By using global ring winding, the torque coefficient of the transverse flux machine (TFM) is proportional to its number of pole pairs, and thus the TFM possesses high torque density ability when compared with other electrical machines. As a special kind of TFM, the claw pole machine (CPM) can have more torque due to its special claw pole teeth. The manufacturing of CPM or TFM with silicon steels was very difficult in the past, and is a handicap for the progress of this kind of machine. Thanks to the advent of soft magnetic composite (SMC) materials, the manufacturing process of CPM has become more and more simple. More attention has been paid to this kind of technology, and some mass production CPMs with SMC cores have appeared. However, there are few works that discuss the key design issues for this kind of machine. In this paper, a small CPM with SMC is used as as a research benchmark. Various design methods that can be adopted to improve its performance have been studied, including unequal stator claw pole teeth, a skewing magnet design, consequent pole design, and etc. The 3D finite element method (FEM) is used for the machine analysis, and it is verified by the experimental results of a CPM with SMC cores.

This paper uses the Taguchi method to optimize the manufacturing process and robust design of a low-cost permanent magnet motor with soft magnetic composite (SMC) cores. For the manufacturing process, SMC cores are produced by using the molding technology without any wire cutting costs. To maximize the relative permeability and minimize the core loss, the Taguchi method is employed to identify the best control factor values for the heat treatment of SMC cores based on a series of experimental results. Due to the manufacturing tolerances, there are significant uncertainties in the core densities and motor dimensions, which will result in big performance variations for the SMC motors in the batch production. To obtain a robust design less sensitive to these tolerances, the conventional Taguchi parameter design method and a sequential Taguchi optimization method are presented to maximize the average torque and minimize the core loss of a low-cost PM motor. Through comparison, it is found that the proposed optimization method is efficient. It can provide an optimal design with better motor performance and manufacturing quality. The proposed method will benefit the industrial production of cost-effective PM-SMC motors with robust and compact designs.

A serious inrush current may occur when a power transformer is re-energized, which will cause many adverse effects on power equipment and the power grid. The corresponding potential hazards can be reduced if the existing residual flux density ( Br) can be accurately measured. Combined with the field-circuit coupling analysis method, a novel method for measuring the Br based on the phase difference between the applied AC voltage and resulting transient current is proposed in this paper. When the same AC voltage is applied to the transformer winding, the Br affects the resulting transient current. The phase difference between the applied voltage and the resulting current can be calculated by the cross-correlation technique. Based on the finite element method (FEM), the empirical formula for the quantitative measurement of Br in the transformer core is determined. Finally, an experimental study is performed on the square core of single-phase transformers. The experimental results reveal that the proposed measurement method is with high accuracy.

With designing stator teeth by using grain oriented silicon sheets (GO) and other parts still with non-grain oriented silicon sheets (NGO), the electromagnetic performance of interior permanent magnet synchronous machine (GO-IPMSM) can be improved greatly, however its torque ripple will be increased as well. For reducing its torque ripple, optimizing its rotor barrier shape is an effective way. In this paper, the polynomial method is proposed to establish the rotor barrier shape, and the genetic algorithm (GA) method is employed for the optimization process. In case the optimized GO-IPMSM can work normally, its anti irreversible demagnetization ability is analyzed as well. As shown, with the GO is adopted for designing the stator teeth and its rotor barrier shape is optimized, though its torque ability and efficiency have been increased, its anti irreversible demagnetization risk ability is reduced, however the proposed machine can still operate safely.