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This paper investigates an efficient macroscopic modeling method for laminated iron cores made of grain-oriented silicon steel sheets. Under actual operating conditions, the material exhibits nonlinearity as well as a strong anisotropy resulting in a nonuniform distribution of the iron loss and the flux within each lamination. The presented results, based on a benchmark problem, are helpful in building a finite element model that takes into account the effects of the eddy current, induced by the magnetic field normal to the sheets, on the total iron loss and the distortion of the local magnetic flux in the laminations adjacent to the exciting coils, even though both the total flux inside the entire lamination stack and the source voltage are sinusoidal. Index Terms--Additional iron loss, arbitrary anisotropy, flux inside lamination, modeling of laminated iron core.

The interaction of moving conducting fluids with electric and magnetic fields provides the magnetohydrodynamic (MHD) phenomenon. Based on this principle, MHD pump uses the 'Lorentz force' to move fluid. The railgun channel is one important segment in an electromagnetic launcher (EML). As is known, one of the possible ways to increase the EML efficiency is to segment the working channel. For this purpose, MHD flow study is necessary. It is required to have the knowledge of the flow field and the temperature to design an MHD pump. The purpose of this paper is to investigate the effect of the magnetic flux density and current on the flow and the temperature distribution in an MHD pump. To solve the governing differential equations, a finite-difference-based code is developed and utilized. The temperature and velocity are calculated by solving the energy and the Navier-Stokes equations. Results show a maximum value of velocity for different values of magnetic flux density (B). However, the temperature stays almost constant with magnetic field. In addition, as current increases, the velocity and the temperature increase too. Index Terms--Energy and momentum equations, magnetic flux density, magnetohydrodynamic (MHD) pump.

This paper proposes design and analysis of a new linear motor called flux reversal linear synchronous motor (FRLSM), which is cost effective for long stroke applications. Passive rotor configuration of a typical flux reversal machine (FRM) can be utilized for a linear machine with less permanent magnet (PM). Three different design choices are investigated and compared both in thrust and normal force. The investigation shows extremely low force ripple and good thrust linearity through skewing and three-phase sinusoidal control. Reduced PM configuration generates about 21% higher thrust even with half amount of PM. Index Terms--Finite element method, flux reversal machine, linear synchronous motor.

This paper presents a novel method for analyzing transient magnetic fields in laminated iron cores. It is based on the finite-element method and a newly developed homogenization method is applied to model the lamination effectively. The homogenized constitutive relations, of which the approximation is only applicable to low-frequency problems, are derived analytically, neglecting eddy currents induced by time-varying magnetic fluxes parallel to the lamination. The loss due to the neglected eddy currents is estimated in the postprocessing state utilizing the obtained magnetic field variation. The calculated magnetic field is in good agreement with the measurement for a benchmark problem. It is demonstrated that the homogenized relations can be applied to the low-frequency problems. Index Terms--Anisotropic nonlinear magnetic field analysis, homogenization method, iron loss, laminated iron core.

In order to find an applicable power supply used in electric guns, there have been two types of the magnetic flux compression linear generator (MFCLG) that use the solenoids as the stators. That is to say, a piston armature or a solenoid armature is used within the stator. Although they can amplify the current theoretically, they can only compress the component of the magnetic flux. So their efficiency is low, and there exist some difficulties, which is difficult to solve in terms of the engineering technology. In addition, the use of the solenoid armature leads to the increment of the ineffective part of the solenoid. A kind of the rail stator augmentation MFCLG is presented here. It separates the combustion chamber-cylinder and the generating channel into two independent parts, and with an antirecoil device. The combustion chamber is extended as a cylinder. Within it the piston pushes the stator-armature package to move forward through the connecting rod along the generating channel consisted of the rails. This can compress the magnetic flux to generate the large electric current to be used by electric guns. If we fill the integrated fuel into the combustion chamber, we can realize the successive pulse operation. The separation of the combustion chamber-cylinder and the channel can avoid the high temperature burning gases from entering the channel to cause ablation. The basic mathematic model of this type of the generator is given and its physical properties are analyzed in this paper. It is found that it can compress the magnetic flux perpendicularly and has higher efficiencies for compression and conversion. It can produce large current with sufficient pulse width to supply the electric guns. Besides, a self-excitation method for this type of generator is also put forward, which can omit the seed power source. Instead, it uses the chemical energy that drives and compresses the magnetic flux to generate the electric current to produce the initial seed magnetic flux used by it. Index Terms--Combustion chamber, cylinder, electric generating channel, electric guns, magnetic flux compression, rail stator.

