A Comparison of Converter topologies and Current control strategies for Real-time Load Emulators

Real-time emulation is a popular testing technique which is capable of providing realistic testing environments for the development of products and control algorithms. This method involves the use of a static power electronic converter, which is made to behave as a load or a source in real-time. The two important aspects which are needed for successful power level emulation include: a) an accurate model of the emulation target (load or source) and b) an effective controller which ensures accurate and fast tracking of the references provided by the model. The work presented in this paper compares two current control techniques - the linear synchronous reference frame (SRF) PI based current controller and the non-linear dead beat current controller (DBCC) implemented in the natural reference frame for the load emulation of a dynamic induction motor load, a 3 phase non-linear diode bridge rectifier and an unbalanced load. Two converter configurations i.e, a two level inverter and a modular multilevel converter (3, 5 and 7 levels) have been used for the comparative study. The results of the investigations made through simulations using Matlab-Simulink have been discussed.