Interleaving technique of series connected module-integrated converters for PV systems: Novel approach and system analysis

Conventional interleaving techniques are widely used for parallel connected dc-dc converters. Series connection of dc-dc converters are getting more concerned recently to create a high voltage low current string. However, the interleaving technique of series dc-dc converters has never been addressed. This paper proposes a low cost high performance interleaving technique based on series connection dc-dc converters to reduce the output voltage ripples. The proposed technique is capable for photovoltaic (PV) with mismatched operating conditions. Each PV panel is able to track its own maximum power point (MPP) which simultaneously delivers the maximum power for the system. The proposed technique is mathematically investigated based on both buck-derived and boost-derived converters and proved by Simulink/Matlab simulations and experiment results. Maximum power point tracking (MPPT) algorithm is also tested for a PV/battery charging system with satisfactory performances in both steady-state and transient responses with reduced voltage ripples.