In-wheel axial-flux SRM drive for light electric vehicles

Revenues from global sales of light electric vehicles are expected to grow from $9.3 billion in 2017 to$ 23.9 billion in 2025. In order to boost this growth electric drives with better features and lower costs have to be developed. This paper presents a new in-wheel axial-flux switched reluctance motor with double rotor and a particular disposition of the stator and rotor poles that provides short flux path without flux reversal. The magnetic active parts of the stator and the rotor are built using soft magnetic composites. The motor is fed from batteries trough a on purpose designed electronic power controller. Simulation of the whole drive, using Matlab-Simulink coupled with the results of the three dimensional finite analysis of the motor is carried out. Simulation results prove that the proposed in-wheel axial-flux switched reluctance motor drive is adequate for the propulsion of electric light vehicles

Magnetic noise reduction of in-wheel permanent magnet synchronous motors for light-duty electric vehicles

This paper presents study of a multi-slice subdomain model (MS-SDM) for persistent low-frequency sound, in a wheel hub-mounted permanent magnet synchronous motor (WHM-PMSM) with a fractional-slot non-overlapping concentrated winding for a light-duty, fully electric vehicle applications. While this type of winding provides numerous potential benefits, it has also the largest magnetomotive force (MMF) distortion factor, which leads to the electro-vibro-acoustics production, unless additional machine design considerations are carried out. To minimize the magnetic noise level radiated by the PMSM, a skewing technique is targeted with consideration of the natural frequencies under a variable-speed-range analysis. To ensure the impact of the minimization technique used, magnetic force harmonics, along with acoustic sonograms, is computed by MS-SDM and verified by 3D finite element analysis. On the basis of the studied models, we derived and experimentally verified the optimized model with 5 dBA reduction in A-weighted sound power level by due to the choice of skew angle. In addition, we investigated whether or not the skewing slice number can be of importance on the vibro-acoustic objectives in the studied WHM-PMSM.Postprint (published version

Critical Aspects of Electric Motor Drive Controllers and Mitigation of Torque Ripple - Review

Electric vehicles (EVs) are playing a vital role in sustainable transportation. It is estimated that by 2030, Battery EVs will become mainstream for passenger car transportation. Even though EVs are gaining interest in sustainable transportation, the future of EV power transmission is facing vital concerns and open research challenges. Considering the case of torque ripple mitigation and improved reliability control techniques in motors, many motor drive control algorithms fail to provide efficient control. To efficiently address this issue, control techniques such as Field Orientation Control (FOC), Direct Torque Control (DTC), Model Predictive Control (MPC), Sliding Mode Control (SMC), and Intelligent Control (IC) techniques are used in the motor drive control algorithms. This literature survey exclusively compares the various advanced control techniques for conventionally used EV motors such as Permanent Magnet Synchronous Motor (PMSM), Brushless Direct Current Motor (BLDC), Switched Reluctance Motor (SRM), and Induction Motors (IM). Furthermore, this paper discusses the EV-motors history, types of EVmotors, EV-motor drives powertrain mathematical modelling, and design procedure of EV-motors. The hardware results have also been compared with different control techniques for BLDC and SRM hub motors. Future direction towards the design of EV by critical selection of motors and their control techniques to minimize the torque ripple and other research opportunities to enhance the performance of EVs are also presented.publishedVersio

In-wheel Motors: Express Comparative Method for PMBL Motors

One of the challenges facing the electric vehicle industry today is the selection and design of a suitable in-wheel motor. Permanent Magnet Brushless (PMBL) motor is a good choice for the in-wheel motor because of its lossless excitation, improved efficiency, reduced weight and low maintenance. The PMBL motors can be further classified as Axial-Flux Twin-Rotor (AFTR) and Radial-Flux Twin-Rotor (RFTR) machines. The objective of this dissertation is to develop a fast method for the selection of appropriate in-wheel motor depending on wheel size. To achieve this, torque equations are developed for a conventional single-rotor cylindrical, twin-rotor axial-flux and twin-rotor radial-flux PMBL motors with slot-less stators based on magnetic circuit theory and the torque ratio for any two motors is expressed as a function of motor diameter and axial length. The theoretical results are verified, on the basis of magnetic field theory, by building the 3-dimensional Finite Element Method (FEM) models of the three types of motors and analyzing them in magnetostatic solver to obtain the average torque of each motor. Later, validation of software is carried out by a prototype single-rotor cylindrical slotted motor which was built for direct driven electric wheelchair application. Further, the block diagram of this in-wheel motor including the supply circuit is built in Simulink to observe the motor dynamics in practical scenario. The results from finite element analysis obtained for all the three PMBL motors indicate a good agreement with the analytical approach. For twin-rotor PMBL motors of diameter 334mm, length 82.5mm with a magnetic loading of 0.7T and current loading of 41.5A-turns/mm, the error between the express comparison method and simulation results, in computation of torque ratio, is about 1.5%. With respect to the single-rotor cylindrical motor with slotless stator, the express method for AFTR PMBL motor yielded an error of 4.9% and that of an RFTR PMBL motor resulted in an error of -7.6%. Moreover, experimental validation of the wheelchair motor gave almost the same torque and similar dynamic performance as the FEM and Simulink models respectively