The search for the best configuration of the lightning protection system (LPS) that maximizes the regions inside the building, in which the values of the field are less than the specified threshold levels is an important topic of the LPS design. In this paper, we propose the use of a constrained decision planning tool to optimize the field profile in the regions where the high susceptible equipment will be placed. The induced magnetic flux is evaluated by time-domain simulation. The concepts of 'safe area' and 'connectivity index' are presented and used as measures of this procedure. Index Terms--Electromagnetic compatibility, EMP radiation effects, lightning, time-domain analysis.

A straightforward and physically motivated derivation of the reciprocity integral in magnetic recording theory is given for the quasi-static limit, where electromagnetic radiation and retardation effects are neglected, but frequency dispersion in the read head from all sources, including eddy currents, is specifically accounted for. This work attempts to correct some errors or misconception on this subject matter that remain in the literature. Index Terms - Flux linkage, frequency dispersion, high frequency read head, reciprocity integral, reciprocity principle.

The power loss of electrical steel sheet given in the data sheets of the steel manufacturers is related to linearly alternating flux conditions, measured with an Epstein frame or a single sheet tester, respectively. In the application of the material in electrical machines, we find large areas with rotational flux conditions, i.e., in the T-joint region of three-phase power transformers or above the stator teeth of three-phase motors and generators. The most general description of the magnetization process in this case is an elliptically rotating flux. The paper outlines the magnetic behavior of steel sheet under these flux conditions, and finally defines a simple method to predict the total power loss under elliptically rotating flux from data measured under linearly alternating and circularly rotating flux conditions only.

This paper describes a new method for the magnetic force analysis of high [T.sub.c] superconductor based on the flux flow and creep model. The introduction of the artificial conductivity, which is used in the conventional method, is not needed. The CPU time requirement of the calculations is considerably lower than that in the case of the conventional method. Thereby th vibration of a levitated permanent magnet was numerically analyzed by taking into account the flux flow and creep.

In the conventional magnetic field analyses that are applied to such things as rotating machines, the magnetic properties of the arbitrary direction have been modeled by using the magnetic properties of the easy axis and its perpendicular direction. Such kind of numerical modeling can not exactly show the phase difference between the magnetic flux density B and the magnetic field strength in the case of a rotating magnetic flux excitation. In this paper, the B- and H-values are measured as vector quantities under the rotating magnetic flux excitation. The magnetic properties of the material are expressed by the magnetic reluctivity tensor based on the measured results. This new expression is applied to the rotating magnetic field problem. As a result, it is shown tha our new method is applicable to the problem in the case of the rotating magneti flux excitation.

This paper describes a 3D computation of transverse flux inductors used for heating strip and thin slabs. The adopted mathematical model consists of a differential equation system for the steady-state eddy current problem in a configuration comprising a magnetic vector potential and a scalar potential and a Fourier's thermal conduction equation for moved media. The finite element method is applied in conjunction with the Galerkin method. The simplifications and boundary conditions required for an efficient solution are discussed. The discretization of the numerical model is set up with the aid of macroelements and includes upwards of 100 000 nodes for simple builds. The suitability of the numerical method developed for optimum design of transverse flux inductors is demonstrated by some results.

Within a conductor the field near a corner is represented by two modes, each of which is a solution of the diffusion equation. The resulting relationships between normal and tangential fields on the conductor surface are thereby extended from right-angled corners discussed previously to those of any angle, and are shown to reduce to the well-known surface impedance expression as a plane surface is approached. These surface expressions are implemented by cross-coupling scalar potential values across the corner in a 2-D finite-elemen computation and are compared with a vector potential computation which includes the conductor.

