Torque Distribution of Electric Vehicle with Four In-Wheel Motors Based on Road Adhesion Margin

With the worsening of energy crisis and environmental pollution,electric vehicles with four in?wheel motors have been paid more and more attention. The main research subject is how to reasonably distribute the driving torque of each wheel. Considering the longitudinal motion,lateral motion,yaw movement and rotation of the four wheels,the tire model and the seven DOF dynamic model of the vehicle are established in this paper. Then,the torque distribution method is proposed based on road adhesion margin,which can be divided into anti ? slip control layer and torque distribution layer. The anti?slip control layer is built based on sliding mode variable structure control,whose main function is to avoid the excessive slip of wheels caused by road conditions. The torque distribution layer is responsible for selecting the torque distribution method based on road adhesion margin. The simulation results show that the proposed torque distribution method can ensure the vehicle quickly adapt to current road adhesion conditions,and improve the handling stability and dynamic performance of the vehicle in the driving process.

Torque Distribution Strategy for Integrated Starter/ Generator Hybrid Bus Implemented by Fuzzy Algorithm

A torque distribution strategy was designed by using fuzzy logic to realize the optimal control. The vehicle load zones were dynamically divided into several zones by several torque lines to indicate the drivers demand and the high or low efficient operating areas of the diesel engine. The fuzzy logic controller with trapezoid membership function and Mamdani rule reference mechanism was utilized. There are over 100 rules used in this fuzzy-based torque distribution strategy which are sorted into four rule-bases. The fuel economy and acceleration tests were designed to test and validate the integrated starter/generator (ISG) bus perfor-mance using fuzzy-based torque distribution strategy. The fuel economy is improved 7.7% compared with the rule-based strategy. Finally the road test results reveal that there is about 15% improvement of fuel economy. And the 0-50 km/h acceleration time is 9.5% shorter than the original bus.

Mode switching torque distribution strategy of timely four-wheel driven high-gap plant protection machine

The high-gap plant protection machine is taken in this paper as the research object to ensure the good driving power and safety of the high-gap plant protection machine,and the control strategy of inter-shaft torque distribution is established under different working conditions to improve vehicle power and lateral stability.The anticipated demand torque is initially determined based on the structural characteristics and operational principles of the plant protection machine.Subsequently,a hierarchical control framework is devised by incorporating a formulated switching control strategy.Finally,a simulation model for torque distribution control strategy between shafts is developed on the Matlab/Simulink platform,followed by simulation and experimental verification.The results are presented as follows:the inter-shaft torque distribution strategy established in this paper increases the average longitudinal acceleration by 0.13 m/s^(2) and 0.14 m/s^(2) under the control of low and high to low adhesion road surfaces,respectively.Under the control of the single-line shifting condition,the yaw velocity can successfully follow the expected value with a maximum value of 0.61 rad/s.The side deflection angle of the center of mass does not exceed 2.8°,which can follow the ideal trajectory and improve power and safety.

Lateral stability region conservativeness estimation and torque distribution for FWIA electric vehicle steering

Estimation of the lateral stability region and torque distribution on steering is very important to improve stability in lateral handling for all wheel drive electric vehicles.Based on the built-nonlinear vehicle dynamic model,the lateral stability region of the vehicle related to steering is estimated using Lyapunov function.We obtained stable equilibrium points of non-straight driving according to the estimated lateral stability region and also reconstructed the Lyapunov function matrix,which proved that the closed-loop system composed of yaw rate and lateral velocity is satisfied with negative definite property.In addition,the designed controller dynamically allocates the drive torque in terms of the vertical load and slip rate of the four wheels.The simulation results show that the estimated lateral stability region and the designed controller are satisfactory in handling stability performance against different roads and vehicle parameters.

Torque Distribution Strategy of Electric Vehicle with In-wheel Motors Based on the Identification of Driving Intention

A driver’s intention is recognized accurately by employing fuzzy identification and a logic threshold including acceleration intention and steering intention.Different torque distribution control strategies are developed for different intentions and the driver’s torque demand is amended by fuzzy identification so that the response of the vehicle is more consistent with the driver’s intention of operation.Finally,a simulation model is built using MATLAB/Simulink to validate the control strategy.Simulation results show that the system accurately identifies the driver’s intention and improves the acceleration performance and steering stability of the vehicle.

Reducing Operation Emissions and Improving Work Efficiency Using a Pure Electric Wheel Drive Tractor

In response to the problems of excessive greenhouse-gas and particulate emissions and the low traction efficiency of conventional diesel tractors in the field,a purely electric wheel-side drive tractor was studied,including an electric motor drive system,a battery ballast system,and an electro–hydraulic suspension system.This paper develops a dynamics model of an electric tractor-ploughing unit under complex soil conditions,leading to the proposal of an active control method for drive wheel torque and a joint control method for the traction force of the suspension system and the front-and rear-axle loads of a tractor.Finally,the tractor is prototyped and assembled,and ploughing tests are carried out.The ploughing results show that the active torque-distribution control method proposed in this study reduces the tractor slip by 14.83%and increases the traction efficiency by 10.28%compared with the average torquedistribution mode.Compared with the conventional traction control mode,the joint control method for traction and ballast proposed in this paper results in a 3.7%increase in traction efficiency,a 15.05%decrease in slip,and a 4.9%reduction in total drive motor energy consumption.This study will help to improve the operation quality and traction efficiency of electric tractors in complex soil conditions.

Effect of the Reaction Field on Molecular Forces and Torques Revealed by an Image-Charge Solvation Model

We recently developed the Image-Charge Solvation Model(ICSM),which is an explicit/implicit hybrid model to accurately account for long-range electrostatic forces in molecular dynamics simulations[Lin et al.,J.Chem.Phys.,131,154103,2009].The ICSM has a productive spherical volume within the simulation cell for which key physical properties of bulk water are reproduced,such as density,radial distribution function,diffusion constants and dielectric properties.Although the reaction field(RF)is essential,it typically accounts for less than 2% of the total electrostatic force on a water molecule.This observation motivates investigating further the role of the RF within the ICSM.In this report we focus on distributions of forces and torques on water molecules as a function of distance from the origin and make extensive tests over a range of model parameters where Coulomb forces are decomposed into direct interactions from waters modeled explicitly and the RF.Molecular torques due to the RF typically account for 20% of the total torque,revealing why the RF plays an important role in the dielectric properties of simulated water.Moreover,it becomes clear that the buffer layer in the ICSM is essential to mitigate artifacts caused by the discontinuous change in dielectric constants at the explicit/implicit interface.

A Novel Electric Dual Motor Transmission for Heavy Commercial Vehicles

As a vital vehicle part,the powertrain system is undergoing a fast transition towards electrification.The new integrated electric drive system has been widely used,especially for passenger cars.In this work,a novel electric dual motor transmission is proposed for heavy commercial vehicles.The transmission scheme is firstly introduced,which can achieve 9 different operating modes including 5 single motor modes and 4 dual motor modes.Then,the mode shift map with minimum energy consumption is designed based on the motor efficiency map and the proposed energy management strategy.The driving power is appropriately distributed between the two motors in dual motor modes under the condition of minimum power consumption.In addition,a coordinated control strategy is developed for mode shift control without power interruption.The results show that the electric dual motor transmission has advantages in power consumption and power shift ability compared with the conventional single motor automated manual transmission.