Showing papers on "Boost converter published in 2013"

Fundamentals of Power Electronics

Abstract: This chapter gives a description and overview of power electronic technologies including a description of the fundamental systems that are the building blocks of power electronic systems. Technologies that are described include: power semiconductor switching devices, converter circuits that process energy from one DC level to another DC level, converters that produce variable frequency from DC sources, principles of rectifying AC input voltage in uncontrolled DC output voltage and their extension to controlled rectifiers, converters that convert to AC from DC (inverters) or from AC with fixed or variable output frequency (AC controllers, DC–DC–AC converters, matrix converters, or cycloconverters). The chapter also covers control of power converters with focus on pulse width modulation (PWM) control techniques.

Design and Implementation of a Highly Efficient Three-Level T-Type Converter for Low-Voltage Applications

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.

RF Energy Harvesting and Transport for Wireless Sensor Network Applications: Principles and Requirements

Abstract: This paper presents an overview of principles and requirements for powering wireless sensors by radio-frequency (RF) energy harvesting or transport. The feasibility of harvesting is discussed, leading to the conclusion that RF energy transport is preferred for powering small sized sensors. These sensors are foreseen in future Smart Buildings. Transmitting in the ISM frequency bands, respecting the transmit power limits ensures that the International Commission on Non-Ionizing Radiation Protection (ICNIRP) exposure limits are not exceeded. With the transmit side limitations being explored, the propagation channel is next discussed, leading to the observation that a better than free-space attenuation may be achieved in indoors line-of-sight environments. Then, the components of the rectifying antenna (rectenna) are being discussed: rectifier, dc-dc boost converter, and antenna. The power efficiencies of all these rectenna subcomponents are being analyzed and finally some examples are shown. To make RF energy transport a feasible powering technology for low-power sensors, a number of precautions need to be taken. The propagation channel characteristics need to be taken into account by creating an appropriate transmit antenna radiation pattern. All subcomponents of the rectenna need to be impedance matched, and the power transfer efficiencies of the rectifier and the boost converter need to be optimized.

Design Methodology of Bidirectional CLLC Resonant Converter for High-Frequency Isolation of DC Distribution Systems

Abstract: A bidirectional full-bridge CLLC resonant converter using a new symmetric LLC-type resonant network is proposed for a low-voltage direct current power distribution system. This converter can operate under high power conversion efficiency because the symmetric LLC resonant network has zero-voltage switching capability for primary power switches and soft commutation capability for output rectifiers. In addition, the proposed topology does not require any snubber circuits to reduce the voltage stress of the switching devices because the switch voltage of the primary and secondary power stage is confined by the input and output voltage, respectively. In addition, the power conversion efficiency of any directions is exactly same as each other. Using digital control schemes, a 5-kW prototype converter designed for a high-frequency galvanic isolation of 380-V dc buses was developed with a commercial digital signal processor. Intelligent digital control algorithms are also proposed to regulate output voltage and to control bidirectional power conversions. Using the prototype converter, experimental results were obtained to verify the performance of the proposed topology and control algorithms. The converter could softly change the power flow directions and its maximum power conversion efficiency was 97.8% during the bidirectional operation.

An LLC Resonant DC–DC Converter for Wide Output Voltage Range Battery Charging Applications

Abstract: In this paper, resonant tank design procedure and practical design considerations are presented for a high performance LLC multiresonant dc-dc converter in a two-stage smart battery charger for neighborhood electric vehicle applications. The multiresonant converter has been analyzed and its performance characteristics are presented. It eliminates both low- and high-frequency current ripple on the battery, thus maximizing battery life without penalizing the volume of the charger. Simulation and experimental results are presented for a prototype unit converting 390 V from the input dc link to an output voltage range of 48-72 V dc at 650 W. The prototype achieves a peak efficiency of 96%.

