Parameter Self-tuning Method Of Linear Induction Traction Motor

Initial parameters of motors are very important for the success of the vector control system.However,the conventional measurement of the initial parameters of motors is not suitable for the linear induction motor.Due to the primary of linear induction motor mounted on the bogey and secondary laid on the ground,linear induction motor not only can not achieve the ideal no-load operation,but also hardly realize the blocked rotor test which needs the mechanical operation.Moreover,the no-load and blocked rotor tests assumpt that the primary leakage inductance is equal to the secondary one.The air-gap of linear induction motors(LIMs)is large and the flat-solid secondary consists of the aluminum plate and back-iron plates.Hence,the secondary leakage inductance of LIMs is much smaller than the primary one owing to the absence of the squirrel-cage bar and end rings in the secondary.Therefore,it is necessary to find a scheme of parameter identification for linear induction motors.The main purpose of this thesis is to design a parameter identification method for a linear induction motor while it remains still.This thesis first reviews the development history of linear induction motors,the control methods of linear induction motors and the current domestic and foreign studies on the methods of parameter identification.Then the causes of four kinds of end effects and their effects on the linear induction motors are analyzed.Afterwards the T equivalent circuit and mathematical model of linear induction motors considering end effects are derived.Thereafter the equivalent circuit of linear induction motors under single-phase test is deduced.Based on the equivalent circuit,DC test,single-phase high-frequency test and single-phase low-frequency test are applied to the linear induction motor by an inverter.The effects of on-time voltage drop of semiconductor device,delay time and dead time are compensated.In order to verify the accuracy of the single-phase test,the parameter self-tuning method of a linear induction motor is modeled and simulated by MATLAB/SIMULINK.The waveforms of linear induction motor are sampled and results under different ?values are calculated.Then a number of linear induction motors are identified and the results are compared with those of the tradional no-load and blocked rotor tests.Thereafter the frequency range of single-phase high-frequency test and single-phase low-frequency test is discussed.Finally the single-phase test is also applied to the rotating induction motors and the results are compared with those of the traditional no-load and blocked rotor tests.Finally,based on the DSP TMS320F28335 chip,program and hardware of the parameter self-tuning system are carried out.Based on the above analysis and results,it shows that the proposed single-phase test overcomes the shortcomings of traditional no-load and blocked rotor tests that are difficult to be applied to linear induction motors.The single-phase test does not only need additional operation or equipment,but also assumpts that the primary leakage inductance and secondary leakage inductance of linear induction motor are not equal.It can not only identify the parameters of linear induction motor in the static state,but also have a higher accuracy than the no-load and blocked rotor tests.It is not only suitable for linear induction motor,but also can be applied to the rotating induction motor.Therefore the proposed single-phase test has a certain academic value and engineering guiding significance.