Design Comparison of Outer- and Inner-Rotor Permanent Magnet Motors for Hydrofoil Boat

This paper presents the design criteria of a permanent magnet motor for hydrofoil boat applications. Based on the dynamic analysis of hydrofoil boat, the constraints of propulsion motor are derived and therefore the surface-mounted permanent magnet motor is chosen as the competitive candidate. In order to have large power density in the permanent magnet motor, the outer- and inner-rotor motors are investigated and compared to demonstrate their advantages at different design constraints, which will provide the theoretical basis to improve the propulsion system in the hydrofoil boat from the perspective of motor design

Nonlinear Analytical Analysis of External Rotor Permanent Magnet Synchronous Motor

This article proposed a nonlinear analytical model (NAM) for external rotor permanent magnet synchronous motor (ER-PMSM) considering both rotor and stator saturation. The improved magnetic equivalent circuit (IMEC) is introduced to accurately describe the saturation effect of rotor and stator. The air gap reluctance is replaced by magnetic flux source, and, therefore, the size of IMEC can be reduced while keeping high accuracy. For the air gap field calculation, the analytical solution will be obtained based on the modified boundary condition from the IMEC. The complex permeance function is extended to represent the slotting effect of ER-PMSM. Hence, the NAM will be numerically solved from the combination of IMEC and analytical air gap solution. Both finite-element analysis (FEA) and experiment demonstrate that the proposed model has high accuracy and requires little time

Electromagnetic Analysis for Interior Permanent-Magnet Machine Using Hybrid Subdomain Model

This paper proposed a hybrid subdomain model (HSM) for calculating the magnetic field distribution of interior permanent-magnet (IPM) machine accounting for slotting effect, rotor saliency, and iron nonlinearity. In the constant permeability region, i.e., slots, slot-opening, and air-gap, three subdomains are introduced to represent their magnetic field. By applying the subdomains interface conditions and nonlinear boundary conditions, the analytical air-gap field solution can be obtained based on the governing Laplace and Poisson equation. For the iron region, the magnetic reluctance network (MRN) is proposed to account for rotor saliency iron and nonlinearity. The magnetic voltage source is introduced to represent the permanent-magnet (PM) while the air-gap flux source is used to replace the air-gap reluctance network, which is the key to guarantee the computational efficiency and high accuracy. The electromagnetic performances of both flat-shaped and V-shaped IPM machines are investigated to show the advantages of different IPM machine topologies analytically. The HSM predictions for both IPM machines are validated by finite-element (FE) analysis and experimental results

Analytical Calculation of Eccentric Surface-Mounted Permanent-Magnet Motor Accounting for Iron Saturation

This article presents an analytical model to predict the performance of eccentric surface-mounted permanent-magnet (ESPM) motor based on the nonlinear conformal mapping and reluctance network hybrid model (NCRHM). The proposed model can reveal the mutual influence of rotor eccentricity on the stator slotting and iron saturation accounting for the distortion of the equivalent current positions and air-gap path among the conformal mappings. The transformation between magnetic voltage drop of iron and equivalent current in the air region (including air-gap and slot region) is employed to consider the increased iron saturation due to the reduced air-gap length. Based on the proposed model, the electromagnetic performance including flux linkage, back electromotive force (EMF), torque, and unbalanced magnetic force (UMF) can be accurately predicted for any kind of rotor eccentricity. In addition, the NCRHM is compared with the complex permeance model (CPM) neglecting both iron saturation and the field distortion in conformal mappings, which exhibits the great advantage of NCRHM for ESPM motor. The excellent accuracy and great efficiency of the proposed model are validated by both finite-element analysis and test results

Nonlinear Analytical Modelling for Surface-Mounted Permanent Magnet Motors with Magnet Defect Fault

This paper analyzes magnet defect fault signature in the surface-mounted permanent magnet motor (SPMM) using nonlinear analytical model considering the influence of magnet shape and magnetization direction. Based on the surface current method and conformal mapping technique, the magnet defect equivalent current and equivalent nonlinearity current are proposed to represent the magnet defect. Accordingly, the performance of SPMM can be obtained. The proposed model has great potential to investigate SPMM with non-uniform magnet defect and gives theoretical basis for fault diagnosis. The extra sensing coil is added to measure the voltage waveforms, which can also be predicted using the nonlinear analytical model and shows the influence of magnet defect fault. Finally, the finite element analysis and experimental results verify the high accuracy of nonlinear analytical model

Analytical Model of Electromagnetic Performance for Permanent-Magnet Vernier Machines Using Nonlinear Exact Conformal Model

This article investigates the air-gap field distribution of the permanent-magnet Vernier machine (PMVM) using a nonlinear exact conformal model (NECM) to account for slotting effect, flux modulation effect, and iron nonlinearity. The exact conformal model (ECM) based on the region of one-slot and one-flux-modulation-pole (OSECM) are introduced to show the effectiveness of the linear analytical model for PMVM. It can keep high calculation accuracy and significantly reduce the computational burden. Then, the NECM is developed from OSECM by introducing the equivalent saturation current into the air region and coil region. The lumped parameter magnetic circuit model (LPMCM) model is used to obtain the magnetic potential of the iron region and therefore calculate the equivalent saturation current. The NECM which combines LPMCM and OSECM can essentially improve the accuracy of the linear analytical model. The harmonic analysis of the air-gap field is performed to theoretically explain the component of electromagnetic torque. Both finite element model (FEM) simulation and test results are presented to validate the NECM