Abstract
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 to component design, the existence of complex right half plane (RHP) zeros, and increased sensitivity to component mismatches. In this context, this paper presents an improved control and enhanced design method for the three-phase SEPIC-BDI for grid-tied applications. A generalized static linearization approach (SLA) is proposed to mitigate the low-order harmonics. It practically simplifies the control complexity and decreases the required control loops and sensor circuits. The mismatch between the SEPIC converters in each phase is highly mitigated due to the independent operation of the SLA in each phase and the output dc offset currents are reduced. The proposed enhanced design methodology modifies the SEPIC open-loop transfer function by moving the complex RHP zeros to the left half-plane (LHP). Therefore, a simple proportional-integral (PI) controller effectively maintains converter stability without adding higher-order compensators in the literature. Moreover, a straightforward integrator in the control loop eliminates the negative sequence harmonic component (NSHC) and provides a low computational burden. Simulations and experimental results based on 200V, 1.6 kW, 50 kHz prototype with silicon carbide (SiC) devices are provided to validate the effectiveness of the proposed work. The results show that the proposed controller and design method achieve pure output current waveforms at various operating points of the inverter and dc voltage variations.
Highlights
INTRODUCTIONWith the increased deployment and investments of renewable energy sources (RESs), such as photovoltaics (PV), The associate editor coordinating the review of this manuscript and approving it for publication was Shihong Ding
With the increased deployment and investments of renewable energy sources (RESs), such as photovoltaics (PV), The associate editor coordinating the review of this manuscript and approving it for publication was Shihong Ding .wind generation system, and fuel cells, power converters have become key contributors in ensuring reliable and efficient conversion of the extracted power from RESs to the loads and/or utility grid [1]–[3]
The setup uses a 3-phase AC supply (S3P-240-30) with 0-240 V and 10.4 kVA rating. This AC supply is connected to a six-diode bridge-rectifier (75L6P41) followed by 6000 μF to provide pure variable DC voltage to emulate the time-variant characteristics of renewable energy sources
Summary
With the increased deployment and investments of renewable energy sources (RESs), such as photovoltaics (PV), The associate editor coordinating the review of this manuscript and approving it for publication was Shihong Ding. In [21], a 1kW buck-boost single-phase differential inverter has been introduced, where voltage-mode control using a static linearization approach (SLA) is implemented. The design process of these topologies only considers the required ripple components (large-signal modeling) and the power rating of the utilizing components to check the voltage and current stress They did not consider the effect of selected passive elements on the performance of control techniques. Generic, and easy-implemented static linearization approach results in improving highly the operation of differential inverters by reducing the number of control loops, control complexity, and employed sensing circuits. Motivated by the above-mentioned issues and challenges in SEPIC-BDI, this paper presents an improved control and enhanced design method for grid-tied three-phase single-stage isolated SEPIC-BDI.
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