Predictive Current Control of a New Four-Level Voltage Source Inverter

The voltage source inverters capable of generating multilevel voltage waveform are highly used in high-power industrial power conversion systems. These inverters are designed in different voltage levels based on the operating voltage, device voltage rating, and harmonic standards. In this article, a new four-level inverter is developed for 4.16 kV power conversion systems. The new topology will be designed without a series connection of identical voltage rating devices. Furthermore, the back-to-back connection can be formed with the new topology, because it has a DC-bus without any neutral-points. In addition, a simple predictive current control is developed to fulfill the new four-level inverter objectives such as regulation of inverter load currents and floating capacitors voltage. These objectives are mathematically represented in discrete-time using numerical integration methods. The resultant models are used together with a cost function to identify an optimal switching state from all the inverter switching states. The final selected switching state is an optimal one, and it is applied to the inverter. The performance of the new four-level inverter with the predictive current control has been validated through simulation studies.