Showing papers on "Buck–boost converter published in 2013"
TL;DR: The 3LT2C as mentioned in this paper combines the positive aspects of the two-level converter such as low conduction losses, small part count and a simple operation principle with the advantages of the three-level converters such as the low switching losses and superior output voltage quality.
Abstract: The demand for lightweight converters with high control performance and low acoustic noise led to an increase in switching frequencies of hard switched two-level low-voltage 3-phase converters over the last years. For high switching frequencies, converter efficiency suffers and can be kept high only by employing cost intensive switch technology such as SiC diodes or CoolMOS switches; therefore, conventional IGBT technology still prevails. In this paper, the alternative of using three-level converters for low-voltage applications is addressed. The performance and the competitiveness of the three-level T-type converter (3LT2C) is analyzed in detail and underlined with a hardware prototype. The 3LT2 C basically combines the positive aspects of the two-level converter such as low conduction losses, small part count and a simple operation principle with the advantages of the three-level converter such as low switching losses and superior output voltage quality. It is, therefore, considered to be a real alternative to two-level converters for certain low-voltage applications.
828 citations
TL;DR: In this article, an asymmetrical interleaved high step-up converter was proposed for a front-end photovoltaic system, which is composed of a conventional boost converter and coupled inductors.
Abstract: A novel high step-up converter is proposed for a front-end photovoltaic system. Through a voltage multiplier module, an asymmetrical interleaved high step-up converter obtains high step-up gain without operating at an extreme duty ratio. The voltage multiplier module is composed of a conventional boost converter and coupled inductors. An extra conventional boost converter is integrated into the first phase to achieve a considerably higher voltage conversion ratio. The two-phase configuration not only reduces the current stress through each power switch, but also constrains the input current ripple, which decreases the conduction losses of metal-oxide-semiconductor field-effect transistors (MOSFETs). In addition, the proposed converter functions as an active clamp circuit, which alleviates large voltage spikes across the power switches. Thus, the low-voltage-rated MOSFETs can be adopted for reductions of conduction losses and cost. Efficiency improves because the energy stored in leakage inductances is recycled to the output terminal. Finally, the prototype circuit with a 40-V input voltage, 380-V output, and 1000- W output power is operated to verify its performance. The highest efficiency is 96.8%.
259 citations
TL;DR: This paper analyzes the steady-state operation and the range of zero-voltage switching in an ac–ac dual-active-bridge (DAB) converter for a solid-state transformer and develops a switch commutation scheme for the ac-ac DAB converters.
Abstract: Modern development of semiconductor power-switching devices has promoted the use of power electronic converters as power transformers at the distribution level. This paper presents an ac–ac dual-active-bridge (DAB) converter for a solid-state transformer. The proposed converter topology consists of two active H-bridges and one high-frequency transformer. Four-quadrant switch cells are used to allow bidirectional power flow. Because power is controlled by the phase shift between two bridges, output voltage can be regulated when input voltage changes. This paper analyzes the steady-state operation and the range of zero-voltage switching. It develops a switch commutation scheme for the ac–ac DAB converters. Experimental results from a scaled-down prototype are provided to verify the theoretical analysis.
258 citations
TL;DR: In this paper, the state-of-the-art in research works on non-isolated DC-DC buck, boost, buck-boost, Cuk and SEPIC converters and their characteristics, to find a solution best suiting an application with maximum power point tracking.
Abstract: Photovoltaic (PV) is a fast growing segment among renewable energy (RE) systems, whose development is owed to depleting fossil fuel and climate-changing environmental pollution. PV power output capacity, however, is still low and the associated costs still high, so efforts continue to develop PV converter and its controller, aiming for higher power-extracting efficiency and cost effectiveness. Different algorithms have been proposed for Maximum Power Point Tracking (MPPT). Since the choice of right converter for different application has an important influence in the optimum performance of the photovoltaic system, this paper reviews the state-of-the-art in research works on non-isolated DC–DC buck, boost, buck–boost, Cuk and SEPIC converters and their characteristics, to find a solution best suiting an application with Maximum Power Point Tracking. Review shows that there is a limitation in the system's performance according to the type of converter used. In can be concluded that the best selection of DC–DC converter which is really suitable and applicable in the PV system is the buck–boost DC–DC converter since it is capable of achieving optimal operation regardless of the load value with negotiable performance efficiency and price issue.
