Showing papers on "Buck–boost converter published in 2018"
TL;DR: The steady-state analysis of the proposed dc–dc converter with high voltage gain is discussed and the proposed converter prototype circuit is implemented to justify the validity of the analysis.
Abstract: In this paper, a nonisolated dc–dc converter with high voltage gain is presented. Three diodes, three capacitors, an inductor, and a coupled inductor are employed in the presented converter. Since the inductor is connected to the input, the low input current ripple is achieved, which is important for tracking maximum power point of photovoltaic panels. The voltage stress across switch S is clamped by diode D 1 and capacitor C 1. Therefore, a main switch with low on-resistance RDS (on) can be employed to reduce the conduction loss. Besides, the main switch is turned on under zero current. This reduces the switching loss. The steady-state analysis of the proposed converter is discussed in this paper. Finally, the proposed converter prototype circuit is implemented to justify the validity of the analysis.
191 citations
TL;DR: This paper proposes a novel structure for a boost dc/dc converter based on the SEPIC converter, which employs a coupled inductor with a voltage multiplier cell in this structure to improve its high voltage gain and efficiency.
Abstract: This paper proposes a novel structure for a boost dc/dc converter. The presented structure is based on the SEPIC converter. Therefore, the converter benefits from various advantages that the SEPIC converter has such as continuous input current. Also, high voltage conversion gain and higher efficiency are the other advantages of the proposed converter. Input current continuity makes the presented converter suitable for renewable energy sources. Employing a coupled inductor with a voltage multiplier cell in this structure increases its high voltage gain. In addition, lower voltage stress on the main power switch leads to higher conversion efficiency. Also, the energy stored in the leakage inductance of the coupled inductor is recycled, which improves the efficiency more. The steady state analysis and the design of the converter are discussed thoroughly. Experimental results are provided by a 220 W prototype. The results verify the proper operation and feasibility of the presented converter.
165 citations
TL;DR: The voltage gain of the presented converter is higher than conventional converters, such as buck–boost, single-ended primary-inductance converter, Cuk, and Zeta converter, and it can operate at wide output voltage range only by changing the duty cycle of the power switch pulse.
Abstract: In this paper, a novel buck–boost dc–dc converter with continuous input current is proposed The voltage gain of the presented converter is higher than conventional converters, such as buck–boost, single-ended primary-inductance converter, Cuk, and Zeta converters This converter works only by one switch and voltage stress across the switch is low Input current of the proposed converter is continuous so a large filter at the input is not needed Furthermore, continuous input current has made this converter suitable for renewable energy and fuel cell applications In this converter, noninverting output voltage is obtained and high gain of voltage is achieved as well So it can operate at wide output voltage range only by changing the duty cycle of the power switch pulse The presented converter can easily controlled in continuous conduction mode operation, because of using only one power switch In the following, the principle of operation and the mathematical analyses of the proposed converter are explained, finally, validity of the proposed dc–dc converter is verified by the experimental results
157 citations
TL;DR: In this article, a switched-capacitor-based dual-switch dc-dc converter with a high-boost voltage gain is proposed, which can obtain a highvoltage gain with a small duty cycle, which decreases the voltage stress and the conduction loss on the power switches.
Abstract: A switched-capacitor-based dual-switch dc–dc converter with a high-boost voltage gain is proposed in this paper. The proposed converter can obtain a high-voltage gain with a small duty cycle, which decreases the voltage stress and the conduction loss on the power switches. This paper presents the key waveforms, the operating principles at the continuous conduction mode and the discontinuous conduction mode, and the parameter design. Moreover, a comparison between the proposed converter and other nonisolated converters has been completed. To verify the operating principle, a 200 W prototype is constructed with an input voltage of 25–50 V and an output voltage of 200 V. The simulation and experimental results are shown.
128 citations
TL;DR: In this paper, a new structure of non-isolated boost dc-dc converters based on voltage-lift technique is proposed, which generates higher voltage gain than conventional non-boost DC-DC converters.