This paper presents a finite element analysis of nonlinear magnetostatic field based on an artificially hardened model of soft magnetic materials. The nonlinearity of B-H curves is decomposed into two parts, one part with lower nonlinearity degree is included in the left hand side of the field equation and the other in the right hand side as the source term. The iteration error can reach the required error tolerance for all the nonlinear magnetic field problem which have been tried.

Modeling of magnetic recording heads using 2-D and 3-D finite element analysis was investigated for Metal-In-Gap and thin-film heads. It is confirmed that flu concentration as well as core thickness has to be carefully modeled when trying to solve in two dimensions. It is noted that nonlinear 2-D calculations of Metal-In-Gap heads are acceptable, however, 3-D analysis is strongly recommende for thin-film heads.

We propose a new analytical method for computation of magnetic flux lines in 3- space. Using the results obtained from finite element analysis and the magnetic flux line equation in 3-D space, the sequence of line segments that construct the magnetic flux line is computed analytically. The proposed method reduces computational time by nearly five times for the same accuracy with existing procedures, providing cheap and efficient computation. The procedure and some examples to present the usefulness of the proposed method are described.

In spite of extensive optimizations of transformer core designs, investigations of full sized cores showed distinct inhomogeneities of flux density B. Limbs showed discontinuous variations of B in peripheral packages and minima of B in thick central ones. The latter are not caused by global eddy currents but rathe by localized flux components [[Phi].sub.z] normal to the sheet plane. Attempts to determine the respective effective ac-permeability [[Mu].sub.z] yielded values below 100, i.e., almost three orders below [[Mu].sub.x] of the rolling direction. For given B, (planar) eddy current losses [P.sub.z] proved to exceed the respective values [P.sub.x] by two orders, a ratio which increases with increasing length L of the magnetized sheet region. The low ratio [[Mu].sub.z]/[[Mu].sub.x] yields a tendency of constant package flux throughout the whole core. A key criterium for [[Phi].sub.z]-components between packages proved to be the overlap regions which were studied in a comparative way for several step-lap configurations. Distinct differences of respective values of lap-region excitation [V.sub.L] were observed as a function of air gap lengths and the step number N, respectively. Variations of [V.sub.l] - and especially overlaps of high [V.sub.L] in connection with shifted overlap regions - proved to yield [[Phi].sub.z]-components including flux transfer between packages. In complex way, shifts yielded decreasing excitation power, but increased core losses due to planar eddy currents. In addition, package shifts cause both the discontinuities of B of thin peripheral packages and the minima of local B in thick central ones. With respect to core design, it can be assumed that small shifts favor take over of flux without causing significant planar eddy current losses (due to small L), while large shifts increase total losses in a disadvantageous way. With increasing N, these effects become less significant.

A software package based on the finite element technique has been developed to compute two dimensional magnetic field and loss distribution in transformer cores with the aid of a 386 microprocessor based personal computer. The finite element method offers a stable numerical solution with a high degree of precision and the software package takes into account both the non-linear B-H characteristic and the anisotropy of the core material. Optimum design of transformer cores is reasonably fast and cheap with this software in comparison with FEM packages run on mini or main frame computers. This paper describes several important features in developing the software package and shows some computed results for various three-phase three-limb transformer cores.

A plunger-type magnetic actuator is proposed for easier control of displacement, and is subjected to lumped modeling to relate the energy conversion between the Piezo and MM using the inverse magnetostrictive effect. Magnetic flux density and magnetic force in the magnetic actuator are simulated by using a magnetic analysis program. The lumped model was compared with the FEA model. The difference between two methods is within 10%. Index Terms--Lumped modeling, inverse magnetostrictive effect, magnetic actuator, plunger.

One of the important features for the cameras in cell phones today is the optical zooming. This paper presents design and optimization of a zooming mechanism via genetic algorithm (GA). The goal is to maximize voice coil motor (VCM) sensitivity in the zooming mechanism and, simultaneously, to keep various dimensions under physical limitation. The optimization first chooses key independent dimensions as design variables, and then establishes the computation procedure for the VCM sensitivity via equivalent circuitry. The correctness of the expression is validated by finite element analysis (FEA). Optimization results lead to that dimensions of the yokes and magnets reach optima at their extremes in preset constraints, and in result, high uniformity of the magnetic flux intensity along guide ways of the VCM is achieved. Index Terms--Cell phones, genetic algorithm (GA), voice coil motor (VCM), zooming mechanism.

