The high readhesive characteristices of A. C. locomotives with rectifier and no Automatic Current Regulation was explained by N. Irie and K. Kuyama using one-axel slip model by introducing mechanical time constant_??__m, electric time constant τ_e and two grades (tractive effort/velocity, dynamic friction force/slip velocity). However almost all electric locomotives and multiple units with chopper control or three-phase traction have a strong ACR i.e. automatic torque regulator which promotes slip of the wheel that makes anti-slip control necessary.
To apply anti-slip control for such type of electric motor vehicles, we analized a Slip Velocity Feedback Torque Control and succeeded in deducing the same slip equation as that of A. C. locomotives with rectifier and no ACR by introducing two control parameters (electric time constant τ_e and feedback gain K) and then clarified the relations between the control parameters and slip-readhesion modes. Thus we find it easy to get better readhesive characteristics than those of A. C. locomotives with rectifier and no ACR by selecting the control parameters appropriately.

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This paper shows two methods to stabilize the current performance characteristic of a persistent current switch which we intend to install in a superconducting magnet for a magnetically levitated vehicle. The switch consists of a superconductive wire made of NbTi and Cu-30%Ni matrix, a winding form core made of E-glass fiber reinforced epoxy resin, an electric heater, and a thermal insulator. This type of a persistent current switch tends to be unstable in current performance at on-state. The instability is what you call training-effect or degradation. One of the methods to suppress the instability is to adopt low thermal contraction materials for the core, and the other method is to twist double superconductive wires in which a current goes on one wire and returns on the other wire. We made small samples using the stabilizing methods, and examined their current performances. We found them better performing than those using the conventional technology. Then, we made a persistent current switch of which operating current was 600A at on-state and electrical resistance was 50 ohms at off-state.

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In the Japanese a. c. electric railway system, the AT feeding system is regarded as the standard feeding system because it is found suitable for feeding power to the electric car.
In the a. c. electric car, a. c. electric power is converted to d. c. electric power in order to drive d. c. motors, thereby generating higher harmonics in the a. c. side current. On the other hand, as the feeding circuit is a distributed constant circuit composed of RLC, the capacitor of the feeding circuit and the inductance on the side of the power supply cause a parallel resonance at a specific frequency and magnify higher harmonics current. For this reason, in the system of conventional lines which have long feeding distances, a higher harmonics resonance suppressor (i.e., CR equipment) composed of a resistance and a capacitor has hitherto been connected to the end of a feeding circuit. However, connection of a CR circuit to a high voltage circuit of 44kV resulted in increasing the power loss caused by the resistance, which posed a problem to be solved.
We have sought an appropriate place of installation and structure of the CR equipment with a view to reducing the power loss without negatively affecting the higher harmonics resonance suppressing function. The result shows that by merely installing the CR suppressor at the sectioning post we can successfully reduce the number of the CR suppressors; and by parallel-connecting the reactor to the resistance of the CR suppressor we can make two currents flow separately, i.e., the commercial frequency current to the reactor side and the higher harmonics current to the resistance side. This improvement contributes to the reduction of power loss and has already been implemented on the conventional lines.

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For driving a resonant load, for instance an induction heater, a voltage-source inverter or a current-source inverter has been used. It can not operate as a zero-current-switching (zcs) inverter or a zero-voltage-switching (zvs) inverter unless the operating frequency of the inverter is equal to the resonant frequency of the resonant load.
In this paper, a new adjustable frequency quasi-resonant inverter circuit for a resonant load is proposed. The present inverter operates with soft-switching, according as the power source is separated from the resonant circuit during the reverse current modes. It can drive a resonant load that includes an iron-core matching transformer, because the D. C. component of the output current is suppressed by a D. C. blocking capacitor in series to the load. The present inverter has a feature that the output frequency and the output current are adjustable independently. Therefore, the output frequency is controllable on condition that the output power is fixed.

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The analysis of the commutating phenomena in d-c machines is an important problem for machine design and development. However, certain inherent difficulties, such as plural equations, nonlineality and singular point, arise which complicate the solving of commutation equation.
In this paper, we deal with methods of analysis of commutating phenomena in d-c machins.
First, the linearized differential equation of commutation, which is able to treat the narrowing character of the sparkless zone owing to an increase of the armature current, is proposed.
Second, we emphasize improved computational procedure throuth the use of the numerical solution by the use of the eigenvector method. The feature of this method is that eigenvalues, modes of the solution and excitation amplitude can be obtained simultaneously. By these statistics, we can estimate commutation quality in d-c machines. The tested machine is a two-pole separately excited generator with lap windings.

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This paper presents a new approach of strictly analyzing the transient torque components as the corresponding steady state torque pulsation components by introducing the concept of vector transformation method. Based on this approach, a well-known and empirical phenomenon that, when the power source is closed to an induction motor under the condition of slip 0.5, the transient pulsating torque component becomes almost zero is analyzed and the mechanism is clarified. Although this phenomenon has been utilized for energy saving system of blowers, the physical explanation has not been made clear yet until now. The proposed analysis in general clarifies that there can certainly occur such a phenomenon as exposing a reduction effect of transient pulsating torque components to almost zero when the electrical angular frequency of rotor becomes equal to the arithmetic mean of both the frequencies of power source and of transient current component. These are also confirmed by computer simulation results.

