Computer numerical simulations for accelerated design of rare earth permanent magnet motors in renewable energy applications: A review

Rare earth permanent magnet (REPM) motors underpin various emerging fields in electronic and mechanical industries. The rapid growth of renewable energy industries requires the higher performance of the REPM motors, such as the high output torque (≥ 350 N·m), high power (≥ 200 kW), and low ripple torque (< ±5%). To achieve these performances, the fine design for the materials and structures of the REPM motor is required. Computer numerical simulations play important roles in shortening the period and reducing the cost of REPM motor design. Finite difference method (FDM) and finite element method (FEM) are common methods for motor design. Boundary element method (BEM) exhibits advantage in accuracy and efficiency but its commercialization is slower. These three methods have their own advantages and applications. This review discusses the principles and present applications of the FDM, FEM and BEM in details. At present, the electromagnetic and structural simulations are mainly realized by FDM and FEM, while the acoustics simulation is carried out by BEM or combined FEM-BEM. The advantages and limits of various simulation methods in different parts of motor design are comprehensively compared. The recent progress of computer numerical simulations in REPM motor design is summarized, including the simulations in permanent magnets, electromagnetics properties, structure and acoustics characteristics in REPM rotor. In particular, the design of material and electromagnetic structure for the cutting-edge Nd-Fe-B rotor is highlighted. The opportunity and future directions of computational simulations in REPM motor design are also discussed in this review.