Research On A Novel Multi-stator Hybrid Radial And Axial Magnetic Circuit Permanent Magnet Synchronous Machine

Because of its simple structure,reliable operation,high efficiency,small volume and light weight and so on,permanent magnet(PM)machine is widely applied on household appliances,industry,transportation,medical instruments and national defense.According to the position of the permanent magnets placing on the rotor,PM machine is divided into two types:surface type and interior type.Due to interior type machine's low risk of demagnetization and asymmetric flux path,this type is more suitable to be a adjusting speed machine.However,interior type has some disadvantages,such as large leakage.flux on rotor's both ends because.of high magnetic density and narrow adjusting speed range with constant power.In order to improve those shortcomings,this thesis proposes a novel hybrid radial and axial magnetic circuit permanent magnet synchronous machine(PMSM)with flux weakening capability.The research work is as follows:Part ? reviews the development and the advantages of PMSM,displays several kinds of classical hybrid excitation machine(HEM)models which have wide speed range with constant power,elaborating work principle,merits and present research status.The overhang structure for PMSM is introduced to overcome rotor ends leakage flux.Finally,the novel hybrid radial and axial magnetic circuit permanent magnet synchronous machine is introduced-and shows its advantages.Part ? explains the presented machine structural characteristics,analyses magnetic circuits and elaborates how the presented machine to work,and a preliminary conclusion of weakening flux capability comes out by establishing and calculating 3D finite element model.Part ? establishes an equivalent reluctance network analysis model of the presented machine to calculate per polar flux and compares the results with 3D finite element,also verifies that the presented machine has lower rotor ends leakage flux.In part ?,the emergence of cogging torque in PMSM is explained first,and the relationships between the cogging torque and the change rate of air-gap permeance are analyzed under some hypothetical conditions in this paper.Secondly,the paper deducts the presented machine's cogging torque formula with energy method.Finally,adjusting the physical parameters of the formula weakens the cogging torque and verifying by 3D finite element model,studying how cogging torque to change if the angle of the tooth center lines of two stators changes.