Efforts to use microwaves in material processing are gradually increasing. However, the phenomena associated with the processing are less understood; popular mechanisms such as dipolar heating and conduction heating have been mostly explored. The current paper reviews most of the significant phenomena that cause heating during microwave–material interaction and heat transfer during microwave energy absorption in materials. Mechanisms involved during interaction of microwave with characteristically different materials – metals, non-metals and composites (metal matrix composites, ceramic matrix composites and polymer matrix composites) have been discussed using suitable illustrations. It was observed that while microwave heating of metal based materials is due to the magnetic field based loss effects, dipolar loss and conduction loss are the phenomena associated with the electric field effects in microwave heating of non-metals. Challenges in processing of advanced materials, particularly composites have been identified from the available literature; further research directions with possible benefits have been highlighted.

Microwave–material interaction phenomena: Heating mechanisms, challenges and opportunities in material processing

The aim of this work is to establish an accurate yet simple method for predicting flux density distribution and iron losses in linear permanent-magnet synchronous motors (LPMSMs) for iterative design procedures. For this purpose, an improved magnetic equivalent circuit for calculation of the teeth and yoke flux densities in the LPMSMs is presented. The magnetic saturation of iron core is considered by nonlinear elements and an iterative procedure is used to update these elements. The armature reaction is also taken into account in the modeling by flux sources located on the teeth of motors. These sources are time dependent and can model every winding configuration. The relative motion between the motor primary and secondary is considered by wisely designing air gap elements simplifying the permeance network construction and preventing permeance matrix distortion during primary motion. Flux densities in different load conditions are calculated by means of the proposed model. The effects of saturation and armature reaction on the flux density distribution are shown in detail. Using these flux densities, iron losses in the motor are examined and its variations versus motor parameters are then studied. All results obtained by proposed model are verified by finite-element method based on an extensive analysis.

An Improved Magnetic Equivalent Circuit Model for Iron-Core Linear Permanent-Magnet Synchronous Motors

Commercial buildings are attractive targets for introducing innovative cyber-physical control systems, because they are already highly instrumented distributed systems which consume large quantities of energy. However, they are not currently programmable in a meaningful sense because each building is constructed with vertically integrated, closed subsystems and without uniform abstractions to write applications against. We develop a set of operating system services called BOSS, which supports multiple portable, fault-tolerant applications on top of the distributed physical resources present in large commercial buildings. We evaluate our system based on lessons learned from deployments of many novel applications in our test building, a four-year-old, 140,000sf building with modern digital controls, as well as partial deployments at other sites.

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BOSS: building operating system services

Adjustable-speed electric motor/generator drives (ASDs) are used to save electric energy and increase productivity in variable-output work processes of all new and well-established industries such as: digital information gadgets, digital home appliances, automotive and robotics electric actuators, pump compressors, other vehicles, industrial processes, and distributed and renewable energy system electric generators. With power levels that go from less than 1 W to hundreds of megawatts, ASDs have become in the last 20 years a very dynamic worldwide industry/market. The recent advances in electric/magnetic materials, modeling tools, design and fabrication of electric machines for ASDs, corroborated with matched progress in ASD power electronics with power quality control, DSP menu based control, novel sensors and interfacing, field orientation and direct torque control (FOC and DTC), and advanced state observers for motion or current sensorless control, has prompted us to do this selective review. This article selects a few control issues in ASD, such as performance indices, three-phase ac motor control principles, wide constant power speed control, motion-sensorless control of ac drives, variable-speed ac generator control, and linear motor drives control, and discusses their basics, recent progress, and a few directions of ASD research and industrial development for the near future.

Control issues in adjustable speed drives

In this paper, a complementary and modular linear flux-switching permanent magnet (MLFSPM) motor is investigated, in which both the magnets and armature windings are placed in the short mover, while the long stator consists of iron core only. The proposed MLFSPM motor incorporates the high power density of a linear permanent magnet synchronous motor and the simple structure of a linear induction motor. It is especially suitable for long stator applications such as urban rail transit. The objective of this paper is to build the mathematical model for the purpose of control of this motor. The simulation results by means of finite-element analysis (FEA) verified the theoretical analysis and the effectiveness of this model. Both the analytical model and the FEA results are validated by experiments based on a prototype motor.

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Modeling of a Complementary and Modular Linear Flux-Switching Permanent Magnet Motor for Urban Rail Transit Applications

Topology and Selection Definitions, Geometry, and Thrust Generation Linear Synchronous Motor Topologies Calculation of Forces Linear Motion Selection of Linear Motors Materials and Construction Materials Laminated Ferromagnetic Cores Permanent Magnets Conductors Principles of Superconductivity Laminated Stacks Armature Windings of Slotted Cores Slotless Armature Systems Electromagnetic Excitation Systems Superconducting Excitation Systems Hybrid Linear Stepping Motors Theory of Linear Synchronous Motors Permanent Magnet Synchronous Motors Motors with Superconducting Excitation Coils Variable Reluctance Motors Permanent Magnet Hybrid Motors Motion Control Control of AC Motors EMF and Thrust of PM Synchronous and Brushless Motors Dynamic Model of a PM Motor Thrust and Speed Control of PM Motors Control of Hybrid Stepping Motors Precision Linear Positioning Sensors Linear Optical Sensors Linear magnetic Encoders High Speed Maglev Transport Electromagnetic and Electrodynamic Levitation Transrapid System (Germany) Yamanashi Maglev Test Line in Japan Swissmetro Marine Express Building and Factory Transportation Systems Elevator Hoisting Machines Ropeless Elevators Assessment of Hoist Performance Horizontal Transportation systems Industrial Automation Systems Automation of Manufacturing Processes Casting Processes Machining Processes Welding and Thermal Cutting Surface Treatment and Finishing Material Handling Testing Industrial Laser Applications Appendix A Magnetic Circuits with Permanent Magnets Appendix B Permeances for Magnetic Fluxes Appendix C Performance Calculations for PM LSMs Symbols and Abbreviations References

Linear Synchronous Motors : Transportation and Automation Systems

Transverse flux electric motors are made using a unique process where individual components are premade and then assembled together. A stator portion is made by nesting a coil between two stator core portions. The stator core portions are made from laminations or sintered powder materials. A separate rotor portion is provided with a core and two permanent magnets that interact with projections on the stator core portions. In one example, the stator includes support members that support additional magnetic core portions to magnify the magnet flux density in the air gap between the stator and the rotor.

Fabricated components of transverse flux electric motors

Transverse flux electric motors are made using a unique process where individual components are premade and then assembled together. A stator portion is made by nesting a coil between two stator core portions. In a disclosed example, distinct first and second stator core portions are formed. The stator core portions in disclosed examples are made from laminations or sintered powder materials. In a disclosed arrangement, a coil is supported between the core portions of the stator such that the core portions enclose at least part of axial surfaces on the coil. A rotor that has a core and a plurality of magnets is supported relative to the stator for relative rotary motion such that the plurality of magnets of the rotor interact with the stator core portions during the relative rotary motion.

Zbigniew J. Piech

Papers

Linear Synchronous Motors : Transportation and Automation Systems

Fabricated components of transverse flux electric motors

Method for making an electric motor

Materials and Construction

Industrial Automation Systems