Study On Hybrid Excited Switching Flux Machine Using Magnetic Circuit Model

Hybrid excited switching flux machine(HESFM)combines the advantages of dc power switching flux machine(SFM)and switching flux permanent magnet machine(SFPM),which has adjustable magnetic performance and higher torque density.Hybrid excited switching flux machine with magnetic bridge is a kind of parallel hybrid excited topology structure of switching flux machine.With the magnetic bridge,the utilization ratio of the dc excited magnetic motive force(MMF)is improved,and the demagnetization risk of the permanent magnet is reduced.But the magnetic bridge also provides short-circuit magnetic circuit for the permanent magnet flux.The excessive thickness of the magnetic bridge will reduce the utilization ratio of the MMF which is provided by permanent magnet.The reasonable distribution of the electric excited and the permanent magnet is very important.The influence of the structure parameters on electromagnetic performance and the design principle are worth investigating.Firstly,the present situation and development of HESFM are reviewed.The principle of switching flux of machine is introduced,and the variation law of three-phase flux linkage and no-load EMF is analyzed.The mathematical model of the machine is established by deducing the flux linkage equation,voltage equation,torque equation and mechanical equation.Several key parameters in magnetic circuit calculation are investigated.Then,the magnetic circuit model of 12/14 HESFM is established,and the influence of rotor pole number variation on magnetic field distribution,flux linkage,no-load EMF and magnetic regulation ability is analyzed by comparing with 12/10 HESFM.Using the magnetic circuit model under different excitations,analysis the influence of stator parameters on the main flux and magnetic adjustment capability.Finally,according to the design experience of SFPM,the dimension equation of HESFM is deduced.And the method of determining the parameters based on the magnetic circuit model is analyzed in detail.The initial design of the machine is completed and tested by the finite element results.