Matrix Converter Common Mode Voltage Suppression And Deadtime Compensation

The matrix converter has been used in wind power, elevator traction, machinerymanufacturing and other industrial systems due to its compact structure, highreliability, high power density, fast dynamic response and no need of intermediate dclink circuit. However, in the modulation, the problem of common mode voltage(CMV) and deadtime voltage can occur. The CMV will cause the bearing damage ofan ac motor and electromagnetic noise. Besides, the deadtime voltage will lead tooutput voltage error and output current distortion. So this paper conduct research onCMV and deadtime voltage to solve of the problem of CMV and deadtime voltage.In view of the exsisting CMV in the modulation, this paper proposed a CMVinhibition scheme. Firstly, this paper established the matrix converter mathematicalmodel of the space vector modulation (SVM) and double line voltage synthesis(DLVS), analyzed the synthetic process of output voltage and input current, andproved the consistency between SVM and DLVS. Secondly, this paper discussed theformation of CMV, selected a pair of opposite active vectors with the minimumamplitude in the direction of one original active vector and two pairs of oppositeactive vectors with the maximum and medium amplitude in the neighboring directionof original active vectors, respectively. Finally, on the basis of consistency, this paperdeduced the improved DLVS and realized the suppression of CMV.In view of deadtime voltage, this paper proposed a deadtime compensationstrategy. Firstly, this paper deduced the evolve frome conventional matrix converter toultra sparse matrix converter, established the mathematical model of rectifier andinverter side, and analyzed the modulation process. Secondly, aiming at the effects ofthe deadtime effect on output voltage, this paper improved the basic modulation andproposed a time compensation scheme. It can advance or delay the on or off of switchaccording to the direction of output current and realized the enhance of outputperformance.This paper carried out the comparative study on CMV suppression between thetraditional strategy and the improved strategy and the output performance with andwith out deadtime voltage compensation. The results showed that after the CMVsuppression and deadtime voltage compensation, tha matrix converter reduced the CMV and made up for the loss of output voltage, and the input and output powerquality is improved.