Electromagnetic Design And Simulation Of Steady-state Performance For Inverter-by Asynchronous Traction Motor

With the development of AC drive systems, more and more asynchronous traction motors are used in many fields, it is very important to develop and study for the asynchronous traction motor. This thesis presents the analysis and calculation of the electromagnetic design and simulation of steady state performance for the asynchronous traction motor, which is driven by voltage source inverter and controlled by slip frequency. The software of computer aided design (CAD) system for the asynchronous traction motor has also developed.The main works of this thesis are:(1) The present conditions of the drive system are introduced, AC drive systems and the operation characteristics of traction motors are compared, and the asynchronous traction system is briefly reviewed. In the thesis, on the based of the equivalent circuit of induction motors, the principle of main parameters with the change of source frequency is given, and the operation property of motors by changing frequency is also studied. Under the condition of constant voltage-frequency ratio, constant flux, constant current, the steady state performance variable speed and the operating property for AC drive systems are given. Slip frequency control and adjustable performance for the induction motors are also studied in the thesis.(2) Harmonic components of voltage source inverter are analyzed, and electromagnetic relationship of these harmonics for asynchronous traction motors is studied. The harmonic equivalent circuit is established and the losses and torque coursed by harmonic voltage are analyzed, the methods of calculating power factor and efficiency are presented for induction motors when the electrical source contains harmonics.(3) In terms of the accurate T-type equivalent circuit, the electromagnetic design of asynchronous traction motors is presented, and program for the electromagnetic design is also established, in which the harmonic effects are taken into account.(4) Based on the analysis of the traction and brake characteristics of asynchronous traction motors, the steady state performance of the asynchronous traction motor is studied. When the asynchronous traction motors work in the different traction or brake operation, some calculation methods of constant torque, constant power and constant voltage are also given.(5) In order to the electromagnetic design and steady state performance simulation of asynchronous traction motors, the software of CAD system for the variable frequency traction motor system is developed. Two practical variable frequency asynchronous traction motors are designed, it is shown that the software is correct and reliable.