Analysis,design and implementation of a high‐voltage gain DC‐DC converter

An interleaved DC‐DC converter with soft switching technique is presented. There are two converter modules in the adopted circuit to share the load power. Since the interleaved pulse‐width modulation (PWM) is adopted to control two circuit modules, the ripple currents at input and output sides are naturally reduced. Therefore the input and output capacitances can be reduced. In each circuit module, a conventional boost converter and a voltage doubler configuration with a coupled inductor are connected in series at the output side to achieve high step‐up voltage conversion ratio. Active snubber connected in parallel with boost inductor is adopted to limit voltage stress on active switch and to release the energy stored in the leakage and magnetizing inductances. Since asymmetrical PWM is used to control active switches, the leakage inductance and output capacitance of active switches are resonant in the transition interval. Thus, both active switches can be turned on at zero voltage switching. The resonant inductance and output capacitances at the secondary side of transformer are resonant to achieve zero current switching turn‐off for rectifier diodes. Therefore, the reverse recovery losses of fast recovery diodes are reduced. Finally, experiments based on a laboratory prototype rated at 400 W are presented to verify the effectiveness of the proposed converter. Copyright © 2012 John Wiley & Sons, Ltd.     

A high step‐up half‐bridge DC/DC converter with a special coupled inductor for input current ripple cancelation and extended voltage doubler circuit for power conditioning of fuel cell systems

This paper presents a high step‐up soft switched dc–dc converter having the feature of current ripple cancelation in the input stage that is specialized for power conditioning of fuel cell systems. The converter comprises a special half‐bridge converter and a rectifier stage based upon the voltage‐doubler circuit, in which the coupled‐inductor technology is amalgamated with switched‐capacitor circuit. The input current with no ripple is the principal characteristics of this topology that is achieved by utilizing a small coupled inductor. In addition, the low clamped voltage stress across both power switches and output diodes is another advantage of the proposed converter, which allows employing the metal–oxide–semiconductor field‐effect transistors with minuscule on‐state resistance and diodes with lower forward voltage‐drop, and thereby, the semiconductors' conduction losses diminish considerably. The inherent nature of this topology handles the switching scheme based on the asymmetrical pulse width modulation in order for switches to establish the zero voltage switching, leading to lower switching losses. Besides, because of the absence of the reverse‐recovery phenomenon, all diodes turn off with zero current switching. At last, a 250‐W laboratory prototype with the input voltage 24 V and output voltage 380 V is implemented to verify the especial features of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.     

An interleaved high step‐up DC‐DC converter with double boost paths

This paper proposed a novel high step‐up converter with double boost paths. The circuit uses two switches and one double‐path voltage multiplier cell to own the double boost and interleaved effects simultaneously. The voltage gain ratio of the proposed DC‐DC converter can be three times the ratio of the conventional boost converter such that the voltage stress of the switch can be lower. The high step‐up performance is in accordance with only one double‐path voltage multiplier cell. Therefore, the number of diodes and capacitors in the proposed converter can be reduced. Furthermore, the interleaved property of the proposed circuit can reduce the losses in the rectifier diode and capacitor. The prototype circuit with 24‐V input voltage, 250‐V output voltage, and 150‐W output power is experimentally realized to verify the validity and effectiveness of the proposed converter. Copyright © 2014 John Wiley & Sons, Ltd.     

Non‐isolated large step‐down voltage conversion ratio converter with non‐pulsating output current

A non‐isolated dual half‐bridge large step‐down voltage conversion ratio converter with non‐pulsating output current, utilizing one coupled inductor, one energy‐transferring capacitor, and one output inductor, is presented herein. The coupled inductor is connected between the input voltage and the output inductor and plays a role to step down the input voltage. Furthermore, the output inductor is used not only to further step down the voltage but also to provide a non‐pulsating output current. Moreover, the proposed converter can achieve zero‐voltage switching. In this study, detailed theoretical deductions and some experimental results of a prototype with 48 V input voltage, 3.3 V output voltage, and 10 A output current are provided to demonstrate the feasibility and effectiveness of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd.     

