Three‐phase two‐leg buck‐boost DC‐AC inverter with differential power processor unit

Abstract

Renewable energy sources (RESs) need power-electronics-based converters to deliver the acquired power to the grid. Those converters should provide voltage-bucking/boosting capabilities to accommodate various grid modes specially for three-phase distorted commonly unbalanced distribution utility networks. Several power electronic-based converters have been elaborated to fulfill this high-demand market. Single-stage converters are the most dominant in the market where the current source inverters (CSIs), impedance source inverters (ZSIs), and boost inverters are the high-end candidates. The aspects of cost, footprint, and minimal numbers of active switches, in addition to simplified controllability, build the main challenges that face the evolution of robust renewable energy-associated grid-tied converters. This paper presents a novel three-phase differential-mode buck-boost inverter based on two bidirectional buck-boost DC/DC converters and one differential power processor (DPP) unit. The proposed topology is a single-stage DC/AC converter offering bucking/boosting capability, with reduced hardware requirements. The proposed topology features a simplified control methodology in addition to reduced size and cost of the hardware setup which makes it more suitable for grid-tied renewable energy applications. The operation principles, small-signal model, and control strategy of the proposed topology are also illustrated. Simulation and experimental results are presented in details to verify the topologyenhanced performance under various operating conditions. The deducted results elucidate the viability of the proposed configuration alongside with the claimed merits. K E Y W O R D S DC/AC buck-boost inverter, DC/DC buck-boost converter, three-phase DC/AC inverter, threephase two-leg inverter 1 | INTRODUCTION Various renewable energy sources require the utilization of power electronics-based converter for maximum power tracking and grid integration purposes. The conventional two-level voltage source inverter (VSI) has been the most common grid-tied converter topology for DC/AC conversion applications. Due to the voltage buck nature of VSI, the

Seamless transfer control for dual‐mode grid‐connected inverter with automatic PCC voltage regulation

“…Targeted for such application, the grid-connected (GC) DG inverters are normally designed to support two-mode operations, including both GC mode as a controlled current source and standalone (SA) mode as a controlled voltage source to provide uninterrupted power. [3][4][5][6][7][8][9] Figure 1 presents a general transfer process from GC mode to SA mode of grid-tied DG system. Initially, the system operates in GC mode.…”

“…As described in many grid codes, 1,2 distributed generation (DG) systems are supposed to be able to help maintain high power quality and reliable operation of the electrical grid after the grid aborts service for somehow and also able to provide continuous regulated power to critical local loads. Targeted for such application, the grid‐connected (GC) DG inverters are normally designed to support two‐mode operations, including both GC mode as a controlled current source and standalone (SA) mode as a controlled voltage source to provide uninterrupted power 3–9 …”

Multi‐input transformer‐less four‐wire microinverter with distributed MPPT for PV systems

“…Several PCU topologies have been introduced in the literature. [1][2][3][4][5][6][7] The PCU architectures are classified into central inverter, string inverter, and AC-module (or microinverter). Among those configurations, microinverter-where a small inverter is integrated into a single PV module-has become the trend for future PV systems development because of the following merits it offers: (1) maximizing energy harvesting as maximum peak power tracking for each solar module is adopted, (2) low DC voltage levels as no series DC connections are needed, (3) plug and play operation; thus further PV modules can be integrated, (4) simple installation and maintenance, (5) high efficiency and low initial cost compared to central and string inverters.…”

“…Among those configurations, microinverter-where a small inverter is integrated into a single PV module-has become the trend for future PV systems development because of the following merits it offers: (1) maximizing energy harvesting as maximum peak power tracking for each solar module is adopted, (2) low DC voltage levels as no series DC connections are needed, (3) plug and play operation; thus further PV modules can be integrated, (4) simple installation and maintenance, (5) high efficiency and low initial cost compared to central and string inverters. [1][2][3][4][5] Achieving high boosting gain, getting long lifetime product and suppression of the leakage currents due to the stray capacitances of the PV module are three main objectives should be realized when dealing with PV microinverter.…”

“…The most crucial unit in photovoltaic (PV) systems is the power conditioning unit (PCU) which interfaces the PV module into the utility grid or stand‐alone loads. Several PCU topologies have been introduced in the literature 1–7 . The PCU architectures are classified into central inverter, string inverter, and AC‐module (or microinverter).…”