MPCC with Novel Cost Function for MTPA and Feedback Flux Weakening of IPMSM Drives

In model predictive control (MPC) based drives, flux weakening (FW) techniques have not been widely investigated in literature. In this study, an MPC based interior permanent magnet synchronous machines (IPMSM) drive operating in a wide speed range is proposed. To reduce the computational burden of model predictive current control (MPCC), unlike the MPC implementations in literature, the current limit is applied outside the MPCC as a new approach. Also, it is proposed to use different weighting factors for constant torque region (CTR) and constant power region (CPR), which is a novel approach, different from the cost functions in literature since MPCC based controllers in literature do not use weighting factors in the cost function for d- and q-axis current error terms. A short review study on the cost functions is also conducted. The criteria to be considered in the selection of the weighting factor for CPR are determined, i.e., stator current tracking error (SCTE) and phase current distortion rates, i.e. total harmonic distortions (THD). In this study, different weighting factors are determined in CTR and CPR to reduce SCTE and thus to track dq-axis currents accurately. Finally, the base speed needs to be known to set the weighting factors differently in the CTR and CPR regions. Since the base speed depends on the parameters and its preference may decrease the performance of the drive, the feedback flux weakening (FB-FW) strategy mechanism is used to ensure the use of different weighting factors in the CTR and CPR independently of the parameters. The superior performance of the proposed drive is proven by comprehensive simulation results.