Anti-oscillation control method for electric vehicles

Abstract

The present invention discloses an anti-oscillation control method for an electric vehicle, which incorporates an anti-oscillation function and can more accurately and efficiently perform the function by utilizing the real-time weight changes of the electric vehicle. The anti-oscillation control method includes: estimating the vehicle weight by a controller based on vehicle driving information collected from the vehicle; determining, by the controller, a driver's required torque command based on the vehicle driving information collected from the vehicle; determining an anti-oscillation torque based on the vehicle weight based on a calculated speed deviation and the estimated vehicle weight information; and, in the controller, compensating the required torque command with the anti-oscillation torque, and controlling the drive motor according to the compensated motor torque command.

Description

Technical Field

[0001] The present invention generally relates to an anti-oscillation control method for an electric vehicle, and more particularly to an anti-oscillation control method that utilizes weight changes of an electric vehicle driven by a motor to more accurately and effectively perform anti-oscillation control. Background Art

[0002] As is well known, an electric vehicle (EV) is a vehicle (a motorized vehicle or a motor-driven vehicle) driven by a motor as a source of driving force (driving source) for driving the vehicle.

[0003] The powertrain of an electric vehicle includes: a battery that supplies electricity to drive the motor; an inverter that is connected to the battery to drive and control the motor; the motor, which serves as a drive source and is connected to the battery through the inverter so that the battery can be charged and discharged; and a reduction gear that decelerates the rotational force of the motor and transmits the decelerated rotational force to the drive wheels.

[0004] The function of the inverter is to convert direct current (DC) supplied from the battery during motor driving into alternating current (AC), apply the AC to the motor through the power line, and convert the AC generated by the power generation operation of the motor during motor regeneration into DC so that the DC power can be supplied to the battery to charge the battery.

[0005] Due to the system characteristics of such electric vehicles, which are susceptible to surge in low-speed areas, anti-surge technology is applied to alleviate such surge.

[0006] In electric vehicles, when the shock absorbing element is eliminated or made smaller, vibrations such as shocks and jolts (instantaneous and rapid movements) and vibrations of the drive shaft are generated during the step-in / step-out (pressing or releasing the accelerator pedal), which can reduce ride comfort and driving performance.

[0007] Furthermore, in an electric vehicle, since a damping element existing between a motor as a torque source and a power train is eliminated or is small, vibration from the torque source or vibration from the outside is not reduced.

[0008] In order to solve such a problem, an anti-oscillation control technology for suppressing vibration is known, which controls the motor torque output by using an anti-oscillation torque calculated with respect to a model speed.

[0009] According to this anti-bouncing control method, when the vehicle starts again after stopping, anti-bouncing control is performed by the controller, so that surge of the motor speed and oscillation of the powertrain that may occur in the initial stage of vehicle departure can be reduced.

[0010] In the case of a commercial electric vehicle such as an electric truck or an electric bus, which is a motorized commercial vehicle, a change in the gross vehicle weight due to passengers or loads is greater than that of a passenger electric vehicle.

[0011] Thus, when the gross weight of the vehicle is large, various behavior characteristics change. Even on the same road surface, at the same speed and under the same environmental conditions, when the gross weight of the vehicle changes, the surge characteristics transmitted to the driver will also change.

[0012] Anti-sway control for electric vehicles is primarily applied to passenger electric vehicles. Since the total weight of a passenger electric vehicle does not vary much depending on the number of passengers or load, there is no need to differentiate based on vehicle weight during anti-sway control.

[0013] Alternatively, since the total weight of the vehicle varies greatly in commercial electric vehicles, the total weight variation of the vehicle must be considered. However, conventionally, anti-oscillation functions developed based only on no-load conditions are known.

[0014] As the load on the vehicle increases, the characteristics of the vehicle may change, and thus the surge characteristics of the vehicle may also change accordingly. Since existing anti-surge functions are performed based on the condition that the vehicle is not loaded, it is difficult to effectively reduce surge in commercial electric vehicles.

[0015] Therefore, in commercial electric vehicles, there is a need for an effective anti-shock technology that performs an anti-shock function in consideration of a change in the total weight thereof. Summary of the Invention

[0016] Therefore, the present invention proposes an anti-oscillation control method for an electric vehicle, wherein the anti-oscillation function can be performed more accurately and efficiently by utilizing the real-time weight change of the electric vehicle when the electric vehicle is driven by a motor.

[0017] To achieve the above-mentioned objectives, according to an embodiment of the present invention, there is provided an anti-oscillation control method for an electric vehicle, the method comprising: estimating, by a controller, a vehicle weight based on vehicle driving information collected from the vehicle; determining, by the controller, a required torque command of a driver based on the vehicle driving information collected from the vehicle; in the controller, calculating a speed deviation between a model speed and an actual speed of a motor, and then determining an anti-oscillation torque according to the vehicle weight based on the calculated speed deviation and the estimated vehicle weight information; in the controller, compensating for the required torque command by utilizing the anti-oscillation torque, and controlling the drive motor according to the compensated motor torque command.

[0018] Therefore, according to the anti-oscillation control method of the present invention, in commercial electric vehicles, considering the weight variation of the vehicle, by performing differentiated anti-oscillation control according to the vehicle weight, surge in various situations can be more effectively alleviated.

[0019] In particular, according to the present invention, in a commercial electric vehicle such as a large bus or a large truck in which the number of passengers or the weight of loaded cargo varies greatly, the total weight of the vehicle is accurately estimated in real time, and then the estimated weight is accurately reflected to perform anti-oscillation control, thereby maximizing the surge suppression effect.

[0020] In addition, according to the present invention, surge vibration of commercial electric vehicles can be reduced, thereby reducing driver fatigue and improving cargo safety.

