Research On Asynchronous Motor Vector Control System Based On Two Bridge Matrix Converter

Two-bridge matrix converter (TBMC) is a novel alternating current-direct current powerconverter, which are obtained form the traditional matrix converter. Compared with thetraditional matrix converter, it has many advantages. For example, the two-bridge matrixconverter has a safer and simplified commutation，all the line side switches commutate at zerocurrent and load side switches commutate similar to a conventional direct current-alternatingcurrent inverter. It has a high quality input/output waveforms and adjustable input powerfactors. Importantly, since no large energy storage components are needed and it has smallersize, so, the response is faster. The switch number of two-bridge matrix converter can befurther reduced if some limitations are enforced. Different topologies with numbers varyingfrom18to9single directional switches can be obtained under different conditions. The clampcircuit can be largely simplified, only one diode and one capacitor are needed on thetwo-bridge matrix converter. Based on the advantages, the two-bridge matrix converter ismore suitable for alternating current dirve systems. The appearance of two-bridge matrixconverter has improved the alternating current dirve systems.Fristly, this thesis researched the topologies of two-bridge matrix converter. Based on thecharacteristics of the structures, the modulation strategies of two-bridge matrix converters aredetermined. The rectifier stages use the pulse width modulation, and inverter stages ues thespace vector pulse width modulation. On the basis of the modulation strategy, researched onthe damping input filter of two-bridge matrix converter, and get a excellent results. It reducedhigher harmonics and prevented the higher harmonics into the grid. Additional, the input filterprevented the harmonics of grid into the two-bridge matrix converter, and it protected thetwo-bridge matrix converter. More importantly, the use of two-bridge matrix converter couldsatisfy the mandate of power quality.Secondly, analyze the vector control theory of three-phase asynchronous motor, by thetransformations of coordinate, the components between torque and magnetic field of statorwinding current are decoupled, then the asynchronous machine is equivalented to a directcurrent machine. The vector control scheme based on inverter of voltage sourse is introducedand analyzed.Then, based on the research of the two-bridge matrix converter and vector controltechnology, this thesis combines the two-bridge matrix converters and vector control technol-ogy so that a new vector control scheme is presented. The present system not only achievesvector control of asynchronous machine, but also commutates at zero current for thebidirectional switches and decreases the harmonic pollutions of the line side.Finally, the simulation model based on MATLAB/Simulation software is established. Through researching the results of the simulation waveforms, the feasibility and superiority ofusing two-bridge matrix converters in the vector control technology of asynchronous machineis verified.