Abstract: In this paper, a new structure of nonisolated boost dc–dc converters based on voltage-lift technique is proposed. In comparison with conventional nonisolated boost dc–dc converters, the proposed converter generates higher voltage gain. In this paper, the relations between voltage and current of all elements in continuous conduction mode and discontinuous conduction mode are calculated as well as voltage gain in each mode. Then, the critical inductance and stress of switch current are extracted. Finally, the validity of given theories is examined by using the experimental results.
115 citations
TL;DR: In this article, the authors propose an extension of the overlap period of the dc-arm conduction period to a factor of $60 √ √ n. The EO-AAC has its dc current path decoupled from the ac current paths, a fact allowing smooth dc current waveforms, elimination of dc filters and restriction lifting on the feasible operating point.
Abstract: The alternate arm converter (AAC) was one of the first modular converter topologies to feature dc-side fault ride-through capability with only a small penalty in power efficiency. However, the simple alternation of its arm conduction periods (with an additional short overlap period) resulted in 1) substantial six-pulse ripples in the dc current waveform, 2) large dc-side filter requirements, and 3) limited operating area close to an energy sweet spot. This paper presents a new mode of operation called extended overlap (EO) based on the extension of the overlap period to $60^{\circ }$ , which facilitates a fundamental redefinition of the working principles of the AAC. The EO-AAC has its dc current path decoupled from the ac current paths, a fact allowing 1) smooth dc current waveforms, 2) elimination of dc filters, and 3) restriction lifting on the feasible operating point. Analysis of this new mode and EO-AAC design criteria are presented and subsequently verified with tests on an experimental prototype. Finally, a comparison with other modular converters demonstrates that the EO-AAC is at least as power efficient as a hybrid modular multilevel converter (MMC) (i.e., a dc fault ride-through-capable MMC), while offering a smaller converter footprint because of a reduced requirement for energy storage in the submodules and a reduced inductor volume.
107 citations
TL;DR: In this article, a robust voltage control for a floating interleaved boost converter with high voltage gain is proposed, where the reference current value is generated by active disturbance rejection control (ADRC) algorithm in the outer loop based on the output voltage error.
Abstract: In this paper, a robust voltage control is designed for a floating interleaved boost converter with high voltage gain. The proposed controller has an inner loop based on super-twisting sliding mode algorithm, which has continuous control signal and the sliding surface is defined for the inductor current. The reference current value is generated by active disturbance rejection control (ADRC) algorithm in the outer loop, based on the output voltage error. The stability of the sliding mode inner loop and the ADRC outer loop are proven using Lyapunov stability theorem and Routh–Hurwitz criteria, respectively. The robustness of the proposed controller is analyzed in depth, and validated by the simulations and experimental results obtained with a 100 W prototype converter.
104 citations
TL;DR: In this article, an interleaved switched-capacitor bidirectional dc-dc converter with a high step-up/step-down voltage gain is proposed, and the experimental results also validate the feasibility and the effectiveness of the proposed topology.
Abstract: In this paper, an interleaved switched-capacitor bidirectional dc-dc converter with a high step-up/step-down voltage gain is proposed. The interleaved structure is adopted in the low-voltage side of this converter to reduce the ripple of the current through the low-voltage side, and the series-connected structure is adopted in the high-voltage side to achieve the high step-up/step-down voltage gain. In addition, the bidirectional synchronous rectification operations are carried out without requiring any extra hardware, and the efficiency of the converter is improved. Furthermore, the operating principles, voltage and current stresses, and current ripple characteristics of the converter are analyzed. Finally, a 1 kW prototype has been developed which verifies a wide voltage-gain range of this converter between the variable low-voltage side (50–120 V) and the constant high-voltage side (400 V). The maximum efficiency of the converter is 95.21% in the step-up mode and 95.30% in the step-down mode. The experimental results also validate the feasibility and the effectiveness of the proposed topology.
104 citations
TL;DR: A novel high step-up converter based on two switched capacitors and a coupled inductor is proposed in this paper, and the highest efficiency is 96.4%.
Abstract: Due to the relatively low output voltage of photovoltaic (PV) source, a high step-up converter with high efficiency is needed when the PV source is connected to the power grid. A novel high step-up converter based on two switched capacitors and a coupled inductor is proposed in this paper. The operating principle is analyzed and the voltage gain is derived. A 100-W prototype is fabricated in the laboratory to verify the theoretical analysis, and the highest efficiency is 96.4%.
