Constant frequency current modulation algorithm based on linkage flux

The present paper proposes an improved modulation algorithm for current controlled voltage source converters. Its features are fixed switching frequency and precalculated commutation instants, allowing an accurate phase shift of the current ripple during a parallel connection of converters. Moreover it is characterised by the same features of classical hysteresis control in terms of good dynamic performance, good accuracy and simple control technique. Assuming flux linkages as control variables, insensitivity to possible inductance nonlinearity and inductive coupling is achieved. Therefore, the new approach allows to consider an inductive coupling set, with improvements in multiconverter performances. The new approach has been validated and tested both by numerical simulation and experimental set up.