Fuzzy logic controlled direct frequency converters modulated by an expert knowledge-based space vector technique

This paper presents two expert knowledge-based modulated direct frequency converters (XDFC). One uses a direct approach to model the converter operation (D-XDFC), and the other a fictitious link modeling (F-XDFC), The proposed schemes merge fuzzy logic, expert systems and space vectors to control the converters. Their main feature is to achieve a unity AC-AC voltage gain. Hence, eliminating the need for coupling transformers and allowing XDFC driven motors to be rated at the system´s nominal voltage. Output and input currents are simultaneously controlled. An expert space vector modulation (XSVM) is presented, that selects the next converter state using a set of rules based on a sound understanding of the DFC operation. Thus achieves a notorious processing time reduction compared to similar performance control algorithms. The converters´ commutation frequency is kept below 850 Hz, which reduces the converter´s losses, switches´ stress and increases the power level the proposed XDFC may handle