Isolated high voltage‐boosting converter derived from forward converter

A novel isolated high voltage‐boosting converter, derived from the traditional forward converter, is presented in this paper. As compared with the traditional forward converter, the demagnetizing winding of the transformer in the proposed converter is used not only to demagnetize but also to improve the voltage conversion ratio. Therefore, the duty cycle is not limited, and the utilization of the transformer, also called coupled inductor, can be increased also. Furthermore, the proposed converter maintains the advantage of possessing a non‐pulsating output current, leading to a small output voltage ripple. Moreover, by applying one additional voltage‐boosting winding to the transformer, the voltage conversion ratio can be significantly improved. In addition, an active clamp circuit is employed in the proposed converter to reduce the voltage stress of the main switch, caused by the leakage inductance in the transformer, and the switches can achieve zero‐voltage switching. Finally, the analysis of operating principles, choice of the turns, turns ratio, core size, and each wire size of the coupled inductor are described in detail, and the experimental results with a prototype with 12‐V input voltage, 100‐V output voltage, and 100‐W output power are provided to verify the feasibility and effectiveness of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd.     

A single‐switch cascaded high step‐up voltage converter with 95% maximum efficiency for renewable energy systems

This paper proposes a novel nonisolated single‐switch cascaded high step‐up converter. The converter consists of coupled inductors, a clamp circuit, and cascaded capacitors to achieve high step‐up voltage output. Only one switch is used in the proposed converter; the switch can reduce cost efficiently and simplify the control of the proposed converter. The converter also possesses an energy‐recycle mechanism for recycling the spike energy of a leakage inductor. In addition, a clamp circuit is used to reduce voltage‐stress across the switch, and a cascaded design is used to reduce voltage‐stress across diodes and output capacitor. Thus, the proposed converter can select a low‐voltage stress switch for reducing circuit loss and improving the efficiency of the converter. Finally, in this study, a 400‐W nonisolated cascaded high step‐up converter was implemented, of which the input and output voltages are 48 and 400 V, respectively. A microcontroller dsPIC30F4011 was used to control the converter and verify system effects and feasibility. The maximum efficiency of the proposed converter is 95% and the efficiency under a full load is 93%. Copyright © 2015 John Wiley & Sons, Ltd.     

Analysis and design of an active‐clamping zero‐voltage‐switching isolated inverse‐SEPIC converter

This paper presents an active‐clamping zero‐voltage‐switching (ZVS) isolated inverse‐SEPIC converter. The high voltage spikes when turning off the switches are eliminated. The energies stored in the parasitic elements can be recycled to achieve the ZVS of switches. Therefore, the conversion efficiency increases substantially, yet with a reduced circuit cost. Detailed analysis and design of the proposed topology are described. Experimental results are recorded for a prototype converter with a DC input voltage ranging from 130 to 180 V, an output voltage of 12 V and a rated output power of 120 W, operating at a switching frequency of 65 kHz. The average active‐mode efficiency is above 88%. Copyright © 2010 John Wiley & Sons, Ltd.     

Design of a ZVS PWM DC–DC converter for high gain applications

In this paper, a pulse width modulation DC‐DC converter with high step‐up voltage gain is proposed. The proposed converter achieves high step‐up voltage gain with appropriate duty ratio, coupled inductor, and voltage multiplier technique. The energy stored in the leakage inductor of the coupled inductor can be recycled in the proposed converter. Moreover, because both main and auxiliary switches can be turned on with zero‐voltage switching, switching loss can be reduced by soft‐switching technique. So the overall conversion efficiency is improved significantly. The theoretical steady‐state analyses and the operating principles of the proposed converter are discussed in detail for both continuous conduction mode and discontinuous conduction mode. Finally, a laboratory prototype circuit of the proposed converter is implemented to verify the performance of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd.     

An extensible two‐phase high voltage‐boosting converter with automatic current balance

In this study, an extensible 2‐phase interleaved high step‐up converter with automatic current balance is presented. This converter uses coupled inductors and energy‐transferring capacitors to improve the voltage gain of the traditional 2‐phase interleaved boost converter as well as employs these energy transferring capacitors to do automatic current balance. Furthermore, the voltage gain can be enhanced not only by adjusting the turns ratio but also by increasing the numbers of phases, diodes, and energy‐transferring capacitors. Therefore, it can be used in high input current and high step‐up voltage applications. In this paper, the basic operating principles of the proposed converter are described and analyzed, and finally, its effectiveness is demonstrated by experiment. In addition, the field‐programmable gate array, named EP13T100C8N and manufactured by Altera Co, is used as a control kernel, and an experimental prototype, with input voltage of 12 V, output voltage of 200 V, and rated output power of 200 W, is given to provide the effectiveness of the proposed converter.     

