Research On The Method Of Motor Parameter Identification For Dynamic Estimation On The Efficiency Of Motor Systems

One of the most important methods of dynamic estimation of motor system efficiency is the equivalent circuit method, namely using the parameters of equivalent circuit for calculating motor internal losses and then estimating motor efficiency. But the motor parameters in different conditions change significantly, it hard to assess the energy efficiency if we can not identify the parameter on line, and thus it can not be timely and availably adopt energy-saving measures and cause a great waste of energy. Therefore, in order to use this method to assess the energy efficiency accurately, the key problem to be solved is the motor equivalent circuit parameters for on-line identification, and then use the parameter complete dynamic motor energy efficiency estimation. This thesis through a combination methods of theoretical analysis, simulation and experimental study for online identification of induction motor parameters. The main works are summarized as follows:Firstly, this thesis presented the recursive least squares with forgetting factor method for parameter identification which taking into account of the drawbacks of the motor traditional no-load and short-circuit tests. Specific method is used in the thesis which adopts the dynamic equation based on dqO coordinate system of induction motor, derives motor standard mathematical model of least squares algorithm. And this thesis also considers the various factors which affect the identification results of using the recursive least squares with forgetting factor method. Taking Y2-280S-837kW, Y160M1-2,11kW and Y132S-4,5.5kW as simulation examples and taking parameter on-line identification experiment on Y132S-4,5.5kW, the on-line identification motor parameters are achieved. The performance of the proposed method is verified through simulation and experiment.Secondly, the thesis study the method of precise identification of rotor resistance based on the RLS and MRAS which can account squirrel-cage induction motor speed fluctuations. Taking a5.5kW motors as an example, the simulation and experimental study are carried out, and the analysis of parameter identification method applied to the11000kW motor on practical engineering. The results show that the method is suitable for the conditions of obvious fluctuation of rotor speed and rotor resistance changing at the complex operating conditions; meanwhile, it has the characteristics of the less computation, higher accuracy and better dynamic tracking identification performance.Finally, the parameter on-line identification method of motor is used for the estimation of motor efficiency. Taking a5.5kW motor as an example, using parameter identification method for calculating motor parameters, and then assessing the motor energy efficiency by motor equivalent circuit methods. Comparison with the assessment result of torque instrument test, it further verify the correctness and feasibility of the thesis proposed on-line identification of induction motor parameters methods.