257 citations
TL;DR: A novel two-switch high-step-up isolated converter with voltage lift is proposed in this paper, which utilizes a transformer with low turn ratio to achieve high step-up gain and improves conversion efficiency.
Abstract: A novel two-switch high-step-up isolated converter with voltage lift is proposed in this paper. The proposed isolated converter utilizes a transformer with low turn ratio to achieve high step-up gain. The secondary winding charges two boosting capacitors in parallel as switches during the switch-on period, and two boosting capacitors are discharged in series during the switch-off period. Thus, the converter has high voltage gain with appropriate duty ratio. In addition, by using two clamping diodes and a capacitor on the primary side, leakage energy is recycled, and the voltage spikes of the two active switches are clamped, thereby improving conversion efficiency. Finally, experimental results based on a prototype implemented in the laboratory with an input voltage of 24 V, an output voltage of 200 V, and an output power of 200 W verify the performance of the proposed isolated converter; full-load efficiency is nearly 93%.
191 citations
TL;DR: In this paper, the proposed control strategy employs two independent frequencies, one of which operates at high frequency to minimize the size of the inductor while the other one operates at relatively low frequency according to the desired output voltage ripple.
Abstract: This paper proposes a high step-up dc-dc converter based on the Cockcroft-Walton (CW) voltage multiplier without a step-up transformer. Providing continuous input current with low ripple, high voltage ratio, and low voltage stress on the switches, diodes, and capacitors, the proposed converter is quite suitable for applying to low-input-level dc generation systems. Moreover, based on the n-stage CW voltage multiplier, the proposed converter can provide a suitable dc source for an n + 1-level multilevel inverter. In this paper, the proposed control strategy employs two independent frequencies, one of which operates at high frequency to minimize the size of the inductor while the other one operates at relatively low frequency according to the desired output voltage ripple. A 200-W laboratory prototype is built for test, and both simulation and experimental results demonstrate the validity of the proposed converter.
187 citations
TL;DR: A fully electrical startup boost converter for thermal energy harvesting is presented, implemented in a 65-nm bulk CMOS technology and a miniaturized module is demonstrated for energy harvesting applications.
Abstract: A fully electrical startup boost converter for thermal energy harvesting is presented in this paper. The converter is implemented in a 65-nm bulk CMOS technology. With the proposed 3-stage stepping-up architecture, the minimum input voltage for startup is as low as 50 mV while the input voltage required for sustained power conversion is 30 mV. Due to the use of a zero-current-switching (ZCS) converter as the last stage and an automatic shutdown mechanism for the auxiliary converter, conversion efficiency up to 73% is achieved. By incorporating the boost converter and a thermoelectric generator (TEG), a miniaturized module is demonstrated for energy harvesting applications.
180 citations
TL;DR: The proposed converter employs a Zeta converter and a coupled inductor, without the extreme duty ratios and high turns ratios generally needed for the coupled induction to achieve high step-up voltage conversion, to improve the energy-conversion efficiency.
Abstract: The grid-connected AC module is an alternative solution in photovoltaic (PV) generation systems. It combines a PV panel and a micro-inverter connected to grid. The use of a high step-up converter is essential for the grid-connected micro-inverter because the input voltage is about 15 V to 40 V for a single PV panel. The proposed converter employs a Zeta converter and a coupled inductor, without the extreme duty ratios and high turns ratios generally needed for the coupled inductor to achieve high step-up voltage conversion; the leakage-inductor energy of the coupled inductor is efficiently recycled to the load. These features improve the energy-conversion efficiency. The operating principles and steady-state analyses of continuous and boundary conduction modes, as well as the voltage and current stresses of the active components, are discussed in detail. A 25 V input voltage, 200 V output voltage, and 250 W output power prototype circuit of the proposed converter is implemented to verify the feasibility; the maximum efficiency is up to 97.3%, and full-load efficiency is 94.8%.
180 citations
TL;DR: In this paper, a hybrid energy storage system (HESS) using ultracapacitors (UCs) to protect the batteries of an electrical vehicle (EV) from high-peak currents and therefore extend their lifetime is described.