[0021] Furthermore, according to the present invention, a non-volatile computer-readable medium includes program instructions executed by a processor, the computer-readable medium including: program instructions for estimating a vehicle weight based on vehicle driving information collected from the vehicle; program instructions for determining a driver's required torque command based on the vehicle driving information collected from the vehicle; program instructions for determining an anti-oscillation torque according to the vehicle weight based on the calculated speed deviation and the estimated vehicle weight information after calculating a speed deviation between a model speed and an actual speed of the motor; and program instructions for compensating the required torque command with the anti-oscillation torque, and controlling the drive motor according to the compensated motor torque command. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description presented in conjunction with the accompanying drawings, in which:

[0023] Figure 1 is a block diagram showing a configuration of a system that performs anti-oscillation control processing according to the present invention; and

[0024] Figure 2A and Figure 2B is a flowchart illustrating an anti-oscillation control process according to the present invention. DETAILED DESCRIPTION

[0025] It should be understood that the term "vehicle" or "vehicular" or other similar terms used herein generally include motor vehicles, such as passenger vehicles including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft including various boats and ships, aircraft, etc., as well as hybrid vehicles, electric vehicles, plug-in hybrid vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels derived from energy sources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle having two or more power sources, such as a gasoline-powered vehicle and an electric-powered vehicle.

[0026] As used herein, the terms "one", "an" and "described" are intended to include plural forms only for the purpose of describing specific embodiments, and are not intended to limit the present invention. As used herein, the singular "one", "an" and "described" are also intended to include plural forms, unless the context clearly indicates otherwise. It will be further understood that the terms "include" and / or "comprise", when used in this specification, specify the presence of the features, numerical values, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, numerical values, steps, operations, elements, components, and / or their groups. As used herein, the terms "and / or" include any and all combinations of one or more related enumeration items. Throughout the specification, unless otherwise clearly described, the terms "include" and variations such as "comprise" or "contain" will be understood to imply the inclusion of the elements, but do not exclude any other elements. In addition, the terms "unit", "-device", "-part" and "module" described in the specification refer to units for processing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof.

[0027] Furthermore, the control logic of the present invention may be embodied as a non-volatile computer-readable medium on a computer-readable medium containing executable program instructions executed by a processor, controller, or the like. Examples of computer-readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards, and optical data storage devices. The computer-readable medium may also be distributed among networked computer systems such that the computer-readable medium is stored and executed in a distributed manner (e.g., via a telematics server or a controller area network (CAN)).

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice the embodiments. However, the present invention is not limited to the embodiments described herein, but may be implemented in other forms.

[0029] As described above, in commercial electric vehicles such as buses and trucks, the number of passengers and the weight of loaded cargo may vary significantly during vehicle travel, and thus anti-shock control technology that takes into account changes in the total weight of the vehicle is required.

[0030] For this reason, in commercial electric vehicles whose total vehicle weight varies greatly, it is necessary to accurately detect the current vehicle weight in real time and perform anti-shock control based on the current vehicle weight.

[0031] The present invention is characterized in that, after accurately estimating the total weight of a vehicle during traveling in real time, the estimated total weight of the vehicle is reflected to perform anti-shock control.

[0032] Therefore, when anti-booming control is performed according to the gross weight of the vehicle, surging can be effectively alleviated in various situations, and the surging suppression effect can be maximized.

[0033] In the following description, the vehicle weight refers to the total weight of the vehicle when a passenger is present or cargo is loaded therein, adding the weight of the passenger or the weight of the cargo to the weight of the vehicle.

[0034] Figure 1 1 is a block diagram showing a configuration of a system for performing anti-oscillation control processing according to the present invention, and an anti-oscillation control system, which shows a drive motor 41 that drives a vehicle, a reduction gear 42 that reduces the rotational force of the motor 41 and transmits the reduced rotational force, and a drive wheel 43 that is rotated by the rotational force of the motor transmitted by the reduction gear 42.

[0035] The anti-swing control process according to the present invention can be performed by cooperatively controlling multiple controllers provided in the vehicle. However, the anti-swing control process can be performed by an integrated control element. In the following description, the anti-swing control process is performed by cooperatively controlling the first controller 20 and the second controller 30.

[0036] In the following description, the control subject is divided into the first controller 20 and the second controller 30. However, it is understood that a plurality of controllers or an integrated control element is generally referred to as a controller, and the anti-oscillation control process according to the present invention is performed by the controller.

[0037] Figure 2A and Figure 2B is a flow chart showing the anti-oscillation control process according to the present invention. Figure 1 The system configuration is described in Figure 2A and 2B Describe the anti-oscillation control process.

[0038] refer to Figure 1 , an anti-shock control system according to the present invention includes: a first controller 20, which estimates the vehicle weight based on vehicle driving information collected from the vehicle during driving; and a second controller 30, which performs anti-shock control according to the vehicle weight by utilizing the vehicle weight information estimated by the first controller 20.

[0039] In the present invention, the first controller 20 may be a vehicle control unit (VCU) that determines and generates a driver's required torque command based on vehicle driving information and outputs the required torque command.

[0040] In the present invention, the first controller 20 calculates the driver's required torque command in real time based on the driver's driving input information and the vehicle state information in the vehicle driving information determined during vehicle driving, and estimates the vehicle weight in real time to send the calculated required torque command and the estimated vehicle weight to the second controller 30.

[0041] In addition, in the present invention, the second controller 30 may be a motor control unit (MCU) that operates the inverter and controls the motor 41 using a motor torque command.

[0042] In common electric vehicles, the controller that performs anti-oscillation control is the motor control unit. After the motor control unit determines the anti-oscillation torque, it uses the anti-oscillation torque to compensate for the required torque command received by the vehicle control unit, and then controls the motor using the compensated motor torque command.

[0043] However, in the present invention, the second controller 30 (eg, motor control unit) is configured to receive estimated vehicle weight information from the first controller 20 (eg, vehicle control unit) and perform anti-shock control according to the vehicle weight.

[0044] In the present invention, known weight estimation methods can be used for vehicle weight estimation. Many vehicle weight estimation methods using vehicle travel information collected from the vehicle are known, and any of the known weight estimation methods can be applied.

[0045] According to an embodiment of the present invention, in the first controller 20 , the vehicle driving information required for vehicle weight estimation may include vehicle speed, acceleration, and motor torque.

