Study On Novel Photovaltaic Buck-Boost Inverter

With the increasing consuming of energy, the worsening of the environmental condition and the growing demand of sustainable development, many countries throughout the world are eagerly searching for a new kind of regenerative and non-pollution energy. Solar resource is abundant, regenerative, non-pollution and widely distributed. At present, the solar photovoltaic (PV) power generation becomes the main form of the new energy exploitation. The PV inverter is an important part of the PV system. Its efficiency and reliability largely affects the performance and cost of whole PV system. A novel single-stage series-resonant Buck-Boost PV inverter is proposed in this paper. TMS320F2812 is used as the control chip, and a 1kW ZCS prototype is designed in the end.The paper bases the research on the evolution, development trend, topology, control method and the application field of PV inverter in the recent years, then proposes a novel single-stage Buck-Boost PV inverter topology including only five switches and two power diodes, which has a compact structure and low switch frequency. It has not DC capacitor and can generate an ac output voltage larger or lower than the input one in a single stage, can be used in AC module. The new inverter circuit topology provides all the switches for turn-on and the auxiliary switches for turn-off at zero current switching (ZCS) by a resonant tank, so that the switching loss is reduced and system efficiency is improved.This paper gives the structure of the inverter. The operation principle and equivalent circuit under the different states are analyzed in detail. And the mathematics model is founded based on the state-space average method. Based on its input-output character, the inverter using the traditional SPWM control method is simulated, and the simulation results shows that the traditional SPWM control method causes the output voltage zero-crossing distortion. So an improved SPWM control method employing dc bias sine modulation wave is presented to optimize the inverter performance. The respective simulation results of the SPWM and improved SPWM control method shows that the proposed SPWM control method can eliminate the distortion caused by the traditional...