New synchronous machine rotor design for easy insertion of excitation coils based on surrogate optimisation

Abstract

The thesis reviews the development of traditional synchronous machine design and point out one problem with the manufacture of wound rotor synchronous machines. Install and repair process of the rotor windings can be considered labor-costly and time-consuming in synchronous machine design. The conclusion indicates a new winding method would be helpful for not only the new machines but also for rewound machines. A new rotor design for the easy insertion and repair of the rotor windings is then introduced. This new asymmetrical rotor shows good potentials for reducing the maintenance and repair costs of synchronous machines, making it suitable for manufacturers within the mass production markets such as gen-sets, steam turbines, wind power generators. Simulation results from 2-D finite element analysis and experimental results from testing a 27.5 kVA prototype machine have verified the performance of the new rotor. The results show that the asymmetrical machine’s electromagnetic performance is worse than traditional design and need to be optimised. The shape of the rotor is then optimised based on novel surrogate method in order to achieve the lowest power loss under the maximum power output. This method combines surrogate optimistaion with finite element method. It significantly reduces the time cost of the optimization process and can be applied with very complicated geometry design of the rotor. The performance of the new rotor is examined in 2-D finite element software and validated by experiments. After optimisation, the efficiency of the new rotor can reach the same level of the traditional rotor in electromagnetic performance in addition to its easy insertion and repair feature.