Optimum design of PMA-SynRM for zero inductance of Q-axis and experimental verification

Abstract

This paper deals with the optimum design of permanent magnet assisted synchronous reluctance motor (PMA-SynRM) for power improvement . The focus of this paper is found firstly a design solution through the comparison of torque density and d, q-axis inductance according to the rotor magnet and flux barrier shape, secondly, a mixed resolution with central composite design (CCD) is introduced and analysis of variance (ANOVA) is conducted to determine the significance of the fitted regression model . The proposed procedure allows the definition of the rotor magnet and flux barrier shape, dimensions starting from an existing motor or a preliminary design according to the rated wattage . IntroductionThe performance of a synchronous reluctance motor (SynRM) in terms of torque and power factor depends on the two-axis inductance L d and L q of the machine . The large difference of L d -L q and L d / L q ratio are good for the machine's properties . Therefore, Considerable attention has been paid in the past to improve rotor design of SynRM [1]-[3] . By adding a proper quantity of permanent magnets the torque density and power factor of SynRM can be greatly increased . It is called Permanent Magnet Assisted Synchronous Reluctance Motor (PMA-SynRM) . And it is important to select an appropriate combination of design parameters to enhance more torque density than an existing PMA-SynRM . In this paper, finite element analysis for a PMA-SynRM is presented and the d-q axis inductance, torque characteristics analysis are performed . Comparisons are given with inductance and torque characteristics of normal Synchronous reluctance motor and those according to quantity of residual flux density (0T, 0 .4T) in PMA-SynRM, respectively . And then, it is confirmed that the PMA-SynRM results in high output power performance through numerical analysis data . The focus of this paper is to find design solutions through the comparison of torque density and d-q axis inductance, especially torque ripple of PMA-SynRM according to the rotor magnet and flux barrier shape . Coupled finite elements analysis (FEA) and Response surface Methodology (RSM) have been used to evaluate design solutions [4]-[7] . Modelling And Principle Of Pma-synRM 2.1 Principles of PMA-SynRM for High Power ApplicationA normal synchronous reluctance motor runs at a somewhat poorer power factor than the induction motor . This problem can be alleviated by inserting permanent magnets between rotor segments . The principle can be illustrated by the follow-ing theorem . A cross-sectional view of a PMA-Syn-RM is shown in Fig . 1 . When permanent magnets are included in the q-axis flux path the flux linkage expressions become λ d = L d i d (1) λ q = L q i q + λ mq(pm) (2) Where L d and L q are the d-and q-axis inductances and, L d π L q . Torque expression can also be written as T pmr = 3p/4[(L d -L q )i q i d + λ mq(pm) i d ] (3) It can be considered that a theoretical maximum torque for a PMA-SynRM is reached if L q is zero . This possibility can be reached by use of the second...