IEEJ Transactions on Industry Applications
Online ISSN : 1348-8163
Print ISSN : 0913-6339
ISSN-L : 0913-6339
A Three-Phase Grid-Connected Inverter Equipped With a Shunt Instantaneous Reactive Power Compensator
Kazuto TakagiHideaki Fujita
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2018 Volume 138 Issue 6 Pages 530-537


This paper introduces a new three-phase grid-connected inverter for commercial-scale 10-50-kW photovoltaic systems installed on underutilized assets such as rooftops of office buildings. The circuit topology combines an inductorless active bridge with a parallel-connected PWM inverter behaving as an instantaneous reactive power compensator. The active bridge, referred to as 120°-conduction inverter, performs a fundamental-frequency switching and outputs a 120°-block-shaped current, while the instantaneous reactive power compensator suppresses the harmonic current included in the block-shaped current. The main advantage of this strategy is the size reduction of the required ac inductor by a factor of four as well as the reduction in switching device power losses. The theoretical analysis clearly shows that the compensator controls only instantaneous reactive power to synthesize a sinusoidal current, thus eliminating the need for an electrolytic capacitor. A 5-kW experimental setup validates the operating principle and control method of the proposed inverter, and exhibits an inverter efficiency as high as 98.8%.

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© 2018 by the Institute of Electrical Engineers of Japan
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