A more favorable maglev coil system was proposed for the combined propulsion, levitation and guidance (PLG) system. This coil system combines the functions of propulsion, levitaion and guidance of vehicle into one coil. This paper discribes the optimization of coil dimensions for minimizing the apparent power input for propulsion. The coil dimensions are chosen so that the levitation force, the lateral stiffness and the rolling stiffness satisfy necessary values and that the propulsion force is balanced with the running resistance, including the magnetic drag force. Ground coils are assumed to be arranged with either 120 degree pitch or with 60 degree pitch in a single layer. By using numerical examples, it becomes clear that the apparent power input has a minumum value at a certain value of the pole pitch. For example, the optimum pole pitch in the case of 120 degree coil pitch is a little shorter than that of the 60 degree coil pitch. Dependence of the optimum pole pitch on such parameters are investigated. These include mmf and height of the on-board superconducting coil, the cross sectional area of the ground coil, the feeding section length and the mechanical air gap.

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The techniques of MAGLEV are expected to apply not only to rail ways but also to various fields of industries. As one of such fields, the application to process lines of steel plates is now in the limelight. However, as the levitated steel plates are thin and flat in this kind of MAGLEV system, any guide force in conventional MAGLEV ones is not induced. Therefore once the steel plates levitate, soon the gravity force makes them sideslip if electromagnets are slantingly attached to a base table. This paper deals with a control method that lets the steel plate levitate stably and horizontally and deals with various experimental results.

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The authors have proposed the electromagnetic device called the “magnet wheel” with the rotator attached strong permanent magnets and the conducting plate. This has the functions of induction repulsive type magnetic lift force and thrust which are obtained by using the rotator over the conducting plate as the “partial overlap” or the “tilt” method.
This paper presents the performance of self-driven magnet wheel integrated own drive equipment, which is composed by addition of the three-phase armature winding in the place between the permanent magnets and the yoke. As the results for the partial overlap type magnet wheel, the following facts were cleared. The power factor in the input of the self-driven magnet wheel unit is nearly 1.0 in spite of induction repulsive levitation. From the experimental results of the test maglev car mounted four magnet wheel units, it is confirmed that the magnet wheel has the sufficiently large lift force against the own weight and then the half of driving power required for the levitation can be converted into the thrust. By using four wheels, the component of torque is canceled, and the lift force and thrust of the test maglev car are obtained respectively by the summation of those of one unit. The stable levitation was confirmed experimentally.

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As for the structure of the X-YLIM, two kinds of windings (one in the X direction and the other in the Y direction) were wrapped respectively around two horizontal axes, X and Y. By these windings it became possible to generate a two-dimensional travelling magnetic field and drive the moving part in any direction within the two-dimensional place.
In this paper, we take a three-dimensional one-pole model of X-YLIM into consideration, and used three-dimensional finite element method as the analytic technique. This paper examines the followings to obtain guidelines for the future: (1) the flux density with respect to the height of the primary iron core. (2) the flux density with respect to the yoke thikness. (3) the flux density with respect to the primary current. (4) the relationship between the air gap and the thrust.

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In the conventional zero-power controlled electromagnetic suspension (EMS) systems, a magnet unit, which suspend a vehicle, is composed of electromagnets and a permanent magnet. The electromagnets are controlled to maintain air gap length between the magnet unit and the guide rail so that the attractive force due to the permanent magnet are balanced with the suspended weight of the vehicle. This means the number of magnet units must be equal to the number of kinetic degrees of freedom. Consequently, the vehicle needs the mechanism which gives every magnet unit adjustment of the gap length in accordance with the suspended weight.
The authors propose an improved zero-power control. This new technique can remove the gap adjustment mechanism from the vehicle. The improved zero-power control not only levitates a rigid body vehicle with arbitrary number of magnet units but also guides the vehicle without any guide magnets and the detectors under the guide-effective EMS system. The pair of the improved zero-power control and the guide-effective EMS system allow conventional EMS systems to be made more compact in size and lighter in weight. In this paper, the authors explain the principle of the improved zero-power control and clear the property of zero-power control.

