Design and analysis of novel double stator biased flux machines

In this paper, the electric machines with biased flux is well defined. Based on this definition, a view is pointed out, when the single stator of the biased flux machines is separated as double ones, a set of novel structure machines could be derived, which could be designated as double stator biased flux machines (DSBFMs). One kind of DSBFMs is introduced in this paper, and considering the flux polarity in the adjacent coils, these machines are named NNSS DSBFMs. Firstly, the operation principle and the structure of these machines are introduced. Secondly, two structure machines are proposed to demonstrate the principle of DSBFMs, which have 12 stator teeth, coupling with 10-poles and 11-poles rotors, named NNSS-12-10 and NNSS-12-11 DSBFM respectively. Then the coil flux and winding flux of these two machines are thoroughly analyzed. Thirdly, general electromagnetic performance of NNSS-12-10 and NNSS-12-11 DSBFMs are analyzed to evaluate the back-EMF, inductance and cogging torque. The comparative study shows that NNSS-12-11 DSBFM has the better performance. Fourthly, one NNSS-12-11 DSBFM is well designed to evaluate its performance. The simulation results show the machine have has relatively high torque density, little torque ripple and acceptable efficiency. This kind of machines has great potential in high torque low speed direct drive applications. Lastly, a general design guideline for this kind of machines is concluded. Based on this guideline, many more structures of DSBFMs are possible to be derived.