A single‐stage LED streetlight driver with PFC and digital PWM dimming capability

This paper proposes a single‐stage light‐emitting diode (LED) driver that offers power‐factor correction and digital pulse–width modulation (PWM) dimming capability for streetlight applications. The presented LED streetlight driver integrates an alternating current–direct current (AC–DC) converter with coupled inductors and a half‐bridge‐type LLC DC–DC resonant converter into a single‐stage circuit topology. The sub‐circuit of the AC–DC converter with coupled inductors is designed to be operated in discontinuous‐conduction mode for achieving input‐current shaping. Zero‐voltage switching of two active power switches and zero‐current switching of two output‐rectifier diodes in the presented LED driver decrease the switching losses; thus, the circuit efficiency is increased. A prototype driver for powering a 144‐W‐rated LED streetlight module with input utility‐line voltages ranging from 100 to 120 V is implemented and tested. The proposed streetlight driver features cost‐effectiveness, high circuit efficiency, high power factor, low levels of input‐current harmonics, and a digital PWM dimming capability ranging from 20% to 100% output rated LED power, which is fulfilled by a micro‐controller. Satisfying experimental results, including dimming tests, verify the feasibility of the proposed LED streetlight driver. Copyright © 2016 John Wiley & Sons, Ltd.     

A non‐isolated high step‐up DC‐DC converter with integrated 3 winding coupled inductor and reduced switch voltage stress

In this paper, a non‐isolated high step‐up dc‐dc converter based on coupled inductor is proposed. The proposed converter can be used in renewable energy applications. In suggested converter, the high voltage is achieved using 3‐winding coupled inductor, which leads to low voltage rate of the switch. A clamp circuit is used to recycle the leakage inductance energy. Also, the clamp circuit prevents the creation of voltage spikes on semiconductor devices and causes the voltage stress of elements are limited to less than the output voltage. The presented theoretical analyses show that the operation of suggested converter in continuous conduction mode needs to small magnetic inductor. Therefore, the size of coupled inductor's core is reduced, and so the size and cost of presented converter will be decreased. Analysis of the proposed converter is provided with laboratory results to verify its performance.     

A high‐voltage gain nonisolated noncoupled inductor based multi‐input DC‐DC topology with reduced number of components for renewable energy systems

This paper proposes a modular nonisolated noncoupled inductor‐based high‐voltage gain multi‐input DC‐DC converter. Despite the high‐voltage gain of the proposed topology, the average of normalized voltage stress (NVS) on its switches/diodes is low. This property leads to less loss and cost of switches/diodes. Using the same number of components, the proposed topology produces higher voltage gains, in comparison with recently presented high step‐up topologies. Also, the proposed topology utilizes less number of components (capacitors, inductors, diodes, and switches) for producing a desired voltage gain, which can reduce the size, mass, cost, complexity, and losses and improve the efficiency of converter. Continuous current of input sources is another main advantage of the proposed topology. All the abovementioned characteristics have made the proposed topology very suitable for renewable energy systems (or even hybrid/electric vehicles). Design considerations of the proposed topology have also been presented. For better evaluation, the proposed topology has been compared with some of recently presented high step‐up structures, from viewpoints of producible voltage gain, number of components, and normalized voltage stress (NVS) on switches/diodes. Finally, the prototype of 2‐input version has been experimentally implemented. Obtained experimental results confirm appropriate performance of the proposed topology.     

