Synchronizer Hubs Research Articles

Comparative Study of In-Wheel Motor Control Systems Based on Multiple Controllers

This paper proposes a comparative study of hub motor control based on multiple control strategies (pi control, direct torque control, model predictive current control) to address the problem of slow dynamic response in traditional vector control of electric vehicle permanent magnet synchronous hub motors. By strictly extracting the mathematical model of the motor, the desired target voltage vector and current vector are derived using three controllers and applied to the controlled object. Finally, experiments are conducted on a simulation platform, and the experimental conclusions are used to compare and analyze the reliability and adaptability of different controllers.

Sequential Subspace Optimization Design of a Dual Three-Phase Permanent Magnet Synchronous Hub Motor Based on NSGA III

The multiobjective optimization design of dual three-phase permanent magnet synchronous hub motors (PMSHMs) is challenging due to the high dimension and huge computation cost of finite-element analysis (FEA). A new multiobjective optimization strategy is proposed for dual three-phase PMSHMs in this article. All design parameters are divided into two subspaces according to the Pearson sensitivity analysis results to improve optimization efficiency. A new training method is adopted to improve the accuracy of the approximate model. By improving a multiobjective intelligent optimization algorithm, nondominated sorting genetic algorithm (NSGA) III, a new algorithm is proposed, which will greatly shorten optimization time. It is found that the proposed optimization method can significantly improve the performance, such as smaller torque ripple and higher maximum torque for the investigated PMSHM, while the computation resources are reduced. A prototype based on the optimization results is manufactured, and experiments are conducted on the platform to verify the accuracy of the optimization results and the FEA. The effectiveness of optimization and the accuracy of the simulation are verified by the experimental results.

Implementation and Experimental Validation of Efficiency Improvement in PM Synchronous Hub Motors for Light Electric Vehicles

The efficiency of permanent magnet synchronous hub motors (PMSHM) used in light electric vehicles (EVs) is lower than that used in commercial EVs. Therefore, in this study a high-efficiency radial-flux outer-rotor PMSHM was designed for light EVs. The high-efficiency motor will contribute to the reduction of the power consumption demand from the batteries of EVs, the longer life of the batteries and the longer uninterrupted operation of the system. The optimization objectives, such as motor sizing, number of slots and poles, air gap length, material selection, stator winding structure, stator slot shape, magnet thickness, and cutting method for stator sheets were considered to ensure high efficiency and low cogging torque. In this study, three validation stages were followed; electromagnetic analyzes with FEM, analytical calculations, and finally experimental validation. First, the design parameters of the motor were determined based on the analyses results obtained using ANSYS Maxwell software, and then validated both with the analytical calculations and experimental results. The comparison results show that the design data of the motor at the rated speed agree well with the analytical calculations and test results. After obtaining the optimized motor design, the motor was installed on a prototype electric car for the road test. During the test drive, the motor performed successfully and operated compatibly with the rest of the electric vehicle systems such as the motor driver and the battery.

Fault-Tolerant Operation of a Six-Phase Permanent Magnet Synchronous Hub Motor Based on Model Predictive Current Control With Virtual Voltage Vectors

This paper proposes a model predictive current control (MPCC) compensation method based on virtual voltage vectors for single-phase open-circuit faults of an asymmetric six-phase permanent magnet synchronous hub motor (PMHSM). The proposed strategy adopts the normal vector space to decompose the transformation matrix without reconfiguring the controller topology. By analyzing the difference between the open-circuit phase voltage and the state of health, the disturbance term of the prediction vector in the α-β and x-y subspaces is obtained. 64 voltage vectors are obtained from the switching states of the 6-phase two-level inverter, and then these 64 voltage vectors are appropriately compensated and synthesized into 24 new virtual voltage vectors. The new virtual vectors avoid the adjustment of the MPCC weighting factors and the synthesized virtual vectors can suppress current harmonics. Finally, the experimental results show the effective performance of the method before and after the fault-tolerant operation.

Speed Sensorless Model Predictive Current Control Based on Finite Position Set for PMSHM Drives

As an efficient control strategy, model predictive current control (MPCC) has rapid response and simple calculation. This article proposes an improved MPCC scheme for permanent-magnet synchronous hub motor (PMSHM) drives. The mentioned control scheme uses the parameter values at the last moment to obtain the back electromotive force (EMF) and utilizes the obtained back EMF to obtain the predicted current value at the next moment. In the actual application of the motor, to enhance the robustness of the control system, a sliding mode controller is used to replace the conventional proportional-integral (PI) speed loop, and a finite position phase-locked loop based on the dichotomy is added to achieve sensorless speed control and provide an accurate rotor position angle. To improve the steady-state performance, the method of duty cycle is introduced, and the null vector and the actual vector are used together in the same control cycle. The simulation and experimental results both show the effectiveness of the proposed MPCC scheme, and the steady-state performance of MPCC is greatly improved compared with traditional MPCC.