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A reciprocating compressor with a rotary motor which used in a refrigerator and so on, is low efficiency since it has the large mechanical losses due to the crank mechanism. In the linear compressor of free piston with linear motors, it can be decreased the mechanical losses of the crank mechanism and increased system efficiency. However, the dead center in the compressor system which used the crank is mechanically decided, while the piston position control is required in the linear compressor system due to free the piston. So the compressor will be breakdown and the system efficiency will be fairly decreased, if the piston position is not controlled successfully.
A linear pulse motor (LPM) generally has the precise positioning ability in the open-loop control without the position sensor. Therefore, we expect that the sensorless linear compressor system with the LPM can be realized.
In this paper, we examine the piston positioning accuracy and the efficiency of the sensorless linear compressor system with the LPM at the various compressor size and operating condition by using analytical and experimental approaches. As a result, the efficiency of the linear compressor system is higher than that of a conventional reciprocating compressor using an induction motor. The system efficiency is fairly improved in the linear compressor with LPM.

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This paper describes single-sided Linear Induction Motors (LIMs) with a short primary member. In the machines, a solidplate conductor is usually used for the secondary. In this study, we propose partial adoption of wound secondary members in the LIMs. Characteristics of the machine are summarized as follows:
1) Basic characteristics: The wound secondary shortens the magnetic clearance and makes characteristics of the machine superior compared with the solid-plate conductor one. Further, applying the proportional shifting method, we can improve thrust and efficiency characteristics.
2) Primary and secondary winding scheme: Parallel connection is proper for the primary and independently short-circuited scheme for the secondary to obtain stable performance.
3) Transient phenomena at the boundary between the wound secondary and the solid-plate one: In the boundary, especially at the end of the solid-plate conductor, undesirable phenomena develop. Thus, we propose a novel boundary structure, which yields stable transient performances.

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All vehicles used for commuting and deserted sections are the inverter control regenerative brake types. For the purpose of energy saving and maintenance, it is very important to grasp the value of effective coefficient of regenerative energy (the ratio of the regenerative energy to the total brake energy) in actual operation. Field tests proved that the value of effective coefficient of regenerative energy was quite low at deserted sections, while it was satisfactory high at commuting sections. It is required to discuss measures to improve the coefficient of regenerative energy for deserted sections. Therefore, we simulated measures to shorten lengths of train composition and to equip substations with inverters and a tie-feeding system.
Inverter control vehicles are used AC traction motors. On the other hand, the feeding system is direct current. therefore the alternating current of these must be changed into direct current. We theoretically defined the technique to change the AC electric power of those into DC electric power at the simulation.

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A capacitor input type rectifier is spreading widely by reason that its circuit configuration is simple and low cost. However, the rectifier includes many harmonics in an input current, and an input power factor is low. Hence, the input current harmonics cause voltage waveform distortion of an input power source, and the low power factor causes efficiency decline.
Many sinusoidal rectifiers have been proposed to solve these problems. However, most of them have any complicated control such as a pulse width modulation (PWM) or a feed back control. Therefore, the authors have been proposed a twin converter which is composed of a full bridge diode rectifier, a pair of capacitors, a pair of reactors, and a pair of switching devices. The twin converter has simple configuration and simple control strategy. And excellent performance of the twin converter is revealed. However, the design method of the twin converter is not established firmly.
Therefore, this paper studies on design method of the twin converter. And the design method is shown in detail in order to derive optimum values of the pair of reactors and the pair of capacitors. Moreover, experiments are carried out to verify the feasibility of the proposed design method of the twin converter.

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In this paper, we consider configurations of the superconducting magnet (so call SCM) for reduction of weight of magnetic shielding and improvement of electromagnetic force characteristics. We can reduce leakage flux by SCM configuration with small size superconducting coils (so call SC coils) on these ends and make use of it to reduce the weight of magnetic shielding. We vary SCM size (parameter), keeping constant length of bogie, to seek optimal configuration of SCM. Generally speaking, SCM configuration with smaller size SC coils on these ends of coil array (and long pitch SCM configuration) is more advantageous for magnetic shielding, magnetic drag force and levitation force. On the other hands, propulsion force decreases in this case. Therefore compromise must be taken between the former and latter. Optimal SCM configuration designed from the viewpoint of magnetic shielding is consistent with the one which is designed from the viewpoint of electromagnetic characteristics.

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Since ordinary magnetic field poles of PM (permanent magnet) motor generate higher harmonic flux, sinusoidal current will cause torque ripple. They are usually removed by short pitch winding, skew slot method and so on. These methods show a drawback in terms of lower efficiency.
Recently, new current control methods have been proposed to realize zero torque ripple and high efficiency drive at the same time. However, because the optimized reference current waveform obtained by these methods includes zero phase component, normal three phase full bridge inverter and d-q coordinate control method can not be used.
This paper proposes a new current control method that can achieve the zero torque ripple and maximum efficiency by using a normal three-phase inverter. The three-phase optimum current can be derived by satisfying both conditions: (1) the direction of the current resultant vector always agrees with that of the electromotive force resultant vector, and (2) scalar product of the two vectors is held constant. By means of modifying the coordinate transformation angle this method can also make it possible to compensate torque pulsation error with maximum efficiency using general d-q coordinate control method.
The proposed method has been verified by experiments.

