Hub Motor Research Articles

A Novel Strategy of Control Performance Improvement for Six-Phase Permanent Magnet Synchronous Hub Motor Drives of EVs Under New European Driving Cycle

This paper proposes a model predictive current control (MPCC) method of six-phase permanent magnet synchronous hub motor (PMSHM) using auxiliary voltage vectors. First of all, 26 voltage vectors can be obtained from the switching states of six inverters, and 24 auxiliary voltage vectors can be generated by combining them. Second, four virtual voltage vectors can be found through the required locations, and the two vectors with the lowest cost will be selected by cost function. Then, additional current error correction module can better track the current. Finally, the proposed method is compared with the conventional MPCC method and another method with virtual voltage vectors. The innovation of this paper is that the recombination of vectors can better track and predict the current. A current error compensation module is added to reduce the error between the actual current and the predicted current. And the experimental results show that the proposed method has better performance such as smaller torque ripple and current THD both in steady and dynamic states. Finally, the strategy proposed in this paper was applied to the vehicle model through HIL test platform. The possibility of applying the strategy proposed in this paper to pure electric vehicles was verified under New European Driving Cycle (NEDC).

Comprehensive analysis for influence of complex coupling effect and controllable suspension time delay on hub-driving electric vehicle performance

For in-wheel driving vehicle electric vehicles (EVs), mechanical electromagnetic coupling effect caused by the air gap deformation in permanent magnet synchronous hub motor and intensified by the road excitation deteriorates the EVs performance. In this paper, after studying the numerical method for multi-field coupling problems of hub-driving vehicle under the coupled action of electromagnetic field and mechanical field. The experimental validation is investigated. The results indicate that the multi-field coupling effect in hub-driving motor worsens the dynamics performance of the vehicle. To enhance the vehicle performance, suppress mechanical electromagnetic coupling effect and, at same time, reduce the influence of controllable suspension time delay, a delay-dependent H∞ controller is designed based on Lyapunov theory. By applying the particle swarm optimization (PSO) algorithm and the linear matrix inequality theory, the desired output controller gain is derived. Numerical simulations reflect that the active suspension controller considering control time delay not only achieves the favorable riding comfort performance and restrains the coupling effect in hub driving motor but also ensures the suspension deflection and the safety performance requirement. Moreover, it maintains the closed-loop asymptotically stability regardless of t the variation on the sprung mass and control time delay.

Design and Testing of Solar/Electric Cart

In the current study we report design and testing of a light-weight electric/solar four-wheel drive cart capable of running at speeds in the order of 30mile/hour. The cart can carry 4 passengers and transport attached additional load of about 500 kg. The battery block consists of LiFePO4 cells and provides 6000Watt power to 4 hub motor wheels, each of which are rated 1500Watt. The 600Watt solar array secured on the roof provides steady recharging for the lithium-ion batteries. The power distribution and control of hub motors is executed by special programmed microchip controllers and is very important for safe operation of this of four-wheel drive vehicle. The commercial MPPT charge controller is installed to operate the amount of power for battery recharging. During operation the battery recharge could be executed using power of solar panels. Willingness to minimize dependence on the grid which operates 120V 15A, has led us optimize the required tractive effort while minimizing the weight of the cart. The cost of experimental electric/solar four-wheel drive cart is presented by table 1. Many elements of discussed prototype are taken from the shelf, i.e. purchased at the market price. So, the commercial cost of such prototype in mass production is expected to be significantly cheaper.

Design and Test of Auxiliary Steering System of High Clearance Sprayer Chassis Based on Self-steering Structure

A hydraulic assisted steering method was proposed to solve the problem of steering instability caused by insufficient reverse resistance moment of wheel hub motor in four-wheel independently electrically driven high clearance sprayer. Firstly, the principle of steering chassis structure of four-wheel independently electrically driven high clearance sprayer is briefly introduced. On this basis, hydraulic auxiliary steering system is designed. Then a simplified 2-DOF vehicle steering model is established to analyze the Angle control of the auxiliary steering system. Finally, simulation and road surface test are carried out respectively to verify the performance of steering and auxiliary steering coordination control. Under the working conditions of the steering system alone and the steering system and the auxiliary steering system together, the four-wheel electric drive sprayer carried out the obstacle crossing test and the downslope test with the slope of 15° respectively at the speed of 1 m/s on the smooth road surface. The test results show that in the downhill test, the maximum tracking deviation of the steering system alone is 6.1°, the maximum tracking deviation of the steering and auxiliary steering coordination is 0.9°, the maximum tracking deviation of the steering system alone is 12.0°, and the maximum tracking deviation of the steering and auxiliary steering coordination is 1.2° in the obstacle breaking test. The test results verify the feasibility and stability of the hydraulic steering system proposed in this paper. The system has good test performance and can meet the practical requirements.

