Analysis of consequent-pole flux reversal permanent magnet machine with biased flux modulation theory

This paper investigates a consequent-pole flux reversal machine (CP-FRM) with biased flux modulation theory, which employs homopolar permanent magnets (PMs) placed between the adjacent stator poles. The machine topology is introduced from the perspective of FRM with a shifted magnet position and CP arrangement, and the performance comparison between the proposed CP-FRM and its original surface-mounted PM (SPM) counterpart is presented to highlight the torque improvement of the CP structure. Then, a simplified permeance model is applied to the CP-FRM to identify the principal effective air-gap field harmonics engaging in the torque productions. It shows that the CP-FPM works based on a biased flux modulation effect due to its asymmetric air-gap field distribution caused by the CP configuration, which unveils its underlying torque improvement mechanism over its SPM-FRM counterpart. In order to obtain the highest torque capability, the key design parameters are analytically optimized by analyzing the winding configuration, which aids the establishment of a general design guideline for the CP-FRM. The analytical and FE results are validated by the experiments

Gearless generator with magnets on the stator for wind turbine

In this work a new design of multi-pole gearless low-speed Generator with Magnets on the Stator (GMS) for wind turbine is described. Gearless GMS combines both high number of magnetic poles created by magnets and low-pole winding creating strong electromotive force. Therefore GMS has high efficiency and low operational speed. The GMS mathematical model has been developed. The low-speed gearless GMS was designed with the help of the developed mathematical model. Comparison of the designed GMS with a generator with magnets on the rotor (SG) is given. The GMS active material cost is 2.3 times less than that for the SG. The GMS mass is 1.3 times less. The GMS has higher efficiency at the rated speed. Also GMS maintain high efficiency in wide range of torques and speeds and GMS torque ripple is low. © 2018 Web Portal IOP. All rights reserved

Comparative analysis of partitioned stator flux reversal PM machine and magnetically geared machine operating in Stator-PM and Rotor-PM modes

In this paper, the partitioned stator flux reversal permanent magnet (PM) (PS-FRPM) machine and the conventional magnetically geared (MG) machine operating in both stator-PM (SPM) and rotor-PM (RPM) modes are comparatively analyzed in terms of electromagnetic performance to provide design guides for a MG machine regarding: (a) a SPM or RPM type machine and (b) a higher or lower gear ratio machine. It is found that a SPM type machine is recommended, since both PS-FRPM and MG machines operating in SPM modes have a higher phase back-EMF and hence torque than their RPM counterparts, respectively, as a result of a similar phase flux-linkage but a higher electric frequency since the iron piece number is larger than the PM pole-pair number. Moreover, a smaller gear ratio machine is preferred from the perspective of a higher power factor and hence a lower inverter power rating, as the conventional MG machines with higher gear ratios suffer from larger flux-leakage, higher synchronous reactance and hence lower power factors, as well as higher iron losses, than the PS-FRPM machines. However, higher gear ratio machines feature lower cogging torques and torque ripples due to the smaller difference between the PM pole-pair number and iron piece number. Both prototypes of PS-FRPM machine operating in SPM mode and MG machine operating in RPM mode are built and tested to verify the FE predicted results

Efficiency and Sustainability of the Distributed Renewable Hybrid Power Systems Based on the Energy Internet, Blockchain Technology and Smart Contracts-Volume II

The climate changes that are becoming visible today are a challenge for the global research community. In this context, renewable energy sources, fuel cell systems, and other energy generating sources must be optimally combined and connected to the grid system using advanced energy transaction methods. As this reprint presents the latest solutions in the implementation of fuel cell and renewable energy in mobile and stationary applications, such as hybrid and microgrid power systems based on the Energy Internet, Blockchain technology, and smart contracts, we hope that they will be of interest to readers working in the related fields mentioned above

