Control techniques for multilevel voltage source inverters

A multilevel inverter is a power electronic device built to synthesize a desired AC voltage from several levels of DC voltages. Recent advances in power electronics have made the multilevel concept practical. In fact, the concept is so advantageous that several major drives manufacturers have obtained recent patents on multilevel power converters and associated switching techniques. Multilevel inverters have been an important development in recent years, owing to their capability to increase the voltage and power delivered to the motor with semiconductors which are available today. Owing to this high power, these multilevel inverters have a big impact on production, generating important losses when they fail. For this reason, the investigation of methods to increase the reliability of these inverters is of high interest. It is evident that the multilevel concept will be a prominent choice for power electronic systems in future years, especially for medium-voltage operation. This paper proposes a comparison between different switching strategies for cascaded multilevel (CML) inverters, based on sinusoidal pulse width modulation (SPWM) and space vector modulation (SVM). The work strive hard to present the scrutiny that has been made between different open loop pulse width modulation (PWM) control technique for five level CML voltage source inverter. The comparison is made in terms of total harmonic distortion (THD), switching frequency, fundamental and harmonic rms of the voltage and current for different switching techniques.