Issa Batarseh

A Review of Power Decoupling Techniques for Microinverters With Three Different Decoupling Capacitor Locations in PV Systems

The reliability of the microinverter is a very important feature that will determine the reliability of the ac-module photovoltaic (PV) system. Recently, many topologies and techniques have been proposed to improve its reliability. This paper presents a thorough study for different power decoupling techniques in single-phase microinverters for grid-tie PV applications. These power decoupling techniques are categorized into three groups in terms of the decoupling capacitor locations: 1) PV-side decoupling; 2) dc-link decoupling; and 3) ac-side decoupling. Various techniques and topologies are presented, compared, and scrutinized in scope of the size of decoupling capacitor, efficiency, and control complexity. Also, a systematic performance comparison is presented for potential power decoupling topologies and techniques.

Modeling and Control of Three-Port DC/DC Converter Interface for Satellite Applications

This paper presents the control strategy and power management for an integrated three-port converter, which interfaces one solar input port, one bidirectional battery port, and an isolated output port. Multimode operations and multiloop designs are vital for such multiport converters. However, control design is difficult for a multiport converter to achieve multifunctional power management because of various cross-coupled control loops. Since there are various modes of operation, it is challenging to define different modes and to further implement autonomous mode transition based on the energy state of the three power ports. A competitive method is used to realize smooth and seamless mode transition. Multiport converter has plenty of interacting control loops due to integrated power trains. It is difficult to design close-loop controls without proper decoupling method. A detailed approach is provided utilizing state-space averaging method to obtain the converter model under different modes of operation, and then a decoupling network is introduced to allow separate controller designs. Simulation and experimental results verify the converter control design and power management during various operational modes.

Resonant converter topologies with three and four energy storage elements

Generalized half-bridge and full-bridge resonant converter topologies with two, three and four energy storage elements are presented. All possible circuit topologies for such converters under voltage/current driven and voltage/current sinks are discussed. Many of these topologies have not been investigated in open literature. Based on their circuit element connections and source and load excitation types, these topologies are classified into resonant and nonresonant topologies and on their physical realizability. Comparison based on exact steady state analysis are given for typical second- and third-order series resonant converters whereas the fourth-order topology is based on the approximate analysis. >

Multiphase voltage-mode hysteretic controlled DC-DC converter with novel current sharing

Todays on-board high-density, low-output-voltage, high-output-current, fast transient point-of-load (POL) dc-dc converters design requirements for the new generation of integrated circuits, digital signal processors, and microprocessors are increasingly becoming stricter than ever. This is due to the demand for high dynamic performance dc-dc conversion with tight dynamic tolerances for supply voltages coupled with very high power density. In this paper, a multiphase voltage-mode hysteretic controlled POL dc-dc converter with new current sharing is presented. Theoretical analysis is provided for multiphase and interleaved dc-dc converters with new current sharing method. The simulation and experimental results are compared based on a specific design example.

Comparison of basic converter topologies for power factor correction

Basic types of DC-DC converters, when operating in discontinuous conduction mode, have self power factor correction (PFC) property, that is, if these converters are connected to the rectified AC line, they have the capability to give higher power factor by the nature of their topologies. Input current feedback is unnecessary when these converters are employed to improve power factor. In this paper, basic types of DC-DC converter topologies are studied to investigate their self-PFC capabilities. Their input characteristics are compared and their input line current waveforms are predicted.

A Single-Stage Microinverter Without Using Eletrolytic Capacitors

This paper presents a new microinverter topology that is intended for single-phase grid-connected PV systems. The proposed microinverter topology is based on a flyback converter, where an extra switch is added to separate the decoupling capacitor from the PV Module, which allows for a high voltage and voltage ripples across its terminals. This results in reducing the power decoupling required capacitance. In this manner, long life-time low power density film capacitors can be used instead of life-time limited high power density electrolytic capacitors, resulting in remarkable increase of microinverters lifespan. The main advantages of the proposed topology are summarized as: 1) eliminating the double-frequency power ripple using a small film capacitor; 2) using long lifetime film capacitors, which will improve the reliability of the inverter; and 3) requiring no additional circuitry to manage the transformer leakage energy. A 100-W microinverter prototype was built to verify the proposed topology. Experimental results show that the proposed topology and its control scheme can realize the power decoupling, while maintaining very good conversion efficiency numbers.

An Integrated Four-Port DC/DC Converter for Renewable Energy Applications

This paper proposes a novel converter topology that interfaces four power ports: two sources, one bidirectional storage port, and one isolated load port. The proposed four-port dc/dc converter is derived by simply adding two switches and two diodes to the traditional half-bridge topology. Zero-voltage switching is realized for all four main switches. Three of the four ports can be tightly regulated by adjusting their independent duty-cycle values, while the fourth port is left unregulated to maintain the power balance for the system. Circuit analysis and design considerations are presented; the dynamic modeling and close-loop design guidance are given as well. Experimental results verify the proposed topology and confirm its ability to achieve tight independent control over three power-processing paths. This topology promises significant savings in component count and losses for renewable energy power-harvesting systems.

Operation Mode Analysis and Peak Gain Approximation of the LLC Resonant Converter

With the advantage of achieving zero voltage switching for a wide input voltage range, the LLC resonant topology has become increasingly popular for use in high power density and high-efficiency power converter applications. However, when the LLC converter is applied to wide input voltage range applications, the widely used fundamental harmonic approximation is incapable of guiding the design due to its inaccuracy. Thus an accurate LLC converter model is desired. In this paper, a generalized mode analysis is presented that provides highly accurate prediction on resonant current and voltage behavior and dc gain characteristic. Also, because operation modes are affected by load, frequency, and gain conditions, the boundaries and distribution of modes are discussed and illustrated. Based on the mode analysis, an approximation method is developed to estimate the peak gain point, which is useful in LLC design. This approximation demonstrates high accuracy within the simulation results. An experimental prototype is built to verify the analysis.

Power decoupling techniques for micro-inverters in PV systems-a review

This paper reviews the power decoupling techniques of micro-inverters used in single-phase, grid-tied PV systems. The power decoupling techniques are categorized into three groups: (1) PV side decoupling; (2) DC link decoupling; and (3) AC side decoupling. Various topologies and techniques are presented, compared, and evaluated against the size of capacitance, efficiency and control complexity. Finally, potential topologies and technologies are pointed out as the best options for power decoupling implementation.

A Review of Charging Algorithms for Nickel and Lithium Battery Chargers

Battery-charging algorithms can be used for either single- or multiple-battery chemistries. In general, single-chemistry chargers have the advantages of simplicity and reliability. On the other hand, multichemistry chargers, or “universal battery chargers,” provide a practical option for multichemistry battery systems, particularly for portable appliances, but they have some limitations. This paper presents a review of some charging algorithms for major batteries, i.e., nickel-cadmium, nickel-metal-hydride, and lithium-ion batteries for single- and multiple-chemistry chargers. A comparison between these algorithms in terms of their charging schemes and charge termination techniques is included. In addition, some trends of recent chargers development are presented.