Vibration suppression of hub motor electric vehicle considering unbalanced magnetic pull

For the hub motor electric vehicle (HM-EV), the drive motor is directly integrated with the wheel. The unbalanced magnetic pull (UMP) of hub motor would be generated by magnet gap deformation under road surface roughness excitation. The longitudinal and vertical dynamic performances of the HM-EV system are therefore deteriorated. Firstly, to analyze and optimize the longitudinal and vertical dynamic performance of the HM-EV system, a new ten-degree-of-freedom mathematical quarter HM-EV system model equipped with air suspension model, permanent magnet brushless direct current (PM BLDC) hub motor model and rigid ring tire model is proposed. The UMP of PM BLDC hub motor is taken into consideration in this model. A HM-EV system model validation test bench is constructed. The accuracy of the model is verified by experiment. Secondly, based on quarter HM-EV system model, the BP neural network is adopted to calculate the longitudinal and vertical UMP. The relative error between results calculated by BP neural networks and electromagnetic formula is less than 5% and root-mean-square error (RMSE) is less than 2. With proposed BP neural networks calculation method, UMP calculation time is shortened by 70.3%. Finally, the adjustable force is introduced and model predictive control (MPC) method is used to suppress the longitudinal and vertical vibration of HMEV system. Two control methods, namely model predictive control (MPC) and constrained optimal control (COC) are proposed. The simulation results show that by applying MPC, the RMS value of evaluation indexes are decreased by 17.21%–44.10% respectively, which is better than COC (−14.42%–17.21%). With MPC, longitudinal and vertical vibration are suppressed. Comparison of two UMP calculation methods with MPC controller is conducted. The relative errors of evaluation indexes are within 3.85%. Therefore, the driving safety and riding comfort of the HM-EV are improved compared to the passive suspension and COC active suspension.

Some Aspects of Developing and Improving the Mechanical and Operational Features of Wheelchairs for People with Limited Mobility

The present paper presents the field test result softwheel chairs with basic configuration, i.e. self-propelled; motorized with motor-wheels; self-propelled with SOFTWHEELS; and motorized equipped with motor-wheel sand SOFTWHEELS at the same time.Mechanical and operational performance factors are provided for the self-propelled wheel chairs with basic configuration in order to compare them with the ones equipped with supplementary units.Special attention is paid to the standard design and operation principles of the Bikight hub motor wheel, its mechanical and operational features that allow moving a wheelchair without applying the force of user’s hands.Equipping wheel chairs with SOFTWHEEL. So pens new possibilities for people with limited mobility and allows them to travel not only a long well-paved roads but al so along unpaved, gravel, dirt roads and in parks with uneven paths; the vibrations and shocks can be compensated by SOFTWHEELS that greatly improves the quality of motion.Moving along a bumpy road causes a stiff rim to shrink thus resulting in shock-absorber fluctuations for dampening the vibration and impact for the wheelchair users.The design of a wheel chair with hub motor wheels and SOFTWHEELS seems to be the most efficient one.The present paper reviews the mechanical and operational features of the combined use of equipment.

Selected Aspects of Decreasing Weight of Motor Dedicated to Wheel Hub Assembly by Increasing Number of Magnetic Poles

Decreasing the mass of a wheel hub motor by improving the design of a motor’s electromagnetic circuit is discussed in this paper. The authors propose to increase the number of magnetic pole pairs. They present possibilities of mass reduction obtained by these means. They also analyze the impact of design changes on losses and temperature distribution in motor elements. Lab tests of a constructed prototype, as well as elaborated conjugate thermal-electromagnetic models of the prototype motor and modified motor (i.e., motor with increased number of magnetic poles) were used in the investigation. Simulation models were verified by tests on the prototype. Results of calculations for two motors, differing by the number of pair poles, were compared over a wide operational range specific to the motor application in the electric traction. A detailed analysis of the operational range for these motors was also made.

Numerical simulation of heat dissipation of surface mounted permanent magnet synchronous hub motor

Due to the insulation aging, demagnetization and other problems of the permanent magnet and insulating material in the permanent magnet synchronous hub motor under high temperature, the numerical simulation of the heat dissipation of surface mounted permanent magnet synchronous hub motor is proposed. According to the heat transfer of hub motor, the effect degree of heat conduction, heat convection and heat radiation is obtained, the heat transfer coefficient of each part is calculated, and the influence of motor insulation material on temperature rise is analyzed. The experimental results show that the heat dissipation of hub motor under natural cooling condition is poor, and the internal oil cooling method can effectively improve the heat dissipation of hub motor and reduce the temperature difference. When operating at high speed, this reduces the potential safety hazard.

