The Research And Realization Of Carrier Phase Shift Algorithm For The Cells Cascaded High Voltage Inverter

In recent years,high voltage frequency conversion systems are widely used in many industries such as steel rolling, oil production, paper making, water treatment, etc. The cells cascaded converter, as a special form, has obtained more and more applications in the actual production process recently due to its advantage regarding harmonics, power factor, torque pulsation, common mode voltage, etc. So it's very important to speed up its research and development as well as its application in our country,so as to enhance the production efficiency and save the energy.Based on the introduction of several multi-level converter's topology and comtrol algorithm,the commonly used comtrol algorithm of cells cascaded converter is introduced in this paper,including step control algorithm, multicarrier control algorithm and phase shift space voltage vector algorithm.From the perspective of carrier vertical and horizontal phaseshift,some new triangular carrier control algorithm together with a classification algorithm based on the thoughts of degrees of freedom are analyzed for better control performance and simplified system.The simulation module of all these new algorithms for cells cascaded converter was constructed by MATLB/SIMULINK software.Compared with the commonly used algorithms,it analyzes the new algorithm's excellent performance reflected in waveform of voltage,harmonics,ratio of DC voltage,and system losses,which will provide technical and theory support for the development of cells cascaded converter.Then the paper reveals the essence relationship between the triangular carrier phase shift control algorithm and the phase shift space voltage vector algorithm,and a new optimized algorithm is proposed.Third harmonics as well as dc component are simultaneously added to the previous modulation wave to enhance the ratio of voltage as well as reduce the switch losses.This optimized algorithm has the same effect as the phase shift space voltage vector algorithm,and possesses a simple implementation.The simulation results show the new algorithm is feasible.At last,Combined with the cells cascaded converter system I participated in,the soft-hardware realization of the optimized algorithms is introduced and some experiment results are given.