Reseach On Buck Multi-level DC Converter Technology

The multi-level DC converter has been widely researched in high power level application with high voltage output. It has the merits such as each device can withstand lower voltage stress and the system can easily realize high voltage and large scale operation,the waveforms of output voltage and current are closer to sine and contain lower harmonics under the same switch frequency.This paper take flying capacitor multi-level DC converter as the object of study, in view of the phenomenon of deviation voltage stable state value, proposed that by the method of matrix decoupling achieving multi-loop control for flying capacitor voltage and the output voltage. On the basis of upward has designed output voltage controller and flying capacitor voltage controller of Buck TL converter. Simultaneously to obtain suitable bandwide and speed up the system response,added the PI regulator into the controller, after the compensation the voltage controller had a better dynamic characteristic. Simulation results of stable state and dynamic characteristic verified the design is effective.Moreover, this paper also presented the sideband effect of PWM control for Buck TL converter. Compared and analyzed the band width of Buck TL converter and Buck converter by establishing the multi-frequency range model. The simulation and the comparison result indicated that the Buck converter band width is biggest when achieves fs/2, but Buck TL converter band width is biggest when achieves fs, the band width of Buck TL converter to be able to further enhance, the converter has a better dynamic characteristic.