Modular Multilevel Converter with tuned filter: Operational possibility and simple control

The Modular Multilevel Converter (MMC) is an emerging topology which is being used over a range of applications. There are a number of attractive features of the converter compared to other converter topologies currently available. But, the charge balance in the floating capacitor is achieved at fundamental frequency. This is a challenge if the converter is to be used in low frequency application or DC to DC conversion. To overcome this problem, injection of a high frequency common mode voltage has been studied. These methods result in high circulating currents which increase losses in the switches. An alternative method based on the principle of orthogonal power flow theory has also been proposed. This paper gives operational possibility and simple control of such a converter.