Abstract: This paper describes the implementation of a hybrid energy storage system (HESS) using ultracapacitors (UCs) to protect the batteries of an electrical vehicle (EV) from high-peak currents and therefore extend their lifetime. A field-programmable gate array (FPGA) controlled interleaved bidirectional buck-boost converter working in a discontinuous conduction mode, has been designed to transfer the energy between the batteries and the UCs. The FPGA is responsible of generating all the converter gate signals and implements the control stage needed to smooth the battery current peaks. The control strategy is based on dividing the current demand of the motor into two parts (high-frequency current and low-frequency current), the batteries supply the low frequency part and the UCs supply the high-frequency part. Experimental tests have been carried out driving the EV under different scenarios. Experimental results demonstrate the good behavior of the proposed HESS, although the potential battery life extension is still under quantification. The consumption of the EV has been increased due to the converter losses, this increase is minimum under typical driving scenarios, but is quite important in start-stop driving cycles.
169 citations
TL;DR: In this article, a hybrid-switching phase-shift full-bridge dc-dc converter is derived for electric vehicle battery chargers, which provides wide zero-voltage switching range in the leading leg switches, achieves zero-current switching for lagging-leg switches, and uses a hybrid switching method to avoid freewheeling circulating losses in the primary side.
Abstract: This paper first presents a hybrid-switching step-down dc-dc converter, and then, by introducing transformer isolation, a novel hybrid-switching phase-shift full-bridge dc-dc converter is derived for electric vehicle battery chargers. The proposed converter provides wide zero-voltage-switching range in the leading-leg switches, achieves zero-current-switching for lagging-leg switches, and uses a hybrid-switching method to avoid freewheeling circulating losses in the primary side. Because the resonant capacitor voltage of the hybrid-switching circuit is applied between the bridge rectifier and the output inductor for the duration of the freewheeling intervals, a smaller sized output inductor can be utilized. With the current rectifier diode of the hybrid-switching circuit providing a clamping path, the voltage overshoots that arise during the turn-off of the rectifier diodes are eliminated and the voltage stress of bridge rectifier is clamped to the minimal achievable value, which is equal to secondary-reflected input voltage of the transformer. The inductive energy stored in the output inductor and the capacitive energy stored in the resonant capacitor of the hybrid-switching circuit are transferred to the output simultaneously during the freewheeling intervals with only one diode in series in the current path, achieving more effective and efficient energy transfer. The effectiveness of the proposed converter was experimentally verified using a 3.6-kW prototype circuit designed for electric vehicle onboard chargers. Experimental results of the hardware prototype show that the converter achieves a peak efficiency of 98.1% and high system efficiencies over wide output voltage and power ranges.
157 citations
TL;DR: The study presents a non-isolated bidirectional DC-DC converter, which has simple circuit structure and the synchronous rectifier technique is used to reduce the losses.
Abstract: The study presents a non-isolated bidirectional DC-DC converter, which has simple circuit structure. The control strategy is easily implemented. Also, the synchronous rectifier technique is used to reduce the losses. The voltage gain of the proposed converter is the half and the double of the conventional bidirectional DC-DC buck/boost converter in the step-down and step-up modes, respectively. Therefore the proposed converter can be operated in wide-voltage-conversion range than the conventional bidirectional converter. The voltage stresses on the switches of the proposed converter are a half of the high-voltage side. In addition, the operating principle and steady-state analyses are discussed. Finally, a prototype circuit is implemented to verify the performance of the proposed converter.
TL;DR: In this paper, a multiple-input multiple-output dc-dc converter topology is proposed, which is able to accommodate an arbitrary number of sources and loads, and the steady-state and dynamic characteristics of the proposed converter are analyzed.
Abstract: A multiple-input multiple-output dc-dc converter topology is proposed. This converter is able to accommodate an arbitrary number of sources and loads. The steady-state and dynamic characteristics of the proposed converter are analyzed. A controller scheme is proposed that enables budgeting the input powers coming from different energy sources, in addition to regulating the output voltages. Loss and efficiency modeling and sensitivity analysis to the underlying parameters are performed. Several case studies are presented to verify the analytical models and evaluate the performance of the proposed converter.
TL;DR: In this paper, a soft-switched dc-dc converter using voltage multiplier cells is proposed for high-step up application, which has the following advantages: 1) doubled voltage conversion ratio of the basic configuration (N = 1) compared to the conventional boost converter; 2) zero voltage switching turn ON of switches and zero current switching turn OFF of diodes; 3) low input current ripple, reduced size of the passive component and current stresses of switches due to interleaved structure.
