Highly-Reliable Flyback-Based PV Micro-Inverter Applying Power Decoupling Capability without Additional Components

Inhalt:
This paper discusses a verification of an electrolytic capacitor-less PV micro-inverter aiming for high reliability and volume reduction. The inverters, which are connected to a single-phase AC grid, have a double-line-frequency power ripple. Thus, a bulky electrolytic capacitor is generally used in DC side. The proposed converter consists of the fly-back converter, the voltage source inverter (VSI), and small capacitor in the DC link part in order to achieve the power decoupling without the any additional component. In addition, the sensor less magnetizing current control is proposed in order to ensure the compatibility between the surge voltage and cost reduction. Furthermore, it is demonstrated that the discontinuous current mode (DCM) of the proposed fly-back converter has the great power decoupling effect in comparison with the continuous current mode (CCM). From the experimental result, the second-order harmonics in the DCM operation is reduced by 97% in comparison with that in the CCM operation.