The Research On The Control System Of Asynchronous Motor Based On Three-level Inverter

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 asynchronous motor is widely used for its simple construcion,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. Therefore,in this paper,firstly,we give a summary knowledge of variety topologies of multilevel inverters,and then do some deep research on three level inverter and its application in controlling asynchronous motor of frequency conversion.Now,the following several aspects had been researched carefully and deeply.At first,this thesis comprehensively describes the development future of power electronics techniques and the present development condition of multilevel inverter.It also simply compares three-level inverter with two-level inverter to embody the important significance of this thesis.It systemeticly analyses the inherent property of three-level vectors,explains the whole process of phase exchange .It introduces the concrete fulfillment corresponding algorithm with full and accurate data and diagrams. An study of coordinate transformation as well as the mathematical model of the asynchronous motor.Based on the rotor flux orientation theory and this mathematic model,the rotor flux observer is designed to make sure the magnetizing and torque current components of asynchronous motor is decoupled suitably.According to control theory DC motor,current and speed dual closed loop control system of FOC is worked out. Based on this, in Matlab / Simulink environment used modular tools to build a double-closed-loop control system, simulates the design of the system, analyzes the outcome, guides the next step for the realization of the hardware. That based on the hardware of LPC2210 of ARM and EPF10K10 of FPGA. design the the external circuit. It uses HCPL316J to drive the power device of IGBT. in ADS 1.2 and QuartusII 6.0 environment,It designs systematic controlling software of a kind of SVPWM timing control system. Combining with the systematic hardware design,the corresponding error protection software module was developed to enable the system to have more perfect protection and control performance.Finally, he hardware and the control strategy are tested by doing experiments. A series of experiment waveforms of the whole system that observed by the digital oscilloscope are given and they validate that the system is reliable.