Research On The Technology Of Cascaded Multilevel Power Conversion

H-bridge cascaded multilevel power conversion is adapted to the medium voltageand high power applications. The mathematic model of cascaded multilevel circuit ispresented in this paper based on its principle analysis. PWM control technology has beenapplied in the inverters broadly. Compatible with the special character of cascadedmultilevel circuit, discrete natural sampling algorithm suitable for digital control isproposed and multilevel PWM control of cascaded inverters is realized successfully. Inorder to validate the control algorithm, the simulation and a three-cell cascaded invertersexperiment system is set up in this paper. The experiment system utilizes DSP as the keycontroller, and it is also composed of main circuit, control circuit, protect circuit andefficient system control program based on assemble language. No-load test, load test andoutput voltage harmonic analysis of asynchronous motor is performed in theexperimental system. These works will make base for its practical application.