Improved Controller and Design Method for Grid-Connected Three-Phase Differential SEPIC Inverter

Single-ended primary-inductor converter (SEPIC) based differential inverters (SEPIC-BDI) have received wide concerns in renewable energy applications due to their modularity, galvanic isolation, decreased power stages, continuous input current, and step up/down capability. However, its design still has several challenges related component design, the existence of complex right half plane (RHP) zeros, increased sensitivity mismatches. In this context, paper presents an improved control enhanced method for three-phase SEPIC-BDI grid-tied applications. A generalized static linearization approach (SLA) is proposed mitigate low-order harmonics. It practically simplifies complexity decreases required loops sensor circuits. The mismatch between SEPIC converters each phase highly mitigated independent operation SLA output dc offset currents are reduced. methodology modifies open-loop transfer function by moving RHP zeros left half-plane (LHP). Therefore, a simple proportional-integral (PI) controller effectively maintains stability without adding higher-order compensators literature. Moreover, straightforward integrator loop eliminates negative sequence harmonic (NSHC) provides low computational burden. Simulations experimental results on 200V, 1.6 kW, 50 kHz prototype with silicon carbide (SiC) devices provided validate effectiveness work. show that achieve pure current waveforms at various operating points inverter voltage variations.