Investigation of Magnetically Geared Stator Permanent Magnet Machines

Stator-permanent magnet (PM) (Stator-PM) machines include doubly salient PM, flux reversal PM (FRPM), and switched flux PM (SFPM) machines, in which both the PMs and armature windings are placed in the stator, whilst there is neither PM nor coil in the rotor. They have been the subject of much interest over the last 20 years. The operation and interaction mechanisms between the open-circuit and armature excitation magnetomotive forces (MMFs) in stator-PM machines have not been well described, however, which will be explained by the magnetic gearing effect in the first part of this thesis. It is found that similar to magnetic gears and magnetically geared (MG) machines, conventional single-stator-PM machines operate based on the modulation effect of the rotor to the open-circuit and armature excitation MMFs. It is also found that more than 95% of the average electromagnetic torque in SFPM machines is contributed by several dominant open-circuit and armature excitation air-gap field harmonics. The magnetic gearing effect in the partitioned stator SFPM (PS-SFPM) machines, which was proposed recently based on the magnetic gearing effect in the conventional single stator SFPM machines, is also investigated in this thesis. The partitioned-stator-PM machines also operate based on the magnetic gearing effect. Furthermore, over 93% of the electromagnetic torque generated in both the outer and inner air-gaps in the PS-SFPM machines is contributed by the dominant air-gap field harmonics. Consequent-pole PM topology and overlapping armature winding topology for the partitioned stator FRPM (PS-FRPM) machines, based on the magnetic gearing effect in the partitioned-stator-PM machines, are investigated in this thesis. By applying consequent-pole PM topology, about a third of the PM volume can be saved, but the torque density and efficiency are similar. For the overlapping armature winding topology, higher torque density, smaller loss, and hence larger efficiency etc. can be achieved when the machine stack length is relatively long. Finally, the PS-FRPM machines and the conventional MG machines, both of which have surface-mounted PMs, are compared in terms of electromagnetic performance. Compared with conventional MG machines, PS-FRPM machines have a smaller flux-leakage and hence a higher torque density and a larger power factor due to their smaller PM pole-pair number and iron piece number

Characterization, Design, and Optimization of Dual-Purpose Wind Turbines and Frost Protection Fans

This thesis report outlines the creation of a MATLAB tool to design reversible machines that can function as both wind turbines and as agricultural frost protection fans. Frost protection fans are used to prevent crop loss during radiative freeze events during which a temperature inversion is present. Such a dual-purpose machine fundamentally has the constraint that it must use symmetric airfoils, so a suite of tools for automatically designing an optimized wind turbine blade with symmetric airfoils using the Blade Element Momentum (BEM) theory approach is presented. The BEM code is then re-derived and adapted for use with a frost protection fan, which is analogous to a propeller at zero free-stream windspeed. The relative performance of a blade operating in fan mode is investigated using a turbulent jet entrainment model to predict the time-averaged temperature rise provided by the fan during a thermal inversion event. With these tools, an optimal configuration of blade pitch angle, rotor tilt angle, and tower height can be found for a given wind turbine blade. The models are incorporated into a cohesive program with a graphical user interface. The feasibility of such machines is found to depend heavily on the wind resource at a given site

Index to 1983 NASA Tech Briefs, volume 8, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1983 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Advanced Energy Harvesting Technologies

Energy harvesting is the conversion of unused or wasted energy in the ambient environment into useful electrical energy. It can be used to power small electronic systems such as wireless sensors and is beginning to enable the widespread and maintenance-free deployment of Internet of Things (IoT) technology. This Special Issue is a collection of the latest developments in both fundamental research and system-level integration. This Special Issue features two review papers, covering two of the hottest research topics in the area of energy harvesting: 3D-printed energy harvesting and triboelectric nanogenerators (TENGs). These papers provide a comprehensive survey of their respective research area, highlight the advantages of the technologies and point out challenges in future development. They are must-read papers for those who are active in these areas. This Special Issue also includes ten research papers covering a wide range of energy-harvesting techniques, including electromagnetic and piezoelectric wideband vibration, wind, current-carrying conductors, thermoelectric and solar energy harvesting, etc. Not only are the foundations of these novel energy-harvesting techniques investigated, but the numerical models, power-conditioning circuitry and real-world applications of these novel energy harvesting techniques are also presented

Energy: A continuing bibliography with indexes

This bibliography lists 1169 reports, articles, and other documents introduced into the NASA scientific and technical information system from January 1, 1983 through March 31, 1983

Index to 1985 NASA Tech Briefs, volume 10, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1985 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences