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The output of permanent-magnet-assisted synchronous machines is maximized under constant permanent magnet (PM) volume and machine size by optimizing rotor shape. An automatic shape optimization method combining Rosenbrock's method and adaptive finite-element method is applied for the optimization. Then, a prototype machine is manufactured due to the result of the optimization in order to confirm the validity. It is clarified that the output of the optimized machine significantly increases without decrease in efficiency, increase in PM volume, and increase in machine size compared with that of the conventional machine. [ABSTRACT FROM PUBLISHER]

In this study we investigate a method for accurately calculating the characteristics of salient-pole synchronous machines assisted by permanent magnets. First, the operating principle of the machines is investigated by using both finite element analysis and a simple magnetic circuit. Then, a theoretical representation of the assist effect on the permanent magnets is derived based on the magnetic circuit. Finally, the measured and calculated results are compared in order to confirm the validity of the proposed calculation method. We show that the load characteristics of the proposed machine can be accurately estimated from the no-load and short-circuit characteristics of the conventional machine without permanent magnets, and the size and magnetization of the inserted permanent magnets. [ABSTRACT FROM AUTHOR]

Permanent-magnet-assisted salient-pole synchronous machines (PMa-SMs) are a new type of salient-pole synchronous machines that has PMs between the adjacent pole shoes. The PMs have the ability to improve the output power and the terminal voltage. In this paper, a simple magnetic circuit of PMa-SMs is presented. Using the magnetic circuit, the electric and magnetic basic characteristics of PMa-SMs are calculated. The results are compared with the results by measurements and finite-element analysis (FEA). They have shown that the magnetic circuit calculates the characteristics of PMa-SMs with satisfactory accuracy and that the computational time of the magnetic circuit is much smaller than that of FEA. Influence of the pole-shoe magnetic reluctances on the calculation accuracy by the magnetic circuit is also discussed, and some guidelines to enhance the accuracy have been presented. [ABSTRACT FROM PUBLISHER]

In this paper, we investigate the mechanism of output increase by inserting additional permanent magnets in salient-pole synchronous machines. The machines are modeled not only by finite element methods but also by a simple nonlinear magnetic circuit in order to express the assist effects of permanent magnets by simple theoretical expressions. The no-load saturation curves obtained by the finite element method and the magnetic circuit are compared with those of measurements in order to confirm the validities. It is clarified that the accuracy of the proposed magnetic circuit is nearly identical to that of the finite element method. Furthermore, the mechanism of the output increase by the permanent magnets is revealed by the theoretical expressions derived from the magnetic circuit equations. [ABSTRACT FROM AUTHOR]

A simple magnetic circuit of salient-pole synchronous machines is presented. A method for calculating steady-state electrical performances using the circuit is described. Magnetic saturation including the cross-magnetizing phenomenon is considered in the method. The saturated reactances, field currents, and load angles are calculated easily from the method without much computational effort as compared with the finite element method. Despite the simplicity of the magnetic circuit, the calculated reactances at various load conditions using the method are close to the measured and FEM values. [ABSTRACT FROM AUTHOR]