Abstract: In this paper, a soft-switched dc-dc converter using voltage multiplier cells is proposed for high-step up application. The proposed converter has the following advantages: 1) doubled voltage conversion ratio of the basic configuration (N = 1) compared to the conventional boost converter; 2) zero voltage switching turn ON of switches and zero current switching turn OFF of diodes; 3) low input current ripple, reduced size of the passive component and current stresses of switches due to interleaved structure, and 4) increased flexibility in device selection by adjusting the number of voltage multiplier cells. The proposed converter is compared to some high step-up converters. Experimental results from a 1-kW prototype are provided to validate the proposed concept.
TL;DR: In this article, a new hybrid modular multilevel converter for interfacing a full-scale, permanent magnet synchronous generator (PMSG)-based direct-drive variable-speed wind energy conversion system (WECS) is presented.
Abstract: The trend towards multimegawatt (multi-MW) wind turbines and the increasing interest in direct-drive variable-speed wind energy systems have made multilevel converters a promising candidate for large wind energy conversion systems This paper presents a new hybrid modular multilevel converter for interfacing a full-scale, permanent magnet synchronous generator (PMSG)-based direct-drive variable-speed wind energy conversion system (WECS) The proposed hybrid converter, which is used on the grid side of the system, consists of a three-level modular multilevel converter (MMC) in series connection with three H-bridge modules The generator-side converter is based on a conventional three-level neutral-point-clamped converter The proposed hybrid converter, as opposed to the existing full-scale multilevel converter-based wind energy systems, provides structural modularity and a higher dc-bus voltage utilization This paper formulates and analyzes the internal dynamics of the proposed hybrid converter including the circulating currents and the capacitor voltage ripples The ac components of the circulating currents, if not properly reduced, increase the amplitude of the capacitor voltage ripples, rating values of the converter components, and losses Based on the analysis, closed-loop circulating current and capacitor voltage ripple reduction techniques are developed The reduction of capacitor voltage ripples help reduce the capacitor value A mathematical model is also developed for the overall WECS Performance of the overall WECS, under the proposed multilevel converter-based topology and controls, is evaluated based on time domain simulations in the PSCAD/EMTDC environment
TL;DR: In this paper, a non-isolated, high boost ratio hybrid transformer dc-dc converter with applications for low-voltage renewable energy sources was proposed, which utilizes a hybrid transformer to transfer the inductive and capacitive energy simultaneously.
Abstract: This paper presents a nonisolated, high boost ratio hybrid transformer dc–dc converter with applications for low-voltage renewable energy sources. The proposed converter utilizes a hybrid transformer to transfer the inductive and capacitive energy simultaneously, achieving a high boost ratio with a smaller sized magnetic component. As a result of incorporating the resonant operation mode into the traditional high boost ratio pulsewidth modulation converter, the turn-off loss of the switch is reduced, increasing the efficiency of the converter under all load conditions. The input current ripple and conduction losses are also reduced because of the hybrid linear-sinusoidal input current waveforms. The voltage stresses on the active switch and diodes are maintained at a low level and are independent of the changing input voltage over a wide range as a result of the resonant capacitor transferring energy to the output of the converter. The effectiveness of the proposed converter was experimentally verified using a 220-W prototype circuit. Utilizing an input voltage ranging from 20 to 45 V and a load range of 30–220 W, the experimental results show system of efficiencies greater than 96% with a peak efficiency of 97.4% at 35-V input, 160-W output. Due to the high system efficiency and the ability to operate with a wide variable input voltage, the proposed converter is an attractive design for alternative low dc voltage energy sources, such as solar photovoltaic modules and fuel cells.
TL;DR: In this paper, the different converter control strategies are introduced systematically, thereby aiming to provide a framework for classifying the different converters available in literature, and discussed how all converter control schemes theoretically can be regarded as limiting cases of a voltage droop control.
17 Oct 2013
TL;DR: In this paper, the capacitance and inductance selection procedure of the modular multilevel converter is presented, and two analysis criteria are taken into consideration, the circulating current and voltage ripple across submodule capacitors.
Abstract: The paper presents a proposal for capacitance and inductance selection procedure of the modular multilevel converter. Two analysis criteria are taken into consideration, the circulating current and voltage ripple across submodule capacitors. Results are obtained numerically by using the converter averaged model based on state equations. In the modular multilevel converter operating under a direct modulation method, based on sinusoidal modulating signals, circulating currents flows through the converter arms. These currents are strongly dependant on the component parameters of the converter, such as: submodule DC-link capacitor capacitance and arm inductor inductance. Both components form a series resonance circuit in each converter arm. Resonance that occurs in the converter arm has to be avoided and therefore it is important to properly select component parameters while taking into account all possible resonances. Such components selection should be carried out at an early stage of the converter design.
