Since the Electric Power Research Institute in the U.S.A. (EPRI) proposed the FACTS (Flexible AC Transmission System) in 1988, R&D activities of the FACTS are intensively pushed by the liberalization of the power delivery system in the U.S.A. and the Central Europe. Especially, the Unified Power Flow Controller (UPFC) that has been developed by the EPRI and Westinghouse is one of the most functional devices. However, the UPFC has several problems because of having complex transformers. For example, it not only generates comparatively big power losses into the transformers but also has to prevent the magnetic saturation of the transformers. As an effective solution, the Transformerless Reactive Series Compensator (TLRSC) has been proposed. Some basic operations have been already described in detail. However, the TLRSC is directly series-connected with transmission lines and the line current always flows through the TLRSC. Therefore, such special operations as a pre-charging operation, a start-up/shut-down operation and a continuous operation must be considered to realize the TLRSC. In this paper, firstly, a new configuration of the TLRSC with AC switches is proposed. Next, it is focused that the AC switches can carry out the special operations. Finally, it is verified that the new TLRSC doesn't need any transformer at all.

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This paper proposes a Walsh-function based reconstruction-method of command voltage waveform of a PWM inverter. The Fourier harmonics of PWM inverter output voltage show that the PWM switching harmonics spread toward lower frequency range and it makes difficult to reconstruct the PWM command voltage waveform especially in the case when the command voltage waveform has sharp edge. On the other hand, the Walsh harmonics show very good separation between original command voltage component and PWM switching component. Therefore, the Walsh-function based reconstruction-method can reconstruct the PWM command voltage waveform correctly. These remarkable features of the proposed method are clarified by several simulation results.

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TCSC (Thyristor Controlled Series Capacitor) is used mainly to change power system characteristics to improve stability. However, it is basically a static control. Considering its quick response property, it is clear that TCSC has further potential to improve transient stability. By utilizing this remarkable advantage, in this paper, a new torsional vibration suppression control of turbine-generator system is proposed. Based on the 2-inertia system model, the controlled impedance of TCSC can directly affect the generator's mechanical behavior as a controlled input, but it's effect has nonlinearity. In the controller design, two approaches are proposed and compared. One is based on linear approximation and the other considers nonlinearity. The proposed method can be applied to various control systems using TCSC as a high performance control device.

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This paper describes a quasi-optimization of water distribution scheduling based on GAs (Genetic Algorithms) for drinking water plant. An optimal scheduling problem of water distribution plant is formulated as 0-1 integer programming problem. But it is known as one of NP-hard problems. Therefore, it may take much time to calculate the optimal scheduling. But GAs can be expected to semi-optimize the problem faster because of its features.
Firstly in this paper, 3 heuristic algorithms are proposed to apply GAs to water distribution optimization.
Next the effectiveness of 3 heuristics is discussed and GAs is compared with a traditional optimization method, Branch and Bounded Method, in respect to calculation time and optimality by simulation.

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The X-YLIM, which is capable of two-dimensional drive, has been proposed by the authors. Various characteristics of the system using X-YLIM are reported with aim to non-contact transport. In practically, the position of the center of gravity on the carrier is not always the center of it.
In this paper, we examine the following relationships between switching characteristics and effect from the shift in the center of gravity. (1) Accurate reproduction of switching characteristics, when the center of gravity is shifted. (2) Effects of velocity vector component of the carrier in negative phase breaking. Slow X-direction velocity gives large switching angle. (3) Relationship between thrust and switching/rotational angle. Appropriate thrust gives same switching/rotational angle for various shift in the center of gravity. (4) Relationship between switching angle and rotational angle. Appropriate combination of thrust and position of the center of gravity is able to gives the switch as switching angle is equal to rotational angle. So, right-angled turn is able.

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Linear metro with single-sided linear induction motor (SLIM) propulsion and wheel on rail support and guidance came into service in April of 1990 in Osaka and December of 1991 in Tokyo and then it is now constructed or planed at Yokohama, Kobe and Fukuoka in Japan. As the new traffic system is used widely, it becomes one of the most important subjects to decrease the energy consumption.
In this paper, design of the SLIM for the linear metro is formulated as the constrained nonlinear programming problem and optimum design is carried out for maximizing the efficiency. Seven parameters are chosen as independent variables, such as number of poles, pole pitch, stack height, secondary aluminum sheet thickness, overhang length, slot width/slot pitch and rated slip. Output KW/input KVA, maximum flux density in teeth, temperature rise, primary length, stack height, overhang length, maximum thrust and vertical force are selected as constraint function.
In the optimization procedure, the performance characteristics are formulated using space harmonic analysis taking into account end effect, skin effect and air gap leakage. The accuracy of the formulas is verified by experimental results.
It is effective for increasing the efficiency to adopt the copper reaction plate and decrease the mechanical clearance as small as possible.

