Research On The Vector Control Of Ac Induction Brushless Excitation System Of Synchronous Machine

Ac variable frequency induction brushless excitation of cynchronous motor is the new type of brushless excitation. Compared with the existing brushless excitation,the exciter not only can has smaller volume, can output enough excitation power in any speed; And can greatly improve the dynamic performance of excitation system,the rotor current detection of the rotor sensorless is realized. In this paper, the vector control of the brushless excitation system of the theory and technology were studied.Based on the vector control principle, the induction ac exciter is studied. First of all, the mathematical model of ac induction exciter is presented. And adopt new ideas and further deduced the two field-oriented induction motor vector control equation,and analysis the difference between the variable frequency speed motor and ac induction motor, also expounds the two under field-oriented vector control characteristics.In the study of induction ac excitation method, firstly the flux and the excitation current observation method are analyzed, and the improved method of u-i in flux observation is illustrated in detail, also gives the three methods of excitation current observations. Then hysteresis control and PI control of vector control are analyzed,and illustrates direct torque control can be classified as the vector control. The PI regulation and voltage vector PWM control method are given in two field oriented vector control. Finally, the three kinds of excitation controllor of synchronous motor are analyzed.AC induction brushless excitation system is simulated Using MATLAB simulink software. Set the two vector control method and the simulation model of the motor and generator. The simulation results show that the vector control of induction ac brushless excitation system has good static and dynamic performance, can fully meet the requirements of the excitation control of synchronous motor and generator.Finally, the hardware and software of ac variable frequency excitation controller are designed, then set up the experimental platform of ac induction brushless excitation system, and complete the excitation system of vector control experiments.Experiments show that: the excitation current observer can accurately conduct closed-loop control; the exciting current vector control has good dynamic and steady state performance.