Fig. 3. Conventional BHB inverter and proposed two-stage inverter ( (a) conventional BHB topology, (b) proposed two-stage topology, (c) conventional asynchronous PWM modulation method, (d) proposed time-sharing synchronous PWM modulation method, (e) conventional separate dual loop controller, (f) proposed hybrid current controller).
A High Efficiency Two-stage Inverter for Photovoltaic Grid-connected Generation Systems Jiang Liu,Shanmei Cheng ,and Anwen Shen Huazhong University of Science and Technology, Wuhan, China
Abstract
Conventional boost-full-bridge and boost-hybrid-bridge two-stage inverters are widely applied in order to adapt to the wide dc input voltage range of photovoltaic arrays. However, the efficiency of the conventional topology is not fully optimized because additional switching losses are generated in the voltage conversion so that the input voltage rises and then falls. Moreover, the electrolytic capacitors in a dc-link lead to a larger volume combined with increases in both weight and cost. This paper proposes a higher efficiency inverter with time-sharing synchronous modulation. The energy transmission paths, wheeling branches and switching losses for the high-frequency switches are optimized so that the overall efficiency is greatly improved. In this paper, a contrastive analysis of the component losses for the conventional and proposed inverter topologies is carried out in MATLAB. Finally, the high-efficiency under different switching frequencies and different input voltages is verified by a 3 kW prototype.
Keywords: Overall efficiency, Photovoltaic array, Time-sharing synchronous modulation, Two-stage inverter
LINK FULL TEXT: http://jpe.or.kr/archives/view_articles.asp?seq=1351
