Abstract

Microinverters are gaining acceptance in the PV generation market due to their intrinsic modularity and the fact that they can harvest up to 20% more energy over module lifespan. Conventionally, due to power level and simplicity, the topology of choice for implementing microinverters is cascading a flyback type DC-DC converter with a single-phase voltage source inverter. This solution, however, has drawbacks such as a highly discontinuous input current, and the presence of a large second harmonic component in the current drawn from the module. Both disadvantages have the effect of difficulting following the maximum power point of the module and reducing overall performance of the system. To mitigate these issues, in this paper a double boost microinverter topology is presented. The proposed microinverter is implemented by cascading a phase-shifted coupled inductor dual boost DC-DC converter with a single-phase voltage source inverter. Operation of the microinverter is presented and analyzed in this paper. Finally, it is shown through computer simulations that the proposed structure effectively interfaces the PV module to the grid, drawing a mostly DC current with reduced second harmonic ripple, thus showing improved performance.