Analytical Modeling for Optimal Rotor Shape to Design Highly Efficient Line-Start Permanent Magnet Synchronous Motor

Abstract

In this study, an analytical technique for the rotor geometry optimization based on lumped magnetic parametric approach is used to design a two-pole, three-phase, 7.5-kW line-start permanent magnet (LSPM) synchronous motor. The permanent magnet shape substantially affects the air-gap flux density distribution, back electromotive force (EMF) as well as the copper loss, which have a great impact on the performance characteristics of the permanent magnet synchronous motors. Principal advantages involve in adjusting the rotor shape are to achieve the effective air-gap flux density and optimize the fundamental component of the back EMF with low harmonic content for minimum ripple torque. Therefore, to enhance the efficiency (η) and power factor, an optimized slot shape considering various design parameters is selected for the permanent magnet of the rotor in the prototype LSPM machine. A linear saturated lumped magnetic parametric model is developed to exhibit magnetic characteristics, and analytical equations are acquired under the open-circuit condition without considering the slotting effect for design simplicity. The influence of design variables on the air-gap flux density distribution and the flux leakage is investigated precisely using an analytical circuit model. A parametric study of the prototype model demonstrates that the steady-state performance of the LSPM motor are significantly influenced by the design variables. The inductance saliency ratio and electromagnetic torque components are carefully analyzed in terms of their effects on the load characteristics of the LSPM motor in order to determine the optimal shape of the PM slots and the magnetic flux barriers. The validity of the proposed method has been checked by evaluating the numerical solution of the analytical model using a two-dimensional finite element method.INDEX TERMS Analytical method, air-gap flux density, FEM, lumped parametric model, parametric study, rotor design.

Modelling, Analysis, and Design of a Line-Start Permanent Magnet Synchronous Motor

“…However, the accuracy of the FEA comes at the cost of a high computational burden, thus limiting the use of such tool for the design and optimization [4]- [6]. On the other hand, the popular single-phase equivalent circuit of SCIMs [7] or sizing approaches based on lumped parameter magnetic circuits [8], [9] can only be used for the analysis of steady-state conditions or slowly evolving transient. The mid-complexity analytical modelling presented in [10]- [12] allows to describe the behavior of any electro-magneto-mechanical device by means of a lumped-parameters analysis based on state variables.…”

Investigation of the Effects of the Pole Shoe Geometry on the IPM T-LSM Features: Application to Free Piston Engines

“…These latter have been formulated in several forms depending on the considered assumptions and the features under investigations, yielding a simplicityaccuracy tradeoff. For instance, a simple MEC model can be established assuming infinite length machines and infinite iron permeability [34], [35]. However, more representative MECs could be derived by discarding the previous assumptions.…”

FE-Aided Synchronization Analysis of Line-Start Synchronous Reluctance Motors

“…This may be due to the fact that the motor is quite difficult to manufacture. The typical rotor of an LSPM is composed of small rotor slots with one layer of buried PMs [4][5][6][7]. In contrast, a LS-SynRM utilizes rotor slots as part of a flux barrier, such that the regular rotor slot shapes of IMs are generally not feasible for use in this motor.…”