Wide Input Voltage Range Research Articles

A ZVZCS Hybrid Dual Full-Bridge Converter Suitable for Wide Input Voltage Range

A phase-shift modulated converter with two full bridges at primary side and rectifier diodes in hybrid combination at secondary side is proposed in this article. Due to the proposed symmetrical modulation strategy, two full-bridges always equally share the total system power rating, and thus the VA rating of two transformers is minimized. The circulating currents decay to zero in the zero state, contributing to reduce the conduction loss and duty-cycle loss. Zero-voltage or zero-current switching is achieved for all switches over whole input voltage range with an auxiliary inductor. The rectifier output voltage is synthesized of two controlled transformer secondary voltages all the time, which achieves the same output current ripple suppression effect as the conventional input-parallel output-parallel full-bridge converters with interleaved control scheme, and reduces the voltage stress of rectifier diodes. These advantages make the converter suitable for wide input voltage range applications. In this article, the operation principle and steady-state analysis of the proposed converter are illustrated in detail. Experimental results with 220–460 V input voltage are demonstrated to verify the advantages.

Isolated solar electronic unit design including capacitive storage for the uninterruptible power supply of critical DC loads

In this study, to the aim was to design an isolated, reliable and efficient DC-DC (flyback based) photovoltaic energy sourced supply unit, which has its own electrolyte-super capacitor based energy storage unit in order to compensate for disruptions and failures that can occur in photovoltaic solar panels. In this storage unit, a hierarchical charging structure has been developed for eliminating the drawbacks of battery technologies such as cooling issues, chemical dangers, heavy weight, charging and discharging current/voltage limitations. The designed supply unit is capable of operating in a wide range of input voltages for the supply of important and expensive solar-based photovoltaic subsystems. Also, it was designed to supply a steady and balanced power to control systems that have microcontrollers or expensive control elements for different purposes up to 50 W. The design can be considered as a model for an uninterruptible power supply with a specific capacitive storage. The designed unit has important advantages due to its large usage area, especially microgrid and off-grid systems, its low cost and less complex construction. The designed hierarchical charging super capacitor based energy storage unit in this study is expected to have important implications for future research due to its possibility to be developed in accordance with different environmental conditions and objectives.

Analysis of a Hybrid Variable-Frequency-Duty-Cycle-Modulated Low-$Q$ $LLC$ Resonant Converter for Improving the Light-Load Efficiency for a Wide Input Voltage Range

Light load efficiency and output voltage regulation of alow-Q LLC resonant converter is a critical problem for wide input voltage and load range applications. Parasitic capacitances such as rectifier diode junction capacitance (C3) degrade the soft switching performance. Compact size, high density, and high transformer turns-ratio requirements for microinverter applications add significant distributed capacitance (Cd) of the low-profile transformer, worsening the output regulation and zero-voltage-switching (ZVS) capability at light loads. Wide switching frequency requirement for regulation at light loads, which increases core losses and turnOFF switching losses in power MOSFETs, further degrades the power conversion efficiency. The conventional phase-shift modulation causes a high circulating current and loss of ZVS at light loads. Therefore, a hybrid adjustable switching-frequency-dutycycle modulation technique for improving the light load efficiency is proposed and analyzed for a full-bridge LLC resonant converter. Accurate loss analysis for the proposed modulation scheme, including the effect of parasitic capacitances, is performed using time-domain equations. The proposed methodology precalculates the optimal duty cycle at light load conditions for the required input voltage range such that minimum power losses are incurred. Variation in switching frequency at the preselected duty-cycle value regulates the output voltage. ZVS over a wide range of operating conditions is observed. An experimental prototype for a 20-40 V input, 380-V/300-W output LLC converter is tested for the validation of theoretical analysis.

A Double-Transistor Double Primary–Winding Flyback Converter for Marine Resources Monitoring Equipment

