Permanent magnet alternators for stand alone electricity generation

The paper reviews the feasibility and application of permanent magnet alternators to electricity generation in stand-alone renewable energy systems. The characteristics of permanent magnets are reviewed, and guidelines are given with respect to design criteria. It is shown that a high flux density in a machine is important, and also that magnet material is reduced if the diameter of machines is increased. The main sources of losses in permanent magnet machines are reviewed, and the consequences of embedding magnets away from the air gap, or placing them adjacent to the air gap, are discussed. Performance curves of two permanent magnet alternators are given