A NEW MATHEMATICAL-MODEL AND CONTROL OF A 3-PHASE AC-DC VOLTAGE-SOURCE CONVERTER

A new mathematical model of the power circuit of a three-phase voltage source converter (VSC) was developed in the stationary and synchronou s reference frames, The mathematical model was then used to analyze an d synthesize the voltage and current control loops for the VSC, Analyt ical expressions were derived for calculating the gains and time const ants of the current and voltage regulators. The mathematical model was used to control a 140-kW regenerative VSC, The synchronous reference- frame model was used to define feedforward signals in the current regu lators to eliminate the cross coupling between the d and q phases, It allowed the reduction of the current control loops to first-order plan ts and improved their tracking capability, The bandwidths of the curre nt and voltage-control loops were found to be approximately 20 and 60 times (respectively) smaller than the sampling frequency, All control algorithms were implemented in a digital-signal professor, All results of the analysis were experimentally verified.