Model Predictive Control of a New Five-Level Voltage Source Converter

The flying capacitor based multilevel converters are highly susceptible to flying capacitor voltage ripples at low-frequency operation. These ripples significantly influence the device voltage stress and output power quality. This paper presents a model predictive control approach for a new five-level voltage source converter. To implement the proposed approach, mathematical model of a new five-level voltage source converter in discrete-time is developed. A cost function is formulated with output currents, flying capacitors voltage, and flying capacitor voltage ripples, and it is evaluated for all available switching states. The evaluation process gives an optimum switching state, which is applied to the converter. The transient performance of the proposed approach for a new five-level voltage source converter is validated through simulations. The results show the flying capacitor ripples are maintained with in the 5% of their nominal value while regulating the flying capacitor average voltage at their nominal value and actual output currents tracking the reference output currents.