Basic Principles and Characteristics of Hybrid Excitation Type Synchronous Machine

Abstract

Permanent magnet type synchronous machines have been widely used for industrial applications. It is commonly known that they are operated at high efficiency since no excitation input is required. However it is difficult to control the air gap magnetic flux, because the magnetic flux is determined by the property of the permanent magnet and approximately kept constant.
On the other hand synchronous machines with the field winding make it easy to control the air gap magnetic flux. But the copper loss of the field winding becomes large at the rated load.
In order to realize the magnetic flux control easily and improve the performance of the conventional synchronous machine, we propose a hybrid excitation type synchronous machine (HSY) with the permanent magnets and the field winding. Advantages of HSY are (1) it has no brushes (maintenance free), (2) required excitation input is small (high efficiency), (3) it is easy to get a sufficient magnetic flux control, and others. Therefore, HSY has a great possibility to use for various applications.
In this paper, basic principles and characteristics of HSY are mainly discussed and made clear.