Single-Phase AC Grid-Tied Inverter with Buck-Type Active Power Decoupling Circuit Operated in Discontinuous Current Mode

Abstract

This study presents a novel circuit topology for a single-phase inverter using an active power decoupling circuit operated in discontinuous current mode (DCM). In a conventional single-phase grid-tied inverter, bulky capacitors are used in a DC-link to absorb a power ripple with twice the grid frequency. However, electrolytic capacitors limit a converter's lifetime. In contrast, ceramic capacitors are used in the proposed circuit since the required capacitance is reduced. Furthermore, the active power decoupling circuit in DCM has no inductor inside by utilizing the current zero cross featured in DCM for power ripple compensation modes. An experimental verification using a 1-kW prototype shows a 90.2% current ripple reduction caused by the power ripple with twice the grid frequency. The efficiency exceeds 94% in the 20% region of the rated power to 1-kW through 96.0% of the 650 W maximum. According to a theoretical evaluation using a Pareto-front optimization assumed as a 3-kW system, the proposed circuit reaches the maximum power density at 20 kHz which is 115 % higher than that of the passive power decoupling method. The inductor volume in the proposed circuit is reduced by 30.4% compared to a conventional buck-type active power decoupling circuit.

Analysis and Implementation of a 5-Level Hybrid Inverter with Reduced Switching Devices Using Phase-Shifted PWM

“…The redundant switching states during the generation of half-full voltage have been utilized to balance the dc-link capacitor voltage by employing a proper voltage balancing algorithm which ensures symmetric switching time in a carrier period for the controlled-switching devices in the level-generation stage. Also, proper sizing of the dc-link capacitor is necessary to ensure high-quality operation of inverter with reduced output current ripple [14]. The desired dc-link capacitance C 1 or C 2 can be selected as…”

Active Power Decoupling Control for Single-phase Power Conditioning Systems Focusing on Harmonic Voltage

“…However, the lifetime of electrolytic capacitors is approximately 10 years, which is an obstacle to extending the lifetime of the PV system. Many studies have proposed an active power decoupling (APD) method to extend the lifetime of the PV system (1) − (14) . The APD method uses film capacitors and suppresses the DC voltage ripple to extend the lifetime of the PV system.…”

“…A power conditioning system with an APD function consists of a single-phase inverter and an APD circuit. Many circuit types have been proposed for the APD circuit, including a buck converter type (1), (2) , boost converter type (3) , buck-boost converter type (4) , etc.…”

Isolated DC to Single-Phase AC Converter with Active Power Decoupling Capability Using Coupled Inductor

“…However, the electrolytic capacitors may limit the life-time, and increases the circuit volume (7) . In contrast, active power decoupling, which uses passive components with active switches, circuits have been proposed in order to solve this problem (8)- (15) . In these methods, the double-line frequency power ripple is compensated by the small capacitor which permit the large voltage fluctuation.…”