A three-phase synchronous induction motor has a feature of self-starting as a wound-rotor induction motor with a starting resistance enabling starting characteristic superior to that of the traditional brushless synchronous motor with AC exciter. However, the necessity of an excitational DC power supply with a low-voltage and large-current power rating and additional maintaines due to the brushes existence are very disadvantageous.
In this paper, for solution of the above mentioned problems a brushless three-phase synchronous induction motor with two stators and without AC exciter is proposed. The proposed motor has the following mean features:
(1) Superior starting characteristic because of the effects of starting resistance provided at the stator side; the characteristic is as same as that of traditional three-phase synchronous induction motor.
(2) The proposed motor configuration enables the high-voltage and small-current power rating of excitation DC power supply, as a result of the effects of both exciting windings installed in the stator and rotor side.
First, the fundamental configurations and operating principle of the proposed motor are described in detail. Next, for calculation of starting characteristic the equivalent circuits expressed by symmetrical components are proposed. The comparison between the experimental results obtained with a trial machine and the computation results for the starting and load characteristics and their transient ones are also shown. The usefulness of the proposed motor for practical applications and the appropriateness of the equivalent circuits expressed by symmetrical components are investigated too.

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Material Handling System (MHS) is a kind of typical sequential control systems and also an important part of Factory Automation (FA) or Computer Integrated Manufacturing (CIM). The control of MHS is usually performed by Programmable Controllers (PCs) and its description depends on the PCs used. Ladder Diagram (LD) is widely used as a description method of PCs in sequential control systems. In recent years, a new description method called Sequential Function Chart (SFC) is also used in some PCs on the market. In order to apply SFC to MHSs, the authors have already proposed a representing manner called Total-SFC (T-SFC) which consists of SFC, Random Function Chart (RFC) and Interlock Table. Its part of SFC describes sequential control, while RFC and Interlock Table represent extraordinary and emergency processes. In other words, T-SFC offers a technique to describe not only the part of sequential control but also the part of non-sequential control of MHSs. In this paper, we describe the implementation of T-SFC for a general PC in which SFC and LD can be utilized. This paper presents a translation method from T-SFC to widely utilized PC's programs through the use of a T-SFC functional structure tableau, and verifies the validity of the proposed translation method with the demonstration of a simple case study. And, we also discuss the practicability of this T-SFC based approach in comparison with the conventional LD approach and point out the efficiency of T-SFC.

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We have proposed an inductor commutation soft-switched PWM inverter (ICSI) and the carrier frequency modulated ICSI (FM-ICSI) without sensors for the current and voltage. It is realized by connecting a series circuit with an inductor L_ZC and a capacitor C_ZC between the output terminals of the conventional hard switched inverter (CHIS), and by connecting a capacitor C_R in parallel with each main switch. The commutation elements L_ZC, C_ZC and C_R control the magnitude of the circulating current, short current and efficiency of ICSI and FM-ICSI. The circulating current always flows through the main switches and L_ZC and C_ZC from the dc source to realize soft switching. Therefore, in this paper, the relations of the commutation elements and these currents are analyzed and verified experimentally for design of ICSI and FM-ICSI.

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A mixture of plastic pellets or wasted plastic pieces are electrostatically separated. The mixture is charged by friction in a mixer and falls through horizontal electric field of 4kV/cm into three zones under the field. A mixture of two kinds of plastic pellets is separated with purity not less than 90%. A mixture of three kinds of pellets is separated to some extent in the zones at the extreme ends, in the first separation, according to locations of different kinds of pellets in the tribo-lectric charging sequence. This mixture will be separated in successive separations following the first one into respective pellets. A mixer made of a suitable plastic material and adapted to enhance the friction between different kinds of pellets makes easy and reliable the separation. Proper mixing time and high rotational speed of the mixer and low humidity increase the purity of separated pellets. Since the effect of blended additives of pellets on charging characteristics appears with good reproducibility, pellets and wasted plastics with such additives may be successively separated as well into respective plastics.

