Design And Energy Saving Analysis Of Single-winding Double-speed Motor For Contra-rotating Axial Flow Fan

In this dissertation,the counter-rotating axial fan of model FBDCZNo.14/2*45is taken as the research object.When the contra-rotating axial flow-fan deviates from the rated operating point,the problems of the pressure rise and power imbalance,as well as the motor overload or stall and the problem of serious reduction of efficiency is analyzed.In order to improve this situation,this paper designs a single-winding double-speed motor based on the theory of winding theory and symmetry axis method,as well as the characteristics of load torque and power during fan operation.The two-speed asynchronous motor is used as the drive motor for the two-stage impeller before and after the rotary axial fan,replacing the original single-speed asynchronous motor.The fan can adjust the speed ratio of the front and rear two-stage impeller according to different working conditions,so that the fan always works in the high-efficiency operation area.Firstly,according to the relationship between the speed,torque and power of the fan,the design principle of the required two-speed asynchronous motor is proposed.According to the theory of motor winding,the 6/8 pole winding type is designed by the symmetrical axis method,and the winding performance is analyzed.According to the principle of electromagnetic design and the design principle of this paper,the single-winding double-speed asynchronous motor is designed with the variable pole winding.And the magnetic density ratio of each part under two pole numbers is calculated and analyzed to ensure the high utilization rate of magnetic circuit under the two poles.Secondly,the model of the single-winding double-speed asynchronous motor is established.The finite element simulation analysis is carried out on the electromagnetic properties of the two pole numbers.The magnetic densitydistribution diagram,the magnetic field distribution diagram,the mechanical characteristic curve and the electromagnetic transformation,loss,and radial magnetic density wave forms are obtained under two polar states.Moment,Fourier decomposition of the magnetic density waveform is carried out,that is,harmonic analysis.Then according to the transient field solution results,it is post-processed,and the electromagnetic vibration and noise of the motor in the two-pole state are analyzed,which is mainly for the radial electromagnetic force wave of the motor stator system and its radial natural vibration characteristics.The research results show that the two-speed asynchronous motor has better electromagnetic performance and mechanical performance at two speeds,higher operating efficiency,and does not generate excessive electromagnetic vibration and noise.Finally,according to the analysis results of the motor,the energy-saving of the fan is analyzed,the motor not only reduces the production cost,but also the two-speed motor drives the fan to run,to achieve on-demand air supply,greatly improve the operating efficiency of the fan,and achieve energy-saving purposes.