Homopolar and bipolar hybrid excitation synchronous machines

This paper presents a description and operating principle of different hybrid excitation synchronous machines. Four prototype machines of different power rating (3 kW and 15 kW) have been studied. These machines combine two flux sources: permanent magnets, located in the rotor, and field coils, located in the stator. Thanks to this particular configuration the air gap flux can be easily controlled, without any risk of magnets demagnetisation. Tests are performed on the prototype machines to asses their flux weakening capability. Three of prototype machines are modular and can be assembled to have a homopolar or a bipolar configuration. These two configurations are compared using experimental measurements. The advantages and drawbacks of each configuration are described