In-wheel Motor Electric Vehicle Research Articles

Study on Design of the whole vehicle test platform and Modeling simulation for In-wheel motor electric vehicles

In order to meet the needs of actual vehicle research, the whole vehicle test platform for in-wheel electric vehicles is designed based on the idea of modularity. On the basis of the vehicle test platform, a joint simulation platform for in-wheel motor electric vehicles is established based on CarSim-Simulink, and simulation verification is carried out. The results show that the designed real-vehicle platform scheme is feasible, and the established simulation model has high accuracy, which can simulate the experimental vehicle well, accurately reflect the dynamic performance response of the vehicle, and provide a basis for further control algorithm research and verification.

Thrust Ripple Force Minimization and Efficiency Analysis of Electromagnetic Actuator on Active Suspension

A novel electromagnetic actuator for active suspension is designed on an in-wheel motor electric vehicle in this paper. Aiming at reducing thrust ripple force and improving stability of the actuator, a method of calculating the optimum slot width and optimizing edge radian of end tooth is proposed. Firstly, a finite element model (FEM) of the actuator is modeled, and the correctness of FEM is verified through comparisons of simulation results and analytical ones, including counterelectromotive force of coil winding and force characteristic test of the actuator. Based on the FEM, the influence of slot width on electromagnetic thrust and total harmonic distortion (THD) is analyzed, and the slot width is improved. The side effect of the actuator is considered. By improving the edge radian, the fluctuation of the cogging force and thrust ripple is reduced. In addition, output efficiency and energy feed efficiency of the actuator after reducing thrust ripple are studied. The results show the minimum THD is 4.2%, which is obtained at the slot width 4.3 mm, and thrust ripple is 36.5 N. When the edge radian is 60°, the thrust ripple decreases to only 15.7 N, which is reduced by 57.0%. The maximum output efficiency and energy feedback efficiency of the actuator are 87.5% and 27.1%, respectively. Finally, according to actuator characteristic tests of two working modes, it is concluded that the maximum energy feedback efficiency is 25.6%. The input current and current frequency should be gradually increased with the increase of suspension speed under active mode, and the maximum output efficiency is 80.2%. The test results are basically consistent with the FEM analysis values, which verify the correctness of the FEM analysis.

Energy-Efficient Direct Yaw Moment Control for In-Wheel Motor Electric Vehicles Utilising Motor Efficiency Maps

An active energy-efficient direct yaw moment control (DYC) for in-wheel motor electric vehicles taking motor efficiency maps into consideration is proposed in this paper. The potential contribution of DYC to energy saving during quasi-steady-state cornering is analysed. The study in this paper has produced promising results which show that DYC can be used to reduce the power consumption while satisfying the same cornering demand. A controller structure that includes a driver model and an offline torque distribution law during continuous driving and cornering is developed. For comparison, the power consumption of stability DYC is also analysed. Simulations for double lane change manoeuvres are performed and driving conditions either with a constant velocity or with longitudinal acceleration are designed to verify the effectiveness of the proposed controller in different driving situations. Under constant velocity cornering, since the total torque demand is not high, two rear wheels are engaged and during cornering it is beneficial to distribute more torque to one wheel to improve energy efficiency. In the simulated driving manoeuvres, up to 10% energy can be saved compared to other control methods. During acceleration in cornering, since the total torque demand is high, it is energy-efficient to use all the four in-wheel motors during cornering.

Glocal Traction Control for In-wheel-motor Electric Vehicles - A Passivity Approach -

Although traction control of in-wheel-motor electric vehicles (IWM-EVs) has been studied for years, we still face the essential theoretical issue: How to assure the stability of the overall system while attaining both global and local control performances? This issue has been neglected by almost the works in the literature. The main reason is due to the nonlinearity and complexity in vehicle dynamics, especially the vehicle driven by multi-actuators. A new traction method is proposed in this paper in the glocal (global/local) framework to overcome this problem. The command to each local IWM includes two signals: (i) the local signal through anti-slip control in the lower-layer, and (ii) the global signal distributed from the driver or the upper-layer controller that managing the average wheel velocity. Stability of the whole system is guaranteed based on the fundamental passivity theory. The effectiveness of the proposed approach is verified by using Carsim/Matlab co-simulator.