TL;DR: In this paper, a hybrid phase-shift full-bridge and half-bridge converter with shared zero-voltage switching (ZVS) lagging leg is proposed to ensure the switches in the Lagging leg operating at fully ZVS condition, and the dual outputs of the proposed hybrid FB-HB converter are connected in series and the whole dc-output voltage can be regulated by the PWM phase shift control within the desired voltage range.
Abstract: A novel soft-switching hybrid converter combining the phase-shift full-bridge (FB) and half-bridge (HB) LLC resonant converters' configuration with shared zero-voltage switching (ZVS) lagging leg is proposed to ensure the switches in the lagging leg operating at fully ZVS condition. The dual outputs of the proposed hybrid FB-HB converter are connected in series and the whole dc-output voltage can be regulated by the PWM phase-shift control within the desired voltage range. A resonant circuit is used in the secondary side of the FB converter to reset the primary current during the freewheeling period, as well as to transfer more input energy and clamp secondary rectifier voltage. The proposed converter is attractive for hybrid electric vehicle/electric vehicle on-board charger applications. The principle of operation, the validity, and performance are illustrated and verified on a 3.7-kW experimental circuit. Experimental results show that the proposed converter can get good efficiency curves at different operation points, and the maximum efficiency is 98.30%.
28 Mar 2013
TL;DR: Energy harvesting enables the remote sensors of the wireless sensor network to obtain power from the environment for their entire lifetime and an energy storage device, such as a battery, is required to regulate the harvester's output power.
Abstract: This paper presents a single-inductor dual-input–tri-output buck–boost (DITOBB) converter that manages energy harvesting, energy storage, and power rail regulation of an indoor remote sensor system. The converter operates in discontinuous conduction mode (DCM) and regulates the outputs with a combination of pulse-skipping modulation (PSM) and constant-on-time pulse-frequency modulation (PFM). To reduce the quiescent power, all the circuit blocks are turned off when the outputs are within regulation, except a system clock generator. A newly designed relaxation oscillator provides the main clock of the system, which requires neither reference voltages nor comparators. The frequency of the system clock doubles or halves based on the states of the sources and outputs following a proposed algorithm. The DITOBB converter has been designed and fabricated using $0.18\;\upmu \text{m}$ CMOS process. With a quiescent power of 400 nW, the designed DITOBB converter shows a measured peak efficiency of 83% at $100\;\upmu W$ output power.
TL;DR: In this study, a coupled-inductor-based dc-dc converter scheme utilizes only one power switch with the properties of voltage clamping and soft switching, and the corresponding device specifications are adequately designed, allowing for high-efficiency power conversion, high step-up ratio, and various output voltages with different levels.
Abstract: The aim of this study is to develop a high-efficiency single-input multiple-output (SIMO) dc-dc converter. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage dc bus and middle-voltage output terminals. The high-voltage dc bus can take as the main power for a high-voltage dc load or the front terminal of a dc-ac inverter. Moreover, middle-voltage output terminals can supply powers for individual middle-voltage dc loads or for charging auxiliary power sources (e.g., battery modules). In this study, a coupled-inductor-based dc-dc converter scheme utilizes only one power switch with the properties of voltage clamping and soft switching, and the corresponding device specifications are adequately designed. As a result, the objectives of high-efficiency power conversion, high step-up ratio, and various output voltages with different levels can be obtained. Some experimental results via a kilowatt-level prototype are given to verify the effectiveness of the proposed SIMO dc-dc converter in practical applications.
TL;DR: Details on the principle of operation via topological considerations and a mathematical model for a boost dc-dc converter topology with the novel capability of canceling the input current ripple at an arbitrarily preselected duty cycle are provided.
Abstract: This letter proposes a boost dc-dc converter topology with the novel capability of canceling the input current ripple at an arbitrarily preselected duty cycle. This is accomplished without increasing the count of the number of components in contrast to other solutions available in the literature. In addition, the converter features a high voltage gain without utilizing extreme values of duty cycle or boosting transformers. These features make the converter ideal to process electric power coming from low-voltage power-generating sources, such as renewables. This paper provides details on the principle of operation via topological considerations and a mathematical model. The key factor of reactive component sizing is also discussed in detail. The converter was validated in the laboratory through the construction of a hardware prototype.
