Nonlinear Direct Control for Three-Level NPC Back-to-Back Converter PMSG Wind Turbine Systems: Experimental Assessment with FPGA

Finite control set model predictive control techniques have been emerged as good alternatives in particularly for multilevel and multiphase power converters, for which switching vectors with multiple magnitudes/directions are available but the modulator or switching table design becomes complex. In this paper, a finite-control-set model predictive direct torque and power control (FCS-DTC-DPC) for grid-tied three-level neutral-point clamped back-to-back power converters in permanent-magnet synchronous generator wind turbine systems is presented and experimentally compared with its counterpart: switching table-based direct torque and power control (ST-DTC-DPC). Both methods have been implemented and verified at a lab-constructed setup with a fully FPGA-based real-time controller. Experimental results confirm that both achieve (equivalently) good control dynamics, whereas FCS-DTC-DPC outperforms ST-DTC-DPC in terms of steady-state control performances at similar switching frequencies but has a higher computational demanding and is more sensitive to system parameter variations.