Two cost functions evaluation for energy optimal position control with constant and linear torques

Design and verification of two cost functions for energy optimal position control of the PMSM drives loaded with combined constant and linear friction and load torques is the main contribution of this paper. The first cost function respects copper losses minimization only while the second one minimizes copper and friction losses together. Both algorithms expressed analytically respect prescribed maneuver time and prescribed acceleration while drive´s speed is derived to achieve the demanded position in given time. Overall control system complains with principles of vector control and forced dynamics control. For precise tracking of the prescribed state variables a zero dynamic lag pre-compensator is included. Energy demands of both control algorithms are calculated and compared by simulation. Results gained confirmed higher energy savings of the cost function minimizing copper and friction losses together.