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Recently, motor drive systems are increasingly used in many industrial applications such as steel rolling mills, NC machines and robots. With the development of control theory and equipment, the system response has become faster and faster, while the stiffness of the system decreases because of miniaturization and weight reduction of the equipment. As the result, the system has to be treated as a resonance one in some cases. Several control methods such as with H^∞ controller or pole assignment approach have been proposed, among which the resonance ratio control is a very effective method. In these methods, a disturbance observer is usually used to estimate the torsional torque. If there are errors in the outputs of the observer, it is difficult to obtain the desired control characteristics.
In this paper, we propose a novel vibration suppression control method which needs no information about the load side variables, namely torsional torque and load speed. Based on the pole assignment approach, the poles of the system are selected as the gains of the load side variables are equal to zero simultaneously. The effectiveness of the proposed method has been verified by experiments.

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This paper proposes a new high performance speed control method for wide speed range, which is based on instantaneous speed observer considering the characteristics of DC chopper. In order to regulate a motor speed for wide speed reference including a very low speed range, this paper designs the instantaneous speed observer which uses the information of an armature current and an armature voltage. This observer has no effect of inertia variation and disturbance torque completely, but it has the effect of electrical parameter variation. Hence, this paper proposes a new identification algorithm to cancel out the estimation error caused by both the resistance variation and the voltage drop. The proposed observer can always estimate an instantaneous value of motor speed. The proposed total system becomes a new robust speed servo system for a wide speed range.

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Ladder Diagram (LD) has been widely used in industries as a language for sequential controls. However, the LD can not represent sequential flows of control logics explicitly. This leads to difficulties in understanding the control logics for other engineers. To overcome this problem, Sequential Function Chart (SFC) has been proposed. As the SFC can represent the sequential flow explicitly, it is expected to be used more widely. As many knowhows have been required in the LD, it is necessary to develop a transformation algorithm from LD to SFC. In this paper, a technique to transform LD to the corresponding SFC by using Temporal Logic is proposed. In the closed loop system which consists of the controlled plant and LD, the information in the sequence including parallel path divergences is extracted to develop the transformation algorithm. An example is also shown to verify the feasiblity of the proposed algorithm.

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The electrical activity of the nerve cell plays an important role in processing the information in the central nervous system. Hodzkin and Huxley proposed an excellent mathematical model describing its dynamics. This model, however, is difficult to desscribe the large variety of nerve cell properties, because of the higher order differential equations and many kinds of parameters. The KYS (Kimura-Yano-Shimizu) oscillator was proposed to describe the dynamics of the nerve cells. It was shown that this oscillator had the flexibile expressions for the nerve cell functions.
In this paper, the parameters of the KYS oscillator were determined to describe the frequency charecteristics of Hodzkin-Huxley equation. The dynamics of the coupled nerve cells were investigated by the KYS scillators with the settled parameters. Frequency entrainment and propagation of the trigger waves in many coupled oscillators were found in the range of large coupling constant, The frequency of the harmonic oscillations decreased with the coupling constant. The characteristic time and space patterns due to the oscillations were produced in the system.

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In this paper, a sensorless control drive of a salient-pole brushless DC motor with an estimated values correction is proposed. In the system, the position angle and the speed at a rotating condition are estimated basically by the model reference adaptive system (MRAS). At an initial or a starting condition, the position angle is estimated by a new AC current injection method. And at a lower speed region, the estimated position angle and the speed obtained from the MRAS are corrected with a new correcting technique. The position angles and the speeds which were estimated values by the MRAS and the AC current injection method are compared and corrected effectively on the correcting system. The experimental results of the estimated position angles or the speed and the variable speed control with the experimental system are shown in the paper. From these results, the proposed sensorless speed control system may be applicable to as a practical use sensorless brushless DC motor drive system.