103 citations
TL;DR: A single-switch quadratic buck–boost converter with continuous input port current and continuous output port current is proposed in this paper and can obtain a wider range of the voltage conversion ratio with the same duty cycle.
Abstract: A single-switch quadratic buck–boost converter with continuous input port current and continuous output port current is proposed in this paper. Compared with the traditional buck-boost converter, the proposed converter can obtain a wider range of the voltage conversion ratio with the same duty cycle. Moreover, the proposed converter can operate with continuous input port current and continuous output port current compared to the existing counterparts with inherently discontinuous input port current and discontinuous output port current. The operating principle and steady-state performance of the proposed converter under continuous inductor current mode is analyzed in detail. Then, the comparison between the proposed converter and the existing quadratic buck–boost converters has been conducted to demonstrate the unique features of the proposed one. Finally, experimental results from a prototype built in the lab are recorded to verify the effectiveness and validity of the proposed quadratic buck–boost converter.
101 citations
TL;DR: A quasi-Z-source boost dc–dc converter, which uses a switched capacitor, is proposed for fuel cell vehicles, which can obtain a high-voltage gain with a wide input-voltages range and requires only a low- voltage stress across each of the components.
Abstract: A quasi-Z-source boost dc–dc converter, which uses a switched capacitor, is proposed for fuel cell vehicles. The topology can obtain a high-voltage gain with a wide input-voltage range and requires only a low-voltage stress across each of the components. The performance of the proposed converter is compared with other converters which use Z-source networks. A scaled-down 400-V/400-W prototype is developed to validate the proposed technology. The respective variation in the output voltage is avoided when the wide variation in the input voltage happens, due to the PI controller in the voltage loop, and a maximum efficiency of 95.13% is measured.
TL;DR: In this article, a new high step-up interleaved converter is proposed to achieve high voltage gain by adjusting the turn ratio of the coupled inductors, which reduces the voltage stress of switches and diodes.
Abstract: A new high step-up interleaved converter is proposed in this paper. This new high step-up converter utilizes the interleaved boost converter to be in series connection with the voltage-double module. The secondary sides of the coupled inductors are in interleaved series connection and shared by two voltage-double modules to accomplish the interleaved energy storage. Then, the input voltage, coupled-inductors, and multiplier capacitors are in series connection with the output to achieve the purpose of high voltage gain. The proposed circuit can be operated at a lower duty cycle to achieve high voltage gain by adjusting the turn ratio of the coupled inductors. The proposed circuit has less elements and the voltage stress of the switches and diodes can be decreased to reduce the cost. The conduction loss can be reduced and the efficiency can be increased when the switch with lower conduction resistance is applied. Finally, a prototype circuit of a 400 W high step-up converter with input voltage of 24 V and output voltage of 400 V is realized. Through simulation and experiments, the validity and property of the proposed converter can be verified.
TL;DR: A novel non-isolated three-port converter (NITPC) is introduced in this brief, which is a compact but fully functional design by combining and integrating basic converters to form a simplified single-inductor converter structure while keeping a minimum amount of switches.
Abstract: A novel non-isolated three-port converter (NITPC) is introduced in this brief. The purpose of this topology is to integrate a regenerative load such as DC bus and motor with dynamic braking, instead of the widely reported consuming load, with a photovoltaic (PV)-battery system. Conventional methods require either a separate DC–DC converter to process the reversible power flow or employing an isolated three-port converter (TPC), which allows bi-directional power flow between any two ports. However, these methods require many switches, which increases the converter size and control complexity. This brief hence presents a compact but fully functional design by combining and integrating basic converters to form a simplified single-inductor converter structure while keeping a minimum amount of switches. The resultant converter is fully reconfigurable that all possible power flow combinations among the sources and load are achieved through different switching patterns, while preserving the single power processing feature of TPC. This brief presents a design example of the proposed NITPC for a PV-battery powered DC microgrid. Detailed circuitry analysis, operation principles of both DC grid-connected and islanded modes, and experimental results of different modes in steady state and mode transitions are presented.