[0046] The vehicle speed and acceleration among the vehicle travel information required for vehicle weight estimation are detected by the vehicle travel information detector 10. The travel information detector 10 may include a sensor that detects the vehicle speed and acceleration.

[0047] The sensor for detecting the vehicle speed of the driving information detector 10 may be a wheel speed sensor 11 mounted on a wheel. It is known that the wheel speed and vehicle speed information can be obtained from the signal of the wheel speed sensor 11.

[0048] For example, the signals of the wheel speed sensors 11 installed on a plurality of wheels in the vehicle can be used. In this case, when the average speed is obtained by averaging the wheel rotation speeds (wheel speeds) obtained from the signals of the wheel speed sensors 11, the real-time vehicle speed information can be obtained from the average speed of the wheels.

[0049] In addition, the sensor that detects the acceleration of the travel information detector 10 may be the vertical acceleration sensor 12 mounted to the vehicle. In this case, the acceleration is real-time vertical acceleration information of the vehicle detected by the vertical acceleration sensor 12.

[0050] The vertical acceleration detected by the vertical acceleration sensor 12 is used to obtain the gradient information of the road on which the vehicle is currently traveling, and the road gradient (road inclination angle, θ) information is used to estimate the vehicle weight.

[0051] Therefore, the road gradient θ can be obtained by utilizing the vertical acceleration information detected by the vertical acceleration sensor 12. In this case, the road gradient θ can be obtained by further utilizing the vehicle acceleration. The vehicle acceleration can be obtained by differentiating the vehicle speed.

[0052] For example, the road gradient θ can be calculated by the equation “θ=1 / g×(vertical acceleration−vehicle acceleration)” where g is the acceleration due to gravity.

[0053] This method of calculating the road gradient θ is merely an example, and the present invention is not limited thereto, and any method capable of obtaining real-time gradient information on the road on which the vehicle is currently traveling may be applied.

[0054] For example, road gradient information at the current vehicle position may be obtained from a GPS signal received by a GPS receiver of the vehicle and 3D map information, and the vehicle weight may be estimated by utilizing the road gradient information obtained in this case.

[0055] In addition, the motor torque of the driving information used for vehicle weight estimation may be a motor torque command for controlling a driving motor.

[0056] The vehicle driving information required to determine the motor torque command includes the driver's driving input information and vehicle state information. Here, the driver's driving input information may include an accelerator pedal input value (APS value) and a brake pedal input value (BPS value), and the vehicle state information may include vehicle speed.

[0057] The vehicle driving information required to determine the motor torque command can be detected by the vehicle driving information detector 10. To this end, the driving information detector 10 may further include an accelerator pedal detector 14 that detects accelerator pedal input information based on the driver's operation of the accelerator pedal; and a brake pedal detector 15 that detects brake pedal input information based on the driver's operation of the brake pedal.

[0058] Here, the accelerator pedal detector 14 may be a known accelerator position sensor (APS) that is mounted to the accelerator pedal and outputs an electric signal according to a driver's operation state of the accelerator pedal.

[0059] In addition, the brake pedal detector 15 may be a known brake pedal sensor (BPS) that is mounted to the brake pedal and outputs an electric signal according to an operation state of the brake pedal by the driver.

[0060] Finally, the first controller 20 can estimate the current weight information of the vehicle based on the real-time driving information of the vehicle speed, road gradient, and motor torque command. The following equation 1 shows an example of a formula that can estimate the vehicle weight.

[0061] [Equation 1]

[0062]

[0063] Here, m refers to the vehicle weight, η RD Refers to the efficiency of the reduction gear, r tire Refers to the dynamic radius of the tire.

[0064] Furthermore, in Equation 1, Refers to the motor torque, which may be a motor torque command for controlling the drive motor 41 .

[0065] In addition, in Equation 1, f o , f1 and f2 refer to the driving load, v refers to the vehicle speed, g refers to the acceleration due to gravity, and θ refers to the road slope.

[0066] Although the method and equation for estimating vehicle weight are described, the present invention is not limited to the weight estimation method and the above equation. Any known method or equation for accurately estimating vehicle weight can be applied to the present invention.

[0067] For example, the first controller 20 receives the value of acceleration and can calculate the vehicle weight by using the value of vehicle driving force F and acceleration a. In "F=m×a", m corresponding to the vehicle weight can be calculated by using "F / a".

[0068] In addition, as another example of estimating vehicle weight, a patent application named “Vehicle Weight Estimation Method by Acceleration Sensor” was proposed by the applicant of the present application (Korean Patent Application No. 10-2019-0158424 filed on October 8, 2019), and the vehicle weight estimation method can be applied to the present invention.

[0069] In addition, in the present invention, weight estimation prohibition conditions may be set in the first controller 20, and the weight estimation prohibition conditions may include a condition that the road gradient is at least a set value and a condition that the steering angle is at least a set angle.

[0070] That is, when the road gradient is at least a set value and the steering angle is at least a set angle, it is determined that the weight estimation prohibition condition is satisfied, and thus the first controller 20 does not perform vehicle weight estimation. Accordingly, anti-bouncing control considering the estimated vehicle weight is not performed.

[0071] In this case, existing motor control or anti-oscillation control may be performed without using the estimated vehicle weight.

[0072] Alternatively, when the weight estimation prohibition condition is not satisfied, vehicle weight estimation is performed, and then anti-bouncing control taking into account the estimated vehicle weight is performed.

[0073] As described above, in order to determine whether the weight estimation prohibition condition is satisfied, the driving information detector 10 may further include the steering angle sensor 16 that detects the steering angle according to the driver's operation state of the steering wheel.

[0074] At the same time, as described above, the first controller 20 calculates the driver's required torque command in real time based on the driver's driving input information and the vehicle state information during vehicle driving. The driver's driving input information may include an accelerator pedal input value (APS value) and a brake pedal input value (BPS value), and the vehicle state information may include vehicle speed.

[0075] In the first controller 20 , a required torque command may be determined based on the driver's APS value and BPS value reflecting the driver's demand and current vehicle speed information.

