Improved cogging calculation methods for surface mounted permanent magnet synchronous motors

As part of the design process of surface mounted permanent magnet synchronous motors (PMSM), a combination of analytical calculation and finite element analysis (FEA) is proposed for the cogging torque calculation. The analytical methods are recommended for the initial design iterations in view of their high computational speed. In general, however, finite element analysis is more accurate and is therefore recommended for the final design iterations. In order to obtain continuity when switching from analytical calculations to FEA, two modifications are made to the equations upon which the analytical methods are based in order to improve accuracy. This is demonstrated by comparing the results from the unmodified and modified analytical method with those using the finite element method through their application using the nominal parameters of a Control Techniques Dynamics CTD 142UMC300 motor. Air-gap flux density calculations are compared as well as cogging torque calculations

Performance enhancement of underwater propulsion motor using differential evolution optimization

1113-1119This paper describes the performance enhancement of underwater propulsion motor using differential evolution optimization (DEO). Usually during development stage, an analytical subdomain model (ASM) is often preferred to be used in the design of electric machines since ASM has faster computational time compared to the finite element method. differential evolution algorithm is deployed to provide the optimization process in searching the optimal motor parameters iteratively and intelligently with specific objective functions. For this purpose, a three-phase, 6-slot/4-pole permanent magnet synchronous motor (PMSM) intended for the underwater propulsion system is first designed by using ASM and then later optimized by differential evolution algorithm. Five main motor parameters, i.e., magnet pole arc, magnet thickness, air gap length, slot opening, and stator inner radius are varied and optimized to achieve the design objective functions, i.e., high motor efficiency, high output torque, low total harmonic distortion (THDv) in back-emf, and low cogging torque. Results from differential evolution optimization show an improved performance of the proposed PMSM where the efficiency of the motor is increased to 96.1% from its initial value of 94.2%, 13% increase in the output torque, and 4.1% reduction for total harmonic distortion in its back-emf. Therefore, DEO can be highly considered during initial design stage to optimize the motor parameters in developing a good underwater propulsion motor

Permanent Magnet Machine Design with Cold Spray Magnets

With the global trend toward electrification of transport, the interest in various configurations of electric motors is growing. Surface permanent magnet synchronous machines (SPMSM) are used in many high-performance applications due to low inertia, high torque density, and overload capability. Several applications require low torque pulsations as they can lead to mechanical vibrations and acoustic noise in the electric motor. Various techniques have been proposed in the literature to reduce the torque pulsations either by using machine control strategies or by machine design. Optimization of the rotor permanent magnet (PM) shape is one of the effective methods for reducing torque pulsations. Unfortunately, the low versatility of the motor magnet fabrication technologies limits the development of new motor geometries. Current techniques used for the assembly of PMs in motors such as adhesives, slots, or screws are complex, labor-intensive, and offer very little flexibility for advanced motor design geometries. Consequently, alternative fabrication techniques such as cold spray additive manufacturing are worth exploring. Cold spray additive manufacturing is used for shaping PMs for the direct fabrication of electric motor parts without the need for additional assembly steps. This novel technique allows an increase in the design flexibility of electrical machine geometries targeting improved performance. In this thesis, the PM rotors considered are the conventional rectangular-shaped with unskewed magnets (Model A), skewed magnets (Model B), and sinusoidal-petal-shaped magnets (Model C) along the axial direction. The magnitude of magnetization current pulse required to magnetize these rotors is calculated using an FEA package and an impulse magnetizer setup is designed and prototyped for in-situ magnetization. Various stator terminal connection configurations are analyzed and compared for the magnetizer. The performance of the shaped cold sprayed permanent magnet rotors and their effects on back EMF, electromagnetic torque, and cogging torque are analyzed experimentally and comparisons are made between the different rotor designs. Laminated electrical silicon steel sheets are mainly used to produce the stator and rotor core of an electrical machine. In comparison, there are soft magnetic composites (SMC) which consist of a high purity fine iron powder particle coated with the insulation material. Hence, its electrical resistance is much higher than that of laminated steel. Its isotropic magnetic and physical properties help flux to conduct in a three-dimensional direction and effectively dissipate the heat produced from core losses. The product developed using SMC material uses compaction, heating, and pressing techniques to achieve the desired shape and final size of the machine core parts. Hence, the material wastage is lower as compared to the laminated steel core. In this thesis, the impact of a few manufacturing parameters on SMC properties to ensure that optimized motor performance is achieved was analyzed using three SMC different materials (A, B, and C) using FEA software. Furthermore, machine design parameters are tuned to achieve optimal flux weakening. Finally, an FEA-based performance analysis of a 7.12 kW radial flux PMSM with laminated steel and SMC stator core is used to estimate the torque density and losses in the machines. Two different designs of 24/20 slot-pole and 12/8 slot-pole configuration using conventional surface permanent magnet rotor designs are considered. In addition, the ring-type Halbach-array PM rotor fabricated using cold spray additive manufacturing for 12/8 slot-pole is analyzed and optimized with the SMC stator core for high-speed electric vehicle application