The Multilevel Modular DC Converter

Abstract: The modular multilevel converter (M2C) has become an increasingly important topology in medium- and high-voltage applications. A limitation is that it relies on positive and negative half-cycles of the ac output voltage waveform to achieve charge balance on the submodule capacitors. To overcome this constraint a secondary power loop is introduced that exchanges power with the primary power loops at the input and output. Power is exchanged between the primary and secondary loops by using the principle of orthogonality of power flow at different frequencies. Two modular multilevel topologies are proposed to step up or step down dc in medium- and high-voltage dc applications: the tuned filter modular multilevel dc converter and the push-pull modular multilevel dc converter. An analytical simulation of the latter converter is presented to explain the operation.

A High Step-Up Converter With a Voltage Multiplier Module for a Photovoltaic System

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%.

Novel High Step-Up DC–DC Converter for Distributed Generation System

Abstract: In this paper, a novel high step-up dc-dc converter for distributed generation systems is proposed. The concept is to utilize two capacitors and one coupled inductor. The two capacitors are charged in parallel during the switch-off period and are discharged in series during the switch-on period by the energy stored in the coupled inductor to achieve a high step-up voltage gain. In addition, the leakage-inductor energy of the coupled inductor is recycled with a passive clamp circuit. Thus, the voltage stress on the main switch is reduced. The switch with low resistance RDS(ON) can be adopted to reduce the conduction loss. In addition, the reverse-recovery problem of the diodes is alleviated, and thus, the efficiency can be further improved. The operating principle and steady-state analyses are discussed in detail. Finally, a prototype circuit with 24-V input voltage, 400-V output voltage, and 200-W output power is implemented in the laboratory to verify the performance of the proposed converter.

A High Step-Up Three-Port DC–DC Converter for Stand-Alone PV/Battery Power Systems

Abstract: A three-port dc–dc converter integrating photovoltaic (PV) and battery power for high step-up applications is proposed in this paper. The topology includes five power switches, two coupled inductors, and two active-clamp circuits. The coupled inductors are used to achieve high step-up voltage gain and to reduce the voltage stress of input side switches. Two sets of active-clamp circuits are used to recycle the energy stored in the leakage inductors and to improve the system efficiency. The operation mode does not need to be changed when a transition between charging and discharging occurs. Moreover, tracking maximum power point of the PV source and regulating the output voltage can be operated simultaneously during charging/discharging transitions. As long as the sun irradiation level is not too low, the maximum power point tracking (MPPT) algorithm will be disabled only when the battery charging voltage is too high. Therefore, the control scheme of the proposed converter provides maximum utilization of PV power most of the time. As a result, the proposed converter has merits of high boosting level, reduced number of devices, and simple control strategy. Experimental results of a 200-W laboratory prototype are presented to verify the performance of the proposed three-port converter.

PWM-Based Adaptive Sliding-Mode Control for Boost DC–DC Converters

Abstract: In this paper, a robust adaptive sliding-mode controller is designed for a boost converter with an unknown resistive load and external input voltage. Adaptation laws are designed using state observers. The closed-loop system for the boost converter is shown to be asymptotically stable. Finally, the robustness of the adaptive controller to input voltage and load uncertainties and variations is tested experimentally.

Sliding mode control of DC/DC converters

Abstract: Sliding mode control algorithms for buck and boost power converters are surveyed in the paper. Current and voltage controls are demonstrated for the both cases. It is shown, that direct voltage control for a boost converter results in unstable zero dynamics. Chattering suppression based on harmonic cancellation principle along with switching frequency control is demonstrated.

Novel Isolated High-Step-Up DC–DC Converter With Voltage Lift

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%.

Cascade Cockcroft–Walton Voltage Multiplier Applied to Transformerless High Step-Up DC–DC Converter

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.

An Integrated Three-Port Bidirectional DC–DC Converter for PV Application on a DC Distribution System

