Research On Staircase Waveform Inverters With Phase-shifted Control Technology

The basic advantages of multilevel inverters with staircase wave superposition technology are its simplicity for hardware realization and that their switching frequency is lower than a traditional SPWM inverter, which means they have reduced switching losses, increased system efficiency and reduced EMI emission. In phase-shifted control model, by changing the phase angle of the two inverters, the output required fundamental voltage can be controlled without additional higher order harmonics and the fine dynamic performance can be achieved.At the point of keeping the quality of the output waves, staircase wave superposition scheme with phase-shifted control technology has a simple adjusting voltage circuit and the system with this technology has a good reliability. Its principle is analyzed in this paper, and the relation of phase shifted angle, the amplitude of each harmonic content and the THD is also analyzed in detail. Then the system is simulated in MATLAB. In the end,this paper analyses and designs the power and the control circuit by taking a 4.5KVA inverter for an exampleIt is proved that the scheme of the staircase wave superposition technology with phase-shifted control technology has several advantages, through the developing of the 2KVA inverter. Its control circuit is very simple, and the quality of the output waves is very high. Accordingly this technology can be taken as a repertory used in high power condition.