TL;DR: In this article, a new single switch high step-up dc-dc converter with high voltage gain is proposed by combining boost and single-ended primary inductor converter with diode-capacitor circuit.
Abstract: In this paper, a new single switch high step-up dc–dc converter with high voltage gain is proposed. The proposed topology is developed by combining boost and single-ended primary inductor converter with diode–capacitor circuit to reduce the stress across the semiconductor devices. The proposed converter produces low switching voltage and hence it improves its efficiency. The operating principle and the steady-state performance analysis are discussed. The performance of the converter is validated by developing a prototype circuit with input voltage of 30 V, output voltage of 300 V, and output power rating of 250 W. The theoretical analysis and experimental results conclude the proposed converter that is suitable for high-voltage applications.
TL;DR: Experimental results validate the performance and the feasibility of the proposed converter, based on the traditional two-level quasi-Z-source bidirectional dc–dc converter, changing the position of the main power switch.
Abstract: A common ground switched-quasi- Z -source bidirectional dc–dc converter is proposed for electric vehicles with hybrid energy sources. The proposed converter is based on the traditional two-level quasi- Z -source bidirectional dc–dc converter, changing the position of the main power switch. It has the advantages of a wide-voltage-gain range, a lower voltage stress across the power switches, and an absolute common ground. The operating principle, the voltage and current stresses on the power switches, the comparisons with the other converters, the small signal analysis, and the controller design are presented in this paper. Finally, a 300 W prototype with $U_{{\rm{high}}}= {240 \ \rm{V}}$ and $U_{{\rm{low}}}= {40\sim 120\ \rm{V}}$ is developed, and the experimental results validate the performance and the feasibility of the proposed converter.
TL;DR: In this article, a front-end dc/dc converter based multilevel inverter is proposed for multi-input applications, which integrates two different renewable energy sources, resulting in an advantageous compact structure and low conduction losses.
Abstract: A new isolated current-fed zero-current switched (ZCS) front-end dc/dc converter based multilevel inverter is proposed for multi-input applications. The proposed front-end converter with only two controllable switches integrates two different renewable energy sources, resulting in an advantageous compact structure and low conduction losses. The ZCS turn- off is achieved in both the controllable switches with the proposed modulation scheme. The converter maintains ZCS turn- off under a wide load, as well as input voltage variations by employing frequency modulation along with a variable duty ratio technique. Simple structure, soft switching, high gain, and automatic load regulation make the converter structure novel for simultaneous power management in multi-input renewable energy applications. Converter operation and design guidelines have been outlined. A laboratory prototype of the proposed converter is developed and tested at 300-W power level. Simulations and experimental results demonstrate the robust performance of the converter under load, as well as input source voltage variations.
TL;DR: In this paper, an isolated bidirectional soft-switching dc-dc converter combining two-level converters in parallel on the medium-voltage (MV) side and a modular multilevel converter (MMC) on the HV side is presented.
Abstract: DC grid technology is regarded as a promising solution for future electric networks integrating a great amount of renewable energies. It calls for high-efficiency dc–dc converters with high voltage step-up ratio to interconnect medium-voltage (MV) dc distribution grids and high-voltage (HV) dc transmission grids. This paper presents an isolated bidirectional soft-switching dc–dc converter combining two-level converters in parallel on the MV side and a modular multilevel converter (MMC) on the HV side. A dedicated control method of the proposed converter is presented. By the proposed method, a certain reactive current is injected into the MV side by the MMC to ensure soft-switching on the MV side. The proposed converter presents low power-semiconductor total device rating and low semiconductor losses over a wide power range at variable input and output voltages. Simulation of a 50 kV/400 kV, 400 MW converter is conducted to evaluate semiconductor losses and verify the validity of this work.
TL;DR: To further improve the efficiency and stability of the proposed single-phase inverter, PWM strategies combining high- and low-frequency modulation are presented.