[0076] As provided in this article, the process or method of calculating the required torque command is no different from the process and method of calculating the required torque command by the vehicle control unit in a conventional electric vehicle by utilizing the vehicle's driving information collected in real time, and is a known technology, so its detailed description will be omitted.

[0077] Finally, as described above, the current vehicle weight estimated by the first controller 20 and the required torque command calculated therefrom are sent to the second controller 30 in real time.

[0078] refer to Figure 2A and Figure 2B, it can be seen that the following process is performed: in step S11, the driving information collected from the vehicle is input into the first controller 20 and the second controller 30; in step S12, it is determined in the first controller 20 whether the weight estimation prohibition condition is satisfied; when the weight estimation prohibition condition is not satisfied, in step S13, the vehicle weight is estimated in the first controller 20; and in step S14, the estimated vehicle weight and the required torque command are output from the first controller 20.

[0079] Before executing anti-oscillation control, in step S12', the second controller 30 determines whether anti-oscillation control can be executed based on vehicle driving information, that is, whether the anti-oscillation enable state is satisfied. In this case, the vehicle driving information may include gear information (P, R, N, and D gear information) and transaction control system (TCS) operation information.

[0080] Here, the gear position information may be input from a shift controller (not shown) or a shift lever detector (not shown).

[0081] Despite Figure 1 The shift lever detector is not shown in FIG. 3 , however, when the second controller 30 is configured to receive the gear position information (shift lever position information) directly from the shift lever detector, Figure 1 The driving information detector 10 further includes a shift lever detector.

[0082] The shift lever detector detects shift lever position information (P, R, N, and D range information) according to the driver's operation state of the shift lever.

[0083] In the present invention, when the gear position is the P gear as the parking gear position or the N gear as the neutral gear, the second controller 30 determines that the anti-oscillation enable state is not satisfied and does not perform the anti-oscillation control.

[0084] Additionally, during TCS operation, it is determined that the anti-oscillation enable state is not satisfied, and anti-oscillation control is not performed.

[0085] Alternatively, when the gear is not P or N, that is, when the current gear is D as a driving gear or R as a reverse gear and TCS is not working, it is determined that the anti-shock enabling state is satisfied.

[0086] As described above, when it is determined that the anti-oscillation enabling state is satisfied, the second controller 30 determines the anti-oscillation mode by using the current driving information of the vehicle in step S13 ′.

[0087] In the present invention, in order to effectively control anti-oscillation, anti-oscillation modes can be classified according to driving conditions. The anti-oscillation modes are classified to distinguish anti-oscillation torque according to the driving conditions of the vehicle, and can be modes corresponding to braking, acceleration, constant speed, or anti-oscillation prohibition conditions.

[0088] For example, in the present invention, the anti-oscillation mode may include at least two modes of the anti-oscillation off mode ("AJ 0" mode), the braking mode ("AJ 1" mode), the fuel supply mode ("AJ 2" mode) and the fuel reduction mode ("AJ 3" mode).

[0089] The anti-oscillation off mode is a mode in which the anti-oscillation control is turned off, and the braking mode is an anti-oscillation mode when braking is performed due to the driver stepping on the brake pedal.

[0090] The situation where anti-oscillation control is turned off can be determined as: the situation where the predetermined anti-oscillation prohibition condition is met, or the situation where the current gear is P gear as the parking gear, or N gear as the neutral gear, even if it does not correspond to the anti-oscillation prohibition condition.

[0091] In addition, the throttle mode is an anti-oscillation mode (torque increases) when the driver steps on the accelerator pedal, while the throttle mode is an anti-oscillation mode (torque decreases) when the driver releases the accelerator pedal.

[0092] In the above description, the anti-sway mode has been described as including a total of four modes, but this is merely an example and the present invention is not limited thereto. Various changes may be made to the anti-sway mode in terms of the type or number of anti-sway modes, the definition of each anti-sway mode, and the driving conditions determined for each mode.

[0093] For example, in the present invention, the anti-oscillation mode may include a creep mode in which the motor torque changes within a predetermined range for a set time, replacing the anti-oscillation off mode. In this case, the anti-oscillation mode may include at least two modes of a braking mode, a fuel supply mode, a fuel withdrawal mode, and a creep mode.

[0094] Next, in steps S14' to S19, when the anti-oscillation mode is determined, the second controller 30 determines an anti-oscillation torque value considering the current vehicle weight by using the estimated vehicle weight received from the first controller 20, and then, in step S20, determines a final motor torque command by using the anti-oscillation torque to compensate for the required torque command received from the first controller 20.

[0095] When the final motor torque command is determined as described above, the second controller 30 operates the inverter and controls the motor 41 according to the motor torque command in step S21 .

[0096] refer to Figure 2A and 2B In order to determine the anti-shock torque value considering the vehicle weight, in the second controller 30, in step S14', the model speed of the motor is calculated, and the speed deviation between the model speed and the actual speed of the motor is calculated. In step S15, the motor vibration value is obtained by the deviation between the model speed and the actual speed of the motor.

[0097] In addition, as described below, in the second controller 30, in step S16, the current loading stage is determined by the estimated vehicle weight, a dead zone corresponding to the determined anti-oscillation mode and loading stage is determined, and in step S17, it is checked whether the speed deviation is included in the dead zone.

[0098] Next, when the speed deviation is not included in the dead zone, in the second controller 30, in step S18, the torque factor value corresponding to the anti-oscillation mode and the loading stage is determined, and then in step S19, the anti-oscillation torque value is determined by using the motor vibration value and the torque factor value.

[0099] The process of determining the anti-oscillation torque will be described in more detail below.

[0100] Anti-oscillation torque is torque that prevents vibration (shock and oscillation) of the powertrain that may occur during acceleration and deceleration of the vehicle. The anti-oscillation torque of a motor-driven vehicle (electric vehicle) can be calculated by utilizing real-time driving information of the vehicle. Here, the driving information may include information about the wheel speed and motor speed detected by sensors 11 and 12, respectively.

