Fundamental characteristics of a five-level double converter for induction motor drive

Multilevel power converters have been receiving increased attention because they can withstand high voltage and generate a nearly sinusoidal waveform. Large-motor drive systems are generally used with transformers to control the voltage stress on semiconductor devices in the converter circuit. If multilevel converters are instead used for this purpose, the transformers can be omitted because these converters reduce the voltage stress on each switching device. However, multilevel converters have certain disadvantages such as the need to balance the voltage of the DC-bus capacitors. In this paper, a control strategy for a five-level double converter system is investigated. First, the performance of a five-level diode clamped inverter is analyzed by simulation, secondly, a control method for a five-level double converter is proposed, and finally, the validity of the proposed method is verified by simulation and experiment