EPE Association: EPE 2011 - LS6b: Topic 15: Converter Control for Renewable Energy Sources

EPE 2011 - LS6b: Topic 15: Converter Control for Renewable Energy Sources
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2011 ECCE Europe - Conference > EPE 2011 - Topic 15: Non-rotating power generation and storage systems > EPE 2011 - LS6b: Topic 15: Converter Control for Renewable Energy Sources

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   Capacitor Voltage Balance Limits in a Multilevel-Converter-Based Energy Storage System
By Sendoa BURUSTETA, Josep POU, Salvador CEBALLOS, Iker MARINO, José Ángel ALZOLA [View]
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Abstract: This paper studies an energy storage system based on a three-level DC-DC converter and a grid-connected neutral-point-clamped inverter. The main advantages of this multilevel power conversion system are highlighted and the neutral-point voltage oscillations are analyzed. A modulation algorithm for the DC-DC converter which includes the neutral-point voltage balance control is used to improve the voltage balancing capabilities of the inverter. Some figures are presented to show the extended operating areas without neutral-point voltage oscillations thanks to the contribution of the DC-DC converter to the voltage balance. Finally, some guidelines to size the DC-link capacitors are given for a practical application.

   CURRENT-FED QUADRATIC FULL-BRIDGE BUCK CONVERTER FOR PV SYSTEMS INTERFACING: STATIC OPERATION
By Juha HUUSARI, Teuvo SUNTIO [View]
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Abstract: Interfacing a single photovoltaic (PV) module into either a single-phase or a three-phase inverterrequires an interfacing converter with wide conversion range and sufficient dynamic headroom. Interms of avoiding issues with common-mode currents between the PV module and the inverter, aconverter with galvanic isolation is preferred. This is especially important with the emerging thin-filmmodules that have larger cell-to-frame parasitic capacitances compared to traditional modules. Thispaper presents the current-fed quadratic full-bridge buck converter (CFQFB) for the first time anddiscusses its steady-state operation. The foundation for the proposed topology is based on the conceptof true current-fed converters that differ fundamentally from the conventional voltage-fed convertersas will be discussed. The relevant analytical steady-state equations and waveforms are presented firstwith the operational details of the proposed converter. The analytical claims are verified withextensive measurement results from a corresponding 190-W prototype. According to themeasurements, the prototype reached an efficiency of 92\% at the maximum power point (MPP) of thePV module.

   Small-signal Model of Photovoltaic Power Converter for Selection of Perturb and Observe Algorithm Step Time
By Michael SOKOLOV, Tim C. GREEN, Paul D. MITCHESON, Doron SHMILOVITZ [View]
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Abstract: This paper describes small-signal analysis of a photovoltaic boost converter with an emulated load controller and a resistive load. The simulation results of the derived model are compared to time-domain large-signal simulation results for verification. This analysis helps select the time interval between iterations of Perturb and Observe algorithm. It was found that output voltage takes longer time to reach steady-state than input voltage and current, however, the Perturb and Observe algorithm step time can be shorter than output voltage convergence time.

EPE 2011 - LS6b: Topic 15: Converter Control for Renewable Energy Sources
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2011 ECCE Europe - Conference > EPE 2011 - Topic 15: Non-rotating power generation and storage systems > EPE 2011 - LS6b: Topic 15: Converter Control for Renewable Energy Sources
	[return to parent folder]

	Capacitor Voltage Balance Limits in a Multilevel-Converter-Based Energy Storage System By Sendoa BURUSTETA, Josep POU, Salvador CEBALLOS, Iker MARINO, José Ángel ALZOLA	[View] [Download]
Abstract: This paper studies an energy storage system based on a three-level DC-DC converter and a grid-connected neutral-point-clamped inverter. The main advantages of this multilevel power conversion system are highlighted and the neutral-point voltage oscillations are analyzed. A modulation algorithm for the DC-DC converter which includes the neutral-point voltage balance control is used to improve the voltage balancing capabilities of the inverter. Some figures are presented to show the extended operating areas without neutral-point voltage oscillations thanks to the contribution of the DC-DC converter to the voltage balance. Finally, some guidelines to size the DC-link capacitors are given for a practical application.

	CURRENT-FED QUADRATIC FULL-BRIDGE BUCK CONVERTER FOR PV SYSTEMS INTERFACING: STATIC OPERATION By Juha HUUSARI, Teuvo SUNTIO	[View] [Download]
Abstract: Interfacing a single photovoltaic (PV) module into either a single-phase or a three-phase inverterrequires an interfacing converter with wide conversion range and sufficient dynamic headroom. Interms of avoiding issues with common-mode currents between the PV module and the inverter, aconverter with galvanic isolation is preferred. This is especially important with the emerging thin-filmmodules that have larger cell-to-frame parasitic capacitances compared to traditional modules. Thispaper presents the current-fed quadratic full-bridge buck converter (CFQFB) for the first time anddiscusses its steady-state operation. The foundation for the proposed topology is based on the conceptof true current-fed converters that differ fundamentally from the conventional voltage-fed convertersas will be discussed. The relevant analytical steady-state equations and waveforms are presented firstwith the operational details of the proposed converter. The analytical claims are verified withextensive measurement results from a corresponding 190-W prototype. According to themeasurements, the prototype reached an efficiency of 92\% at the maximum power point (MPP) of thePV module.

	Small-signal Model of Photovoltaic Power Converter for Selection of Perturb and Observe Algorithm Step Time By Michael SOKOLOV, Tim C. GREEN, Paul D. MITCHESON, Doron SHMILOVITZ	[View] [Download]
Abstract: This paper describes small-signal analysis of a photovoltaic boost converter with an emulated load controller and a resistive load. The simulation results of the derived model are compared to time-domain large-signal simulation results for verification. This analysis helps select the time interval between iterations of Perturb and Observe algorithm. It was found that output voltage takes longer time to reach steady-state than input voltage and current, however, the Perturb and Observe algorithm step time can be shorter than output voltage convergence time.