Simulation Analysis Of Inverter-fed Induction Motors And Study Of Iron Losses Based On Field-circuit Coupled Method

Inverter-fed induction motors have been used widely in the industry production. with the development of electronic technology and microcomputer control technology. However, the design of inverter-fed induction motors become more difficult and complicated because of the non-sinusoidal output signal in the inverter. In order to design inverter-fed induction motors accurately and reasonably, a field-circuit coupled method of designing and analyzing induction motors and control system is presented in this paper. The field-circuit coupled collaborative simulation technology is used in this method based on the induction motor electromagnetic finite element model and the control system model. The interaction between the induction motor and the control system can be analyzed effectively through the method. In addition, with the use of the inverter supply, the analysis and calculation of iron losses become more complex, and which is one of the problems in the design of inverter-fed induction motors. The main work of this paper is as follows:Firstly, the basic theory of inverter-fed induction motor was introduced, which included the two fundamental controlling modes of the frequency transducer, SPWM, CHBPWM and SVPWM these three technologies of PWM and the mathematical model and vector control theory of the induction motor.Secondly, the performance analysis methods of inverter-fed induction motor were discussed, and the steady-state performance calculation and analysis, such as, loss, efficiency and electromagnetic torque, etc. were included. The physical mechanism of ferromagnetic materials losses, the calculation model of every loss in ferromagnetic materials losses and different models of calculating iron loss in motors were stated in detail.Thirdly, the new field-circuit method of analyzing the induction motor and the frequency converter performance was put forward. The simulated model of invert-fed induction motor was built by using Maxwell and Simplorer simulation platform. The electromagnetic finite element model of the induction motor and the RFOC SVPWM fed inverter induction motor variable speed drive system were included. The dynamic performance of induction motor during the no-load starting process and a sudden load condition were described in detail. The detailed design procedure of the control system was presented, such as the model of coordinate change, speed regulator, current regulator, rotor flux observer and SVPWM, etc.Finally, the iron loss in inverter-fed induction motor was studied based on the field-circuit coupled method. Furthermore, the distribution of iron loss and the mode of magnetization in inverter-fed induction motor were also investigated. Finally, the effect of the frequency converter parameters, such as carrier wave frequency, modulation factor and DC bus voltage, on iron losses were analyzed by the simulation.