Solar-Battery-Integrated Hybrid AC/DC Off-Grid System for Rural Households Based on a Novel Multioutput Converter

Solar fed off-grid system capable of catering dc and ac loads simultaneously with battery backup seems to be a propitious solution for rural electrification. However, such hybrid ac/dc off-grid systems reported in the literature have one or more of the following limitations: 1) higher number of converter stages and switch counts; 2) inadequate voltage gain; 3) use of bulky and costly low-frequency transformer; 4) lack of maximum power point tracking (MPPT) capability; 5) lack of battery charge control and/or over-charge/deep discharge protection; 6) series connection of several photo-voltaic (PV)/battery units; 7) lack of ac and/or dc load voltage regulation; and 8) use of a dedicated converter for MPPT control. A two-stage hybrid ac/dc off-grid system can be formed by integrating some of the high-frequency transformer-based four-port dc–dc converters reported in the literature. However, such dc–dc converters have higher number of control variables than required for this application thus leading to higher switch count. To overcome all these limitations of existing schemes, this article proposes a two-stage hybrid ac/dc off-grid system capable of catering ac and dc household loads simultaneously. All of the claims of this scheme are substantiated through exhaustive experimental validation carried out on a 400-W laboratory prototype.