Abstract: In this paper, dual-buck structured single-stage buck–boost inverters that use power MOSFETs to achieve high efficiency are presented. The proposed inverters require fewer switches, and half of the switches have reduced current stresses. They have no shoot-through problem; therefore, high system reliability can be obtained. The dead-time in PWM signals can be minimized or eliminated, which improving the quality of the output ac voltages and increasing the efficiency. In the proposed inverters, MOSFETs can be used without reverse-recovery issues of their body diodes to boost the efficiency and increase the switching frequency. To further improve the efficiency and stability of the proposed single-phase inverter, PWM strategies combining high- and low-frequency modulation are presented. A hardware prototype of the single-phase inverter was built and tested using resistive, inductive, and nonlinear loads. Experimental results for a 300-W prototype inverter show a 97.4% peak efficiency with a 25 kHz switching frequency.
TL;DR: In this article, a hybrid multilevel dc-ac converter structure is proposed to reduce converter footprint, active and passive components' size, and on-state losses relative to conventional modular multi-level converters.
Abstract: Efficient medium and high-voltage dc–dc conversion is critical for future dc grids. This paper proposes a hybrid multilevel dc–ac converter structure that is used as the kernel of dc–dc conversion systems. Operation of the proposed dc–ac converter is suited to trapezoidal ac-voltage waveforms. Quantitative and qualitative analyses show that said trapezoidal operation reduces converter footprint, active and passive components’ size, and on-state losses relative to conventional modular multilevel converters. The proposed converter is scalable to high voltages with controllable ac-voltage slope; implying tolerable dv/dt stresses on the converter transformer. Structural variations of the proposed converter with enhanced modularity and improved efficiency will be presented and discussed with regards to application in front-to-front isolated dc–dc conversion stages, and in light of said trapezoidal operation. Numerical results provide deeper insight of the presented converter designs with emphasis on system design aspects. Results obtained from a proof-of-concept 1-kW experimental test rig confirm the validity of simulation results, theoretical analyses, and simplified design equations presented in this paper.
TL;DR: In this article, a new pulse width modulation (PWM) switching technique was proposed for controlling a bidirectional isolated dc-ac-ac converter employing a high-frequency link transformer.
Abstract: Galvanic isolation based high-frequency transformers have become very attractive in bidirectional dc/ac converters. This paper presents a new pulse width modulation (PWM) switching technique for controlling a bidirectional isolated dc–ac–ac converter employing a high-frequency link transformer. The proposed PWM technique has the ability to control the input dc current and to inject a sinusoidal three-phase current to the grid at unity power factor. The primary-side is an H-bridge converter used to convert the dc voltage to a high-frequency square-wave single-phase voltage. The secondary side is a matrix converter used to convert the grid three-phase voltage to a high-frequency single-phase waveform. The dc–ac–ac converter utilizes a high-frequency link transformer for the galvanic isolation between the H-bridge and matrix converters as alternative for the bulky line-frequency transformers (50/60 Hz). The bidirectional power flow is controlled by the phase shift angle between the primary and secondary voltages of the high-frequency transformer. The mathematical model and the circuit operational modes are presented along with the voltage controllable limit. The feasibility of the proposed PWM switching technique and the accuracy of the mathematical model are demonstrated experimentally by using a 200 V/1 kW laboratory prototype system.
TL;DR: In this article, a non-isolated bidirectional quadratic converter characterized by high voltage gain in both stepdown (Buck) and step-up (Boost) operation modes is proposed.
Abstract: Energy storage devices are essential to provide voltage and frequency stability in renewable energy sources, such as solar and wind. Due to operational requirements of distributed generation systems, energy storage devices like batteries and supercapacitors need bidirectional dc–dc converters to allow charge or discharge exchange according with the necessary conditions. In this paper, a new nonisolated bidirectional quadratic converter characterized by high voltage gain in both step-down (Buck) and step-up (Boost) operation modes is proposed. In addition to the wide conversion range, it presents continuous input and output current and reduced charging/discharging ripple. All these features allow an optimized operation between the dc bus and storage devices. The operation principle of the proposed converter in both condition modes (step-down and step-up), the converter design, as well as the theoretical analysis in different conditions will be discussed. Finally, the performance of the proposed converter is confirmed through simulation and experimental results.
TL;DR: In this paper, the authors derived the requirements of each switch to eliminate the dc offsets in both inductor current and transformer magnetizing current with a settling time shorter than half the switching period.