Analysis on the Cogging Torque of Permanent Magnet Machine for Wind Power Applications

This paper discusses the new feature implemented in most social media messaging applications: the unsent feature, where the sender can delete the message he sent both in the sender and the recipient devices. This new feature poses a new challenge in mobile forensic, as it could potentially delete sent messages that can be used as evidence without the means to retrieve it. This paper aims to analyze how well Autopsy open-source mobile forensics tools in extracting and identifying the deleted messages, both that are sent or received. The device used in this paper is a Redmi Xiaomi Note 4, which has its userdata block extracted using linux command, and the application we’re using is WhatsApp. Autopsy will analyze the extracted image and see what information can be extracted from the unsent messages. From the result of our experiment, Autopsy is capable of obtaining substantial information, but due to how each vendor and mobile OS store files and databases differently, only WhatsApp data can be extracted from the device. And based on the WhatsApp data analysis, Autopsy is not capable of retrieving the deleted messages. However it can detect the traces of deleted data that is sent from the device. And using sqlite3 database browser, the author can find remnants of received deleted messages from the extracted files by Autopsy

High performance and low-cost permanent magnet devices

In this thesis the investigation of the modelling, design and analysis of novel permanent magnet machine for cost sensitive applications is presented. More specifically, a novel technique of arranging Ferrite permanent magnets with low energy density to achieve high airgap flux densities like those encountered in devices equipped with high cost rare-earth permanent magnets, thus, achieving significant cost savings, without substantial change in performance. Consequently, a spoke-type rotor equipped with axially magnetized permanent magnets in addition to the conventional circumferential permanent magnets is proposed, in order to increase the flux focusing and the airgap flux density

Design optimisation of brushless permanent magnet synchronous motor for electric vehicles

A novel new application of optimisation algorithm “Bess Algorithm” in the design of electric machine is presented in this thesis. The optimisation has the ability to perform global and local search and can be applied on constrained, unconstrained optimisation problem with multi-objective function, which all counted when consider optimisation algorithm for the design of electric machine. The searching procedure of the optimisation algorithm has been described in detailed. Furthermore, novel instructions and recommendation were implemented to tune the optimisation parameters, particularly for the purpose electric machine design, which in turn reduced the search space, increase efficiency and ability to find optimal solution with lower computation time. The optimisation was applied to search for optimal parameters of a benchmark electric machine with multi-objective to reduce the cost and increase the power density, power-volume ratio and efficiency. Throughout the thesis, a full detailed analytical model for the design of brushless permanent magnet synchronous motor that account for electromagnetic and thermal aspects was described. The optimisation was employed to search for optimal parameters of the analytical model that satisfy the design requirements. Then, the generated optimal parameters were evaluated and verified by Finite Element Analysis, FEA. The results from the FEA show good agreement with their corresponding values in the analytical model within acceptable range. At the same operational conditions and output specifications, the results show that the power density, volume to power ratio and cost of the new optimised motor IV were all increased by 19%, 39%, 24% respectively and the efficiency reduced only by -1%. The optimisation was also compared with one of the most usable optimisation algorithm used in the design of electric machine i.e. Genetic Algorithm. The results show that bees algorithm has more ability to cover the search space with less number of recruited bees and less number of iterations and higher computation efficiency

