| Research Abstract |
We have first proposed an improved PFC, Power Factor Correction, converter in this research. It is composed of two half-bridge PFC structures in common with a neutral source line and two smoothing capacitors, and connected to the single-phase three-wire distribution system. It has been made clear that both capacitor voltages can be always in balance without extra control schemes, though the conventional half-bridge PFC converters tend to have the unbalanced ones.
The above distribution system is employed extensively in Japan, USA and the other countries. It has two ac sources with the same voltage and in phase. Numerous ac loads may be connected to the distribution system. As a consumer makes use of these loads at random, two source currents tend to be unbalanced. If many working loads lean to a one-sided source, the power interruption may occur by the operation of circuit breakers. Therefore, even if the load currents are unbalanced, it is desired to equalize both source currents by in
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serting Current Balancer into the distribution system.
The above-proposed PFC converter can operate not only as the ac-dc converter but also as the dc-ac inverter. Furthermore, two respective half-bridge structures, Converter 1 and Converter 2, can be individually controlled. For example, while Converter 1 operates as the ac-dc converter, another Converter 2 can make the dc-ac conversion as the inverter simultaneously. In this research, we have investigated a Current Balancer by applying the above property of the proposed converter.
There may be several ac loads with poor power factor, such as induction motors, in the distribution system. The employment of Static Var Generator must be effective for compensating their reactive powers. Moreover, conventional diode rectifiers with large smoothing capacitors, made use of the popular dc sources in TVs, computers, and so on, flow out the harmonic currents into the ac source, unless the PFC converters. In order to prevent the troubles by harmonics, it is preferred to employ Active Filter into the distribution system. Therefore, we have improved the above Current Balancer to the novel ac-dc converter combined with several power compensator functions. It has been confirmed by the simulations and the experiments that itself can output the dc power to its load, and simultaneously it can perform as Current Balancer, Static Var Generator and Active Filter in order to compensate the power qualities of the single-phase three-wire distribution system, where various ac loads are connected besides the proposed converter. Less
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