[0101] In addition to the motor speed and wheel speed, the vehicle's acceleration value is also available. The acceleration, along with the wheel speed, can be used to calculate the model speed of the motor.

[0102] The motor speed is the rotation speed of the motor detected by the motor speed sensor 13. In the anti-oscillation control, the motor speed detected by the motor speed sensor 13 is the actual speed of the motor.

[0103] Motor speed sensor 13 may be a typical resolver mounted to motor 41 (drive motor) of the electric vehicle.

[0104] The wheel speed is the rotation speed of the wheel detected by the wheel speed sensor 11. The wheel speed is used to calculate the model speed of the motor, so that in the second controller 30, the anti-oscillation torque can be calculated based on the actual speed of the motor and the model speed.

[0105] In the present invention, as described below, the anti-oscillation torque according to the vehicle weight is obtained by further utilizing the estimated vehicle weight obtained from the first controller 20 .

[0106] In an electric vehicle (motor-driven vehicle) in which anti-oscillation control is performed, the motor torque command for motor control can be determined as the sum of the required torque command according to the driver's request and the anti-oscillation torque for reducing vibration as shown in the following equation 2: Figure 2B This can even be applied to the present invention in the same manner.

[0107] [Equation 2]

[0108] Motor torque command = required torque command + anti-oscillation torque.

[0109] When calculating the anti-oscillation torque, the model speed refers to the motor speed ignoring vibration, and may be an equivalent wheel speed obtained by converting the wheel speed detected by the wheel speed sensor 11 into the speed of the motor 41 using the gear ratio between the motor and the wheel.

[0110] The model speed can be referred to as the reference speed value required for anti-oscillation control of the motor. Anti-oscillation control is control to offset speed fluctuations of the motor. For this anti-oscillation control, a reference speed is required to determine the magnitude of the motor speed fluctuation.

[0111] Such a model speed may be a speed calculated by back-calculating from the wheel speed to a value associated with the motor using the wheel speed.

[0112] When calculating the model speed, in addition to the wheel speed, the vehicle acceleration value can also be used to improve the anti-oscillation control performance. Therefore, the anti-oscillation control can be performed in advance by predicting the change of the model speed calculated using the acceleration value.

[0113] Since this calculation process of the model velocity is also a known technique through known anti-oscillation control, its detailed description will be omitted in this specification.

[0114] Methods for calculating the model speed include a calculation method based on the wheel speed and a calculation method of wheel speed estimation as a method of more actively utilizing anti-oscillation. During the wheel speed estimation, acceleration values are utilized.

[0115] Furthermore, as described above, in the present invention, the anti-oscillation torque may be determined in the second controller 30 by the actual speed and the model speed of the motor 41 and a value corresponding to the estimated vehicle weight (ie, the vehicle weight estimated in the first controller).

[0116] More specifically, when the current motor speed (i.e., the current actual speed of the motor) is detected by the motor speed sensor 13 and the current model speed of the motor based on the wheel speed detected by the wheel speed sensor 11 is obtained, the anti-oscillation torque can be calculated based on the model speed and actual speed of the motor and the estimated vehicle weight of the first controller.

[0117] In the present invention, the anti-oscillation torque can be determined as a value corresponding to the deviation between the model speed and the actual speed of the motor. The motor vibration value can be obtained by using the deviation between the model speed and the actual speed of the motor, and the anti-oscillation torque value can be determined based on the motor vibration value.

[0118] In this case, the anti-oscillation torque value can be calculated by multiplying the motor vibration value by the torque factor value. Here, the torque factor value is determined based on the current vehicle weight (estimated vehicle weight).

[0119] In the present invention, the process and method of obtaining the motor vibration value by utilizing the deviation between the model speed and the actual speed of the motor is no different from the known process and method of obtaining the motor vibration value, and the motor vibration value can be determined by the known calculation process and method.

[0120] Furthermore, in the present invention, in order to effectively control anti-oscillation, the anti-oscillation mode can be divided into several modes according to the driving condition. The anti-oscillation mode is classified to differentiate the anti-oscillation torque according to the driving condition of the vehicle, and can be a mode corresponding to braking, acceleration, constant speed, or anti-oscillation prohibition conditions.

[0121] For a specific example, in the present invention, the anti-oscillation mode may include an anti-oscillation off mode ("AJ 0" mode), a braking mode ("AJ 1" mode), an oil feed mode ("AJ 2" mode), and an oil reduction mode ("AJ 3" mode).

[0122] The anti-oscillation off mode is an anti-oscillation mode in which the anti-oscillation control is turned off, and the braking mode is an anti-oscillation mode when braking is performed due to the driver stepping on the brake pedal.

[0123] In addition, the throttle mode is an anti-oscillation mode (torque increases) when the driver steps on the accelerator pedal, while the throttle mode is an anti-oscillation mode (torque decreases) when the driver releases the accelerator pedal.

[0124] In the above description, the anti-sway mode has been described as including a total of four modes, but this is merely an example, and it should be noted that the present invention is not limited thereto. Various changes can be made to the anti-sway mode in terms of the type or number of anti-sway modes, the definition of each anti-sway mode, and the driving conditions determined for each mode.

[0125] In addition, in the present invention, an anti-oscillation dead zone can be set, and the anti-oscillation dead zone is a speed range in which anti-oscillation control is not used based on the speed deviation between the model speed and the actual speed of the motor. The anti-oscillation dead zone can be set based on the speed deviation of each anti-oscillation mode.

[0126] In this case, the minimum speed and maximum speed of the speed deviation range corresponding to the dead zone of each anti-oscillation mode are predetermined, and the speed interval between the minimum speed and the maximum speed set for each anti-oscillation mode is the dead zone of anti-oscillation shutdown of each mode.

[0127] In the present invention, the dead zone is an anti-oscillation shut-off interval set to prevent anti-oscillation failure caused by disturbances at extremely low speeds of the motor.

[0128] In addition, anti-oscillation control is fundamentally applied in motor-driven vehicles to solve problems such as vibration of the powertrain caused by fluctuations in motor speed. When the motor speed fluctuates, anti-oscillation torque needs to be applied to the vehicle to prevent such problems.