The finite-element method enables an accurate analysis for the study on effects of armature reaction in electromagnetic devices, particularly those with complex structures and three-dimensional (3-D) magnetic flux paths. This paper investigates the effects of armature reaction on the parameters and performance of a permanent-magnet (PM) claw pole motor with soft magnetic composite (SMC) core, based on the magnetic field analysis using the 3-D nonlinear time-stepping finite-element method. The current in the stator winding produces a magnetic field, which interacts with the air gap field generated by the rotor magnets. Consequently, the air gap flux density profile against the rotor position produced by the rotor magnets deviates, and so does the back electromotive force. Since the stator field also changes the local saturation level of the magnetic core, the winding inductance varies with both the rotor position and stator currents. The inclusion of these effects in terms of parameter variations in the motor model is important for accurate performance analysis. On the other hand, the pattern of inductance against the rotor position and stator currents can be employed to effectively predict the rotor position at standstill and low speeds for robust sensorless control. The parameter computations are verified by experimental results on the PM claw pole SMC motor prototype. Index Terms--Armature reaction, finite-element magnetic field analysis, inductance, PM claw pole motor, SMC motor, winding flux.

This paper reports on optimized fabrication technologies for electromagnetic actuator systems and their characterization. These actuators consist of three-dimensional microstructures of increasing complexity like electroplated micro coils, flux guidances, insulation and planarization layers. The microstructures are fabricated by UV depth lithography using AZ9260, electrodepositable photo resist and Epon SU-8. Electroplated nickel iron and copper is used for the generation of flux guidance and coils. The magnetic flux is generated and guided in plane by a three dimensional double meander coil wound around laterally toothed stator poles. The traveller's comb shaped poles reach in between the stator poles and, therefore, are attracted from both sides. Thus, the attraction forces exceeding thrust, common to any VR-motor concept, are eliminated. The micro actuator was simulated, fabricated and successfully tested. Index Terms--ED-photo resist, epon SU-8, micro coils, UV-depth lithography, variable reluctance micro actuator.

A triaxial orthogonal magnetometer head is presented in this paper. The head is constructed using a single piece of an amorphous wire. The wire is bent into three mutually orthogonal U-shaped branches on each of which a pickup coil is wound. The performance of the proposed head is evaluated in comparison to that of a triaxially assembled sensor head by using three separate uniaxial fluxgate heads. The input--output characteristics of each channel and the cross- talk effect are investigated. A simple calibration method is shown to decrease the cross-talk effect and to improve the orthogonality of the single wire head. Noise level is evaluated for both heads. Index Terms--Fluxgate sensor, fundamental mode, triaxial magnetometer, U-shaped, vector magnetometer.

In order to improve amenity for patients in hospitals, we have designed an open type of magnetically shielded room (MSR) for magnetic resonance imaging combined with cancelling coils, which enable transparent opening. First, an optimal arrangement of cancelling coils is investigated using three-dimensional magnetic field analysis. Secondly, the validity of the analysis method is verified and the realization of an open type of MSR designed both for keeping low leakage flux density and for maximizing the opening is confirmed by experiments using a small MSR model. Index Terms--Amenity of patients, cancelling coil, magnetic field analysis, magnetic resonance imaging, magnetically shielded room.

We have developed a digitally controlled flux-locked loop (FLL) system using a double-counter method to achieve both high performance and low cost. This system is composed of generally used electric devices. The system slew rate is about 1.3 k [[PHI].sub.0]/S, where [[PHI].sub.0] is the flux quantum. The measurable flux amplitude and dynamic range are 218 [[PHI].sub.0] and 141 dB at 1 Hz and 22 [[PHI].sub.0] and 121 dB at 10 Hz, respectively. A white noise level measured in the magnetically shielded room (MSR) is 36.1 fT/[Hz.sup.1/2]. Magnetic measurements with a first-order gradiometer were done outside the MSR, and the developed system can detect a magnetocardiogram in an unshielded condition. Index Terms--Double-counter method, flux-locked loop (FLL), magnetically unshielded, magnetocardiogram, SQUID.

