Abstract: In consideration of low power density of electric excitation claw-pole synchronous alternators and some difficulties in magnetic field regulation of permanent magnet claw-pole synchronous alternators,a novel hybrid excitation brushless claw pole alternator（HEBCA） is proposed in this paper.Its magnetic field is contributed by a permanent magnet and an excitation coil.The machine topology and operation principle are described.In addition,the no-load magnetic field distributions and the capability of flux control are obtained based on the three-dimensional finite element analysis（3-D FEA）.A prototype alternator is designed and tested.The measured results agree well with finite element predictions.It shows that HEBCA has higher power density and air gap flux density than the claw-pole alternators with only electric excitation in the same structure parameter.And it also has the advantages of good low-speed characteristics and low excitation losses.