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A stable position control method of a permanent magnet-type bearingless motor under loaded conditions has been already proposed by the authors. In the proposed control method, the permanent magnet MMF is replaced by the equivalent motor winding current. Information on both a magnitude and a direction of air gap flux is obtained by synthesizing the equivalent current and the q-axis current. A mutual interference between radial force components in two perpendicular axes, caused by an influence of amature reaction, is successfully decoupled.
In this paper, the definition of the equivalent current of permanent magnet is made clear. The equivalent current is dependent on the motor parameters. The influence of the error in the measured equivalent current to the rotor radial position control is discussed. The mutual interference of the radial forces, caused by the measurement error of the equivalent current, is confirmed by experiments. A required accuracy of the measured equivalent current is found. In addition, the influence of the error in the measured leakage reactance to the equivalent current is also presented.

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The superconducting magnetically levitated vehicle has guidance coils that produce vehicle guidance forces according to a null flux principle. However, the expected forces dont have significant damping forces to suppress a lateral vibration of the vehicle. Even though the experimental system has some magnitude of damping, it is still small. Moreover, since the guidance forces are very weak at low speeds, the minimum levitating speed is limited. The paper proposes a guidance method using LSM armature coil currents. When the currents are decomposed into dq frame variables so that the d-axis is assigned to the filed axis, the d-axis component of currents generates the lateral forces. The lateral forces of the vehicle are formulated, and the guidance force coefficient is defined. And the author shows the design formula of the guidance regulator system that employs a dynamic compensator using a feedback signal of lateral displacement. The calculated results show that the guidance regulator system works very well as we specify.

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An interior permanent magnet synchronous motor (IPMSM) with variable permanent magnet flux linkage is introduced in this paper. By adapting movable flux-shortening iron pieces in the flux barriers of the rotor, it is possible to decrease the permanent magnet flux linkage to some extent. In the flux-weakening control region, _??_he required d-axis current to weaken the armature flux linkage becomes smaller due to the decrease of the permanent magnet flux linkage. The constant output power operating range of the proposed IPMSM thus can be extended compared to the conventional IPMSM under the same limitation of the supply ability of the inverter. The becoming smaller d-axis also contributes to the improvement of the efficiency as well as the power factor characteristics especially at light load, high speed operation. By choosing suitable inserting scheme of the movable iron pieces, it is possible to realize optimal operating performance for the proposed IPMSM. The advantages of the IPMSM proposed in this paper are simulated and are verified with experiments.

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This paper describes a method of snowfall detection, which is mainly utilized in road management, using spatio-temporal data. Our method extracts snowflakes taken with a flat target painted black for the background of images. First, it extracts bar regions in time differential images. Next, the extracted bar regions are classified into two categories: (1) snowflake candidates, in which the bar regions are a regular distance apart in spatio-temporal data, and (2) noise, in which the regions are near. Finally, the method judges snowfall conditions according to feature parameters such as the spatio-temporal distribution for snowflake candidates. Experimental results show that our method can detect snowfall even at low intensity and the error rate is estimated to be very low, and also indicate that this method has the potential of application to road images in which the target does not exist.

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As the herald of real-world ITS application, Vehicle Information and Communication System (VICS) service has entered into the nation-wide deployment stage and the Electric Toll Collection System (ETC) is moving ahead to actual deployment. In 2000, the Advanced Cruise-Assist Highway System (AHS) demonstration will be conducted as a step toward real operations. Under such circumstances, a technology examination about increasing efficiency of the image sensor system is needed. We proposed a new technique to fuse many kinds of sensors related to the road traffic toward the actual deployment of AHS. A technique to fuse two kinds of the image sensors on the bases of multitask scheduling using the both preemption and time slice algorithm on the real time operating system is proposed in this paper. Furthermore, we establish the fused sensor and demonstrate the excellent performance of this sensor by doing inspection about detection ability of traffic condition, speed of passing vehicle, illegal parking and road condition in the actual outdoors environment.