Torque control of new energy four wheel hub motor based on distribution algorithm

Due to the nonlinear, strong coupling and uncertain parameters of the new energy four-wheel hub motor, it is more difficult to control the torque of the motor. In order to solve this problem, a torque control method of the new energy four-wheel hub motor based on the distribution algorithm is proposed. The dynamic model of the new energy four-wheel hub motor is established, and the unmeasurable flux, electric power and other state variables in the motor model are derived according to the degree of freedom of the body. The whole four-wheel hub motor is taken as the research object, and the optimal efficiency of the drive system is taken as the goal, and the distribution algorithm is used to control the electromagnetic torque of the motor. The simulation results show that after the torque control of new energy four wheel hub motor, the driving range of the vehicle is longer, the amplitude of stator flux changes little, the stator current changes and the stability of motor speed are good, and the torque control effect is better.

Multi-objective optimization of the suspension parameters in the in-wheel electric vehicle

The hub motor significantly increases the unsprung mass of electric in-wheel vehicles, which deteriorates the ride comfort and safety of vehicles and which can be effectively improved by optimizing the main suspension parameters of vehicles reasonably, so a multi-objective optimization method of main suspension parameters based on adaptive particle swarm algorithm is proposed and the dynamic model of a half in-wheel electric vehicle is established. Taking the stiffness coefficient of the suspension damping spring and damping coefficient of the damper as independent variables, the vertical acceleration of the body, the pitch acceleration and the vertical impact force of the hub motor as optimization variables, and the dynamic deflection of the suspension and the dynamic load of the wheel as constraint variables, the multi-objective optimization function is constructed, and the parameters are simulated and optimized under the compound pavement. The simulation results show that the vertical acceleration and pitch acceleration are reduced by 20.2% and 18.4% respectively, the vertical impact force of the front hub motor is reduced by 3.7%, and the ride comfort and safety are significantly improved.

Dynamic Characteristics Analysis of the Hub Direct Drive‐Air Suspension System from Vertical and Longitudinal Directions

Hub direct‐drive electric vehicles are driving with hub motors, which cause negative vibration directly on wheels and suspensions. To better analyze the problems of dynamic deterioration resulted by coupling excitations from random road and unbalanced magnetic pull (UMP), a cooperative hub direct drive‐air suspension (HDD‐AS) system is developed, and evaluation indices based on vertical and longitudinal dynamic coupling mechanism are proposed. The vertical and longitudinal characteristics in the time domain under different damping coefficients and motor speeds are demonstrated, and comparison between traditional electric wheel and suspension‐integrating models and HDD‐AS system model is conducted. Then, the responses of random road excitation and UMP are analyzed, and explanations of vertical and longitudinal characteristics in the frequency domain under different damping coefficients are given. These results provide important insights into the influence of coupling excitations and damping coefficient on the HDD‐AS system model. Finally, the effectiveness of the proposed model is verified by the experiment on the test bench.

Computational Investigation and Optimization of Cooling System Used For Hub Motors

The main aim of doing this project is to fix the strategy to provide the cooling for a hub motor so that there will be no effect on the copper windings of the motor while operating under variable load conditions. This works is carried out because of the fact that if the motor reaches the higher limits of its operating temperatures then the winding will get heated up and also there would be possibility of damage of the motor. So basically, we have proposed a fin attached casing from which the 30 numbers of fins are protrudes from the outer surface of hub motor and these fins are mounter in the open atmospheric condition considering the convectional heat transfer as low as possible based on the flow velocity of air and that is 5 W/m2K. Also, this value had been justified based on analytical approach followed in the study in order to find out the efficiency of the fins installed. We chose the casing material as stainless steel and fin material as aluminum because they have good thermal conductivity. The Computational investigation is carried out using ANSYS Module and the parameters i.e. Temperature distribution, Total heat flux and Directional heat flux were investigated based on the optimization technique followed based on two models that are a) Hub-Motor with Fin b) Hub-Motor without Fin. From the numerical investigation we achieved the Fin efficiency as 99%, followed by Heat dissipation from fin is 232.12 W and Fin effectiveness as 0.032 and hence results into an efficient model for the better cooling of the hub-motors of chosen dimension.

Structure design and coordinated control of electromagnetic and frictional braking system based on a hub motor.