TL;DR: In this paper, the authors proposed an LCL dc-dc converter concept which is capable of achieving very high stepping ratios with megawatt-level power transfers, which can find potential application in connecting high-power dc sources to high-voltage dc transmission including future dc transmission networks.
Abstract: This paper proposes an LCL dc-dc converter concept which is capable of achieving very high stepping ratios with megawatt-level power transfers. The converter can find potential application in connecting high-power dc sources to high-voltage dc transmission including future dc transmission networks. This converter is based on two ac/dc insulated-gate bipolar transistor-based converters and an internal passive LCL circuit without internal ac transformers. The LCL circuit is designed to enable voltage stepping without any reactive power circulation and with potentially soft switching operation which minimizes the switching losses. The designed converter has the ability to achieve current regulation even under extreme external dc faults and, therefore, the converter can operate through dc faults. The switch utilization is better than similar topologies and losses are reasonably low. A dual-active-bridge transformer-based converter design is presented to compare with the proposed LCL converter. A detailed PSCAD model confirms conclusions using a 100-MW 20-kV/300 kV test system. An LCL 200-W 20-V/100-V dc/dc prototype converter is built to validate the proposed topology.
TL;DR: The operating principles, voltage balancing methods, and limitations of the converter are analyzed together with extensive simulation results of the topology and experimental results from a low-power laboratory prototype are presented that verify the operation of the hybrid converter under SHE-PWM.
Abstract: This paper presents the hybrid seven-level cascaded active neutral-point-clamped (ANPC)-based multilevel converter. The converter topology is the cascaded connection of a three-level ANPC converter and an H-bridge per phase. The voltage of the H-bridge is actively maintained to the required level through selection of the switching states of the converter. The topology is operated under selective harmonic elimination pulsewidth modulation (SHE-PWM), maintaining the switching frequency of the converter to a minimum. The operating principles, voltage balancing methods, and limitations of the converter are analyzed together with extensive simulation results of the topology. Experimental results from a low-power laboratory prototype are presented that verify the operation of the hybrid converter under SHE-PWM.
TL;DR: This paper presents the control of a Z-source neutral point clamped inverter using the space vector modulation technique, which enables the operation of the Z- source arrangement to be optimized and implemented digitally without introducing any extra commutations.
Abstract: The Z-source inverter is a relatively recent converter topology that exhibits both voltage-buck and voltage-boost capability. The Z-source concept can be applied to all dc-to-ac, ac-to-dc, ac-to-ac, and dc-to-dc power conversion whether two-level or multilevel. However, multilevel converters offer many benefits for higher power applications. Previous publications have shown the control of a Z-source neutral point clamped inverter using the carrier-based modulation technique. This paper presents the control of a Z-source neutral point clamped inverter using the space vector modulation technique. This gives a number of benefits, both in terms of implementation and harmonic performance. The adopted approach enables the operation of the Z-source arrangement to be optimized and implemented digitally without introducing any extra commutations. The proposed techniques are demonstrated both in simulation and through experimental results from a prototype converter.
TL;DR: In this article, a bridgeless PFC single-ended primary inductor converter with ripple-free input current is proposed, where the input bridge diode is removed and the conduction loss is reduced.
Abstract: Conventional power factor correction (PFC) single-ended primary inductor converter (SEPIC) suffers from high conduction loss at the input bridge diode. To solve this problem, a bridgeless SEPIC converter with ripple-free input current is proposed. In the proposed converter, the input bridge diode is removed and the conduction loss is reduced. In addition, the input current ripple is significantly reduced by utilizing an additional winding of the input inductor and an auxiliary capacitor. Similar to the conventional PFC SEPIC converter, the input current in a switching period is proportional to the input voltage and near unity power is achieved. The operational principles, steady-state analysis, and design equations of the proposed converter are described in detail. Experimental results from a 130 W prototype at a constant switching frequency of 100 kHz are presented to verify the performance of the proposed converter.
TL;DR: An improved full-bridge three-level (IFBTL) dc/DC converter for a wind turbine in a dc grid is presented by inserting a passive filter into the dc/dc converter to improve the performance of the converter.
