A kind of alloy designed for HSPMG rotor sleeve

As one of the most important kinds of distributed generation systems, the micro turbine generation system can be flexibly installed near the end user, and becomes an important trend of development in DGS gradually. The high speed permanent magnetic generator (HSPMG) can be properly applied in a micro turbine generation system and benefits the system from high efficiency, high power density, simple structure, and good reliability [1]. For this kind of machine, to protect and fix the rotor and magnets under a large centrifugal during the high speed operating, a sleeve is often added to rotor outer surface, and metal sleeves are usually implemented [2,3]. In a HSPMG, the operating frequency is more than 1kHz, and the higher order harmonics of air-gap flux would cause significant eddy current loss in metal rotor. Thus, the resistivity and permeability affect generator magnetic circuit and output performance directly. On the other hand, the generated loss and sleeve thermal conductivity influence the working temperature of rotor, which determines the safety and reliability of magnets and the HSPMG. In this case, the electrical magnetic and thermal characteristics of the rotor sleeve are important for the HSPMG design. In this investigation, a new kind of alloy sleeve mainly made of iron and copper is designed and applied in a 100kW HSPMG which adopts a closed oil system in the stator. Considering influences of sleeve material characteristics on both the magnetic circuit and heat transfer paths comprehensively, the output and thermal performance of the HSPMG with the proposed sleeve is studied based on electromagnetic-fluidthermal analysis. Meanwhile, the variations of the machine output and working temperature with the rotor sleeve are researched, which provides a reference for the new alloy design for electric machines.