Abstract: In this paper, an integrated three-port bidirectional dc-dc converter for a dc distribution system is presented. One port of the low-voltage side of the proposed converter is chosen as a current source port which fits for photovoltaic (PV) panels with wide voltage variation. In addition, the interleaved structure of the current source port can provide the desired small current ripple to benefit the PV panel to achieve the maximum power point tracking (MPPT). Another port of the low-voltage side is chosen as a voltage source port interfaced with battery that has small voltage variation; therefore, the PV panel and energy storage element can be integrated by using one converter topology. The voltage port on the high-voltage side will be connected to the dc distribution bus. A high-frequency transformer of the proposed converter not only provides galvanic isolation between energy sources and high voltage dc bus, but also helps to remove the leakage current resulted from PV panels. The MPPT and power flow regulations are realized by duty cycle control and phase-shift angle control, respectively. Different from the single-phase dual-half-bridge converter, the power flow between the low-voltage side and high-voltage side is only related to the phase-shift angle in a large operation area. The system operation modes under different conditions are analyzed and the zero-voltage switching can be guaranteed in the PV application even when the dc-link voltage varies. Finally, system simulation and experimental results on a 3-kW hardware prototype are presented to verify the proposed technology.

50 mV-Input Batteryless Boost Converter for Thermal Energy Harvesting

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.

A Boost Converter With Capacitor Multiplier and Coupled Inductor for AC Module Applications

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%.

Analysis of Power Sharing and Voltage Deviations in Droop-Controlled DC Grids

Abstract: This paper analyzes the influence of the converter droop settings and the dc grid network topology on the power sharing in a dc grid based on voltage source converter high voltage direct current technology. The paper presents an analytical tool to study the effect of the droop control settings on the steady-state voltage deviations and power sharing after a converter outage, thereby accounting for dc grid behavior. Furthermore, an optimization algorithm is developed, taking into account two conflicting optimization criteria. The simulation results show that, when selecting appropriate values for the converter gains, a tradeoff has to be made between the power sharing and the maximum allowable dc voltage deviation after an outage.

High-Efficiency Isolated Bidirectional AC–DC Converter for a DC Distribution System

Abstract: A high-efficiency isolated bidirectional ac–dc converter is proposed for a 380-V dc power distribution system to control bidirectional power flows and to improve its power conversion efficiency. To reduce the switches’ losses of the proposed nonisolated full-bridge ac–dc rectifier using an unipolar switching method, switching devices employ insulated-gate bipolar transistors, MOSFETs, and silicon carbide diodes. Using the analysis of the rectifier’s operating modes, each switching device can be selected by considering switch stresses. A simple and intuitive frequency detection method for a single-phase synchronous reference frame-phase-locked loop (SRF-PLL) is also proposed using a filter compensator, a fast period detector, and a finite impulse response filter to improve the robustness and accuracy of PLL performance under fundamental frequency variations. In addition, design and control methodology of the bidirectional full-bridge CLLC resonant converter is suggested for the galvanic isolation of the dc distribution system. A dead-band control algorithm for the bidirectional dc–dc converter is developed to smoothly change power conversion directions only using output voltage information. Experimental results will verify the performance of the proposed methods using a 5-kW prototype converter.

Open- and Short-Circuit Switch Fault Diagnosis for Nonisolated DC–DC Converters Using Field Programmable Gate Array

Abstract: Fault detection (FD) in power electronic converters is necessary in embedded and safety critical applications to prevent further damage. Fast FD is a mandatory step in order to make a suitable response to a fault in one of the semiconductor devices. The aim of this study is to present a fast yet robust method for fault diagnosis in nonisolated dc–dc converters. FD is based on time and current criteria which observe the slope of the inductor current over the time. It is realized by using a hybrid structure via coordinated operation of two FD subsystems that work in parallel. No additional sensors, which increase system cost and reduce reliability, are required for this detection method. For validation, computer simulations are first carried out. The proposed detection scheme is validated on a boost converter. Effects of input disturbances and the closed-loop control are also considered. In the experimental setup, a field programmable gate array digital target is used for the implementation of the proposed method, to perform a very fast switch FD. Results show that, with the presented method, FD is robust and can be done in a few microseconds.

Fault-Tolerant Strategy for a Photovoltaic DC--DC Converter

Abstract: The photovoltaic (PV) technology has a small impact on the environment and is suitable for a wide range of applications. The main barrier for a more extensive implementation has been the reliability, mainly related to the power converters. According to this consideration, this paper presents an open-circuit fault diagnosis and fault-tolerant scheme for a three-level boost converter in a PV power system using batteries as storage devices. The fault diagnostic method takes advantage only of the control variables used for maximum power point tracking and output dc-link capacitor voltage balance. The fault-tolerant strategy requires only a few components added to the original three-level boost converter, so that, under an open-circuit power switch fault, it can be partly reconfigured into a two-level boost converter ensuring battery energy supply. Experimental results verify the proposed fault diagnostic method and reconfiguration for fault-tolerant operation.

