A Multi-Input Microinverter for Solar Photovoltaic Application

This paper proposes a Multi-Input Single-Output flyback-based microinverter (MI) for solar photovoltaic (PV) application. Maximum Power Point (MPP) operation of multiple PV modules is realized by dedicated high-frequency DC-DC conversion stages based on flyback converters. All the DC-DC stages are connected in series at their output side, yielding a high step-up voltage gain while using lower turns of the individual flyback stage. Due to the multi-input nature of the proposed MI, it can process more power at a relatively lower voltage gain. As all the flyback stages share a common unfolding inverter that operates at grid frequency, the switch requirement of the inversion stage is reduced as compared to a conventional single-input single-output MI operating with ‘N’ number of PV modules. This MI is controlled by implementing a magnetizing current control technique. The control algorithm of this proposed MI is discussed along with an estimation based technique for the voltage outputs of the flyback based DC-DC stages. The use of this voltage estimation technique for magnetization current control reduces the requirement of voltage sensors. Extensive simulation studies have been performed to demonstrate the feasibility of the multi-input single-output MI having a power rating of 700 W.