Fault-tolerant model predictive control of six-phase permanent magnet synchronous hub motors

Permanent magnet synchronous hub motors (PMSHMs) have been gradually introduced into the applications of electric vehicles. On this basis, the six-phase motor has the characteristics of high reliability, high power density and low torque ripple. And its fault tolerance is a large advantage compared with the three-phase motor. The multi-phase permanent magnet synchronous motor is redundant due to the number of phases. When the motor fails, it does not have to stop running, merely adjust its control mode and enter the fault-tolerant compensation control algorithm to resume the operation of the system. The FCS-MPC algorithm can replace the cascade structure in the traditional control and eliminate the modulation module. This makes it have good steady-state performance. The speed response is also improved. It can be combined with multiple control objectives with strong flexibility by simply changing the objective function. The prediction model is compensated. Finally, the experimental results show the effectiveness of this method.

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.

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.

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

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.

Driving-Cycle-Oriented Design Optimization of a Permanent Magnet Hub Motor Drive System for a Four-Wheel-Drive Electric Vehicle

The electrical drive system is crucial to the drive performance and safety of electric vehicles (EVs). In contrast to the traditional two-wheel-driven EVs, the hub motor four-wheel-drive system can steer the vehicle by controlling the torque and speed of each wheel independently, yielding a very simple distributed drivetrain with high efficiency and reliability. This article presents a system-level design optimization method for a permanent magnet hub motor drive system for a campus patrol EV based on a practical driving cycle. An outer rotor permanent-magnet synchronous hub motor (PMSHM) and an improved model predicate current control are proposed for the drive system. Due to the lack of reducers, the direct-drive PMSHM needs to face more complex working conditions and design constraints. In the implementation, the motor design requirements are obtained through the collection of practical EV driving cycles on the campus. Based on these requirements, two models are proposed as the preliminary designs for the PMSHM. To improve their performance, an efficient multiobjective optimization method is employed to the motor considering different operational conditions. The finite-element model and thermal network model are employed to verify the performance of the optimized PMSHM. An optimal design scheme is selected by comparing the comprehensive performance of the two optimized motors. In addition, a duty-cycle model predictive current control is adopted to drive the motor. Finally, a prototype is developed and tested, and the experimental results are presented.

Design optimisation of an outer‐rotor permanent magnet synchronous hub motor for a low‐speed campus patrol EV

This study proposes an outer-rotor permanent magnet synchronous hub motor (PMSHM) with similar pole and slot numbers for an electric vehicle (EV). First, the design rule of the motor size is introduced. Second, the appropriate numbers of motor poles and slots are selected to improve the torque density and save the radial space of the motor. Meanwhile, the selected poles and slots numbers can ensure that the high-efficiency area of the motor meets the requirements of the test EV. Moreover, different winding arrangements are studied to select the appropriate winding arrangement method for the motor. Then, the key dimensions of the stator are optimised to improve the torque output and reduce the core loss of the motor by using the finite element analysis. The results indicate that the proposed outer-rotor PMSHM with similar pole and slot numbers and double-layer short distance concentrated slot winding exhibits high-efficiency and high-torque output. Finally, the predicted performance of the proposed PMSHM is verified by experiments on a prototype. Furthermore, the vehicle test is also carried out, and the results show that the prototype maintains high efficiency in the main working area of the EV.

Genetic PI based model and path tracking control of four traction electrical vehicle

Modeling and control of four-wheel electric vehicles are difficult due to their dynamic parameters and variable road conditions. In this paper, a robust and adaptive electric vehicle model and position control that can be adapted to state variables using a dynamic lateral and longitudinal model of a four-wheel electric vehicle have been proposed. The longitudinal and lateral forces have been modeled according to Newton’s second law, depending on the parameters such as the vehicle’s size, width, height, weight and slope angle by using dynamic equations of the vehicle. In this paper, a permanent magnet synchronous hub motor has been used for each wheel of the electric vehicle. The magic formula wheel model has been used to determine the relationship between the slip and the friction of the designed vehicle. Using the slip system, the relationship between the speed of the electric vehicle itself and the wheel speeds have been defined. The proportional controller at the position loop and proportional + integral controller at the speed loop of the designed system have been used. In the path tracking control system, position controls have been made in the X and Y coordinate planes. A P position controller and a PI speed controller have been used for each plane. Thus, there are 6 controller coefficients in total. Because of the complicated structure of the system, it is difficult to determine the most suitable controller coefficients by analytical methods. Therefore, the genetic algorithm which is one of the heuristic algorithms has been used in determining these coefficients. Simulation studies have been conducted with a different path and position references to see the effectiveness of the proposed electric vehicle model and position control. The obtained results show that the proposed model and control system are robust, effective and reliable.