This paper presents an efficient finite-element-based approach for a cogging torque analysis of pancake-type motors with inherent three-dimensional (3-D) flux distributions. For such cases, 3-D finite element analysis (FEA) that accounts for all 3-D effects is often required for convincing and reliable results. However, to obtain sufficient information, a considerable number of models may need to be created and result in a time-consuming analysis process using 3-D FEA. Therefore, a method named the '2-D Plus' is proposed to significantly improve the time efficiency of analysis based on two-dimensional techniques without sacrificing accuracy. Complete and smooth cogging torque waveforms can then be rapidly produced with the aid of only two extra 3-D models. The results from the presented technique agree well with that from 3-D simulations. The effectiveness of the proposed method in cogging torque analysis is thus verified. Index Terms--Cogging torque, finite element analysis, 3-D flux distribution.

A one-piece permanent magnet rotor, made with bonded Nd-Fe-B magnet and soft magnetic powder core, was successfully fabricated. By pressing these different powders in the same cavity, it is expected that the mechanical tolerance can be very accurate and that the bonding strength can be very strong. Furthermore, because the magnet and the iron yoke are bonded to be as one component in a series of process, various shape of magnet segment can be obtained, not like the previous designs such as rectangle or simple arc segment. For the bonded magnets, both isotropic and anisotropic bonded magnet can be used. When oriented bonded magnet with Br = 0.9 T was used, we could get magnetic flux comparable to that with sintered Nd-Fe-B, when properly designed. Index Terms--Materials processing, permanent magnet machines, torque ripple.

For electrical machines with three-dimensional (3-D) magnetic fluxes, the magnetic properties of magnetic materials under 3-D excitations should be properly determined and applied in machine design and analysis. This paper presents the construction and calibration of the H (field strength) and B (flux density) sensing coils of a 3-D magnetic property testing system, and the correction of measurement error due to the misalignment of sensing coils with excitation fields. The 3-D tester has been used to measure the magnetic properties of soft magnetic composite (SMC), a material specially developed for application of 3-D flux electrical machines. Some 3-D results have been obtained on a cubic SMC sample. The measurement errors caused by the misalignment of sensing coils and excitation fields are corrected by a rotational transformation of coordinates. Index Terms--Calibration, misalignment, rotational transformation of coordinates, sensing coils, three-dimensional (3-D) magnetic property tester.

This paper presents analysis and measurement results of a high-frequency (HF) coaxial transformer with Faraday shield. The simulation results demonstrate that the magnetic flux and eddy current distribution are not impacted by the inclusion of a Faraday shield. The Faraday shield's maximum eddy current density is less than 17% of the maximum density found in either of the other two windings. The experimental results demonstrate that the voltage ratio, coupling coefficient and load characteristic of the HF coaxial transformer with Faraday shield at frequencies up to 1 MHz are in agreement with the turns ratio and load regulation for a transformer in which capacitive effects are neglected. Index Terms--Coaxial transformer, eddy current, Faraday shield, high-frequency transformer.

Natural gas transmission pipelines are commonly inspected using magnetic flux leakage (MFL) method for detecting cracks and corrosion in the pipewall. Traditionally the MFL data obtained is processed to estimate an equivalent length (L), width (W), and depth (D) of defects. This information is then used to predict the maximum safe operating pressure (MAOP). In order to obtain a more accurate estimate for the MAOP, it is necessary to invert the MFL signal in terms of the full three-dimensional (3-D) depth profile of defects. This paper proposes a novel iterative method of inversion using adaptive wavelets and radial basis function neural network (RBFNN) that can efficiently reduce the data dimensionality and predict the full 3-D depth profile. Initials results obtained using simulated data are presented. Index Terms--Adaptive wavelets, iterative inversion, MFL inspection, RBFNN.