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SFC (Sequential Function Chart) is a kind of graphic representations, which is included in IEC standards for sequential control systems. It is introduced as a specific form of PC's (Programmable Controller's) programs. For the simplicity of graphic representations and the clarity of relations of sequences, SFC is much superior to Ladder Diagram that has been so far, widely used in sequential control systems. Each element of SFC is meaningful just by the connections and SFC is strong in the representation of a flow of control sequence. However, SFC has a weak point that it is difficult to describe logic by conditions in detail like interlock relations and to represent interrupt processing. But production rules are obviously suitable for representing logic by conditions and also for interrupting process.
In this paper, we propose a method to translate SFC into production rules, and to implement SFC by production rules using RTPS (Real Time Production System) in which PSL (Production System Language) is used to describe production rules. SFC has three description elements: step representing states in systems, transition representing transition conditions of systems, and link representing the connections between step and transition. We classify the flows of SFC to three types: single sequence, selective sequence and parallel sequence, and, show that each sequence can be described by pairs of transition-step. Conceming a pair of transition-step, a rule for translating the pair of transition-step into production rules is presented. These production rules will be represented by PSL. Finally, we show an example that is implemented by an RTPS.

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Warp sizing is an important pre-process of weaving. The sizing machine, however, has many parameters (e. g. concentration of sizing agents, viscosity of sizing agents, pressure of squeezing roller, speed of winding roller, etc.) to be set for realizing required strength, elongation, fuzz, and abrasion proof of warp. Only experts have been able to fulfill this difficult tuning.
This paper presents fuzzy modelings of the sizing machine for constructing an assisting system of the machie operation. A fuzzy neural network is used for the automatic fuzzy modeling. The obtained fuzzy models are sufficiently precise and the acquired fuzzy rules coincide well with experts' experience.

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Cable-in-conduit type forced flow cooled superconductor (CICC) has many strands in a conduit. It has attractive characteristics of stability, insulation and mechanical rigidity, etc. Its hydraulic diameter is, however, relatively so small that pressure rise will be large at quench. By the way, attractive characteristics has been found out. It is that the normal zone propagates with high speed in some condition, which will help the stored energy been consumed in large area and reduce temperature gradients. We discuss this high speed quench propagation. We made a forced flow cooled superconducting coil with a CICC. The CICC was 12m long and the test coil was a solenoidal coil with 0.3m diameter. Each turn was apart from each other. We can neglect heat conduction between each turns, so that the test coil is an ideally one dimensional model. We measured the propagation speed at quench in 6.5T magnetic field, and compared them with numerical simulation results. They agree well, including the high speed quench propagation characteristics.

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The continuous development of electric power utilities has led to the increase in the problems concerning fault currents. The use of fault current limiters, which suppress fault currents below a certain level, has been examined in many places. The authors have studied a superconducting fault current limiter that is based on the magnetic shielding characteristics of superconductors.
In this paper, three kinds of fault current limiters with high T_c superconductors and their results tested at liquid nitrogen temperature are presented. The experimental results show that the impedances of limiters in the fault condition became higher than those in the normal condition but were lower than the anticipated ones.
Next, a numerical calculation model to analyze the experimental results is presented. The calculation results with this model agreed with the above experimental ones very well.
From these studies it is concluded that it is necessary for the sudden transition from the superconducting state to the fully resistive state to be caused by the suitable means.

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Recently, various nonlinear compensation systems have been proposed for tracking the reference input fastly and finely. Using a nonlinear element, these systems can give a good response to a step reference which conceals overshoot and has fast rising time. However, the systems are constructed under hypothesis that the plant's parameters are accurate and time-invariant. In practice, it is difficult to obtain plant's parameters accurately, and it is usual that the plant changes with time and operating state. Then, the effect of parameter variation must be considered.
In this paper, we propose a model tracking system. This system is composed of a nominal model and a tracking system with a robust compensator. The nominal model produces an ideal response to the nominal plant. If the actual plant is equal to the nominal plant, the response of the nominal model tracking system will be the same as one of the nominal model. In use of H_∞ control theory, the robust compensator is designed to gurantee system stability, to attenuate the effect of paremeter variation and to track the ideal response under paremeter variation.
As an application, we design the nominal model tracking system to the speed control system. From computer simulations We can show that the nominal model tracking system is very effective.

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Vibration suppression and disturbance rejection controls are important issues in recent steel rolling mill systems due to the application of high response Ac drive system. Various methods have been already proposed, for example, simple acceleration feedback, state feedback and H∞ control, etc.
In this paper, I will propose a novel controller for a 2-inertia system which is the simplest model of the rolling mill system, where the roll is coupled with the motor by a long shaft. By realizing “Manabe Polynomials” using the “resonance ratio control” based on the disturbance observer, the 2-inertia system can be controlled quite effectively. Moreover, the order of the proposed controller is only 2.
I will show some simulation results to demonstrate that the proposed controller suppresses the torsional vibration and the disturbance torque effectively in various 2-inertia systems with a wide range of the ratio between the motor and load inertia moments.

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In many industrial application fields, servo drive systems have widely applied to various load systems with complicated mechanisms such as low stiff structures and gears with backlash. Since such systems form multimass resonant systems and cause mechanical vibration, suppression of the vibration is required to achieve the high performance motion control. To overcome this problem, the modern control theory-based various techniques are suggested by using simple feedforward control or feedback control.
The paper presents the vibration suppression control of a robot arm with a flexible joint by feedforward control based on a transfer function of the robot arm. The proposed controller can be simply realized using a conventional position controller and it generates a position command which does not cause the resonant vibration. The algorithm is quite practical, however, it is sensitive to mechanical parameters because the feedforward controller is designed by mechanical system parameters. Therefore, an auto-measurement of mechanical parameters using a Fast Fourier Transform (FFT) is also proposed to achieve the necessary control accuracy for practical usage. Experiments with the prototype show an effectiveness of the proposed control.

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