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This paper presents a stormwater inflow prediction method based on a rainfall-runoff model. The rainfall-runoff model is derived by using system identification method with a nonlinear model called Hammerstein model, which consists of a static nonlinearity followed by a linear time invariant (LTI) system. It is shown that the Hammerstein model can represent nonlinear phenomena of a rainfall-runoff process effectively, thus the introduction of the Hammerstein model improves the accuracy of inflow prediction results. The effectiveness of the proposed method is illustrated through numerical simulations by using the rainfall-runoff data which is acquired in actual urban catchment and a sewerage treatment plant.

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The aim of the paper is to highlight the subharmonic generation in a high frequency time-sharing inverter. The paper presents the basic configuration and the mode of action of the inverter, followed by an approximate and an accurate analysis. Last one is performed by simulation. The main objective of the paper is the analysis of subharmonic generation.

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In this paper, we propose the optimal slip ratio estimation method based on Fuzzy Inference. One of the remarkable advantages of electric vehicle (EV) is the quick and precise torque response of electric motor, which realizes a novel traction control system (TCS). To prevent wheel skid phenomena, the optimal slip ratio control has been successfully developed. It maintains the slip ratio to the optimal value which gives the maximum driving force. The remaining problem is how to generate the optimal slip ratio command to the controller. First, we indicate that the effective estimation of the optimal slip ratio is difficult for a simple gradient method, which is one of the well-known optimization methods. Various knowledge obtained by experiments can be easily installed into Fuzzy Inference. Therefore, its estimation performance can be easily improved by accumulation of human experiences. This is a remarkable advantage in nonlinear estimation of actual road-tire characteristics. The effectiveness of the proposed estimation and control methods is confirmed by numerical simulation.

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In this paper, a novel prototype of pulse density modulated voltage source high-frequency resonant inverter using IGBT modules is presented for driving a silent discharge (SD) type ozone generating tube. An optimum design procedure of the series resonant inductor, which compensates the capacitance of the ozone generating tube, is described. The effective power regulation scheme, which is based on PDM (Pulse Density Modulation) and PWM (Pulse Width Modulation) hybrid control strategy implemented on DSP, and characteristics of this ozone generating tube load are illustrated. The effectiveness of this high-frequency inverter type ozonizer is proved in experiment, together with the simulation results.

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In recent years, several harmonic problems have been occurred in distribution system by load current harmonics of many smart machines with power electronics technology. Installing LC filters on power systems is conventional technology of reducing voltage distortion. And also, active filter is usually installed on power systems because of the same purpose. However, it is difficult to adjust the parameters of those systems for any kind of power systems, because of a variety of power system configurations. For the above mentioned problem, we have developed a new system which reduce voltages and currents distortion by using synchronous machine. It is named Harmonics Compensating Synchronous Machine. The Harmonics Compensating Synchronous Machine has been studied by the authors, and was confirmed compensating power system 5th and 7th harmonics by using 6kVA trial model. This paper describes the performances of developed 100kVA new machine and its control system using 3.3kV AC transmission line model. Further more this paper also describes field study results of the system installed in an actual 10MVA-distribution substation.

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In regard to a noise from encapsulation for power semiconductor devices, we investigated the vibration action of a flange which is the main cause of noise occurrence. Furthermore, we studied the influence of the vibration on the reliability of the power semiconductor encapsulation, and looked at a plan to reduce the vibration. We found that Lorentz power caused the flange to vibrate from the magnetic flux change which accompanies switching of a main current. The flange vibrated with a maximum amplitude of 8μ with 2.5kHz (current: 600A). The vibration amplitude of the encapsulated semiconductor device was estimated as about 60μm. At this time, the largest stress occurrence was 12kg/mm². The value was 1/2 or less that the limit fatigue of the flange composed of 42 alloy. We concluded there would be no problem regarding fatigue destruction of the flange.
Furthermore, when a vibration absorber was fixed between the flange and the insulator, the vibration of the flange could be reduced to about 1/10. This measure was considered to contribute to low noise operation.

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