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We have developed and proposed a novel harmonic compensation system consisting of shunt LC filters on load side, a step-down transformer on receiving end, and a small capacity active filter which one end is connected to the secondary winding of the transformer and the other to the load bus.
The active filter which just constitutes the bypass-circuit against the main service transformer is current-controlled to give adequate damping to the harmonic resonance condition caused between the inductance behind the load bus and the capacitance of var equipment on the load bus especially at lower harmonic frequencies.
We have installed this new scheme of harmonic compensation system in combination with TCR-type SVC and shunt LC filters at the Yamanashi Maglev Test Line.
We will describe the outline of the reactive power and harmonic current compensation systems, and harmonic resonance test results which show satisfactory performance of the active filter.

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In recent years, the soft-switching techniques have attracted attention for its peculiar advantages such as low swtching loss, high-power density, EMI/RFI noise reduction and so on. Authors have already reported before about quasiresonant DC-DC converter using new phase-shift PWM control scheme. By using proposed control scheme, circulating current is elimineted and ZVS (Zero Voltage Switchig) is achieved with small commutating current. As a result, the conduction losses caused by their currents are substantially reduced.
In this paper, authors apply a proposed control scheme to a quasi-resonant high-frequency transformer link DC-AC converter. As a result, all switching devices in this DC-AC converter can achieve soft-switching with small commutating current irrespectively of inverter mode and rectifier mode. Its operating principle and unique features are described as compared with the symmetrical control scheme of DC-ACconverter. Operating performance of this DC-AC converter in steady-state are illutrated by means of simulating results.

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As for traction motor for railway vehicle, over fifty thousands DC motors are used only in Japan Railways Companies. Insulation breakdown is one of the biggest problem for traction motor and various kind of insulation tests are carried out for every motors at the time of overhaul. The methods and the way of these insulation tests are determined about thirty years ago or more. Materials of insulation and how to compose these materials have progressed in these days. So it is important to research what kind of insulation test is suited for traction motor.
This time we made a research to estimate various kinds of insulation tests by carrying out dielectric breakdown test for over 150 motors. And this paper describes the result.

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The equivalent circuit has been used to calculate performance of induction motors. In this calculation, the primary and secondary leakage reactance correspond to half the reactance determined by the locked rotor test. The present paper investigates the most suitable search coil for determining the stator leakage reactance that accounts for the current that flows in the end ring. This coil was applied to two induction motors in order to determine stator leakage reactance. One of the sample motors was equipped with a squirrel-cage rotor with semi-closed slots and end rings. In this motor, the core stack length of this rotor was equal to that of the stator. The other motor was equipped with a squirrel-cage rotor with closed slots and end rings. The core stack length of this rotor was also equal to that of the stator. Two equivalent circuits were used in the simulation in order to determine stator leakage reactance during asynchronous operation. When the leakage flux due to the current that flows in the end ring is accounted for, the results of simulation are in good agreement with those of the search coil test. Thus, leakage flux due to end ring current does contribute to overall stator leakage reactance.

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In this paper we present a method for calculating saturated reactances of salient-pole synchronous machines and calculate variations of reactances of a vector-controlled salient-pole synchronous motor using the method. We also consider the causes of the variations of reactances.
The proposed method uses two-dimensional numerical magnetic field analysis and revised dq-axis equations in which the effect of the cross-magnetizing phenomenon is included. The values of the field currents calculated with the method show good agreement with the measured values.
The method is used to calculate and analyze the reactances of the vector-controlled motor at various load points. The findings are as follows.
(1) Numerical values of the mutual reactances between d- and q-axis x_dq, x_fq are not negligible.
(2) Variations of the armature leakage reactance x_l and the field leakage reactance x_lf in the field-weakening region are considerable despite the small main magnetic flux.
(3) The main cause of the variation of x_l, x_lf is saturation at the pole tips. This saturation occurs because of the difference between the armature m. m. f. distribution and the field m. m. f. distribution.

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