A two degrees of freedom system for wheel traction applications

In this paper, the use of conical induction machines is proposed for an in-wheel traction application. Such machines offer a rotational movement combined with a translational motion of the rotor. The horizontal movement is essential when active engagement and disengagement of the motor from the wheel without any extra mechanical component is required. This paper first investigates the basic concepts of how the conical machine functions and then proposes a mission strategy for a relevant traction application. A detailed description of the full scheme is given. In order to achieve the required performance, an innovative control method for both degrees of freedom of the machine (i.e. torque production and axial movement) is proposed and validated against a small-scale demonstrator of the whole system

In-wheel motor vibration control for distributed-driven electric vehicles:A review

Efficient, safe, and comfortable electric vehicles (EVs) are essential for the creation of a sustainable transport system. Distributed-driven EVs, which often use in-wheel motors (IWMs), have many benefits with respect to size (compactness), controllability, and efficiency. However, the vibration of IWMs is a particularly important factor for both passengers and drivers, and it is therefore crucial for a successful commercialization of distributed-driven EVs. This paper provides a comprehensive literature review and state-of-the-art vibration-source-analysis and -mitigation methods in IWMs. First, selection criteria are given for IWMs, and a multidimensional comparison for several motor types is provided. The IWM vibration sources are then divided into internally-, and externally-induced vibration sources and discussed in detail. Next, vibration reduction methods, which include motor-structure optimization, motor controller, and additional control-components, are reviewed. Emerging research trends and an outlook for future improvement aims are summarized at the end of the paper. This paper can provide useful information for researchers, who are interested in the application and vibration mitigation of IWMs or similar topics

Advanced Integrated Power and Attitude Control System (IPACS) study

Integrated Power and Attitude Control System (IPACS) studies performed over a decade ago established the feasibility of simultaneously satisfying the demands of energy storage and attitude control through the use of rotating flywheels. It was demonstrated that, for a wide spectrum of applications, such a system possessed many advantages over contemporary energy storage and attitude control approaches. More recent technology advances in composite material rotors, magnetic suspension systems, and power control electronics have triggered new optimism regarding the applicability and merits of this concept. This study is undertaken to define an advanced IPACS and to evaluate its merits for a space station application. System and component designs are developed to establish the performance of this concept and system trade studies conducted to examine the viability of this approach relative to conventional candidate systems. It is clearly demonstrated that an advanced IPACS concept is not only feasible, but also offers substantial savings in mass and life-cycle cost for the space station mission

Traction motors for electric vehicles: Maximization of mechanical efficiency – A review

With the accelerating electrification revolution, new challenges and opportunities are yet emerging, despite range anxiety is still one of the biggest obstacles. Battery has been in the spotlight for resolving this problem, but other critical vehicle components such as traction motors are the key to efficient propulsion. Traction motor design involves a multidisciplinary approach, with still significant room for improvement in terms of efficiency. Therefore, this paper provides a comprehensive review of scientific literature looking at various aspects of traction motors to maximize mechanical efficiency for the application to high-performance Battery Electric Vehicles. At first, and overview on the mechanical design of electric motors is presented, focusing on topology selection, efficiency, transmission systems, and vehicle layouts; Special attention is then paid to the thermal management, as it is one of the main aspects that affects the global efficiency of such machines; thirdly, the paper presents a discussion on possible future trends to tackle ongoing challenges and to further enhance the performance of traction motors

Aspects of, and new approaches to, the design of direct drive generators for wind turbines

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Electromagnetic evaluation of an in-wheel double rotor axial-flux switched reluctance motor for electric traction

Peer ReviewedPostprint (published version