[0129] However, under normal driving conditions, motor speed fluctuations rarely occur or disappear due to changes in vehicle weight. Typical situations affected by vehicle weight changes include starting from a standstill and operating at low speeds.

[0130] In the case where the vehicle is heavy, when the driver inputs an intention to start the vehicle and transmits the intention to the vehicle, that is, when there is a driving input for starting the vehicle, the motor speed increases, but the vehicle is heavy and may not move.

[0131] This phenomenon occurs over a longer period of time before the wheels actually move compared to when the vehicle is lighter. In this case, the motor speed fluctuates.

[0132] Furthermore, when the vehicle is heavier, the torque factor applied to the anti-oscillation torque is increased, thereby suppressing motor speed fluctuations. This is also true when the road is busy, especially when the vehicle is starting from an uphill road and traveling at a low speed, or when the vehicle is moving backward on a downhill road.

[0133] Therefore, when calculating the anti-oscillation torque, it is necessary to use a torque factor value that takes into account the vehicle weight. Therefore, in the present invention, a torque factor value corresponding to the current vehicle weight is determined and used to calculate the anti-oscillation torque.

[0134] To this end, in the present invention, the second controller 30 is configured to determine the anti-shock mode corresponding to the current driving condition through the vehicle's driving information, and to determine the current loading stage of the vehicle by utilizing the current vehicle weight value estimated by the first controller 20 (i.e., the estimated vehicle weight of the first controller).

[0135] In addition, the second controller 30 determines whether a speed deviation between the model speed and the actual speed of the motor 41 corresponds to the current loading stage and the anti-oscillation dead band set in the anti-oscillation mode.

[0136] When the second controller 30 determines that the speed deviation corresponds to the anti-oscillation dead band, the second controller 30 does not perform the anti-oscillation control by keeping the anti-oscillation control in an inactive state.

[0137] Alternatively, when the second controller 30 determines that the speed deviation does not correspond to the anti-oscillation dead zone, the second controller 30 performs anti-oscillation control. In this case, a torque factor value corresponding to the current loading stage and the anti-oscillation mode is determined, and the anti-oscillation torque is calculated by multiplying the motor vibration value corresponding to the speed deviation between the model speed and the actual speed of the motor by the torque factor value.

[0138] In the present invention, the vehicle weight range is divided into a plurality of sections so that the current loading stage of the vehicle can be determined by the second controller 30 based on the vehicle weight estimated by the first controller 20, and then the loading stage of the vehicle is predetermined for each divided section. Information on the weight section of each loading stage is input to the second controller 30 and set therein.

[0139] Multiple loading stages with different vehicle weight ranges are set in the second controller 30. For example, the entire vehicle weight range can be changed when passengers are boarded or cargo is loaded. The entire weight range including the vehicle's unloaded state can be divided into four stages: an unloaded stage, a first loaded stage, a second loaded stage, and a third loaded stage.

[0140] In this case, in the vehicle weight, except for the empty state, the third loading stage may be set as the maximum weight portion, the second loading stage may be set as the second maximum weight portion, and the first loading stage may be set as the minimum weight portion.

[0141] The weight portion corresponding to each loading stage may vary according to the characteristics of the application vehicle, and each loading stage is not determined to be a specific weight portion.

[0142] In addition, a loading stage corresponding to the current weight value is determined by the second controller 30 based on the vehicle weight value estimated by the first controller 20. In this case, in order to prevent frequent changes in the loading stage, it is preferable to set a boundary value dividing each loading stage so that the boundary values of the entrance and exit of each loading stage are different with a hysteresis.

[0143] Table 1 below shows a mapping diagram of the torque factor value set for each anti-oscillation mode when the vehicle is in an unloaded state during the loading phase. Tables 2 and 3 show mapping diagrams of setting the minimum dead zone speed for each anti-oscillation mode and the maximum dead zone speed for each anti-oscillation mode, respectively, when the vehicle is in an unloaded state during the loading phase.

[0144] [Table 1]

[0145] Anti-Jerking (AJ) Mode 0 1 2 3 · Torque factor 0 0.3 0.2 · ·

[0146] [Table 2]

[0147] Anti-Jerking (AJ) Mode 0 1 2 3 · Speed deviation (rpm) 0 -7 -5 · ·

[0148] [Table 3]

[0149] Anti-Jerking (AJ) Mode 0 1 2 3 · Speed deviation (rpm) 0 7 5 · ·

[0150] According to the examples in Tables 2 and 3, when the vehicle is unloaded and the anti-oscillation mode is the braking mode ("AJ 1"), when the speed deviation (rpm), which is the difference between the model speed and the actual speed of the motor, is between the minimum speed of -7 and the maximum speed of 7 (the dead band is -7 to 7 rpm), the anti-oscillation control is not performed and is turned off.

[0151] In addition, according to the examples in Tables 2 and 3, when the vehicle is unloaded and the anti-shudder mode is the fueling mode ("AJ 2"), when the speed deviation (rpm) is between the minimum speed of -5 and the maximum speed of 5 (the dead band is -5 to 5 rpm), the anti-shudder control is not executed and is turned off.

[0152] Furthermore, according to the example in Table 1, when the vehicle is unloaded, the torque factor value is determined to be 0.3 in the braking mode, and the torque factor value is determined to be 0.2 in the accelerator mode.

[0153] Next, Table 4 below shows a mapping diagram for setting the torque factor value for each anti-oscillation mode when the loading stage of the vehicle is the first loading stage, and Tables 5 and 6 show mapping diagrams for setting the minimum dead zone speed for each anti-oscillation mode and the maximum dead zone speed for each anti-oscillation mode, respectively, in the case of the first loading stage.