A driver model–based direct yaw moment controller for in-wheel motor electric vehicles

In this article, a driver model–based direct yaw moment controller, selected as the upper controller, is developed, of which the control target is determined through a reference driver model in accordance with the driver’s intention. The sliding surface is chosen by the difference between the desired yaw rate and the real output yaw rate. Then, the desired yaw moment is calculated by the sliding mode control. In the lower controller, a novel control torque distribution strategy is designed based on the analysis of the tire characteristics. In addition, an admissible control set of the control torques is calculated in real time through an embedded tire model “UniTire.” Finally, a driver-in-the-loop experiment, via the driving simulator, is conducted to verify the proposed direct yaw moment controller.

Differential steering-based electric vehicle lateral dynamics control with rollover consideration

This article investigates the differential steering-based schema to control the lateral and rollover motions of the in-wheel motor-driven electric vehicles. Generated from the different torque of the front two wheels, the differential steering control schema will be activated to function the driver’s request when the regular steering system is in failure, thus avoiding dangerous consequences for in-wheel motor electric vehicles. On the contrary, when the vehicle is approaching rollover, the torque difference between the front two wheels will be decreased rapidly, resulting in failure of differential steering. Then, the vehicle rollover characteristic is also considered in the control system to enhance the efficiency of the differential steering. In addition, to handle the low cost measurement problem of the reference of front wheel steering angle and the lateral velocity, an [Formula: see text] observer-based control schema is presented to regulate the vehicle stability and handling performance, simultaneously. Finally, the simulation is performed based on the CarSim–Simulink platform, and the results validate the effectiveness of the proposed control schema.

Calculation of the Iron losses in a Spoke-Type Permanent Magnet Synchronous In-Wheel Motor for Electric Vehicles by Utilizing the Bertotti Model

This paper presents an analytical method for the calculation of the iron losses in a spoke-type permanent magnet synchronous in-wheel motor. According to the magnetic field distribution, the iron cores are divided into tooth, yoke, bridge, and shoe. Based on the boundary conditions of the subdomain model, the bridge is equivalent to the fan-shaped region with constant permeability. Then, the no-load and on-load magnetic fields in the air gap, tooth, yoke, bridge, and shoe are analytically calculated. The impacts of slotting and bridge saturation are considered. On the basis of the analytical expression of the magnetic fields, the iron losses of the tooth, yoke, bridge, and shoe are obtained by the Bertotti model. The analytical results in the no-load and on-load conditions are compared with that of the finite-element analysis. The validity is verified by the finite-element analysis.

MPTC for PMSMs of EVs With Multi-Motor Driven System Considering Optimal Energy Allocation

This paper presents a compound propulsion system with a high-speed permanent-magnet synchronous motor (PMSM) and two in-wheel motors for electric vehicles (EVs). In this paper, the longitudinal dynamic model of EVs is first presented. Then traction distribution ratio α is introduced to express the traction distribution between the front and the rear axles. Moreover, the function of power consumption concerned with the traction distribution ratio α is established. Therefore, the α that minimizes the power consumption function is selected as the optimal traction distribution ratio. To improve the performance of motor controllers, the model predictive torque control (MPTC) method is employed for high-speed and in-wheel motor drives. Experimental comparison with field-oriented control (FOC) shows the advantages of MPTC in dynamic response. Finally, experimental comparisons and hardware-in-loop (HiL) tests are presented to verify the MPTC method and the proposed energy allocation method, respectively.

Electromechanical Coupling Mechanism and Control Strategy for In-Wheel-Motor-Driven Electric Vehicles

This paper presents a control methodology for solving the vibration issues emerged in in-wheel motor electric vehicles (IWM-EVs). Unlike existing techniques and methods, the proposed investigation focuses on the electromechanical coupling effects between the subsystems in IWM-EV, which were considered as another negative effects bought by power integration. To this aim, an integrated model which describes the dynamic coupling process between electromagnetic excitation in motor and transient dynamics in vehicle is established and developed. The characteristics of the electromechanically motivated harassment are discussed and its coupling mechanism is analyzed. The key factors are extracted and adopted as the feedback signals in the design of control methods. The effectiveness verification is conducted within numerous practical scenario of vehicle dynamics. Theoretical analysis and simulation results reveal that the proposed approaches can prevent further enlargement of air-gap deformation and unbalanced electromagnetic excitation by cutting off the electromagnetic force outputting periodically, which are benefitted to attenuate the negative issues arisen by electromechanical coupling in IWM-EV. In addition, a more balanced outcome in vehicle dynamics is achieved by the independent-phase chopping method with a less side effect on output torque and speed tracking ability.

