Voltage Sensorless Direct Model Predictive Control of 3L-NPC Back-to-Back Power Converter PMSG Wind Turbine Systems with Fast Dynamics

Full power rating three-level neutral-point clamped (3L-NPC) back-to-back power converters seem promising for wind turbine systems with high power. Direct Model Predictive Control (DMPC) is an attractive technique, in particular, for multi-level converters. Voltage sensorless control makes the voltage measurements obsolete. This work proposes and verifies an Initial Bias Compensation based Virtual Flux (IBC-VF) voltage sensorless DMPC scheme for 3L-NPC back-to-back power converter Permanentmagnet Synchronous Generator (PMSG) wind turbine systems. With the proposed VF estimation scheme, no grid side voltage measurement information is required; both generator and grid side controllers are realized using DMPC concepts incorporating both targeting and (nonlinear) constraint set into a single cost function with great flexibility. Compared to conventional filter based voltage sensorless control strategies, the proposed one shows fast dynamics and accurate estimation of the voltage (virtual flux), which leads to overshoot-free power/current and DC-link voltage control.