[0154] [Table 4]

[0155] Anti-Jerking (AJ) Mode 0 1 2 3 · Torque factor 0 0.3 0.3 · ·

[0156] [Table 5]

[0157] Anti-Jerking (AJ) Mode 0 1 2 3 · Speed deviation (rpm) 0 -5 -5 · ·

[0158] [Table 6]

[0159] Anti-Jerking (AJ) Mode 0 1 2 3 · Speed deviation (rpm) 0 7 5 · ·

[0160] In the present invention, the torque factor value and the dead zone are determined by a map, namely, a map that sets the torque factor value according to the loading phase and the anti-oscillation mode, and a map that sets the minimum speed and maximum speed of the dead zone for each anti-oscillation mode. The map is pre-input into the second controller 30 and stored in the second controller 30 for use.

[0161] According to the examples in Tables 5 and 6, when the estimated vehicle weight corresponds to the first loading stage and the anti-shudder mode is the braking mode ("AJ 1"), when the speed deviation (rpm) is between the minimum speed of -5 and the maximum speed of 7 (the dead band is -5 to 7 rpm), the anti-shudder control is not executed and is turned off.

[0162] In addition, according to the examples in Tables 5 and 6, when the estimated vehicle weight corresponds to the first loading stage and the anti-shudder mode is the fueling mode ("AJ 2"), when the speed deviation (rpm) is between the minimum speed of -5 and the maximum speed of 5 (the dead band is -5 to 5 rpm), the anti-shudder control is not executed and is turned off.

[0163] Furthermore, according to the example of Table 4, in the first loading stage, the torque factor value is determined to be 0.3 in the case of the braking mode, and the torque factor value is determined to be 0.3 even in the case of the throttle mode.

[0164] Next, Table 7 below shows a mapping diagram for setting the torque factor value for each anti-oscillation mode when the loading stage of the vehicle is the second loading stage, and Tables 8 and 9 show mapping diagrams for setting the minimum dead zone speed for each anti-oscillation mode and the maximum dead zone speed for each anti-oscillation mode in the case of the second loading stage.

[0165] [Table 7]

[0166] Anti-Jerking (AJ) Mode 0 1 2 3 · Torque factor 0 0.4 0.3 · ·

[0167] [Table 8]

[0168] Anti-Jerking (AJ) Mode 0 1 2 3 · Speed deviation (rpm) 0 -3 -3 · ·

[0169] [Table 9]

[0170] Anti-Jerking (AJ) Mode 0 1 2 3 · Speed deviation (rpm) 0 7 5 · ·

[0171] In addition, according to the examples in Tables 8 and 9, when the estimated vehicle weight corresponds to the second loading stage and the anti-oscillation mode is the braking mode ("AJ 1"), when the speed deviation (rpm) is between the minimum speed of -3 and the maximum speed of 7 (the dead band is -3 to 7 rpm), the anti-oscillation control is not executed and is turned off.

[0172] In addition, according to the examples in Tables 8 and 9, when the estimated vehicle weight corresponds to the second loading stage and the anti-shudder mode is the fueling mode ("AJ 2"), when the speed deviation (rpm) is between the minimum speed of -3 and the maximum speed of 5 (the dead band is -3 to 5 rpm), the anti-shudder control is not executed and is turned off.

[0173] Furthermore, according to the example of Table 7, in the second loading phase, the torque factor value is determined to be 0.4 in the case of the braking mode, and the torque factor value is determined to be 0.3 in the case of the accelerator mode.

[0174] Next, Table 10 below shows a mapping diagram for setting the torque factor value for each anti-oscillation mode when the loading stage of the vehicle is the third loading stage, and Tables 11 and 12 show mapping diagrams for setting the minimum dead zone speed for each anti-oscillation mode and the maximum dead zone speed for each anti-oscillation mode in the case of the third loading stage.

[0175] [Table 10]

[0176] Anti-Jerking (AJ) Mode 0 1 2 3 · Torque factor 0 0.5 0.4 · ·

[0177] [Table 11]

[0178] Anti-Jerking (AJ) Mode 0 1 2 3 · Speed deviation (rpm) 0 -2 -2 · ·

[0179] [Table 12]

[0180] Anti-Jerking (AJ) Mode 0 1 2 3 · Speed deviation (rpm) 0 7 5 · ·

[0181] According to the examples in Tables 11 and 12, when the estimated vehicle weight corresponds to the third loading stage and the anti-oscillation mode is the braking mode ("AJ 1"), when the speed deviation (rpm) is between the minimum speed of -2 and the maximum speed of 7 (the dead band is -2 to 7 rpm), the anti-oscillation control is not executed and is turned off.

[0182] In addition, according to the examples in Tables 11 and 12, when the estimated vehicle weight corresponds to the third loading stage and the anti-shudder mode is the fueling mode ("AJ 2"), when the speed deviation (rpm) is between the minimum speed of -2 and the maximum speed of 5 (the dead band is -2 to 5 rpm), the anti-shudder control is not executed and is turned off.

[0183] Furthermore, according to the example of Table 10, in the third loading stage, the torque factor value is determined to be 0.5 in the case of the braking mode, and the torque factor value is determined to be 0.4 in the case of the fuel delivery mode.

[0184] In Tables 1 to 12, "·" does not represent 0 (zero) but represents an arbitrary number.

[0185] As can be seen from Tables 1 to 12, in the present invention, the torque factor value for determining the anti-oscillation torque for each loading stage and the speed deviation range of the dead zone in which the anti-oscillation control is turned off are preset. In addition, the torque factor value and the speed deviation range of the dead zone for each anti-oscillation mode are preset.

[0186] The values in Tables 1 to 12 are exemplary, and the present invention is not limited thereto. The anti-oscillation mode, the torque factor of each loading stage, the speed deviation range of the dead zone, and the minimum and maximum speeds of the dead zone may be appropriately changed and adjusted according to vehicle characteristics.

[0187] When anti-oscillation torque is excessively applied when the vehicle is relatively light, unnecessary vibrations are applied to the powertrain. Therefore, when the vehicle weight corresponds to a lower loading stage, the torque factor value can be set lower, and the speed deviation range corresponding to the deadband can be set wider.

[0188] In addition, when the vehicle weight corresponds to a higher loading stage, the torque factor value may be set to a higher value, and the speed deviation range corresponding to the dead band may be set to a narrower range.

