On an occasion of the newly-founded factory, a cogeneration system driven by 2 sets of 36kW gas-engine was installed in the structure. After one year, several running data were measured and collected.
This paper describes the points of a planning to be considered of a cogen. system, and some characteristics concerned with air-conditioning/heating at the generation of electric power.

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A development for the superconducting magnetic levitation system as a new high speed transportation has been progressing. And Now, a new test track is under construction in Yamanashi Prefecture.
This paper describes the function, configration, and characteristics of the new LSM propulsion system including power supply, compare with those in Miyazaki test track and conventional motor drive sysytems.

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Recent inertial confinement fusion research got a large stride toward the energy development's program by progress of implosion experiments on high power glass laser. Gekko XII experiments demonstrated required temperature of 10keV and implosion density of 600g/cc, separately. [1] Now, to achieve these conditions simultaneously, efficient high power energy driver developments become an essential research subject. Light-ion-beam driver based on the pulsed power technology is the most important candidate for inertial fusion energy, due to its high efficiency and low cost potentiality. Present conceptual design of fusion reactor requires driver parameters of an output power 200-500TW, a beam energy 10-20MJ, an efficiency more than 10% and voltage 30MV with several Hz repetitive operation. This high voltage pulse is generated by an induction adder which is powered by conventional pulsed power systems. A magnetically-insulated ion diode converts the high power electric energy into light ion beam. Low divergence lithium ion beams of 30MeV particle energy will be focused on the fuel pellet with more than 100TW/cm².

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In order to achieve a longer service life of an implantable cardiac pacemaker, a secondary (rechargeable) battery system and a charging system to charge a secondary battery transcutaneously from outside of a living body have been studied at our laboratories. Some basical findings about a relationship between a transformer gap and its coupling ratio and other items were obtaind. A transformer small enough to put in a current cardiac pacemaker was experimenally made and tested regarding effects of the gap and a relative horizontal position change of the primary and secondary coils on transmission efficincy.

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A new DC-DC converter based on the resonant technology has been developed.
A parallel resonant circuit topology has been chosen for the system, because it has advantage over a series resonant converter in view of the capability to eliminate variations of switching frequency with changes of load current.
The new power supply efficiency was improved and its size was reduced in comparison with our conventional ones.
The circuit analysis and the practical design considerations are described. Moreover, experimental results for a 5kW SWR are also shown in this paper.

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An induction heating cooker has many advantages. It is safe, clean, easy operation and highly efficient, because it heats a metal pan directly by electromagnetic induction phenomena.
But the conventional induction heating cooker has demerit of unheating the aluminum pans. Because they have low resistivity and are a non-magnetic material. This demerit is an obstacle for market penetration.
This paper reports the induction heating cooker for aluminum pans that was achieved heating efficiency 63%, which was developed by the low heat loss exciting coil under high frequency current and a single ended push-pull (SEPP) resonant inverter using IGBT.

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This paper deals with a practically-effective control scheme incorporated in the voltage fed full-bridge series resonant high-frequency inverter using Static Induction high-power Transistors (SITs), which is based upon a loadadaptive variable frequency modulated phase-shift PWM control strategy.
The functional control scheme is introduced to this inverter system, which can accomplish the output power regulation under variable frequency PWM- related conditions so that the switching losses of SITs may be lowered as much as possible in spite of largely-changed and time-varying load requirements.
The operating principle of load-adaptive variable frequency PWM series resonant inverter system with a new control scheme is described along with its operating characteristics in steady-state. The 20KW-200KHz trially-produced prototype inverter system suitable for induction heating in industry is demonstrated including specially-designed transformer, SIT stacks with water cooling system, and building block assembly for high-power use.
Its experimental results are illustrated together with simulation results and are discussed from a practical point of view. Finally, the further improved variable frequency PWM series resonant inverter topology incorporating partially-inserted capacitive lossless snubbers is proposed for soft-switching and evaluated as compared with the inverter mentioned above.