Analysis and Optimization of Radial Force of Permanent-Magnet Synchronous Hub Motors

Permanent-magnet synchronous hub motors (PMSHMs) have been investigated for electric vehicles. However, there are some challenges such as effective cooling and radial force. As PMSHMs are installed on the wheels, the radial force will directly affect the ride comfort of the vehicle. This article presents the analysis and optimization of the radial force for PMSHMs. The radial force densities of the symmetry and asymmetry PMSHMs are analyzed first. It is found that the symmetry PMSHMs have balanced force, while the asymmetry PMSHMs normally have big unbalanced radial force and vibration. To reduce the radial force of the asymmetry PMSHMs, an improved sequential Taguchi optimization method (ISTOM) with mixed orthogonal array is presented for an asymmetry PMSHM in this article. It can be found that the proposed method is efficient and can significantly reduce the radial force of the hub motor.

MPTC of a six-phase PMSHM with auxiliary voltage vectors

Permanent magnet synchronous hub motors (PMSHMs) have been gradually introduced into the applications of electric vehicles. In order to output more torque, many researchers turned their research direction to six-phase motors. Because it is composed of two sets of three-phase windings, there will be interference between the windings, affecting the performance of the motor. In order to improve the steady and dynamic-state performance of permanent magnet six phase synchronous motor, a predictive torque control method based on multi vector model is proposed in this paper. Finally, experimental results show the effectiveness of this method.

Automotive Transmission Gearbox Synchronizer Sintered Hub Design

Sintered hubs are typically used in automotive transmission gearbox synchronizer due to its near net shape. Sintered hubs have complex design due to their functional and packaging requirements. The required hardness and density are obtained using different grades of sintered powders, sintering temperature and the press load capacity. Many sintering materials with good mechanical properties are available with or without secondary heat treatment. However, there are concerns of sintered hub failure in the vehicle validation or during the intended service of the vehicle. This paper describes the design of automotive gearbox synchronizer sintered hub to meet the endurance life of the gearbox. The sintered hub wear on the synchronizer hub face and tooth flank are studied experimentally in the gearbox rig level test. This study is done for materials such as medium carbon sinter-hardened PM grade, sintered high carbon diffusion alloyed PM grade and sintered high carbon diffusion alloyed PM grade along with induction hardening process. The different gearbox loading conditions cause wear up to 70 µm on the synchronizer hubs. The hub to gear interface as well as hub tooth to sleeve tooth interface contact pressures and wear are studied based on the test results. The amount of hub digging is proportional to the applied load and the test duration. The medium carbon sinter-hardened material can withstand less pressure and less time when compared with the high carbon diffusion alloyed material with induction hardening. The design considerations to avoid hub digging and or material changes with process changes are analyzed. This paper also describes prediction methodology in FEA for the failure modes of synchronizer hub spline tooth crack and strut detent slot crack. The physical validation shows good trend matching correlation with the high-fidelity approach in CAE.

State Feedback Control for a PM Hub Motor Based on Gray Wolf Optimization Algorithm

This paper presents an optimal control strategy for a permanent-magnet synchronous hub motor (PMSHM) drive using the state feedback control method plus the gray wolf optimization (GWO) algorithm. First, the linearized PMSHM mathematical model is obtained by voltage feedforward compensation. Second, to acquire satisfactory dynamics of speed response and zero d -axis current, the discretized state-space model of the PMSHM is augmented with the integral of rotor speed error and integral of d -axis current error. Then, the GWO algorithm is employed to acquire the weighting matrices Q and R in linear quadratic regulator optimization process. Moreover, a penalty term is introduced to the fitness index to suppress overshoots effectively. Finally, comparisons among the GWO-based state feedback controller (SFC) with and without the penalty term, the conventional SFC, and the genetic algorithm enhanced proportional–integral controllers are conducted in both simulations and experiments. The comparison results show the superiority of the proposed SFC with the penalty term in fast response.

Use of small punch test to estimate the mechanical properties of sintered products and application to synchronizer hubs

Powder metallurgy is a manufacturing technology widely used, especially in the automotive sector. In order to assure the quality of these components different conventional tests are employed directly on the final product, but in order to make the mechanical characterization of sintered materials, standard mechanical tests can only be performed onto samples compacted and sintered in controlled conditions similar to the ones used in real production. The final mechanical properties of these products after compacting and sintering are the input needed to define and analyze new geometries and products. The use of the small punch test (SPT) to mechanically characterize in a direct way the final sintered products was explained in this research work and the regressions to determine the tensile mechanical properties of the aforementioned products were also developed.

Tire-Road Friction Coefficient Estimation and Experimental Setup Design of Electric Vehicle

Nowadays, electric vehicles have become an important area because of air pollution, increasing use of renewable energy sources and being exhausted of oil fuels. In our country even the usage of electrical vehicles is not widespread nowadays, but also very popular and it is thought that it will increase. In this area, new studies and projects appear continuously Real systems are moving systems and it is difficult and expensive to evaluate by electrical vehicles; therefore an experiment mechanism has been created. In this study two fixed magnet synchronous hub motors have been used as wheels and the other one as load. In order to find the speed of the wheel, load value and coefficient of friction related to sliding, Burckhardt model has been used and the results obtained with different speed and road conditions have been presented here.