Self-excited wound type induction generator excited with capacitor, changing its speed as wind generator and being used for a separetely small power source, is researched.
The voltage and frequency of this generator change in accordance with capacity C of capacitor, generator speed and loads etc.
The constant voltage generator with constant C is achieved by means of returning the secondary power of the induction generator to the primary source through a converter, an inverter and a transformer and controlling the inverter control angle. But the frequency changes slightly.
In order to disappear frequency variation under constant C, a constant frequency source such as a synchronous generator or a constant frequency generator is connected to the primary or the secondary side of the transformer and parallel operation of them is made. And so constant voltage and constant frequency are achieved in spite of the change of generator speed and load. Characteristics by means of these various connections are compared.
The constant frequency generator is better than the synchronous generator concerning life and maintenance etc. In the parallel operation with the constant frequency generator connected to the primary or the secondary of the transformer, various characteristics at constant voltage and commercial frequency are compared and researched.

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Solenoids are presently used as cheap and robust switching components. These are variable reluctance devices with their characteristics dictated by a highly nonlinear magnetic circuit. This paper describes the research work done on converting a switching solenoid into a proportional device. It first investigates the magnetic characteristics of a solenoid, followed by developing a control model for the device. Based on this model, a dual rate cascade control scheme with a nonlinear force mapper is proposed for proportional control. This scheme is tested out by simulation and implemented on a Digital Signal Processor based controller.

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In this paper, a novel method to reduce harmonics involved in ac line currents of a diode rectifier circuit with a smoothing capacitor inside the dc output is proposed. This circuit consists of passive rectifier devices only. It is applied to the conventional double connected diode rectifier, 12-phase rectifier, and is added an auxiliary circuit which is composed of an interphase transformer with a secondary winding and a single-phase diode rectifier. Input voltage waveforms of the proposed circuit are quasi 24-step voltages which correspond to those of the conventional 24-phase rectifier.
In this paper, circuit performances of the proposed method are discussed by analyzing the input voltage waveforms. Then, effects on harmonic reductions can be clarified by theoretical and experimental results, and ratings of system components are investigated.

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In the practical requirement for high-efficiency, high power density and high-performance in the switched-mode power supplies and their related application systems, a variety of circuit topologies of DC-DC converters incorporating soft-switching PDM, PFM and PWM control schemes have attracted special interest in the fields of low power and high power applications. Some types of quasi-resonant soft-switching PWM converters have remarkable advantages such as lowered switching losses of power semiconductor devices, reduced dynamic electrical stresses, constant frequency operation, simple control scheme as well as reduced EMI noise.
However, most of soft-switched quasi-resonant PWM converters developed so far include some inherent items which have to be solved such as reduced power conversion efficiency due to significant circulating current generation. In recent years, the newly modified prototype of soft-switched PWM DC-DC converter with a high-frequency transformer link has been proposed, which is capable of excluding circulating current operation mode.
This paper presents a novel high-frequency transformer link soft-switching PWM DC-DC converter using active switches in rectifier circuit. Its operating principle and unique features are described as compared with the previously developed DC-DC converter. Operating performance of this converter in steady-state are illutrated and disccused including the simulated analytical and experimental results.

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This paper proposes a square-wave-voltage power distribution system and describes the problems and solutions of the system. The steep transition of the square-wave voltage causes large overshoot voltage at the output terminal of the power line. In order to control the overshoot, a resonant commutated square-wave inverter (RCSI) is developed. An experimental system for the square-wave power distribution system with the RCSI was built and tested. Several test data show the superiority of the system over the conventional sine-wave-voltage power distribution system: the input capacitor of the rectifier in the proposed system can be made 1/20 of that in the conventional system, and the permissive transmission power increases to twice of the conventional system.

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This paper proposes a PWM current source inverter-induction motor drive system with photovoltaic generation. Solar cells are inserted in dc link to obtain constant current characteristics and they are connected to the utility system by using a PWM converter. The PWM converter is controlled to obtain the maximum output photovoltaic (PV) power. The PWM inverter supplies sinusoidal currents for an induction motor which is driven by constant V/f control. A pulsewidth control is utilized in the inverter section because of constant dc link current caused by a peculiar V-I characteristics of solar cells. In the presented system, the PV power is not only used for the inverter-induction motor drive but also flowed into the utility system. The experimental results in the steady state show that the proposed system has sinusoidal current with unity power factor in the utility system, the maximum output PV power, and sinusoidal current/voltage for a motor. The demonstrated results for the separation of the utility system or the motor from the converter-PV-inverter system are given.

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Increasing vehicular traffic are causing traffic jam and social economic loss in recent years. Dynamic traffic management systems based on actual traffic conditions are expected to reduce these problems. Computer simulation is a powerful tool to evaluate the system performance of new traffic management system, since it is difficult to evaluate it under various traffic conditions in the real world due to huge costs and safety concerns.
In this paper, we propose a new microscopic traffic simulation model by object-oriented programming style. In this model, the street network is composed of nodes and links and vehicles run autonomously in the street network. The autonomous vehicle movement model is composed of decision model that depends on the driver's character and vehicle motion model that depends on the attribution of the vehicle. Then, we analyze the quality of our proposed model and show the effectiveness for evaluating the performance of the traffic management systems.

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In hybrid (HB) type stepping motors, two and five-phases are used respectively for medium and high resolution purposes, but three-phase motors have been disregarded. Then we started in the development of three-phase HB-type motors, believing in their possibilities. In this paper, design consideration and measured performance of three-phase HB-type motors are described. The developed motor (B) with 3.7° step angle has comparable torque characteristics and reduced vibration as compared with the usual two-phase motor, and the motor (A) with 0.6° step angle is able to rotate at a speed of over 2, 000 rpm by attaching an elastic inertia damper. In conclusion, three-phase HB-type stepping motors are expected to have a bright future.

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Electrostatic motors have been believed to be weaker than electromagnetic motors which are typically used for mechatronic devices. However, electrostatic motors are preferable to electromagnetic ones for micro mechanical applications since their force per volume ratios increase as their dimensions are reduced. This follows that a large output should be obtained if a large number of such small sized motors with high force per volume ratios are linked and their outputs are aggregated. This paper proposes an electrostatic drive technology which is applicable to such a large output motor. The element motor, which is named Dual Excitation Electrostatic Stepping Motor, consists of a pair of plastic films, slider and stator. Both of the films have parallelly located electrodes embedded in them, and the slider moves along the surface of the stator when defined rectangular pulse voltages are applied to the electrodes both in the slider and the stator. Force generation characteristic of the electrostatic motor is calculated by surface charge method. A prototype fabricated using flexible print board technology weighs 7g and generates a thrust force of 1.9N at an excitation of ±1000V.

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Simulation methods are widely used to analyze a non-liner circuit like a thyristor converter. Those methods are useful to study on behavior of the non-liner circuit. However, the methods need the long time to obtain the results. This is because the current and voltage waveforms should be calculated repeatedly in a very short interval for accurate results. It takes too long to study on main circuit constants by the simulation methods, in which there are many cases to calculate. Therefore, a method which enables to analyze the characteristics of the thyristor converter easily and shortly will be needed to design the circuit constant. This paper proposes a new method to analyze a thyristor converter used in the AC inverter rolling stocks easily and shortly. Also, analysis results show the effectiveness of the method.

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