Experimental investigation of a Doubly-Excited Flux-Switching Machine for aircraft DC power generation

This paper presents an experimental study on a new design of a Doubly-Excited Flux-Switching Machine (DEFSM) proposed for variable speed DC power generation in future aircraft. This machine uses excitation coils associated with permanent magnets to control the flux-linkage. This gives the possibility of using a diode bridge rectifier which is more reliable than an active bridge. After presenting its design and some of its main characteristics, an experimental investigation of the electromagnetic and thermal performances has been performed on a 3 kW prototype. It is shown that the generated power can be easily controlled using the excitation current which is very interesting for wide-speed-range applications. The unique design of the stator makes it possible to have a low remanent back EMF. This characteristic makes this machine inherently safe in case of fault since no flux weakening is needed. The thermal analysis has shown that the permanent magnets can be kept at relatively low temperatures which makes them more resistant to demagnetization. All of this makes the DEFSM a strong candidate for future aircraft power generation.