This paper presents the motor manufacturing technology using dividing stator cores. The novel manufacturing technology called Poki-Poki motor has been developed from 1993, and applied to various motors used in such products as information devices, industrial equipments, electrical household appliances, motor vehicles and elevators, etc.. Poki-Poki motor can provides not only high productivity but also light and compact devices, saving energy, high efficiency.

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A switched-mode power converter has prominent features of small size, and high efficiency. On the other hand, it has inherently a defect of surge and noise generation due to switching process. Furthermore improvement for the good features has been required, and a good solution for the suppression of EMI problems has been also required. Concerning these topics, a lot of discussions have been recently reported. This paper summarizes some advanced technologies for solving the above-mentioned demands.

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A voltage sag compensating system using a SMES is presented. Based on the previous works, we have carried out experiments for voltage sag compensation on the laboratory-built system to validate the proposed minimum energy injection voltage sag compensation algorithm. In order to improve the compensating performance of the system, two-degree of freedom voltage control is proposed. In this paper, the circuit configuration and the feedback voltage control system of compensator are described and the experimental results are reported.

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This paper describes a novel type inverter power supply using a voltage boost function for magnetron drive. This inverter can be performed the high power factor (PF) operation even if it is connected with the magnetron with the high oscillation voltage (Ebm), because of the voltage- boost function of an active clamp scheme. Then the operating characteristics of this inverter are evaluated from a practical point of view as compared with the conventional inverter.

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In this paper, a novel type of active auxiliary quasi resonant commutation leg link Snubber for three phase soft switching inverter circuit, which can be completely turned on and turned off with ZVS & ZCS hybrid mode transition is presented and discussed. The operating principle of this auxiliary hybrid resonant commutation leg link (AHRCLL) snubber circuit is described, and its optimum circuit parameters are determined from a simulation point of view. In addition to these, the performances of this resonant snubber-assisted three phase voltage source type soft switching inverter are evaluated and discussed on the basis of simulation analysis.

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It is necessary to consider variations of circuit element values for a power electronic converter design to satisfy a given specification for a frequency characteristic or a dynamic transient response because the variations of element values generate those of the designed characteristic. This computation is so-called tolerance or worst-case analysis. There are some types of the method for the analysis; Monte Carlo analysis, mesh analysis, interval analysis, etc. However it generally takes a lot of time for them. This paper describes parallel tolerance analysis techniques to reduce their computation times.

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While bridge-type converters magnetize their transformers in both the positive and negative directions, forward-type converters magnetize them in only one direction. This suggests that in forward-type converters the magnetizing current flows in only one direction, and transformers supposedly operate only in the first quadrant of the BH plane. By determining the path followed by the magnetizing current under each operational mode of a forward-type converter, I show that these accepted theories are not necessarily correct. And by examining the behavior of the magnetizing current in two-transistor forward doubling circuit, I explain the peculiar shapes in voltage waveform.

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we have developed a new power conditioner for residential photovoltaic system which equips 5 DC-DC converters at most with independent maximum power point tracking control. Each DC-DC converter is connected to a string which consists of several photovoltaic modules on a roof, so every string can be independently operated at maximum power point. That means mismatch power losses of MPPT (Maximum Power Point Tracking) control have decreased to almost nothing, and then, it has expanded a possibility of layout of photovoltaic modules' location on roofs.

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Aiming to develop the small-sized photovoltaic power generation system, a compact DC/AC converter circuit for interconnection between solar cell and power utility line is studied, utilizing CLL-resonant high frequency-linked DC/AC converter. An output current control method of the DC/AC converter is proposed and some simulation results are presented in this paper.

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Generally, conventional type active filter utilizes voltage source inverter, which requires high frequency switching devices in order to compensate high order harmonics. But due to the switching frequency characteristics of the devices, it is difficult to reduce the electro-magnetic noise. To reduce the switching frequency, current source inverter is one of the good solution. But, it is not in practical use. So we proposed the new type active filter using linear power amplifier without switching operation. But the efficiency of this type active filter is very low. So we study on the reduction of the capacity of linear power amplifier by using combined type active filter in this paper.

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It is described that a novel quasi-resonant high frequency inverter which has ZCS switching arm and ZVS switching arm. Pulse phase-shifted modulation as a power control of proposed inverter allows soft switching of all active power switches from full load to less than 10% power under constant operation frequency.

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This paper presents a PWM signal correction technique to prevent magnetic saturation of high-voltage transformer under wide range load in high-voltage X-ray generators. A high-frequency PWM inverter provides asymmetric voltage caused by uneven delays of control ICs on its drive and control circuits, and power switching devices. The magnetic core of the high-voltage transformer connected to the high-frequency PWM inverter would be in magnetically asymmetric condition, and finally fallen into the magnetic saturation. The PWM signal correction technique which controls the average inverter output current to zero is proposed and discussed. The effectiveness of the PWM signal correction are confirmed based on measured magnetized current of the high-voltage transformer and the inverter output current waveforms.