Two types of media with a high-[B.sub.2] Fe-Co soft underlayer (SUL) were prepared to reduce the film thicknesses of the Ru intermediate layer and the SUL. The crystal orientation of the media was greatly changed by using a thin Ta underlayer. The magnetic properties of the SULs were similar, independent of the existence of the Ta underlayer. However, the media with high orientation have l arge [H.sub.c] and squareness ratio. The Ru layer thickness for obtaining the maximum [H.sub.c] and squareness ratio is 5-7 nm. This seems to be due to the imperfection of Ru orientation. From the read-write properties, the minimum of the Ru layer thickness is 7 nm. However, from vibrating-sample magnetometer measurements, the magnetic interaction between the recording layer and the Fe-Co SUL is broken by using an Ru layer of 1-3 nm. The intermediate layer thickness could be reduced down to about 1 nm if the orientation is improved. Index Terms--Fe-Co, high-saturation magnetic flux density, intermediate layer, perpendicular recording media, Ru, soft underlayer (SUL).

The reusable linear magnetic flux compressor has been regarded as a preferred pulsed power supply for the electric gun. Some papers have discussed models for optimal design of this compressor. However, none of them have discussed the resistance calculation of the compressor coil particularly, which is the key issue of the compressor design. Based on a two-dimensional finite element model which can simulates current distributions a in the conductors of the compressor coil, this paper presents a method for the resistance calculation of the compressor cot. In order to verify the proposed method, a physical model of the compressor coil has been built in the laboratory. The comparisons between the calculated and measured results show that the proposed method is an effective tool for resistance calculation of the compressor coil. Index Terms--Coil, finite element, magnetic flux, resistance.

By inserting only 0.75 nm-thick Cu layer between the CoFe/Cu/CoFe/IrMn spin-valve stack and Ta underlayer, magnetoresistance (MR) ratio and AR were about 1.8 and 1.4 times, respectively, as large as those without the Cu layer. Atomic force microscopy, x-ray diffraction, and MR measurements suggest that the Cu 'islands' formed in the initial growth stage modified the interfaces of the spin-valve and the structure of the component layers, resulting in the enhancement of the spin-dependent electron scattering. When the inserting Cu thickness (t) was larger than 1.5 nm, not only the MR characteristics but the magnetic properties, such as coercivity of the free layer, was improved in comparison with that of t = 0 nm. This is due to the considerable increase in the crystallinity of the spin-valve films. In this thickness range, Cu is expected to function as the buffer 'layer'. Index Terms - Cu islands, spin-valve, GMR, coercivity

A new type of a parametric motor using a laminated iron core is proposed in this paper. The structure and the fundamental performance characteristics of the motor are discussed. It is clarified that the output and efficiency of the trial motor are comparable to conventional single phase induction motors. The behavior of the magnetic flux in the stator core of the motor is also studied to understand the operating mechanism of the motor.

We investigated the operating mechanism of the microstrip-line type pickup coil used for thin-film permeance measurements up to GHz range. We found that some flux lines form continuous loops around the ground plane when the coil has a sample window. How the flux distribution changes and how the induced voltage increases when a magnetic sample is inserted was clarified by measurements of flux distribution and finite element calculations.

The existing methods of measurement of the flux and loss distribution in the laminations of rotary electrical motor is to employ arrays of search coils made from 40 Standard Wire Gauge (s.w.g.) enamelled copper wire and arrays of miniature thermistors. These introduce unacceptable air gaps between laminations and consequently make the core building difficult. To overcome this drawback, thin film sensors have been deposited on electrical steel sheets which build up the stack of the core of a rotary motor.

Statistical treatment of the succession in time of the Barkhausen-noise pulses shows that magnetic noise possesses characteristics that are similar to those of electric shot noise. On the other hand, the electric shot-noise intensity in a noisy component is known to be related directly to the square root of the dc current through the component. Hence, it is intriguing to relate in the same manner the magnetic-noise flux-fluctuations to a magnetic entity similar to the dc current in the electric case. The present work is a successful attempt to demonstrate that such relationship exists. This is attained by employing the duality that relates the time-derivative of the magnetic flux to the electric current. The magnetic noise measurements of commercially available thin-film magnetoresistors confirm the applicability of the proposed approach. The noise was generated by exciting the magnetoresistors by an ac magnetic field along their easy axes. The level of the resulted flux time-derivative was changed by varying the excitation frequency.

