This paper presents a literature overview of all techniques proposed until the submission of this paper in terms of mitigating power oscillation in single-phase applications. This pulsating energy is the major factor for increasing the size of passive components and power losses in the converter and can be responsible for losses or malfunctioning of the dc sources. Reduction of power ripple at twice the fundamental frequency is one of the key elements to increase power converter density without lack of dc stiffness. Pulsation reduction is achieved by incorporating control techniques or auxiliary circuitries with energy storage capability in reactive elements to avoid this oscillating power to propagate through the converter, creating what is called as single-phase power decoupling. The topologies are divided as: rectifiers, inverters, and bidirectional. Among them, it is possible to classify as isolated and nonisolated converters. The energy storage method may be classify as: capacitive and inductive. For the power decoupling technique, it is convenient to divide as control and topology. The power decoupling technique may be implemented as series or parallel with respect to the ac, dc or link side. This paper represents the best reference on this topic.

Low-Frequency Power Decoupling in Single-Phase Applications: A Comprehensive Overview

Double-line frequency ripple power is inherent in single-phase rectifiers and inverters, and, if not managed properly, it can be adverse to system performance at both the ac and dc sides. Therefore, numerous active power-decoupling techniques have been introduced to decouple the double-line frequency ripple power. However, no comprehensive comparisons are available on the permitted minimum capacitance for power decoupling, dc voltage utilization, current stress, modulation complexity, and even application evaluations, except for power rating and component counts. All of these aspects are critical when choosing appropriate power-decoupling techniques for different applications. In this article, the minimum capacitance to decouple the ripple power and the current stress of power devices in the main circuit are derived in light of different voltages across energy storage capacitors. By considering the ripple power paths, we investigate the dc voltage utilization of both the main circuit and power-decoupling circuit. Combined with other features, including component counts and modulation complexity, the overall characteristics of different power-decoupling techniques are compared and summarized to effectively evaluate their performance in different applications.

Capacitance, dc Voltage Utilizaton, and Current Stress: Comparison of Double-Line Frequency Ripple Power Decoupling for Single-Phase Systems

This paper describes a single-phase full-bridge inverter that possesses limited current ripple at the dc link while providing a sinusoidal square power at the ac output. This is achieved through the addition of an extra pair of switches and complementary control for the full-bridge inverter. The extra switches operate to prevent the double-line frequency ripple current from flowing into the input of the inverter. In doing so, the pulsation component of the sinusoidal square output power is confined to flow between the output capacitors and the load. Thus, the dc link input only supplies the dc component of the output power. Simulation and experimental results validating the proposed solution are presented.

Enhanced Single-Phase Full-Bridge Inverter With Minimal Low-Frequency Current Ripple

In this paper, a novel single-stage three-port inverter that connects photovoltaic (PV) panel to a single-phase power grid is introduced In a single-phase grid-connected PV panel, the input power is constant during the line-frequency period, while the output power oscillates at double-line frequency A series active power decoupling circuit utilizing thin-film capacitors is incorporated to a conventional flyback inverter to handle input and output power differences Therefore, popularly low-reliable electrolytic capacitors are replaced with small long-lifetime thin film The proposed inverter can extract the maximum power from PV, deliver a low total harmonic distortion sinusoidal current to the output, and decouple the input and output powers The proposed power decoupling circuit shares the inverter main switch Thus, these functions are achieved using just three switches and a simple control scheme which is applicable for both charging and discharging states Operation principle and control strategy are discussed in detail Experimental results based on a 100-W prototype inverter verify feasibility and functionality of the proposed inverter

A Single-Phase Grid-Connected Photovoltaic Inverter Based on a Three-Switch Three-Port Flyback With Series Power Decoupling Circuit

This paper proposes a generalized control method for battery-driven switched reluctance motor (SRM) drives based on integrated multiport power converter (IMPC) with small-ripple bidirectional power flow ability in electric vehicles. Large power ripple caused by the current commutation is a challenge issue for SRM drives, which would lower the system efficiency, requires extra heat dissipation in the battery and shortens its lifetime. The detailed model of the SRM drive and IMPC is developed which covers both motoring and generating modes of operation. Based on this model, an advanced multiobjective power flow control method with repetitive controller is proposed to restrain battery current ripple. Because of the unified model, a seamless transition between various modes can also be achieved. Finally, simulation and experimental results demonstrate the feasibility and superior performance of the proposed control method.

Modeling, Control, and Seamless Transition of the Bidirectional Battery-Driven Switched Reluctance Motor/Generator Drive Based on Integrated Multiport Power Converter for Electric Vehicle Applications

Power maintenance in a real time microgrid plays an important role in today's scenario. This paper describes a power decoupling approach using a four-switch three port DC/DC/AC converter in a DC microgrid. The system is designed with three topologies connected with a DC source, a capacitor and an AC port. The power flow control technique is used so that the converter is decoupled to obtain low frequency ripple power. The system is compact and cost effective. The system is designed with two inductors current control. Results show that the described topology is feasible and analyzed the designed power control technique.

V. Karthikeyan

Papers

A Power Decoupling Method Based on Four Switch Three-Port DC/DC/AC Converter in DC Microgrid