This paper proposes a new type of Modular Multilevel Converter (MMC) applying a three winding transformer. In general, MMC requires a buffer reactor in each arm, which increases number of components and con verter footprint. The proposed MMC with three winding transformer does not require the buffer reactors. We de scribe mathematical properties of the proposed MMC. We also confirmed it operated as same as typical MMC (with reactor topology) by experimentation using a prototype lOkVA converters.

SUMMARYRecently, renewable resource supplies, such as fuel cells, photovoltaic cells, wind power, and engine generators for distributed power systems have been studied intensely. Conventional compensators with switching devices are constructed based on a voltage source inverter using six arms. Therefore, conventional power quality compensators require a large electrolytic capacitor in the DC link part of the equipment. The use of a large capacitor hinders downsizing efforts and the lowering of equipment costs.Direct converters, which do not have a large electrolytic capacitor and an initial charge circuit, can be used to realize downsizing and lowering of equipment costs, when compared with conventional converters. This paper proposes a new application of a matrix converter to a PM generator for power quality compensation, such as reactive power compensation, harmonic current, and power interruption. The novel point of this work is that the matrix converter provides reactive power with harmonic current. Simulated and experimental results confirm that the matrix converter can maintain high performance the same as a conventional active filter and an uninterruptible power supply (UPS).

Recently, renewable resources supplies, such as fuel cells, photovoltaic cells, wind power and engine generators, for distributed power system have been studied intensely. Conventional compensators with switching devices are constructed based on a voltage source inverter using six arms. Therefore, conventional power quality compensators require a large electrolytic capacitor in the dc link part of the equipment. The use of a large capacitor hinders downsizing efforts and the lowering of equipment costs. Direct converters, which do not have a large electrolytic capacitor and an initial charge circuit, can be used to realize downsizing and lowering of equipment costs, when compared with conventional converters. This paper proposes one of new applications of a matrix converter to a PM generator for power quality compensation, such as reactive power compensation, harmonic current and power interruption. The novel point of this work is that the matrix converter provides reactive power with harmonic current. Simulated and experimental results confirm that the matrix converter can maintain high performance as same as a conventional active filter and an uninterruptible power supply (UPS).

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