Li, J.; Wu, H.; Xu, T., and Lin, P., 2020. A double-transistor double primary–winding flyback converter for marine resources monitoring equipment. In: Liu, X. and Zhao, L. (eds.), Today's Modern Coastal Society: Technical and Sociological Aspects of Coastal Research. Journal of Coastal Research, Special Issue No. 111, pp. 340–344. Coconut Creek (Florida), ISSN 0749-0208.The DC bus power-supply mode is the most convenient for marine resources monitoring equipment, and secondary electric power supplies at power supply nodes are featured by a wide variation range of input voltage and high electromagnetic interference (EMI) requirements. A double-transistor double primary–winding flyback converter with wide input range, low EMI noise, and active auto-starting function was designed in this study. The main circuit of this converter solves the withstanding voltage problem of switching tube via series connection of double transistors under high-voltage condition. Through the intertexture structure of the double primary windings, the main transformer reduces the drain-source voltage spike of the switch and effectively mitigates the common-mode EMI noise at output end. The large starting circuit loss is solved, and the converter efficiency is improved under wide input range through the active auto-starting circuit. The experimental results show that when the bus node voltage varies within a wide range of 100 V–1000 V, the converter efficiency is always greater than 85%, and EMI performance is superior, thus satisfying the requirements of bus power-supply system.

Two-Mode Low-Voltage DC/DC Converter With High and Wide Input Voltage Range

It has been proposed that the main battery voltage of electric vehicles should be increased to increase the driving distance and decrease the charging time. Thus, a low-voltage dc/dc converter (LDC) with high and wide input voltage range is required for electronic loads. This article proposes a two-mode LDC and the entire input range is divided into two low and high input voltage ranges. The converter has two operating modes corresponding to these input voltage ranges. In the low input voltage range, it operates as a three-switch double-ended active clamp forward converter. In the high input voltage range, it operates as an asymmetric half-bridge converter. Changing the operating mode according to the input voltage, the proposed converter can have low-voltage stresses on the switches and a low dc offset current of the transformer resulting in high efficiency for the entire input voltage range. In order to confirm the validity of the proposed converter, a 600 W prototype is implemented and experimented.

A Novel LLC Converter With Topology Morphing Control for Wide Input Voltage Range Application

Wide voltage gain range applications are challenging for dc/dc converters, and the system efficiency would be degraded in order to satisfy the voltage gain requirement. Inductor–inductor–capacitor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> ) resonant converters have gained popularity owning to its high efficiency feature. However, wide voltage gain range applications also challenge the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converters from the following three aspects: 1) large switching frequency operating range is required to meet the voltage gain requirement, which degrades the converter electromagnetic interference (EMI) performance and challenges the optimization of magnetic components; 2) small inductor ratio is required to boost the voltage gain, which increases the resonant tank root-mean-square (rms) current and conduction loss; and 3) control instability issues may occur at both maximum voltage gain and minimum voltage gain, which reduce the converter reliability. To address these issues, in this article, a novel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter with topology morphing control is proposed for wide voltage gain range applications. Three operation modes, dual full-bridge (DFB), hybrid full-bridge and half-bridge (HFBHB), and dual half-bridge (DHB), can be achieved by adopting the topology morphing control, which can cover a wide voltage gain operation range. Operational principles, design considerations, and experimental validations of the proposed converter are presented.

Fixed-Frequency Hybrid Conduction Mode Control for Three-Level Boost PFC Converter

Discontinuous conduction mode (DCM) and critical conduction mode (CRM) have held dominant positions in low-power boost power factor correction (PFC) control. Typically, two-level DCM and CRM suffer from high peak current and variable frequency at several-hundred kilohertz, respectively. The two factors can cause secondary effects such as high electromagnetic interference, current stresses, input filter design difficulty, and switching losses. Only to take merits of DCM and CRM that are fixed frequency and lower peak current, this article utilizes three-level boost (TLB) and its three-level current-slope options. This article proposes a hybrid conduction mode (HCM) control, which adopts adaptive single-switch on-time to achieve fixed-frequency quadrangular CRM operation. At lower input voltage, low inductor current enters DCM so that TLB PFC experiences hybrid operation modes depending on varying ac input. Analyses and experiment results in this article confirm that the proposed HCM control can achieve huge reductions of switching losses and peak current stress, improving efficiency in wide-range input voltage and load at the cost of acceptable PF drop. Moreover, a simple voltage-balancing scheme is implemented to the proposed control and verified effective to resolve the inherent topology issue.

Dynamic AC Line Frequency Response Method for LUT-Based Variable On-Time Control in 360–800 Hz CRM Boost PFC Converter

To improve the input current total harmonic distortion (THD), the look-up table (LUT) method is used in the 360-800 Hz critical conduction mode (CRM) boost power factor correction (PFC) converter. When the ac line frequency changes drastically and suddenly, the zero-crossing detection method needs the half ac line period to follow the sudden frequency jump, causing a mismatching between the LUT and the ac line frequency. This mismatching in the time domain leads to a large current spike in the input current and even destruction in the PFC converter under some severe conditions. In this letter, a dynamic ac line frequency response method is proposed to eliminate this mismatching. The proposed method only needs to sample the input voltage, leading to a good performance in following the sudden frequency jump in a wide input voltage range. The effectiveness of the proposed method is verified with a 160 W GaN-based CRM boost PFC converter.

