Repetitive scheme plugged-in parallel with Deadbeat controller for VFD fed by cascaded multilevel inverter

This paper proposes an experimental Real Time Digital Feedback Controller (RTDFBC) combined with a Repetitive technique to control a Variable Frequency Drive (VFD) fed by a cascaded Multi-Level Inverter (MLI). The proposed controller is Deadbeat type compensating for non-cyclical disturbances while the repetitive controller compensates for cyclical fluctuations (Dead-time effect, DC voltage imbalance effect) by generating proper compensating d-q voltages. This digital control is characterized by a very fast transient response, low switching losses, and a proper compensation for load disturbances and cyclical fluctuations. Theoretical analysis, simulation, and experimental results are described in this paper.