Voltage swell ride-through capability with enforced, fixed input voltage for PWM current-source rectifiers

The constant search for increased efficiency, reduced costs, size, and weight of high-power static converters has led these towards higher operating voltages and overall semiconductor ratings. This trend has pushed high-power converters to their operational limit, especially in terms of their insulation capacity. Disturbances such as voltage swells therefore arise as compelling constraints for these applications. In view of this, this paper proposes a voltage swell ride-through strategy for PWM current-source rectifiers, its main feature being the capacity to enforce a fixed converter input voltage throughout the disturbance. This technique enables high-power converters to exert their maximum capacities, operating right on the edge of their operational envelope. Particularly, ride-through is accomplished first by drawing inductive current, and secondly by increasing the DC-link current in case the former action does not suffice. Importantly so, these measures do not mar the converter performance at all given their transient, sporadic nature. Further, a nonlinear control strategy obtained from the complex state variable model of the converter is employed to linearize and decouple its d-q axes dynamics, thus assuring a constant response independent of the drive operating point. Finally, experimental results from a TMS320C32 DSP-based system are used for evaluation and validation of the proposed ride-through strategy.