Abstract: This paper presents an improved full-bridge three-level (IFBTL) dc/dc converter for a wind turbine in a dc grid by inserting a passive filter into the dc/dc converter to improve the performance of the converter. The passive filter can effectively reduce the voltage stress of the medium frequency transformer in the IFBTL dc/dc converter. A modulation strategy, including two operation modes, is proposed for the IFBTL dc/dc converter. Then, a voltage balancing control strategy is proposed for the IFBTL dc/dc converter. Furthermore, the control of the wind turbine based on the IFBTL dc/dc converter in a dc-grid system is presented. Finally, a small-scale IFBTL dc/dc converter prototype was built and tested in the laboratory, and the results verify the theoretical analysis.
TL;DR: In this paper, a comparative analysis among boost, quadratic boost and cubic boost reveals that the Quadratic Boost exhibits the best trade-off between duty ratio range and converter efficiency.
Abstract: A quadratic boost converter with high DC gain to step up the voltage of a standard photovoltaic panel up to 400 V is analysed. First of all, a comparative analysis among boost, quadratic boost and cubic boost reveals that the quadratic boost exhibits the best trade-off between duty ratio range and converter efficiency. A hysteretic comparator is employed as a modulator to ensure the converter operation with high values of the duty ratio without risk of modulation saturation. A two- loop sliding-mode control is used to regulate the output voltage. An internal loop controls cycle by cycle the input current whose reference is established by an outer loop that processes the output voltage error by means of a proportional-integral compensating network. The measured results in a 100 W prototype operating in continuous conduction mode of average values, ripples, frequency and efficiency for different equilibrium points are in good agreement with the theoretical predictions.
TL;DR: In this article, the authors proposed a new pulse duty cycle control method with pulse frequency modulation for an interleaved single-stage flyback ac-dc converter, which can cover wide power range for outdoor LED lighting applications.
Abstract: In outdoor light-emitting diode (LED) lighting systems, there are a lot of applications. Depending on the output power rating, the power stage to drive an LED can be classified into single-stage and two-stage structures. The single-stage structure is for low-power LED lighting applications. However, it is difficult to apply at over 60-70 W of output power because of its low efficiency and huge transformer at high power. On the other hand, the two-stage structure is usually used for high power applications. However, it is undesirable to cover wide output power range because of its poor power factor (PF) under the light load condition. To solve these problems, this paper proposes a new pulse duty cycle control method with pulse frequency modulation for an interleaved single-stage flyback ac-dc converter. The proposed converter provides high efficiency under heavy loads with low ac line condition and under light loads with high ac line condition. In addition, the proposed converter shows high PF and low total harmonic distortion even when the output power is very low. As a result, a single LED ac-dc converter can cover wide power range for outdoor LED lighting applications. To verify the validity of the proposed converter, an 81-W prototype converter has been implemented and experimented on.
TL;DR: In this article, an integrated boost resonant converter with low component count, galvanic isolation, simple control, and high efficiency across a wide input and load range is proposed for photovoltaic power conditioning.
Abstract: Effective photovoltaic power conditioning requires efficient power conversion and accurate maximum power point tracking to counteract the effects of panel mismatch, shading, and general variance in power output during a daily cycle. In this paper, the authors propose an integrated boost resonant converter with low component count, galvanic isolation, simple control, as well as high efficiency across a wide input and load range. Provided is a discussion of the converter synthesis, key operational features, converter design procedure, and loss analysis, as well as experimental verification by way of a 250-W prototype with a California Energy Commission efficiency of 96.8%.
TL;DR: In this article, a wide-range zero-voltage switching (ZVS) PSFB converter with reduced conduction loss caused by circulating current is proposed, which adopts the large resonant inductance and replaces clamp diodes in the conventional PSFB converters with MOSFET switches.
Abstract: A conventional phase-shift full-bridge (PSFB) converter with two clamp diodes and an additional resonant inductor is widely used for front-end dc/dc stage in the distributed power system. However, the hold-up-time requirement limits its operating duty ratio at normal operation. It results in conduction loss caused by circulating current. Therefore, a wide-range zero-voltage switching (ZVS) PSFB converter with reduced conduction loss caused by circulating current is proposed in this paper. The proposed converter adopts the large resonant inductance and replaces clamp diodes in the conventional PSFB converter with MOSFET switches. With these modifications, the proposed converter can achieve the ZVS operation over wide load range as well as can reduce the conduction loss caused by the circulating current. These advantages result in the improvement of whole load efficiency. The operational principle and analysis of the proposed converter are presented and verified by the 1.2-kW prototype.