Hybrid-Switching Full-Bridge DC–DC Converter With Minimal Voltage Stress of Bridge Rectifier, Reduced Circulating Losses, and Filter Requirement for Electric Vehicle Battery Chargers

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.

Modeling and Control Design of the Interleaved Double Dual Boost Converter

Abstract: The interleaved double dual boost (IDDB) is a non-isolated step-up dc-dc converter capable of high voltage gain and suitable to high-power applications. In this paper, the modeling and control design of this converter, valid for an arbitrary number of phases, is presented. The developed approach is then applied to a six-phase IDDB, and experimental results are obtained with a prototype operating with an input voltage of 60 V, an output voltage of 360 V, and with a nominal output power of 2.2 kW. The applications of this converter include electrical vehicles and renewable energy conversion.

Study of a non-isolated bidirectional DC–DC converter

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.

A Multiple-Input Multiple-Output DC–DC Converter

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.

High Step-Up Soft-Switched Converters Using Voltage Multiplier Cells

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.

High Step-Up DC/DC Topology and MPPT Algorithm for Use With a Thermoelectric Generator

Abstract: A thermoelectric generator (TEG) is a low-voltage high-current dc power source with a linear V-I characteristic, and therefore, it is desirable to create a power converter with a topology and control method suited to these attributes. Due to the TEG's low voltage, a topology that produces a high step-up gain for a moderate duty cycle is required to reduce voltage and current stresses within the converter. The linear V-I characteristic produces a P-I characteristic with a flatter peak relative to other sources. This can result in large operating point variations while performing maximum power point tracking (MPPT); thus, an algorithm with low steady-state error is desired. This paper presents a novel high step-up dc/dc converter topology operating with a fractional short-circuit MPPT algorithm for use with a 4.2-V, 3.4-A (for matched load at ΔT = 270 °C) TEG module and a converter output of 180 V. Compared to existing high step-up dc/dc converters, the proposed converter achieves higher gain with similar component count. Experimental results are reported to confirm the converter analysis and better performance of the short-circuit MPPT algorithm over the perturb and observe algorithm.

A New Hybrid Modular Multilevel Converter for Grid Connection of Large Wind Turbines

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

Capacitor Voltage Regulation in Single-DC-Source Cascaded H-Bridge Multilevel Converters Using Phase-Shift Modulation

Abstract: Cascaded H-bridge multilevel power electronic converters generally require several dc sources. An alternative option is to replace all the separate dc sources feeding the H-bridge cells with capacitors, leaving only one H-bridge cell with a real dc voltage source. This will yield a cost-effective converter. However, the required capacitor voltage balancing is challenging. In this paper, using the phase-shift modulation approach, a new control method for cascaded H-bridge multilevel converters fed with only one independent dc source is presented. The proposed method has a wide voltage regulation range for the replacement capacitors in the H-bridge cells. Experimental and simulation results support the proposed control method.

A DC–DC Boost Converter With Variation-Tolerant MPPT Technique and Efficient ZCS Circuit for Thermoelectric Energy Harvesting Applications

Abstract: This paper presents a dc-dc boost converter with the maximum power point tracking (MPPT) technique for thermoelectric energy harvesting applications. The technique realizes variation tolerance by adjusting the switching frequency of the converter. A finely controlled zero-current switching (ZCS) scheme together with the accurate MPPT technique enhances the overall efficiency of the converter because of an optimal turn-on time generated by a one-shot pulse generator that is proposed. Moreover, the ZCS technique can deal with low- and high-temperature differences applied to the thermoelectric generator. This allows a wider range of conversion ratios compared to those of conventional converters used for thermal energy harvesting. Experimentally, the converter implemented in a 0.35-μm BCDMOS process had a peak efficiency of 72% at the input voltage of 500 mV while supplying a 5.62-V output.