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A description and a brief analysis of a half-bridge IGBT inverter suitable for heating magnetic and nonmagnetic materials at high-frequency, are presented. The series-parallel scheme is adopted and an optimum mode of operation is selected which results in a maximum current gain and practically no voltage spikes in the devices at turn-off. The inverter system circuit model was analyzed using the state variable approach, and including the effect of branch stray inductances and snubber components. The actual performance was tested on a 50-150kHz prototype rated at 6kW. The developed hybrid inverter is characterized by its simplicity of design and operation, yet is versatile in performance. Experimental results are presented to confirm the validity of the inverter system model used for the analysis.

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Inverter power supplies utilizing IGBTs for microwave ovens, developed in 1988, have been being improved for these several years in order to progress there many good performances such as low weight, compact size, power source flexibility and high controllability.
A new cooking power control function “High Power Sprinter” has been developed for additionally improving cooking performance of micro wave ovens. The new function has to novel and superior techniques, a starting output power sequential control technique and an instantaneous peek power suppressing skill, in order to simultaneously realize high micro wave output power and high reliability of micro wave ovens.
Owing to a new auto cooking system using the new function having above novel skills, additional cooking performance improvements of micro wave ovens have been achieved. Especially cooking performances of speed cooking and energy saving are attractive futures in view of future cooking appliances' trends.

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A static var generator (SVG) using self-commutated inverters of 80MVA capacity was developed and successfully applied to actual 154kV power system to stabilize the power system.
After in stallilling it at a power system site, a field test was conducted to confirm the system stabilizing effect. The test results displayed the expected performance, and the SVG was proved to be an effective power system stabilizer. The SVG has been continuously operating since then.
This paper describes the outline of 80MVA SVG, technical features and the test results.

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We were the first In Japan to successfully develop a utility interconnected photovoltaic power generating system with reverse power flow capability in an occupied private residence, Interconnected operation with reverse power flow from the system began in Osaka on July 31 1992. With 1.8kW solar cells, the system generated 8kWh and reversed 73% of the generated power to the utility on a typical day.

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A photovoltaic generation system employing a interconnected inverter is now in the spotlight for its effectiveness in the popularization of clean energy in which no fossil fuels are used. Using storage batteries in this system allows a variety of functions to be added, making it possible to realize a further value-enhanced system. Since the interconnected inverter we have recently developed is equipped with a bidirectional converting function, the following functions can be additionally obtained. Namely, load levelling can be conducted by recharging storage batteries using power at midnight, and power can be supplied uninterruptedly to loads even during a power failure, thus serving as a UPS, as well.

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This paper describes a method to compensate reactive power in the utility line, which is generated from electric and electronic apparatus of home appliance, by using a series-resonant high-frequency linked DC-AC converter aiming at development of a small sized active filter. The distortion of voltage and current waveforms due to the large number of small size home applieances used, becomes as large as we can not neglect it. Therefore, for reducing the distortion of voltage and current waveforms in the utility line, it is necessary to develop a small sized active filter.
We adopted a series-resonant high-frequency linked DC-AC converter as a converter used in the reactive power compensator because it is possible to use smaller passive circuit elements, such as an isolation transformer.
In this paper, the equivalent circuit which describes the macro-scopic behavior of the converter is derived. Then, on the basis of the equivalent circuit of converter, a method of the output current control of the converter in order to compensate the reactive power is described. Usefulness of the proposed method is confirmed by the experimental results of the current control and the reactive current compensation.

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A three-phase inverter-fed permanent magnet field synchronous motor is used in many industrial applications as a DC-brushless servomotor. In this brushless servomotor, a rotor position sensor and a rotating speed sensor must be mounted on the motor shaft. However, these sensors cause troubles in the system and reduce the reliability of the system. In this paper, many methods which determine the rotor position angles and the rotating speed of these permanent magnet synchronous motors by using the instantaneous values of phase voltages and phase currents sensing are explained. And the point at issue of the sensorless systems are put in order.

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Of the testing machines which have hitherto been used in the automobile industry, DC motors with a reduced torque ripple have played the leading role. However, it has recently been taken notice of to use a combination of a squirrel-cage Induction Motor which can satisty with ease the speed-up, maintenance-free and space-saving requirements and a High-Precision Vector Controlling Inverter. This kind of AC variable speed drive has gradually been cleared of the problem of torque ripples involved therein and is now being put to practical use as a product which can be utilized for a testing machine.
THis manuscript introduces the results of trial manufacture of a high-speed vector motor having a basic speed of 4000rpm, Power of 75kW with the maximum speed of 10000rpm showing a successful reduction of the torque ripple of the motor lock test to a level of ±0.5%/FS.