A new technique for measuring B-H curves of grain-oriented silicon steel along arbitrary directions has been developed. As the control of waveform is not necessary in the new technique, it is possible to measure B-H curves up to high flux densities which are required for calculating flux distribution using the finite element method.

The operation of a zero-flux type current sensor that uses negative feedback through the magnetic circuit is analyzed. By focussing on the intrinsic current transformer-like operation of the sensor, we clarify the principle mechanism of operation. We also reveal that this type of sensor has high-performance characteristics which are not achieved with conventional sensors. Analytical results agree well with experimental ones.

In this paper, we describe an experimental study of the distribution and causes of the iron loss occurring in a parametric induction motor, with a view to further improving the characteristics of a motor and establishing the design method of the motor. It is clarified that a greater part of the iron loss in the motor occurs in the common magnetic circuit, and is caused by an alternating magnetic flux normal to the lamination plane. It is also clarified that the iron loss occurring in the common magnetic circuit is closely related to the magnetic anisotropy and the area of contacting surfaces between the exciting cores and the common magnetic circuit.

This paper provides a refinement on the system state-space model formulation of the transverse flux homopolar linear machine prototypes as proposed in (1)-(3), such that the saliency effects of these systems can be properly accounted. Due to the periodic relative position-dependent characteristics of the machine primary and secondary sides, by introducing appropriate weighting concept onto the convolution technique, an integrated and compact set of matrix representations regarding to the system state-space equations can be derived. Numerical verifications are supported by experimental results to illustrate the adequacy of the proposed technique.

Remedies for various deleterious effects on the fields of permanent magnet solenoids arising from practically necessary structural compromises are discussed and means of meeting some common mutually contradictory technical requirements are suggested. Among them are reduction of flux leakage by an order of magnitude, remedies for problems caused by access holes, provision of field-free regions within the magnetic structures for field sensitive components and elimination of unwanted partial shielding due to iron pole pieces.

Permanent magnet flux sources of the enhanced 'magic' ring/'magic' sphere types with an outer to inner radius ratio of 6 can be made to be mechanically field adjustable from 0.0 T to + or - 4.0 T in working gaps transverse to the applied field. In adjustable sources of similar size with gaps longitudinal to the field, the somewhat smaller field range of -3.0 to 3.4 T is attainable. The cylindrical sources pose no difficulties of access or adjustability and ways of providing these for the spheres as well are discussed.

Miniature fluxgate sensors with symmetrical closed core elements on both sides of the planar coils were manufactured using standard microtechnology. The new sensors have shown substantial improvement over the standard single-sided microfluxgate sensors: for the same field range the sensor noise was reduced 10-times to 20 nT rms (20 mhz ... 10 Hz) and the perming suppressed below 5 [micro]T, for field shocks of 6 mT. The maximum sensitivity for sinewave excitation was 32 V/[micro]T for 1 MHz frequency and 200 mA p-p excitation current amplitude. Pulse shape of the excitation current allows use of high current peaks to suppress perming, while the rms value is low. Using a 20% duty factor squarewave excitation with 180 mA p-p amplitude, the sensitivity was twice that of the sinewave excitation, while the chip temperature dropped from 80 [degrees] C to 40 [degrees] C. Index Terms--Fluxgate, magnetic field sensors, magnetometers, microfluxgate.

If the air-gap flux of the induction motor is saturated, the conventional adaptive speed estimator cannot avoid the influence of the nonlinear inductance variation. This paper presents a new speed estimation scheme that estimates the rotor speed and the mutual inductance simultaneously. The proposed estimator consists of an error between the flux derived from the stator voltage equation and the flux estimated from the rotor flux observer. Introducing a new error correction term into the speed estimator increases the estimation ability of the conventional speed estimator although the motor flux is saturated. The experimental results show the validity of the proposed method. Index Terms--Flux saturation, induction motor, mutual inductance, speed estimator.