Abstract: This paper discusses dynamic behavior of a dual-active-bridge (DAB) dc–dc converter. Conventional phase-shift control methods for the DAB converter may cause dc offsets in both inductor current and transformer magnetizing current in transient states. The dc offset in the inductor current would introduce an excessive peak current through the switching devices. The dc offset in the magnetizing current may induce magnetic-flux saturation. Conventional methods simultaneously turn on and off the diagonal switches in each H-bridge converter and produce a square-wave voltage with a 50% duty ratio. In contrast, the proposed method in this paper independently controls each switch to modify the duty ratio in transient states. This paper clearly derives the requirements of each switch to eliminate the dc offsets in both currents with a settling time shorter than half the switching period. Experimental results using a 5-kW 20-kHz system verify the validity of the proposed control method, which is effective not only in a single step change, but also in a continuous change in the phase-shift reference.
TL;DR: This paper proposes a unique integrated and isolated dual-output dc–dc resonant converter, which can interface both HV traction batteries and LV loads, and the variable dc-link voltage strategy is utilized to enhance the efficiency over the entire output voltage range.
Abstract: This paper proposes a unique integrated and isolated dual-output dc–dc resonant converter, which can interface both HV traction batteries and LV loads. In addition, the proposed topology is bidirectional, capable of delivering power from HV traction batteries to the grid for vehicle-to-grid (V2G) applications. To increase the power density of the converter, the dual-output dc–dc resonant converter combines magnetic components of resonant networks into a single three-winding electromagnetically integrated transformer. The resonant converter uses a half-bridge topology with split capacitors as the resonant network components to further reduce the size of a converter. The variable dc-link voltage strategy is utilized to enhance the efficiency over the entire output voltage range. A 3.3-kW converter is designed and developed for validation of various operation modes, including grid-to-vehicle, V2G, and HV-to-LV charging.
TL;DR: In this paper, a one-and-a-half-stage forward-flyback converter with high power factor (PF), high efficiency, low output ripple current, and long lifetime was proposed.
Abstract: A “one-and-a-half stage” forward-flyback converter for electrolytic capacitor-less light-emitting diode (LED) driver with high power factor (PF), high efficiency, low output ripple current, and long lifetime has been proposed and studied in this paper. The basic topology of the proposed topology is a single-switch forward-flyback converter for achieving high PF. In addition, a buck converter is inserted between the forward subconverter and the load for creating two paralleled power transfer paths. The most of input energy directly reaches the load through flyback subconverter, and only about 1/4 of total energy is transferred to the load through forward subconverter and buck converter. Therefore, the proposed topology is a “one-and-a-half stage” converter and can achieve higher efficiency than the traditional two-stage topologies. At the same time, power decoupling can be realized and the electrolytic capacitor can be eliminated. Optimal control scheme, detailed analysis, and design considerations for this improved converter are presented. Finally, an experimental prototype for 28 V/700 mA LED driver was built up to verify the theoretical analysis.
TL;DR: In this article, a modified series-capacitor (SC) high conversion ratio (HCR) dc-dc converter is proposed to eliminate the problem of high switchvoltage stress of the existing converter encountered during start-up using a simple circuit modification Although an extra capacitor is required in the proposed converter, total series capacitance is the same as that of the conventional SC converter.
Abstract: In this letter, a modified series-capacitor (SC) high conversion ratio (HCR) dc–dc converter is proposed The proposed converter inherits most of the advantages of the existing SC HCR dc–dc converter and can eliminate the problem of high switch-voltage stress of the existing converter encountered during start-up using a simple circuit modification Although an extra capacitor is required in the proposed converter, total series capacitance of the proposed converter is the same as that of the conventional SC converter In addition, input capacitance of the proposed converter can be reduced by less than half of that of the SC buck converter A 1-kW prototype converter is built and tested to verify the performance of the proposed converter
TL;DR: In this article, a bidirectional resonant dc-dc converter is proposed for wide voltage gain range applications (e.g., energy storage systems), which is achieved by configuring a full-bridge mode and a half-bridge operation during each switching cycle.
