Maria C. Mira

Analysis, Design, Modeling, and Control of an Interleaved-Boost Full-Bridge Three-Port Converter for Hybrid Renewable Energy Systems

This paper presents the design, modeling, and control of an isolated dc-dc three-port converter (TPC) based on an interleaved-boost full-bridge converter with pulsewidth modulation (PWM) and phase-shift control for hybrid renewable energy systems. In the proposed topology, the switches are driven by phase-shifted PWM signals, where both phase angle and duty cycle are the controlled variables. The power flow between the two inputs is controlled through the duty cycle, whereas the output voltage can be regulated effectively through the phase shift. The primary-side MOSFETs can achieve zero-voltage-switching (ZVS) operation without additional circuitry. Additionally, due to the ac output inductor, the secondary-side diodes can operate under zero-current-switching (ZCS) conditions. In this study, the operation principles of the converter are analyzed and the critical design considerations are discussed. The dynamic behavior of the proposed ac-inductor-based TPC is investigated by performing state-space modeling. Moreover, the derived mathematical models are validated by simulation and measurements. In order to verify the validity of the theoretical analysis, design, and power decoupling control scheme, a prototype is constructed and tested under the various modes, depending on the availability of the renewable energy source and the load consumption. The experimental results show that the two decoupled control variables achieve effective regulation of the power flow among the three ports.

Boost converter with combined control loop for a stand-alone photovoltaic battery charge system

The converter control scheme plays an important role in the performance of maximum power point tracking (MPPT) algorithms. In this paper, an input voltage control with double loop for a stand-alone photovoltaic system is designed and tested. The inner current control loop with high crossover frequency avoids perturbations in the load being propagated to the photovoltaic panel and thus deviating the operating point. Linearization of the photovoltaic panel and converter state-space modeling is performed. In order to achieve stable operation under all operating conditions, the photovoltaic panel is linearized at the maximum power point (MPP) and at the voltage and current source regions. A settling time under 1 ms is obtained which allows fast MPP tracking implementation.

Power flow control of a dual-input interleaved buck/boost converter with galvanic isolation for renewable energy systems

DC microgrids or nanogrids have attracted increasing research interest in recent years. Therefore, as a critical component, dc-dc converters with multiple inputs are required. In this paper, a dual-input interleaved buck/boost converter is proposed and its corresponding power flow control methods are analyzed and designed accordingly. Furthermore, the design guidelines are discussed. Finally, in order to verify the validity of this study, the measurement results are presented.

Analysis and comparison of magnetic structures in a tapped boost converter for LED applications

This paper presents an analysis and comparison of magnetics structures in a tapped boost converter for LED applications. The magnetic structure is a coupled inductor which is analyzed in a conventional wire-wound core as well as in a planar structure for different interleaving winding arrangements. The analysis is performed in terms of leakage inductance, winding capacitance and winding loss. Efficiency measurements are performed to verify the effect on the converter performance.

Analysis and comparison based on component stress factor of dual active bridge and isolated full bridge boost converters for bidirectional fuel cells systems

This paper presents an analysis and comparison of isolated topologies for bidirectional fuel cell systems. The analyzed topologies are the dual active bridge (DAB) and the isolated full bridge boost converter (IFBBC). The analysis is performed based on the component stress factor (CSF). Results highlight that the DAB has lower CSF than the IFBBC for narrow converter operating points. On the other hand the IFBBC presents a more homogeneous CSF over the entire converter operating range. Finally, experimental results obtained from a 30-80 V 80 A 6 kW 40 kHz IFBBC are presented. The converter achieves efficiencies up to 98.2% and 97.45% depending on the converter power flow.

Isolated Boost Converter with Bidirectional Operation for Supercapacitor Applications

This paper presents an isolated bidirectional dc/dc converter based on primary parallel isolated boost converter (PPIBC). This topology is an efficient solution in low voltage high power applications due to its ability to handle high currents in the low voltage side. In this paper, the converter has been modeled using non-ideal components and operated without any additional circuitry for startup using a digital soft-start procedure. Simulated and measured loop gains have been compared for the validity of the model. On-the-fly current direction change has been achieved with a prototype interconnecting two battery banks. A second prototype has been constructed and tested for supercapacitor operation in constant power charge mode.

MOSFET loss evaluation for a low-power StandAlone photovoltaic-LED system

This paper presents a performance evaluation and comparison of state-of-the-art low voltage Si MOSFETs for a stand-alone photovoltaic-LED Light to Light (LtL) system. The complete system is formed by two cascaded converters that will be optimized for a determined solar irradiation and LED illumination profiles. The comparison is performed based on dynamic characterization and evaluation of the devices energy loss at different current levels.

A three-port topology comparison for a low power stand-alone photovoltaic system

Three-port converter (TPC) topologies for renewable energy systems aim to provide higher efficiency and power density than conventional cascaded structures. This work proposes an analytical comparison of different TPC topologies for a photovoltaic LED lamp stand-alone system. A comparison using component stress factor (CSF) is performed, which gives a quantitative measure of the performance of the converter. The candidate topologies are compared to each other according to a defined LED lighting strategy and a solar irradiation profile.

Analytical comparison of dual-input isolated dc-dc converter with an ac or dc inductor for renewable energy systems

This paper presents two configurations of dual-input (DI) or three-port (TPC) isolated dc-dc converters for hybrid renewable energy systems such as photovoltaics and batteries. These two converters are derived by integrating an interleaved boost converter and a single-active bridge converter with an ac inductor as a power interfacing element or phase-shift soft-switching converter with an output dc inductor. Both converters are controlled by a pulse-width modulation and phase-shift hybrid modulation scheme. The two converter topologies are, even though quite similar from the topological and control perspective, distinct in operation principles, voltage/power transfer functions, loss distributions, soft-switching constraints, and power efficiency under the same operating conditions. Moreover, the inductor design differs greatly between these two cases. In this paper, a comprehensive comparison is given for the first time and thereby the corresponding design tradeoffs are discussed. Finally, a laboratory 1 kW prototype is constructed and tested to verify the theoretical analysis.