High Step-Up Quasi-Resonant Converter Featuring Minimized Switching Loss Over Wide Input Voltage Range

This article proposes a high step-up quasi-resonant converter that minimizes switching loss over a wide range of input voltages. By employing a bidirectional switch and corresponding switching modulation, the proposed converter achieves the main switch with almost zero voltage, and therefore incurs very little switching loss at all active switches. Moreover, no instantaneous reactive current flows through the circuit under wide variations of input voltages and loads. The duty cycle of primary-side switches is fixed to 0.5; then, the input and clamp capacitor voltages become identical, and thereby the following resonant capacitor voltages remain in balance. As a consequence, the proposed converter becomes compact and achieves high boost-ratio and high efficiency over a wide range of input voltages. The operating principle of the converter is presented along with its design procedure. 400-W/380-V prototype of the proposed converter has been implemented and tested at 40-60 V to verify its effectiveness.

Triple-Mode Isolated Resonant Buck–Boost Converter Over Wide Input Voltage Range for Residential Applications

This article proposes a triple-mode isolated resonant buck-boost converter over a wide input voltage range for residential applications of photovoltaic arrays and fuel cells. First, in case that the input voltage is smaller than the nominal voltage, it operates in a resonant-boost mode that boosts the input voltage by using a bridgeless structure on the secondary-side. Next, if the input voltage is within the range of the nominal voltage, it operates in a fully series-resonant mode, which results in high efficiency by the soft-switching on the primary-side switches and reduced conduction loss. Last, if the input voltage is more than the nominal voltage, it operates in a pulsewidth modulation series-resonant buck mode, which can achieve the step-down conversion by reducing the duty cycle. Unlike the conventional resonant converters, the proposed converter achieves high efficiency and less number of power components over a wide input voltage range. Finally, the performance of the proposed triple-mode isolated resonant converter has been fully verified on a prototype 400 W test-bed in the wide input voltage of 35-65 V.

Impact of Transformer Turns Ratio on the Power Losses and Efficiency of the Wide Range Isolated Buck–Boost Converter for Photovoltaic Applications

In this paper, the impact of transformer turns ratio on the performance of the quasi-Z-source galvanically isolated DC-DC converters is studied. Embedded buck–boost functionality enables these converters to regulate the input voltage and load in a wide range, which makes them suitable for such demanding application as photovoltaic microconverters. The isolation transformer here plays a central role as its turns ratio defines the point of transition between the boost and buck modes and overall capability of the converter to regulate the input voltage in a wide range at high efficiency. The studied quasi-Z-source galvanically isolated DC-DC converter is benchmarked in terms of power loss of components and weighted power conversion efficiency for three different turns ratios of isolation transformer to achieve the best and optimized turns ratio lead to the efficient operation. Operation in a wide range of input voltage at high efficiency is the main criterion for assessing the effect of turns ratio on the efficiency of the converter. The proposed loss model and theoretical predictions of the efficiency were validated with the help of a 300 W experimental prototype of the photovoltaic microconverter based on the quasi-Z-source galvanically isolated DC-DC converter topology.

Dual-Mode Stable Performance Phase-Shifted Full-Bridge Converter for Wide-Input and Medium-Power Applications

Power converters with an extended range of line voltage are the main requirement in today's industrial applications such as photovoltaics- and supercapacitors-based energy systems. The variation in the line voltage severely degrades the performance of power converters, because of the extended freewheeling interval, more circulation current, narrow range of zero voltage switching, and increased EMI. This article suggests a modified phase-shifted full-bridge converter that cuts the freewheeling interval and minimizes these problems. It extends the input voltage range by keeping the operational duty cycle of the converter high over the wide range of input voltage while maintaining the performance stable. The proposed converter consists of four low-profile transformers having reconfigurable interconnection structure. There are two distinct reconfigurable modes, a series mode and a parallel mode, which can be configured with changes in the operational conditions. The operation of the proposed converter with high switching frequency improves the power density. Additionally, the use of multiple transformers minimizes the heat management efforts and reduces the overall volume of the converter. The proposed work, in this article, is validated in hardware characterization for a wide range of input voltage 100-400 Vdc and up to the load power of 1 kW. The measured energy efficiency of the proposed converter remains stable over the complete range input voltage 100-400 Vdc.

