Research On Offline Parameter Identification For Induction Motors

In the modem high-performance servo control system,induction motors are widely used in various fields such as industrial situations,due to its simple structure,low cost,adaptability and other merits.Offline parameter identification is performed to acquire the required motor parameters at standstill,whereof the results could be provided for the set-up of the drive system,and as the initial values with accuracy in the following online parameter identification.In this paper,focusing on the parameter identification of three-phase squirrel-cage induction motor,two different kinds of offline parameter identification algorithm are studied.The schemes are thoroughly analyzed theoretically and proved by simulation or experimental results.The main contents of this paper include:(a)Taking the characteristics of induction motors in the single-phase test into account,the ARMAX model for identification is derived from basic equations of induction motors under the ?-? coordinate system.According to the principles of the parameter identification algorithms,prediction error method is chosen.As for numerical solutions by iterative search methods,Gauss-Newton method is used and the convergence problem is discussed.The scheme is well proved by simulation.(b)Taking advantage of different responses to the excitations from different elements in the equivalent circuit,the inputs are specially designed to identify inductive parameters respectively.The equivalent circuit based scheme is also well proved by simulation.(c)Based on TMS320F28335 digital signal processor,the experimental platform is designed.With pseudo-random binary sequence being the excitation signal,the PEM based offline parameter identification scheme is used to acquire parameters of the motor,and the analysis and compensation of inverter nonlinearity are made as well.The effectiveness is verified by the experimental results.