**5. Conclusions**

A compact single-stage micro-inverter with advanced control schemes for PV systems is described. The proposed micro-inverter achieved a high voltage-conversion ratio and high efficiency by using a new topology that consists of an interleaved boost converter, a full-bridge converter, and a voltage doubler. The leakage inductance of the transformer and the capacitors of the voltage doubler ensure ZVS condition without any additional components. A variable-switching-frequency control scheme is applied to the micro-inverter to decrease THD by reducing the grid ripple current. An advanced burst-control scheme increases MPPT efficiency with smaller input ripple voltage than the conventional burst control causes. A fabricated 320-W prototype micro-inverter was very compact and slim with 60-mm width, 310-mm length, and 30-mm height. It achieved CEC weighted efficiency of 95.55%, MPPT efficiency > 95% over the entire load rage, and THD 2.65% at *VIN* = 34 V, *vgrid* = 220 Vrms/60 Hz, and *Po* = 320 W. These results show that the proposed micro-inverter is well suited for PV micro-inverter applications that require low cost, small and slim size, high efficiency, and low noise.

**Author Contributions:** Y.-G.C. conceived the main idea for the proposed micro-inverter and performed overall analysis and experiment with H.-S.L., B.K. led the project and gave technical advice. S.-C.L. contributed to determining circuit parameters and fabricating a prototype. S.-J.Y. contributed to analyzing the experimental results and writing the manuscript with Y.-G.C.

**Acknowledgments:** This research was supported by the Ministry of Science and ICT (MSIT), Korea, under the "ICT Consilience Creative Program" (IITP-2018-2011-1-00783) supervised by Institute for Information & communications Technology Promotion (IITP).

**Conflicts of Interest:** The authors have no conflict of interest.
