Multiple Input Multiple Output (MIMO) Control of a Novel Three Phase Multilevel Inverter

Multilevel inverters (MLIs) have gained wide usage in medium voltage applications due to their modular architecture, ability to use low voltage semiconductor devices and improved voltage harmonics. This paper presents a novel three-phase multilevel inverter design that does not require large DC-link capacitors and only requires each DC source to interface with two grid phases. A novel multiple-input-multiple-output (MIMO) control strategy is proposed to track DC link voltages and grid currents simultaneously. We derive the control law and show simulation in PLECS to demonstrate the steady state and transient operation of our design. We also show a simplified, distributed version of the controller that only requires each converter to measure its own PV voltage and phase current. Lastly, we present simulation of a 6-level 18-converter system to display the scalability of the design.