The integration of input filters in electrical drives

PhD ThesisThe integration of passive components such as inductors and capacitors has gained significant popularity in integrated drive research, and future power electronics systems will require more integrated and standardised packages. These give rise to better power density and improved performance. However, packaging techniques and passive components have been considered a technological barrier which is limiting advances in power electronics. The focus on size reduction should be turned towards the passive components, such as converter chokes, DC-link capacitors and electromagnetic interference (EMI) filters, and achieving greater power density depends on innovative integration concepts, flexibility in structures and extended operating temperature ranges while system integration and modularity are not mutually exclusive. This research considers the possibility of integrating input power filter components into electric machines. Particular attention is paid to the integration of electromagnetic line filter inductors to give better utilisation of the motor volume and envelope. This can be achieved by sharing the machine’s magnetic circuit. An LCL line filter has been chosen to be integrated with a gridconnected permanent magnet synchronous machine. Machines have been proposed in this study for low speed (3000 RPM) and high speed (25000 RPM) operation. The two machines have similar dimensions, but the low-speed machine is less challenging in terms of losses and filter integration, so attention is directed more to the high-speed machine. Both are supplied with low- and high-power drives at power ratings of 4.5 kW and 38 kW respectively. Several novel techniques have been investigated to integrate filter inductors into the electrical machines to produce a single mechanically packaged unit without significant increases in size and losses. Different approaches have been simulated using finite element analysis (FEA) to assess the effectiveness of the integration of passives within the machine structure. Each design has been iteratively optimised to determine the best mass of copper and core for the integrated filter inductors, targeting parity in power density when compared to traditional separate packages. The research demonstrates that an approach utilising a double-slot stator machine (named the integrated double slot (IDS) machine) with input filters wound into the outermost slots is the most appropriate choice in terms of achieving higher power density. The integrated filter inductors mimic the electromagnetic behaviour of the discrete industrially packaged inductors but with a volume reduction of 87.6%. A prototype of the IDS machine design of a 38 kW, 25000 RPM, including filter inductors was manufactured and testedthe General Electricity Company of Libya (GECOL), the Engineering and Physical Sciences Research Council (EPSRC), and the Engineering Doctorate scheme at Newcastle University

Analytical Sizing Models to Assess the Performances of High Specific Power Electric Motors for Hybrid Aircraft

After the industrial and the environmental successes of hybridization railways transport, the hybridization of aviation transport is acquiring more and more consideration. In this context, the European Union in partnership with the aerospace manufacturers, has launched in 2014 a largestre search program Clean Sky 2 aiming to reduce aircraft fuel consumptions and noise levels. Clean Sky 2 research program includes several projects among of them: Academic reSearch on Thermal& Electric Components & Systems "HASTECS project" which aims to identify and to develop the most promising technologies for decreasing the weight and increasing efficiency of hybrid propulsion chain. "HASTECS project" is organized around six Work Packages (WPs) dedicated tothe components of hybrid propulsion chain, for instance, the WP1 is dedicated to electric motors and the WP3 is dedicated to their cooling systems. Indeed, the estimated reduction fuel consumptions for a short range flight would be 3.5% if the specific power of electric machines and power converters with their cooling systems is respectively increased to 5kW/kg and 15kW/kg for2025, and also increased to 10kW/kg and 25kW/kg for 2035. The targets are significantly higher than those of today. Specific power planned of the industrial electric machines and power converters is higher than the currently one. However, these specific powers present some limitations which depend on the involved material properties and by environment conditions such as: thermal limitations and partial discharges risk. For reaching targeted specific powers for instance in electric machines, the mechanical, electrical and the magnetic loads linked to the materials and cooling technologies must be increased. However, considering the limitations and the environment constraints, choice of loads should be adequate. Therefore, it is important to develop models and tools allowing assessing the actual and the future technologies which allow achieving the HASTECS targets. The present thesis focuses to the development of models and tools for satisfying the HASTECS targets about the electric machines and their cooling systems.There are several different electric machine topologies, namely: radial flux machines, axial flux machines, permanent magnet synchronous machines, wound rotor synchronous machines,asynchronous machines, etc. Performing for each electric machine topology a model for identifying the most promising technologies is a very complex and laborious task. Nevertheless, an analytical model of non-salient sine wave electric machines associated to load ability concepts characterizes a quite lot of electric machine topologies. Based on it, a Target Setting Tool is developed for assessing electric motor technologies considering limits and constraints while without specifying the electric motor topology. Therefore, very few input data are required to make quick trade-offs on electric motor performances as specific power and efficiency whereas Target Setting is based on huge assumptions. For assessing cooling system weight, sizing specified structure of electric motor is unavoidable. Moreover, studies of others work packages are strong lylinked to the electric motor structure. Surface Mounted Permanent Magnet Synchronous Motor topology is one of electric motor topology which satisfies the analytical model of Target SettingTool. A sizing tool called "SM-PMSM" has been carried out based on Surface Mounted Permanent Magnet topology helpful for others packages for providing more details and for checking the Target Setting Tool validity. Two sizing of electric motors with their cooling systems were carried out using Target Setting Tool, SM-PMSM and others tools performed by WP3 to identify the required technologies for the term medium (2025) and long (2035) term HASTECS targets. The sizing using these tools was checked by finite element analysis