Search

Due to the unchangeable air-gap flux density, the voltage output by permanent magnet synchronous generator (PMSG) will have a variation when the load changes. In order to reduce the voltage variation when PMSGs provide power for the rectifier load in diesel railway vehicles, an optimal method is presented to design a 9-phase PMSG. This optimal method not only ensures the open-circuit voltage of the generator equals the rated voltage of the load, but also it guarantees the PMSG has a low voltage change rate at the same time. In this paper, the saliency ratio range and the relationship between resistance of load and the induction of d-axis are derived according to the two-axis theory, when the PMSG has the negative or zero voltage change rate. Then based on the result of the derivation, by adding the I-shaped permanent magnet (PM) to the d-axis magnetic circuit of V-shaped interior PM rotor, a V-I-shaped PMSG is formed. After that, the Kriging method and the finite-element method (FEM) are used to establish a multi-objective function model. By calculating the minimum value of the multi-objective function, the construct dimension of the I-shaped PM is obtained. After the optimal design results are verified by the FEM, a 520 kVA 9-phase PMSG is manufactured to validate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

Braking torque is the most important performance parameter for a permanent magnet retarder used in heavy vehicles. This paper proposes a model of the permanent magnet retarder for braking torque at different speeds considering the skin effect, the magnetic leakage, and the actual path of the eddy currents. Based on the magnetic equivalent circuit and the piecewise function method, the static and the transient air-gap flux density models are established, and their accuracy is verified by comparison to the finite element method (FEM). The permeability distribution curve of the retarder stator is obtained by a simple permeability-measuring instrument, considering the skin effect on the permeability of the stator. Thus, the effective permeability function of the stator is obtained at different rotational speeds, and the transient air-gap flux density model is optimized using the effective permeability function. The simulation results showed that the optimized transient air-gap flux density of the calculation model was in good agreement with the FEM. Finally, the calculation model of the eddy current braking torque was verified by the bench test. [ABSTRACT FROM AUTHOR]