Study on electromagnetic vibration of in-wheel motor for electric vehicle

In order to solve the electromagnetic vibration problem of in-wheel motors for electric vehicles, a numerical analysis method is presented for analysing the modal of in-wheel motor. The finite element models of inner stator core, inner stator core with winding and outer rotor are established respectively. The analysis results show that the higher the order of modal vibration shape, the higher the natural frequency. The critical speed of the outer rotor is analysed and studied, which shows that the outer rotor will not cause greater vibration to the in-wheel motor when it works. The harmonic response of in-wheel motor is analysed and the displacement-frequency curves of inner stator and outer rotor are obtained respectively. The analysis results show that the in-wheel motor is not in the frequency range of electromagnetic force wave. When the frequency is higher, the deformation displacement amplitude will reach the maximum.

Analysis of Temperature Field and Water Cooling of Outer Rotor In-Wheel Motor for Electric Vehicle

In view of the narrow installation space of high power density and high torque in-wheel motor, the heat existed the in-wheel motor is balanced by cooling water channel to ensure the heat dissipation of the high power density in-wheel motor. In this paper, Ansoft Maxwell software is used to establish the two-dimensional loss simulation model of in-wheel motor, and the winding loss, stator core loss, rotor core loss and permanent magnet eddy current loss of in-wheel motor are calculated respectively. The temperature field calculation model of in-wheel motor is established. The heat exchange coefficient of motor is calculated, and the equivalent treatment of windings is carried out. The spiral channel is selected to cool the motor. The CFD software is used to simulate and analyze the cooling fluid in the channel. The heat dissipation coefficient curve is calculated. Finally, the calculated results of in-wheel motor loss and heat dissipation coefficient curve are imported into the transient temperature field for simulation, and the temperature field distributions before cooling and after cooling are obtained. The results show that the temperature drop of winding is 32%, the temperature drop of stator core is 30%, the temperature drop of permanent magnet is 26%, and the temperature drop of rotor is 25%. The spiral channel structure adopted in this paper is reasonable and feasible, which provides a certain theoretical reference value for the research and development of in-wheel motor heat dissipation system.

Develop of High Performance Direct-driven In-wheel Motor for Electric Vehicle

Develop of High Performance Direct-driven In-wheel Motor for Electric Vehicle

Study on electromagnetic vibration of in-wheel motor for electric vehicle

Study on electromagnetic vibration of in-wheel motor for electric vehicle

Velocity Optimization for Braking Energy Management of In-Wheel Motor Electric Vehicles

This paper presents two braking regenerative energy optimization controllers for in-wheel motor electric vehicles. The first one is a velocity-tracking controller based on a model predictive control (MPC) method to recover the braking energy. It takes the front and rears in-wheel motor efficiencies into account to distribute the hydraulic and in-wheel motor braking torque of the front and rear wheels. As the vehicle information and intelligence have brought new opportunities for energy management, another velocity optimization controller is designed by considering the restricted condition of terminal distance and terminal velocity. In this strategy, a receding-horizon MPC method is proposed to solve the restricted nonlinear optimal problem. Furthermore, this optimization algorithm is transformed from the time horizon to the distance horizon to satisfy the terminal distance constraint. AMESim/Simulink co-simulations are carried out to evaluate the effectiveness of the proposed controllers. The simulation results indicate that the velocity optimization method can achieve the braking requirement as well as effectively promote regenerative efficiency.

Fault Diagnosis and Fault-tolerant Control Method for In-wheel Motor Electric Vehicles

Fault Diagnosis and Fault-tolerant Control Method for In-wheel Motor Electric Vehicles