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This paper describes the newly developed 2-5kVA high-frequency isolation type UPS (Uninterruptible Power System).
The major feature of this UPS is the adoption of a novel SMR (Switch Mode Rectifier) in the input converter.
SMR, as a single converter which provides functions for high-frequency isolation, enhancement of input power factor and stabilization of DC output voltage. The use of novel circuits configuration, the volume and weight have also been reduced to about 1/2 as compared with conventional commercial frequency isolation systems, furthermore higher conversion efficiency has been realized.

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The usual instantaneous reactive power q has been defined by using of α β components of the voltage and current. The current from the power source contains higher harmonic components when q is used for the control method of an active power filter in unsymmetrical three phase system. The higher harmonic current components are bad for the telecommunication and so on. Therefore, the authors have defined a new instantaneous reactive power whose mean value is equal to the reactive power. By the use of this value, the authors have clarified a new caluculation method for compensating current command which has caused no problems.

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Increase in the number of utility interactive PV Inverter units poses the problem of islanding protection. Many systems have been researched, each of which, however, has generated a dead band near the point of balance between the inverter output power and load power. The new method, called the Slip-Mode-Frequency-Shift system, has proved to be dead-band free, both theoretically and experimentally.

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For a linear induction motor (LIM), the constants of each phase are different due to the moter structure. This can cause the thrust pulsation of the LIM.
This paper paper shows a vector control method with the asymmetrical constants consists of the slip angular frequency control, the time-invariant control and the decoupling control. Consequently, the thrust pulsation is suppressed by this new control method. The speed control characteristics of new system are superior to those of the usual vector control system performed by the average values of asymmetrical constants. And, the influence of the equivalent iron loss resistance are shown.

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A dynamic analysis model of electric system for a solar boat is presented. The experimental data of a solar boat, which is trial production, and simulated value are in pretty good agreement after settling time, but in rapid resopnse for electric phenomena, they are not in good agreement, It is necessary for exact compariosn to get experimental data in high frequency sampling.
A performance of hydrofoil type solar boat is calculated in use of the analisys model. In any type, dispalcement or hydrofoil, it is important to introduce the mode of long time operation of auxiliary battery.

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The DC chopper with Integrated voltage control method is stable and has no steady state error. The 2- or 4-quadrants DC chopper with this method have a lot of good characteristics, for example very simple control circuit and very rapid response.
Applying this Integrated voltage control method, we constructed the speed control circuit for DC servo motor drive. This circuit has two feedback loops: the first one is a DC motor speed feedback loop and the second is a DC chopper output voltage feedback loop which is eliminated DC component by a coupling capacitor. In this speed control circuit, we can determine a damping factor of this control system freely if DC servo motor is over damping.
Now we constructed the new speed control circuit for DC servo motor drive. This circuit has three feedback loops: the first one and the second are a speed feedback loop and a voltage feedback loop, the third is a current feedback loop. In this new speed control circuit, we can determine a damping factor of this new control system independently of the several damping factor of DC servo motor.

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Switched reluctance motor has advantages in a harsh environment and is suited for high speed operation due to a simple and robust structure. It has been applied in the accessory area for gas turbine engines in aircraft and rail traction. However, it has disadvantages about iron loss, windage loss and torque ripple because of doubly salient structure. In thus paper, characteristic of torque distribution is examined by the simulation and experiment. Voltage control angle and applied period to make torque ripple minimum and output power maximum are also examined.

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Ultrasonic motor is a new type motor driven by ultrasonic mechanical vibration and frictional force. This motor has the following features: high-torque at a low revolution speed on directly driving, high-holding torque without electric power, extremely low acoustic noise in operation, and fast response. The driving mechanism and characteristics of this motor, however, have not been sufficiently clarified.
In this paper, the characteristics of the traveling-wave type ultrasonic motor are experimentally obtained using a computer-based measuring system. These experimental results are examined in relation to the mechanical resonant state and mechanical impedance of the ultrasonic motor. The driving mechanism of the ultrasonic motor is discussed on the basis of a slip speed and a frictional force.

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