Research On Asynchronous Motor Vector Control Based On Three-Level Inverter

The asynchronous motor is widely used for its simple construction,ruggedness,high working reliability,relatively low cost,and high environmental adaptability.It is suit for the direction of high voltage,high speed and large capacity.Vector control is its ideal speed modulation method.The harmonics of three-level inverter are less than the traditional two-level inverter's,and it is convenient to realize high sinusoidal voltage output.The maximum voltage strength which each electric component bears is small,and it is easy for three-level inverter to realize large capacity.The research on the asynchronous motor vector control based on the three-level inverter is one novel work.Firstly,this paper introduces the asynchronous motor model,and compares it with the DC motor's.Then the paper studies the principle of vector control,and proposes an improved current model of rotor flux observer.This paper also studies the three-level inverter's topology,working principle,the neutral-potential unbalance mechanism and its controlling strategy.The paper especially studies the SVPWM in details.The interface between the vector control and the three-level inverter is studied in details,including the generation of reference voltage vector,its judging of the sector and triangular regions,and the working mechanism after it sent into three-level inverter.When synthesizing the reference voltage vector,select the vector which only includes P and O states as the starting vector,thus eliminate the vector shift problem when sector changes.This paper fully takes advantages of the powerful functions of MATLAB/SIMULINK to set up the simulation model.This construction is very explicit.The simulation results verify the inverter voltage output is correct,the rotor flux is steady,the asynchronous motor's dynamic and steady state performances and speed modulation are excellent.In the end, the hardware and software systems are designed,and the software is preliminarily debugged.