Abstract: This paper proposes a new bidirectional resonant dc–dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant dc–dc converters, and meanwhile achieves high efficiency throughout the wide range of operation voltage. It is achieved by configuring a full-bridge mode and a half-bridge mode operation during each switching cycle. A fixed-frequency phase-shift control scheme is proposed and the normalized voltage gain can be always from 0.5 to 1, regardless of the load. The transformer root-mean-square (rms) currents in both the forward and reverse power flow directions have a small variation with respect to the voltage gain, which is beneficial to the conduction losses reduction throughout a wide voltage range. Moreover, the power devices are soft-switched for minimum switching losses. The operation principles and characteristics of the proposed converter are firstly analyzed in this paper. Then the analytical solutions for the voltage gain, soft-switching, and rms currents are derived, which facilitates the parameters design and optimization. Finally, the proposed topology and analysis are verified with experimental results obtained from a 1-kW converter prototype.
TL;DR: In this paper, a three-switch, isolated boost dc-dc converter with continuous input current, reduced active switch, one additional diode, and one additional capacitor was proposed.
Abstract: This paper documents a new three-switch, isolated boost dc–dc converter. The major features of the proposed converter are as follows: 1) continuous input current; 2) reduced one active switch, one additional diode, and one additional capacitor; 3) unchanged primary and secondary voltage waveforms of the transformer when the duty cycle is changed; and 4) removal of the snubber circuit. This paper presents the operating principles, analysis, parameter design guidelines, and simulation results for the proposed converter. To verify the performance of the proposed converter, a 400 W prototype was constructed with a 40–60 V dc input. A PID controller was used to maintain the dc output voltage at 400 V. The simulation and experimental results matched those of the theoretical analysis.
TL;DR: The calibration is essential to ensure the reliability and minimize the inductor current and output voltage ripple, thus maintaining the advantages of the three-level operation and further extending the system bandwidth without encountering sub-harmonic oscillation.
Abstract: This paper presents a 50-MHz 5-V-input 3-W-output three-level buck converter. A real-time flying capacitor ( $C_{F}$ ) calibration is proposed to ensure a constant voltage of $V_{g}$ /2 across $C_{F}$ , which is highly dependent on various practical conditions, such as parasitic capacitance, time mismatches, or any loading circuits from $C_{F}$ . The calibration is essential to ensure the reliability and minimize the inductor current and output voltage ripple, thus maintaining the advantages of the three-level operation and further extending the system bandwidth without encountering sub-harmonic oscillation. The converter is fabricated in a UMC 65-nm process using standard 2.5-V I/O devices, and is able to handle a 5-V input voltage and provide a 0.6–4.2-V-wide output range. In the measurement, the voltage across $C_{F}$ is always calibrated to $V_{g}$ /2 under various conditions to release the voltage stress on the high- and low-side power transistors and $C_{F}$ , and to ensure reliability with up to 69% output voltage ripple reduction. A 90% peak efficiency and a 23–29-ns/V reference-tracking response are also observed.
TL;DR: The experimental results demonstrate that the proposed SITITO converter has a peak efficiency of 84.4%.
Abstract: In this paper, we present a single-inductor triple-input–triple-output (SITITO) buck–boost converter in a 0.18- $\mu \text{m}$ CMOS process for dual-source energy harvesting. The converter operates in the single-source mode, dual-source mode (DSM), and backup mode automatically by detecting the input and output conditions. Converter operation in the proposed DSM enables extraction of power from both a photovoltaic cell and a thermoelectric generator in one switching cycle for efficient power extraction. The cycle-by-cycle source-tracking approach selects the appropriate input source according to the maximum power point of the energy transducers. The adaptive on-time circuit with the proposed adaptive peak-inductor-current (APIC) control adjusts the on-time of power transistors to obtain high conversion efficiency under different input voltages. The experimental results demonstrate that the proposed SITITO converter has a peak efficiency of 84.4%. When compared with the conventional constant peak-inductor-current control, an efficiency improvement of 11% is obtained via the proposed APIC control.
TL;DR: This paper presents transformerless high gain boost and buck-boost DC-DC converters with extendable switched capacitor cells (SCs), suitable for applications operating at high voltage, above 300 V, to justify the utility of converters for stand-alone PV systems.