TABLE-BASED direct power control for three-level neutral point-clamped pulse-width modulated rectifier

This study presents a new control strategy for three-level neutral point-clamped pulse-width modulated (PWM) rectifier. The relationship between instantaneous power and voltage vectors is derived mathematically from the model of three-phase three-level voltage source PWM rectifier, and a direct power control (DPC) scheme for three-level PWM rectifier is presented. An optimal switching table is established, from which appropriate voltage vectors can be selected to control active and reactive power directly. Principle for vector switching to avoid excessive ΔV in phase and line-to-line voltages and balance strategy for the neutral point potential are also discussed. A digital-signal-processor-based experimental system is developed to implement a series of experiments. The obtained results have verified the theoretical approach, and the three-level PWM rectifier with proposed DPC exhibits advantages of simple algorithm and good dynamic performance, compared with conventional voltage-oriented control.