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In this paper a novel prototype of the high frequency transformer linked full-bridge type soft-switching phase-shift PWM control scheme DC-DC power converter is presented. A tapped inductor filter is newly implemented in the proposed converter topology to achieve such advantageous characteristics as wide load variation soft-switching PWM constant frequency operation, low circulating and idling currents. The effectiveness of the proposed soft-switching DC-DC power converter is verified in experiment by using 2kW 100kHz breadboard setup using IGBTs. Efficiency of 94% was obtained over the wide load range.

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The single-phase current-fed converter has several advantages, such as no lower-limit of the output-voltage control range and no rush-current of the input-current. However, the converter requires the LC-filter connected in the ac-side of the converter to absorb the switching frequency harmonics. The LC-filter causes an LC resonance in transient states. To solve this, the authors propose a suppression approach using the predictive instantaneous current control method for the single-phase current-fed converter. To illustrate the validity of the theory, experimental results obtained from a 1.0 [kW] setup are shown.

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A new buck-boost (i. e., step-up/down) dc-dc converter (TOKUSADA converter) is introduced and practically evaluated. This converter consists of two self-turn-off switches, two FRDs and a small dc-inductor, and performs boost, buck and even buck-boost operations. Applying the boost and buck operations, this new converter obtains a seamless and wide-range output voltage control from buck region to boost region with a high efficiency especially in larger current conduction. The advantage against the traditional single-switch buck-boost converter and the conventional dual-switch CASCADE converter is analyzed and practically confirmed.

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Recently, the DC-DC converter using high frequency AC link circuit is used. And phase shift control has been conventionally used for the control system. However, by this method, you have to pass much resonance current at auxiliary inductance to perform soft switching for the circulation current caused during the circulated time. Therefore, conduction loss was increased and we were not able to be expected in order to raise efficiency.
So, in this research, secondary side phase shift PWM control is proposed. This system removes the circulation current and can solve the problem of phase shift control, so high efficiency can be made to realize.

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Recently, the generating electricity used clean energy source attracts attention and various research have been investigated. Electric power is taken out effectively in the photovoltaic power generator, and it is research on the control of inverter to use it as an a. c power source. The inverter is controlled by VVVF control when it applied to the load as induction motor, is controlled by MPPT control when it applied to the resistance as the load. The voltage amplification circuit is necessary in order to compose this system and the experiment result, is presented in this paper.

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Even the same photovoltaic can be expected more amounts of electricity by installing a photovoltaic in comparison with Japan in the low latitude area which is suitable for PV system with the daylight hours and the sunlight strength. In this research, a difference of an area of the amount of electricity of PV system is investigated by the actual data and the simulation software, and the predominance of the low latitude area in the PV system is evaluated. So that, economical advantage and shortening of energy pay back time in the low latitude area are confirmed.

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In case of the waste heat recovery in a minor scale incinerator, there are the following problems. The waste heat of a minor scale incinerator has unstable amount of generating, temperature, and generating time, because the system is operated only in daytime.
In this paper, the themoelectric-generation system which has a Latent heat accumulator was proposed, so that these problems will be solved. The themoelectric generator is applicable to recovery of unstable waste heat. However, when a capacity of the themoelectric generator is set to peak amount of waste heat, the themoelectric generator has an excess of capacity. Latent heat accumulator can reduce the capacity of the themoelectric generator, so that the cost of the waste heat recovery system could be lowered.

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In the large-scale factories, a lot of inverter loads exist, and these inverter loads are connected into ac system by using rectifiers to each inverter load. Moreover, DGs (Distributed Generators) or ESSs (Energy Storage Systems) which have dc outputs will be introduced to distribution system more and more, and these are connected into ac system by using inverters in conventional ac systems. Therefore, it is expected that the meaning to achieve dc distribution system which can reduce losses due to rectifiers and inverters, will be developed.
In this paper, dc loop type distribution system is proposed. Moreover configurations and simulation results of the inverter, the bi-directional rectifier, the PFC (Power Factor Corrector) and dc/dc converter which are used in this system are shown.

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This paper presents a nodal admittance approach steady state analysis and performance evaluations of the three-phase self-excited induction generator (SEIG) driven by variable speed prime mover such as wind turbine and micro gas turbine. The essential features of the present algorithm of the steady state analysis of the three-phase SEIG are that the variable speed prime-mover characteristics included in the approximate equivalent circuit of the three-phase SEIG and then its performances are evaluated on line with speed change of the prime-mover without complex computations. Furthermore, a closed-loop voltage regulation scheme of the three-phase SEIG driven by variable speed prime mover such as wind turbine is designed and discussed herein by using static VAR compensator (SVC). The digital simulation and experimental results prove the effectiveness and validity of the proposed SVC controlled by PI regulator in terms of fast response and high performances of three-phase SEIG driven by variable-speed prime mover.

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[in Japanese]

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