A Nonisolated Wide Input Series Resonant Converter for Automotive LED Lighting System

In this article, a reconfigurable nonisolated buck–boost (BB) integrated full-bridge series resonant converter (FBSRC) based light emitting diode (LED) driver is proposed for wide input voltage automotive lighting applications. The proposed LED driver is derived by the integration of BB operation with FBSRC. It can be reconfigured into three different resonant converter topologies such as BB integrated FBSRC, BB integrated half-bridge series resonant converter (BB-HBSRC), and conventional HBSRC and, hence, produces three levels of voltage gains. By transformation from one topology to other based on the input voltage range and with asymmetrical pulsewidth modulation control, it can operate for wide input voltage range while maintaining the soft switching. The main advantages of the proposed configuration are smooth transformation into three different topologies without any additional switching devices, no topological transitions within a switching cycle in steady state, use of simple proportional–integral controller, soft switching, and wider voltage gain with buck/boost operation. In addition, dimming control is also achieved using pulsewidth modulation technique. Detailed theoretical analysis of the proposed converter is presented. To verify the analysis and performance, a prototype of 22.7 W, 22.5 V LED driver is designed, simulated, and tested for a wide input voltage range of 18 to 120 V.

Design and Economic Evaluation of Low Voltage DC Microgrid based on Hydrogen Storage

ABSTRACT This study provides designing and techno-economic analysis of a low voltage (48 V) DC microgrid for domestic load application. In present DC microgrid, photovoltaic (PV) is considered as main power generator to deliver the load demand while fuel cell (FC) and battery are considered as backup power sources. To establish a 48 V DC bus, suitable DC-DC converter having wide input voltage range (22–65 V) is designed to stabilize the variable output voltage of PV and FC generators. The converter efficiency was found to be ≈ 87%. A techno-economic study is also carried out to assess the levelized cost of electricity in microgrid using different energy storage systems, i.e. battery and hydrogen. Lead-acid and lithium-ion are considered as battery storages while high-pressure cylinder and metal hydride storages are considered for hydrogen storage. It is found that PV-battery is most economical configuration; however, PV-FC-battery is better choice for high reliability of overall system. PV-FC-battery configuration has lower cost of electricity as compared to PV-FC alone system. In battery storage system, lithium-ion battery shows faster charging/discharging and efficient operation as compared to lead-acid battery application. In hydrogen storage system, if high-pressure hydrogen is considered, the levelized cost of electricity is reduced significantly as compared to metal hydride storage. However, metal hydride is much better choice for hydrogen storage as compared to the high pressure considering the safety concern.

Full-bridge resonant converter with hybrid control for wide input voltage range applications

This paper proposes a hybrid control strategy for a full-bridge resonant converter. In the applications with a wide input voltage, a resonant converter with variable frequency control (VFC) has to modulate the converter operating in a wide switching frequency range to satisfy gain requirements, which results in some problems such as difficulty in optimizing the design of magnetic components, increased power loss and deteriorated electromagnetic interference. By use of VFC, primary-side phase shift control and secondary-side phase shift control, the frequency variable range can be greatly reduced and the conversion efficiency can be increased, which make the converter appropriate for a wide input voltage range. With this hybrid control strategy, the converter can automatically convert to the corresponding control mode according to variations of the input voltage and load, which has a good transient performance. The working principle, gain characteristics and design considerations of a hybrid controlled CLL resonant converter are introduced in detail. Experimental results are shown to demonstrate its validity and feasibility.

A Common Grounded Type Dual-Mode Five-Level Transformerless Inverter for Photovoltaic Applications

This article presents a novel dual-mode five-level common grounded type (5L-DM-CGT) transformerless inverter topology for a medium-power application with a wide input voltage range (200–400 V). It consists of nine semiconductor switches, two inner flying-capacitors, and a small LC filter at the output side. Due to the direct connection of the negative terminal of the photovoltaic to the neutral point of the grid, there is no leakage current in the 5L-DM-CGT. Depending on the magnitude of the input voltage, the converter can operate in both buck and boost mode to produce the same ac output voltage. The theoretical analysis shows the advantages of the dual-mode inverter for various industrial applications. Finally, the laboratory test results are presented to verify the theoretical analysis. Measurement results show that the proposed inverter rated at 1 kW has around 97±1% efficiency over a wide range of load with a peak efficiency of 98.96% at 130 VA in buck mode and peak efficiency of 99% at 122 VA in boost mode.