A new type of built-in composite electromagnetic and frictional braking structural scheme and its corresponding coordinated control strategy were proposed to enhance the braking effects for the electric vehicle. Fuzzy control theory was applied to design the coordinated control strategy for the electromagnetic and frictional braking system. In comparison to lower braking strength and moderate braking strength, the slip ratio of high braking strength was maintained at near 0.15. It effectively avoided the wheel getting locked and provided relatively large braking torque in the process of braking. The integrated system using a fuzzy control strategy can effectively shorten the braking time, enhance the braking safety in the braking process.

The Eco-Driving Considering Coordinated Control Strategy for the Intelligent Electric Vehicles

Minimum energy consumption with maximum comfort driving experience defines the ideal human mobility. Recent technological advances in most highly automated driving systems on electric vehicles with regenerative braking system not only enhance the safety and comfort level but also present a significant opportunity for automated eco-driving. This research focuses on the longitudinal eco-driving considering the coordinated control for 4WD intelligent electric vehicles. The intelligent electric vehicle framework with 4-wheel hub motors is established and the intention-aware longitudinal automated driving strategy for overall traffic situation levels is proposed. Further, the coordinated control strategy arbitrates the control mode basing on the traffic situation level and distributes braking forces between the electronic hydraulic braking system and the cooperative regenerative auxiliary braking system. The proposed strategy is verified in the co-simulation environment and field test respectively. Test results show optimal control effects in overall traffic situation levels and an enhanced energy recycling efficiency.

A new model predictive torque control strategy for permanent magnet synchronous hub motor of EVs

This paper presents an optimal control strategy for a permanent magnet synchronous hub motor (PMSHM) of EVs drive using three voltage vectors. First, in order to simultaneously control torque and flux excellently, three voltage vectors including two active vectors and one zero voltage vector are selected. Second, the duration of the three voltage vectors in one period is calculated by the principle of simultaneous deadbeat control of torque and flux. Moreover, the cost function which eliminates the weight coefficient is proposed to reduce the amount of calculation. Finally, the proposed method is compared with the one- and two-vector-based model predictive torque control (MPTC) methods both in simulation and experiment. It is found that the proposed threevector-based MPTC can obtain better performance such as smaller torque ripple and current total harmonic distortion (THD) both in steady and dynamic state.

Torque Observation and Improved Sensorless Control of Hub Motor for Armored Vehicles

Torque Observation and Improved Sensorless Control of Hub Motor for Armored Vehicles

An Investigation of the Effect of the Hub Motor Weight on Vehicle Suspension and Passenger Comfort

An Investigation of the Effect of the Hub Motor Weight on Vehicle Suspension and Passenger Comfort

Power system parameters matching of in-wheel motor drive electric vehicle

Based on the line-controlled chassis platform, the low-speed outer rotor motor is used to drive the wheel directly in the designed in-wheel motor line-controlled electric vehicle. The power system parameters of the designed four-wheel independent drive electric vehicle are matched and simulated by offline simulation. Firstly, based on the theoretical basis of the research on the parameter matching of the power system of pure electric vehicles, the type selection and parameter matching of the hub motor and power battery are carried out according to the established dynamic and economic indicators. Then, the designed component parameters are repeatedly corrected until the design goal is achieved; Finally, the vehicle model is built in AVL cruise, and the design results are simulated by software.

A new model predictive torque control strategy for permanent magnet synchronous hub motor of EVs

A new model predictive torque control strategy for permanent magnet synchronous hub motor of EVs

Method of Improving Lateral Stability by Using Additional Yaw Moment of Semi-Trailer

The lateral stability control of tractor semi-trailer plays a vital role for enhancing its driving safety, and the distributed electric drive structure of a hub motor creates opportunities and challenges for realising the lateral stability accurately. Based on the dynamics simulation software TruckSim, a nonlinear dynamic tractor semi-trailer model is established, and a MATLAB/Simulink linear three-degree-of-freedom monorail reference model is established. The upper controller adopts fuzzy proportional–integral–derivative control to export active yaw torque values of the tractor and semi-trailer. The lower controller outputs the driving/braking torque of each wheel according to the target wheel driving/braking rules and torque distribution rules. The tractor produce an active yaw torque through conventional differential braking the hub motor is installed on both sides of the semi-trailer, and the active yaw torque is produced by the coordinated control of the driving/braking torque of the hub motor and the differential braking of the mechanical braking system. To prevent wheel locking, the slip rate of each wheel is controlled. Finally, based on the TruckSim–MATLAB/Simulink cosimulation platform, cosimulation is performed under typical working conditions. The simulation results show that the control strategy proposed in this report is superior to the conventional differential braking control (ESP). It can not only improve the lateral stability of the vehicle more effectively, but also improve the roll stability.