Design And Finite Element Analysis Of Brushless Synchronous Motor

There are brushes and slip rings in traditional electrically excited synchronousmotor, the brushes and slip rings produce electric arc and spark. Traditionalelectrically excited synchronous motor cannot be used in explosion condition.Traditional brushless synchronous motor system is composed of synchronous motor,rotating rectifier and an AC exciter which is coaxially connected with synchronousmotor. This structure increases the axial length and makes the system complicated.A new structure of brushless synchronous motor system with only one core ispurposed in this thesis to solve above problems. Structure design and workingprinciple are declared.Parameters of a100kW synchronous motor system are calculated using themagnetic circuit method. These parameters are checked and improved by AnsoftRMxprt. The power angle characteristics and d-and q-axis inductance curve areobtained using the finite element analysis software named Ansoft Maxwell. And themath model is summarized based on its working principle and electromagneticcharacteristics.Finite element analysis is done to compare four different structures ofsingle-phase excitation system. The electromagnetic coupling between differentwindings and air-gap magnetic field distribution are obtained. Four poles concentratedstator single-phase excitation winding structure is selected. Finite element analysis ofthe above structure is done. The relationship between stator and rotor’s magnetic fieldand the rotor position angle when motor is standstill is showed. The frequencycharacteristics of the single-phase excitation system are showed when the motor isstandstill and at rated speed. The motor core loss characteristics are showed atdifferent frequencies. The results of induced voltage analysis and its FFT analysis ofthe single-phase excitation system are showed on condition that motor rotates atdifferent speed. The current, torque, efficiency etc are analyzed on condition that themotor is at rated state. The results show that the design of electrically excitedbrushless synchronous motor is reasonable and the electromagnetic properties arestable, so it has certain feasibility.