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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]

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]

To improve output performance of salient-pole synchronous machines, permanent-magnet-assisted salient-pole synchronous machines (PMa-SMs) that have permanent magnets (PMs) between the field poles were previously developed. The PM effect of increasing the output power and the terminal voltage has already been confirmed by finite element analysis (FEA) and experiments under steady states. In this paper, demagnetization in the PMs due to sudden three-phase short circuits is evaluated by FEA. The results show that irreversible demagnetization arises in the PMs of a PMa-SM with relatively smaller circumferential PM length. Effects of the PM shape and damper bars on the irreversible demagnetization are also investigated. The results show that making the PM shape a rectangle and adding damper bars on the outer surfaces of the PMs are effective to reduce the demagnetization, while increasing the number of the conventional damper bars is not effective. [ABSTRACT FROM PUBLISHER]

The characteristic improvements of salient-pole synchronous generators by inserting additional permanent magnets are investigated from both results of finite-element analyses and experiments. First, the assist effects of the magnets in a megavoltampere-class generator are analyzed by the finite-element method. It is clarified that the additional permanent magnets have the effects of reducing magnetic saturation at the rotor-pole bodies, as well as the effects of increasing the direct flux linkage of armature windings. It is also clarified that the output of the generator can be increased by more than 20% by inserting the magnets without any increase in total machine size and decrease in efficiency. Finally, the characteristic improvements are validated by the experiment of a small prototype generator. The experimental and calculated results are found to be in good agreement. [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]