Design And Research On Novel Brushless Electrically Excited Synchronous Motor

Synchronous motor is a kind of commonly used alternating current motor; it can beused not only as a generator motor but also as a compensation motor. Synchronousmotor drive system has many advantages, such as large capacity, high efficiency, smallvolume, small moment of inertia, adjustable power factor, strong overload ability.Synchronous motor drive system has been widely used in the environment that requiredposition, velocity, acceleration and other adjustable variety.Conventional electrically excited synchronous motor stator has three-phasesymmetric winding, the rotor has exciting winding and damping winding. This paperproposed a new brushless electrically excited synchronous motor. The new brushlesselectrically excited synchronous motor does not need separately excited and the brushand slip ring that been used in the traditional synchronous motor rotor. So the structureis simplified, and it is easy to maintain and it can adjust the excitation without the brush.The new brushless electrically excited synchronous motor’s basic structure andworking principle was analyzed in this paper. In the inner circumference of the statorcore, a deep slot near the intermediate position is grooved,and a certain number of turnsof the windings was placed in the slot to constitute a single-phase excitation winding.Aslot in the outer circumference of the rotor core is grooved too,and it is corresponding tothe slot in the stator and has the same width,and a certain number of turns of thewindings was placed in the slot to constitute a single-phase induction windings.Whenthe stator single-phase excitation windings pass into the single-phase ACpower,according to the transformer principle,the single-phase induction windings in therotor would induce the induced electromotive force.The induced single-phase AC isrectified to DC by rotating rectifier,the output current to provide excitation current.Withthe change of the stator winding single-phase excitation voltage, the rotor DC excitationcurrent would change,so it can adjust the excitation without the brush.Electromagnetic relation of the synchronous motor was analyzed in this paper.Magnetic potential and voltage balance equation, Equivalent circuit diagram, phasordiagram and power flow was given in this paper. The mathematical model of theelectrically excited synchronous motor was given under the stator three phase rest frameand rotating coordinate system base on ideal synchronous motor model. Theelectromagnetic of the new motor was calculated and the specific parameters of themotor were given. This paper analyzed the magnetic field distribution of the motor byusing simulation platform to build the new electrically excited synchronous brushless motors finite element model. The motor magnetic field lines and the magnetic fluxdensity distribution is given and the performance under different load were analyzed inthis paper.This paper introduces the new brushless synchronous motor excitationparameters and the development process of the prototype.)。The motor experimentalplatform was built. A series of experiments was done to study the motor properties andverify that the design was reasonable.The experimental data shows that the planestructured by the field winding of the stator side and the induction windings of the rotorside is perpendicular to the plane structured by the power windings and the magneticfield coupling relations is small,so after power, the induced electromotive force value onthe other side is very small. Experimental results showed that the prototype had thenovel structure and the reasonable design, and it can adjust the excitation without thebrush.