include additional components. The present invention aims to provide a control method for an electric vehicle that can generate and simulate a virtual multi-stage shifting sensation, similar to that of a vehicle equipped with a multi-stage transmission, through motor control while driving in an electric vehicle without a multi-stage transmission. In the following description, the motor refers to a drive motor that drives a vehicle, and the vehicle to be controlled in the present invention may be an electric vehicle equipped with a reduction gear and lacking an internal combustion engine (conventional engine) and a multi-stage transmission. As mentioned above, in the case of pure electric vehicles (motor-driven vehicles) driven by a motor, unlike conventional internal combustion engine vehicles, multi-stage transmissions are not used; instead, a reduction gear using a f