Permanent magnet working point ripple in synchronous generators

The Journal of Engineering

Stefan Sjökvist¹  Morgan Rossander¹  Sandra Eriksson¹ 

[1] Division of Electricity, Department of Engineering Sciences, Uppsala University, Box 534, 75121 Uppsala, Sweden

关键词: electrical loading;    magnetic field;    passive rectification;    AC load;    PM working point ripple;    DC load;    magnetic flux density;    permanent magnets;    power 100 kW;    magnetic flux density ripple;    slot-related harmonics;    electrical machines;    finite element method simulations;    synchronous generators;    electrical frequency;   

DOI  :  10.1049/joe.2016.0309

学科分类：工程和技术（综合）

来源: IET

【 摘 要 】

Permanent magnets (PMs) are today widely used in electrical machines of all sorts. With their increase in popularity, the amount of research has increased as well. In this study, the magnetic flux density ripple of the working point of the PMs in a 100 kW PM synchronous generator has been investigated for three different load cases: no load, AC load, and DC load. The PMs will be subjected to a shift in working point as a consequence of the characteristics of the electrical loading. This study is based on finite element method simulations where the ripple of the magnetic flux density in the PMs was recorded at three positions within a PM. The slot harmonic of 7.5 times the electrical frequency ( f el ) was present in the results for all load cases, but mainly at the surface of the PM, as expected. Results showed an unexpected harmonic of 1.5 f el , assumed to be an undertone of the slot harmonics. The 6 f el harmonic for the DC load case was significantly higher than for the AC load case and is caused by the current fluctuation during passive rectification. For the studied machine, the added harmonics in the magnetic field due to passive rectification are less than the slot-related harmonics.

【 授权许可】

CC BY