[0189] Each value in Tables 1 to 12 may vary depending on vehicle characteristics and therefore needs to be set based on data obtained through preliminary testing and evaluation of the relevant vehicle.

[0190] For example, the speed deviation range of the dead zone may be set to be wider or narrower according to the characteristics of the anti-oscillation mode.

[0191] Furthermore, as described above, the reason for differentiating the dead zone according to vehicle weight (loaded phase) is that, in heavy vehicle conditions, active anti-bouncing control may sometimes be necessary. When active anti-bouncing control is executed, the absolute values of the minimum and maximum speeds in the dead zone are set to be smaller, and the speed deviation range of the dead zone in which anti-bouncing control is not executed or turned off is reduced.

[0192] Although exemplary embodiments of the present invention have been described in detail, the scope of the claims of the present invention is not limited thereto and those skilled in the art will appreciate that various modifications, additions and substitutions are possible without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. An anti-oscillation control method for an electric vehicle, the method comprising: estimating, by a controller, a vehicle weight based on vehicle travel information collected from the vehicle; determining, by a controller, a driver's desired torque command based on vehicle driving information collected from the vehicle; After calculating a speed deviation between a model speed and an actual speed of the motor, the controller determines an anti-oscillation torque according to the vehicle weight based on the calculated speed deviation and estimated vehicle weight information; The required torque command is compensated by utilizing the anti-oscillation torque, and the controller controls the drive motor according to the compensated motor torque command; wherein a weight estimation prohibition condition is set in the controller, the weight estimation prohibition condition including a condition that the slope of the road on which the vehicle is traveling is at least a set value and a condition that the steering angle is at least a set angle; Estimating the vehicle weight, determining the required torque command, determining the anti-shudder torque, and controlling the drive motor are performed only when the weight estimation prohibition condition is not satisfied.

2. The method according to claim 1, further comprising: The controller determines an anti-oscillation mode corresponding to the current driving condition from a plurality of anti-oscillation modes preset in the driving information collected from the vehicle. Among them, when determining the anti-shock torque according to the vehicle weight, The motor vibration value is obtained by calculating the speed deviation. The torque factor value is determined by the estimated vehicle weight and the determined anti-oscillation mode, The anti-oscillation torque is determined by the obtained motor vibration value and the determined torque factor value.

3. The method according to claim 2, wherein: In the controller, when a plurality of loading stages having different vehicle weight ranges are set and a loading stage corresponding to the estimated vehicle weight is determined, a torque factor value corresponding to the determined anti-oscillation mode and loading stage is determined.

4. The method according to claim 3, wherein: The torque factor value is determined by the controller via a map in which the torque factor value is set according to the anti-oscillation mode and the loading phase.

5. The method according to claim 3, wherein In the controller, the anti-oscillation mode and dead zone are pre-set. The dead zone is the speed deviation range for shutting down the anti-oscillation control for each loading stage. When a speed deviation calculated from a model speed and an actual speed of the motor is included in a speed deviation range of a dead zone corresponding to the current anti-oscillation mode and the loading stage, an anti-oscillation torque according to the vehicle weight is determined, and control of the drive motor according to the compensated motor torque command is not performed.

6. The method according to claim 5, wherein: The controller determines a speed deviation range using a dead zone corresponding to the current anti-oscillation mode and loading stage by using a map setting the anti-oscillation mode and the minimum speed and maximum speed of the speed deviation range for each loading stage.

7. The method according to claim 5, wherein: When the set vehicle weights of the plurality of loading stages correspond to a higher loading stage, the speed deviation range of the dead band is set to a narrower range.

8. The method according to claim 5, wherein When the set vehicle weights of the plurality of loading stages correspond to a higher loading stage, the torque factor value is set to a higher value.

9. The method according to claim 2, wherein: The multiple anti-oscillation modes include at least two of the following modes: a braking mode when the driver steps on the brake pedal, a throttle-in mode when the driver steps on the accelerator pedal, a throttle-out mode when the driver releases the accelerator pedal, and a creep mode in which the motor torque changes within a predetermined range for a set time.

10. The method according to claim 1, wherein In the controller, a plurality of loading stages having different vehicle weight ranges are set; When determining the anti-oscillation torque according to the vehicle weight, the motor vibration value is obtained by utilizing the calculated speed deviation; When a loading phase corresponding to the estimated vehicle weight is determined, determining a torque factor value corresponding to the determined loading phase; The anti-oscillation torque is determined by utilizing the obtained motor vibration value and the determined torque factor value.

11. The method according to claim 10, wherein: In the controller, a dead zone is pre-set, which is the speed deviation range for turning off the anti-oscillation control for each loading stage. When a speed deviation calculated by using the model speed and the actual speed of the motor is included in a speed deviation range of a dead band corresponding to the current loading stage, the anti-oscillation control is not activated in the controller.

12. The method according to claim 11, wherein When the set vehicle weights of the plurality of loading stages correspond to a higher loading stage, the speed deviation range of the dead band is set to a narrower range.

13. The method according to claim 11, wherein When the set vehicle weights of the plurality of loading stages correspond to a higher loading stage, the torque factor value is set to a higher value.

14. A non-transitory computer-readable medium containing program instructions for execution by a processor, the computer-readable medium comprising: program instructions for estimating a vehicle weight based on vehicle travel information collected from the vehicle; program instructions for determining a driver's desired torque command based on vehicle travel information collected from the vehicle; After calculating a speed deviation between a model speed and an actual speed of the motor, determining a program instruction for an anti-oscillation torque according to the vehicle weight based on the calculated speed deviation and estimated vehicle weight information; By using the anti-oscillation torque to compensate for the required torque command, the program command of the drive motor is controlled according to the compensated motor torque command; wherein a weight estimation prohibition condition is set, wherein the weight estimation prohibition condition includes a condition that the slope of the road on which the vehicle is traveling is at least a set value and a condition that the steering angle is at least a set angle; Estimating the vehicle weight, determining the required torque command, determining the anti-shudder torque, and controlling the drive motor are performed only when the weight estimation prohibition condition is not satisfied.

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