The Algorithm Analysis And Optimized Control Of Multilevel Inverter Based On Cells Cascaded

In recent years variable speed drives in high voltage range are widely used in many industries such as water treatment, oil and natural gas industry, paper industry, etc. The cells cascaded converter as a special kind of the multilevel converter has drawn tremendous interest recently due to its advantage regarding harmonics, power factor, torque pulsation, common mode voltage, etc. So it's very important to speed up researching and developing cells cascaded converter as well as prompting its application in china.The topology and work principle of cells cascaded converter is introduced particularly in this paper based on the introduction of several high voltage converters'topology. The compare and analysis of control algorithm for this kind of converter is done in detail, which include step control algorithm and multicarrier control algorithm. The simulation module of cells cascaded converter is constructed by MATLB/SIMULINK software and several parameters is compared including the using ratio of DC voltage, waveform of voltage and current, harmonics, and common mode voltage. These will provide technical support in theory for the development of cells cascaded converter. Two kinds of optimized algorithm are proposed based on the simulation. The first method is used to eliminate the dead time. The SPWM signals of the same bridge is opened or closed according to the load current's polarity.Then the dead time in SPWM signals can be eliminated which will help to improve the performance and simplify the system's construction. The other method has both the advantage of step waveform algorithm and multicarrier algorithm, which can reduce the switch loss. The results of simulation show that these two optimized algorithm are feasible and excellent.At last, the hardware circuit and control programme of cells cascaded converter which I was participated in is introduced and some experiment results are given.