Stability control of in-wheel motor electric vehicles under extreme conditions

To investigate the stability of in-wheel motor electric vehicles (IWMEVs) under extreme conditions, a novel control strategy including active rear steering (ARS) mode and direct yaw moment control (DYC) mode is proposed in this paper, utilizing the adaptive dynamic neural network (ADNN) algorithm to make the most of the two control modes. Firstly, a three-degree of freedom nonlinear vehicle model as well as some subsystems is established. Then, a two-layer stability control strategy is put forward, where the upper-layer calculates the desired rear steering angle as well as the differential torque of the rear wheels and the lower-layer executes commands and returns relevant signals. Besides, a stability controller based on ADNN algorithm is designed in the upper-layer so as to take advantage of the two modes under extreme conditions. Next, the impacts of initial values of the connection weights on the ability of ADNN algorithm to train and learn are revealed. Consequently, the optimal initial values can be ascertained before the following simulations. Finally, the closed loop simulations of ARS and DYC are carried out under some extreme conditions such as high velocity and low adhesion coefficient roads, and the results indicate that compared with DYC’s difficulty in playing its role, ARS mode can significantly improve the stability of IWMEVs even under extreme conditions.

Disturbance Observer-Based Sideslip Angle Control for Improving Cornering Characteristics of In-Wheel Motor Electric Vehicles

In this paper, a robust sideslip angle controller based on the direct yaw moment control (DYC) is proposed for in-wheel motor electric vehicles. Many studies have demonstrated that the DYC is one of the effective methods to improve vehicle maneuverability and stability. Previous approaches to achieve the DYC used differential braking and active steering system. Not only that, the conventional control systems were commonly dependent on the feedback of the yaw rate. In contrast to the traditional control schemes, however, this paper proposes a novel approach based on sideslip angle feedback without controlling the yaw rate. This is mainly because if the vehicle sideslip angle is controlled properly, the intended sideslip angle helps the vehicle to pass through the corner even at high speed. On the other hand, the vehicle may become unstable because of the too large sideslip caused by unexpected yaw disturbances and model uncertainties of time-varying parameters. From this aspect, disturbance observer (DOB) is employed to assure robust performance of the controller. The proposed controller was realized in CarSim model described actual electric vehicle and verified through computer simulations.

Suppression of Switched Reluctance Motor Vibration of In-Wheel Motor Electric Vehicle

Switched reluctance motor (SRM) has got great attention in in-wheel motor electric vehicle (IWM-EV), but SRM vertical force, the vertical component of SRM unbalanced radial force, yields SRM vertical vibration and does harm to dynamic performance of IWM-EV. In order to reduce the SRM vertical vibration, electromagnetic active suspension and a linear quadratic Gaussian (LQG) controller were used to suppress the unbalanced radial force in this paper. All the models and the controller were constructed in Matlab/Simulink R2015b. The controller considers five performance indexes: vehicle body acceleration, SRM airgap eccentricity, SRM stator acceleration, suspension dynamic deflections, and tyre deformation. Analytic Hierarchy Process (AHP) was used to calculate the weighted coefficients of performance indexes. Simulations indicate that this electromagnetic active suspension can reduce SRM vertical vibration obviously and improve dynamic performance of IWM-EV.

The study on Differential Steering Control of In-wheel Motor Vehicle Based on Double Closed Loop System

This paper describes a novel differential steering control system for an in-wheel motor electric vehicle with four axles. Basically, the vehicle dynamic model and the differential steering model are established based on the platform of MATLAB/Simulink respectively. A two-degree-of-freedom vehicle model is established to get the referential yaw rate. Next, a double closed loop control system based on the sliding mode structure control is proposed to improve the handing stability. The yaw rate is controlled through a differential torque controller. Meanwhile, a torque compensation controller for non-steering wheel motors is designed to solve the problem of steering power loss. Furthermore, the simulation for validation is performed. The results show that the control system can regulate the vehicle states effectively to enhance the stability. The simulation also indicates that the control strategy can provide a good performance even in complex driving conditions.

Fault-Tolerant Control of Electric Ground Vehicles Using a Triple-Step Nonlinear Approach

This paper investigates a triple-step approach-based fault-tolerant control (FTC) strategy for in-wheel motor electric ground vehicles, whose purpose is to preserve stability, improve handling with in-wheel motors and/or steering system faults. The proposed scheme is divided into two levels. The first level is the integrated vehicle motion control with model uncertainties, disturbances and the possible actuator faults, in which a triple-step nonlinear controller with on-line updating laws is designed. The second level is the driving reference signal generation, where the triple-step feedback law is used to provide a quantitative driving guidance and a residual signal with threshold for monitoring and evaluating drivers. The proposed FTC scheme not only achieves the vehicle safety but also the high-availability of the closed-loop driver-vehicle system. Simulation results show the effectiveness of the proposed scheme.