The circuit topology for single-phase grid-connected system and the control technology on converters

With the continuously reducing cost of grid-connected photovoltaic (PV) power generation and the further intensification of energy crisis, grid-connected PV power technology obtains more and more application. The topology for single-phase grid-connected PV system and the control technology based on TMS320LF2407 digital signal processor (DSP) are summarized in this paper. The functions, such as operation, control and protection, are realized by DSP with its richer external circuits. The phase-shift full-bridge ZVS PWM converter is adopted in the first stage in this grid-connected inverter, reducing the weight and volume of this system, decreasing the switching loss by using soft-switch. The full-bridge DC-AC inverter is adopted in the second stage and the outputting current is controlled to synchronize to the utility grid. Simultaneously, the maximum power point tracking (MPPT) and anti-islanding protection function are included. At last this system is validated with strong credibility, high efficiency and good stability.