A Novel High Voltage Ratio Single-stage Inverter With Buck-Boost Characteristic

A novel high voltage ratio single-stage inverter with buck-boost characteristic ispresented in this paper, which is referred to high voltage ratio single-stage inverter(HVRSSI). The specific operating mode and implementation mechanism of HVRSSI isstudied, voltage relationship of HVRSSI is derived, and the cycle work process of novelcircuit is described. Small-signal model of HVRSSI DC link voltage is built, indirectPID control and direct fuzzy control of HVRSSI DC link voltage is raised, closed-loopcontrol is achieved. In order to validate the proposed circuit, Saber analog and mixedsignal simulation software is applied. The hardware technology of experimentalprototype is described in detail.1kW prototype was built in laboratory for experimentalverification.Unlike traditional voltage source inverter, DC link capacitor of traditional voltagesource inverter is replaced by a unique LC structure in proposed novel inverter. At thistime upper and lower tubes of inverter can be simultaneously turned on. Shoot-throughstate constitutes one working model of inverter circuit, the defect of traditional voltagesource inverter is overcame. The shoot-through mode is used to achieve substantialboost function of DC link voltage, meanwhile the reliability of novel inverter isimproved.In some certain control mode, AC output voltage is relevant to modulation factor Mand input voltage. In a wide range of input voltage variation, AC output voltage can becontrolled to remain constant by adjusting modulation factor M. Unlike conventionalsingle-stage inverter (such as Z-source/quasi-Z-source inverter), boost ratio B ofHVRSSI is inversely proportional to duty cycle D. In a small shoot-through duty cycle,a high boost ratio can be obtained. The deficiency of insufficient boost capacity causedby "mutual restraint between modulation factor M and shoot-through duty cycle D " ofexisting single stage inverter is well overcame.Unlike other single-stage inverter, AC output voltage trends of HVRSSI withmodulation factor M is consistent with counterpart of conventional voltage source inverter, that is, it is proportional to M, the consistency makes adjustment more quickly.Finally,1kW prototype was built in the laboratory. The associated performance ofproposed circuit is detected. The experimental results is consistent with theoreticalanalysis and simulation. Effectiveness and practicality of proposed circuit are verified.