Two-Mode Controlled Single/Dual-Input DC–AC Inverter With Wide-Range DC Input

This article presents a two-mode controlled step-up inverter (TMCSI), which is capable of handling single or dual inputs with a wide range of dc input voltage. In comparison to traditional multistage dc/dc power conversion systems, the power conversion stage is reduced and the voltage/current stress of device is significantly alleviated without using high-voltage dc-bus capacitors. As a result, the reliability and overall conversion efficiency are improved accordingly. By combining the two working modes, the proposed inverter achieves uniform distribution of duty ratio under single/dual-input with a wide range of input voltage, and thereby is very suitable for systems having large input voltage variation. Moreover, based on the dual-input TMCSI, a novel power allocation method is also proposed to improve the system load-bearing ability. The power allocation method is controlled separately from two working modes that allows the two-input sources directly supply the ac load simultaneously. In this article, topology derivation, two-mode control strategy, characteristics of steady principle, and design criteria for the key circuit parameters are systematically analyzed, and important conclusions are obtained. Finally, the experimental results from the single/dual-input 500 VA 96-192 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> input and 220 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ac</sub> /50 Hz output inverter prototype verify the effectiveness of the proposed TMCSI topology and its associated power regulation approach.

A Soft-Charging-Based SC DC–DC Boost Converter With Conversion-Ratio-Insensitive High Efficiency for Energy Harvesting in Miniature Sensor Systems

This paper introduces a fully integrated switched-capacitor (SC) DC-DC boost converter suitable for energy harvesting in miniature sensor systems with varying harvesting source and battery voltages. Unlike the conventional SC DC-DC boost converters, where efficiency is optimized only for a few topology-dependent voltage conversion ratios (VCRs), the proposed soft-charging-based SC converter achieved VCR-insensitive evenly high efficiency for a wide range of input and output voltages. A test chip was fabricated in 180nm process, and the measured peak efficiency and average efficiency are 85.3% and 83.6%, respectively, for 1.8V regulated output voltage and a wide range of input voltages (0.95–1.8 V). Also, a peak efficiency of 88.9% and average efficiency of 87.6% are achieved for a wide range of battery output voltages (3.0–4.2 V) and a 1.2V harvesting source input voltage.

A Novel High-Gain DC-DC Converter Applied in Fuel Cell Vehicles

The DC-DC converter for fuel cell vehicles should be characterized by high-gain, low voltage stress, small size and high-efficiency. However, conventional two-level, three-level and cascaded boost converters cannot meet the requirements. A new non-isolated DC-DC converter with switched-capacitor and switched-inductor is proposed in this paper, which can obtain high-gain, wide input voltage range, low voltage stresses across components and common ground structure. In this paper, the operating principle, component parameters design, and comparisons with other high-gain converters are analyzed. Moreover, the state-space averaging method and small-signal modeling method are adopted to obtain the dynamic model of converter. Finally, simulation and experimental results verify the effectiveness of the proposed topology. The input voltage of the experimental prototype ranges from 25 V to 80 V. The rated output voltage is 200 V and rated power is 100W. The maximum efficiency is 93.1% under rated state. The proposed converter is suitable for fuel cell vehicles.

Single-stage LLC AC/DC converter with wide input range and low bus voltage

The traditional single-stage boost LLC resonant AC/DC converter has been widely studied due to advantages such as few power stages, high power factor, and soft switching. However, it also has several disadvantages, such as a low and narrow input voltage, a DC bus voltage that is much higher than the input voltage, and high stress of the switching devices. Therefore, it is generally used in power grids under 110 V. In order to overcome the above problems, this paper proposed a buck-boost LLC resonant AC/DC converter for both 110 V and 220 V power grids. In addition to its traditional structure, the proposed converter has the advantages of a wide input voltage range and a low bus voltage. The proposed converter adopts the PFM–PWM hybrid control strategy. In this paper, the working principle of the proposed converter is analyzed in detail, the realization of the power factor correction mechanism and the soft switching are described, and the design methods of the key parameters are given. Finally, an experimental prototype with a 110 V-250 V input and a 48 V/100 W output is built. Experimental results verify the correctness of the theoretical analysis of the converter and its applicability to power grids.