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Information about the road condition is indispensable to achieve the assistance for safe driving, the optimization of traffic management and the increasing efficiency in road management that are the master plan of ITS. Therefore, an advanced system in corporating a new technique, which can detect the road conditions efficiently, is needed from the viewpoints of both vehicle and road facility system. We proposed elsewhere a new discriminating method of the road condition by means of texture analysis and multivariate discriminant analysis based on image processing as an approach from the viewpoint of the road facility system. However, toward practical use, there remained many problems to be solved to cope with the passing vehicle, passers-by and the weather changes. A technique to reduce these disturbing factors is proposed in this paper. Furthermore, we establish the experimental system and demonstrate the excellent performance of this system by doing inspection about discrimination ability of road condition in the actual outdoors environment.

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In recent years, speed sensorless control drives of Inductin motor are made practicable. As the advance of technology, speed sensorless control drives are required to expand drive region. Moreover, some speed sensorless control methods using an adaptive flux observer can identfy stator & rotor resistance without regenerative region. This paper proposes a novel speed sensorless control method using dual adaptive flux observer. This method realizes stator & rotor resistance identification including regenerative region. This method has the observer for rotor resistance & speed identification and the other one for stator resistance identification. The experimental results confirm the validity of proposed method.

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This paper reports results from performance comparison on the high efficient reluctance torque motors. The compared motors were SynRM (Synchronous Reluctance Motor), SPMSM (Surface Permanent Magnet Synchronous Motor), IPMSM (Interior Permanent Magnet Synchronous Motor) and typically low-cost IM (Induction motor). The all tested motors has the same distributed winding stator and we evaluated the performance differences which is generated from the rotor configuration. It was found that the IPMSM was superior in terms of efficiency and SynRM was most lowest cost and its efficiency was higher than typical IM which has rotor copper losses.

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The paper describes a comprehensive analysis of winding and inverter faults in the Switched Reluctance Motor (SRM). The analysis is based on a new method which allows dynamic simulation of phase interaction arising from mutual coupling, winding failures and inverter failures. The method represents the SRM accurately using a lumped parameter, magnetic equivalent circuit in which the air gap and rotor/stator pole permeances including those in the pole-tips are represented by one expression. A method to derive the parameter from single-phase magnetisation data is described. The analysis includes coil open-circuit, coil partial and full short-circuit, phase to phase short-circuit, coil to ground short-circuit, semiconductor switch short-circuit and bus short-circuit faults in a 3-ph 6/4 SRM with both series and parallel connected phase coils. The effect of pole magnetic polarity is also included. The faults are classified in terms of torque production, unbalanced radial forces, heat rise in coil and the risk of semiconductor switch failure by excessive current.

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This paper presents a voltage source soft switching space voltage vector modulated inverter which incorporates two types of soft commutations; lossless snubber capacitor single operating scheme and active auxiliary resonant DC link snubber scheme. The operating principle of soft commutation is described. In addition, the effectiveness of its improved soft switching scheme is proven on the basis of simulation data.

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This paper presents an approximate equation to evaluate the regulated output power of asymmetrical ZVS-PWM high frequency quasi resonant inverter for induction heating. Its approximate output power regulation characteristics derived from a theoretical point of view are discussed for induction heating loads as compared with the simulation results.

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This paper presents an electromagnetic induction eddy current-based continuous fluid heating appliance using voltage-fed quasi resonant high-frequency soft switching inverter with time ratio control scheme. Its power regulation characteristic are illustrated and this new consumer appliance is evaluated on the basis of its computer simulation and 4kW experimental setup.

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Novel topologies of three-phase rectifiers with half-voltage dc outputs are proposed. The proposed systems consist of double diode bridge circuits with additional switching devices and a three-phase transformer with a rating of around 50% power capacity of the dc output power. The rectifier can generate 24-step input voltage with a total harmonic distortion of 7.7%.

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In the superconducting magnetic levitation train, the race-track coil is often used for levitation or propulsion. However, it is difficult to analyze the magnetic field produced by the race-track coil which has linear and semicircular parts of exciting current. Therefore, the analytical solution of magnetic field by this coil has not been obtained yet. Then, in this letter, the exact theoretical analysis is carried out on magnetic field and self-inductance of a race-track coil. In addition, the validity of the theory is confirmed by comparing a measured value with a calculated one.

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