Limitations of simplified fuzzy logic controller for IPM motor drive

This paper explores the limitations of a simplified fuzzy logic based speed controller incorporating approximated maximum torque per ampere (MTPA) mode of operation of an interior permanent magnet synchronous motor (IPMSM) as compared to a non-simplified fuzzy logic based system without MTPA mode operation. The fundamentals of fuzzy logic algorithms as related to motor control applications are illustrated. Non-linear expressions for q- and d-axis currents are derived and subsequently incorporated into the control algorithm for maximum torque operation with the simplified FLC. This is contrary to the conventional control of IPMSM, which linearizes the q-axis current expression by setting the d-axis current equal to zero. The simplified fuzzy speed controller for the IPMSM drive has been found to maintain high performance standards with a much simpler and less computation intensive implementation than the non-simplified fuzzy based algorithm. It is the purpose of this work to further investigate the efficacy of such simplifications in the FLC based IPMSM drive with MTPA by comparison with a non-simplified FLC based IPMSM drive system. Both systems have been tested extensively in simulation.