Hybrid DC–DC converter with high efficiency,wide ZVS range,and less output inductance

In this paper, a new soft switching direct current (DC)–DC converter with low circulating current, wide zero voltage switching range, and reduced output inductor is presented for electric vehicle or plug‐in hybrid electric vehicle battery charger application. The proposed high‐frequency link DC–DC converter includes two resonant circuits and one full‐bridge phase‐shift pulse‐width modulation circuit with shared power switches in leading and lagging legs. Series resonant converters are operated at fixed switching frequency to extend the zero voltage switching range of power switches. Passive snubber circuit using one clamp capacitor and two rectifier diodes at the secondary side is adopted to reduce the primary current of full‐bridge converter to zero during the freewheeling interval. Hence, the circulating current on the primary side is eliminated in the proposed converter. In the same time, the voltage across the output inductor is also decreased so that the output inductance can be reduced compared with the output inductance in conventional full‐bridge converter. Finally, experiments are presented for a 1.33‐kW prototype circuit converting 380 V input to an output voltage of 300–420 V/3.5 A for battery charger applications. Copyright © 2015 John Wiley & Sons, Ltd.     

适合大电流输入高压输出的软开关直流变换器

首先,提出了一种LLC谐振的软开关直流变换器,其中原边包含4个开关管、2个变压器绕组和1个耦合电容,并利用耦合电容构造了2个变压器绕组同时工作的回路,实现了两者的均流;副边包含2个二极管和2个谐振电容,构成了一个谐振式倍压电路;然后,利用变压器漏感、励磁电感和谐振电容产生LLC谐振来传递能量,各开关管能实现零电流开通,二极管零电流关断,且承受的反向电压为输出电压,关断损耗也很小;最后,分析了电路各阶段的工作原理,推导了电压增益特性,并设计了一款22~28 V输入、360 V输出、额定负载800 W的样机。实验测试结果证明,电路最高效率达到93.5%,同时也证明了电路的有效性。     

A novel active‐clamp zero‐voltage‐switching buck‐boost converter

An active‐clamp zero‐voltage‐switching (ZVS) buck‐boost converter is proposed in this paper to improve the performance of converter in light load condition. By employing a small resonant inductor, the ZVS range of switches could be adjusted to very light load condition. Moreover, 2 clamping capacitors are added in the converter to eliminate the voltage spike on the switches during transition. The operating principle of the proposed converter is analyzed, and the optimal design guide for full range ZVS is also provided. A 60‐W output prototype is experimentally built and tested in laboratory to verify the feasibility of proposed converter. The measured results show the critical ZVS operation of power switches at 1 and 0.7‐W output power for buck and boost mode, respectively. The peak conversion efficiency is up to 92.3%.     

A soft‐switching high step‐up DC‐DC converter with a single magnetic component

A soft‐switching high step‐up DC‐DC converter with a single magnetic component is presented in this paper. The proposed converter can provide high voltage gain with a relatively low turn ratio of a transformer. Voltage doubler structure is selected for the output stage. Due to this structure, the voltage gain can be increased, and the voltage stresses of output diodes are clamped as the output voltage. Moreover, the output diode currents are controlled by a leakage inductance of a transformer, and the reverse‐recovery loss of the output diodes is significantly reduced. Two power switches in the proposed converter can operate with soft‐switching due to the reflected secondary current. The voltages across the power switches are confined to the clamping capacitor voltage. Steady‐state analysis, simulation, and experimental results for the proposed converter are presented to validate the feasibility and the performance of the proposed converter. Copyright © 2012 John Wiley & Sons, Ltd.     

Analysis and implementation of a high‐efficiency zero‐voltage‐zero‐current‐switching DC–DC converter

A high‐efficiency zero‐voltage‐zero‐current‐switching DC–DC converter with ripple‐free input current is presented. In the presented converter, the ripple‐free boost cell provides ripple‐free input current and zero‐voltage switching of power switches. The resonant flyback cell provides zero‐voltage switching of power switches and zero‐current switching of the output diode. Also, it has a simple output stage. The proposed converter achieves high efficiency because of the reduction of the switching losses of the power switches and the output diode. Detailed analysis and design of the proposed converter are carried out. A prototype of the proposed converter is developed and its experimental results are presented for validation. Copyright © 2011 John Wiley & Sons, Ltd.     

High‐efficiency current‐doubler rectifier with low output current ripple and high step‐down voltage ratio

This paper presents a current‐doubler rectifier with low output current ripple and high step‐down voltage ratio. In the proposed rectifier, two extra inductors are introduced to extend the duty ratio of the switches, which in turn reduces the peak current through the isolation transformer as well as the output current ripple; two extra diodes are used to provide discharge paths for the two extra inductors. To highlight the merits of the proposed rectifier, its performance indexes, such as voltage gain function, secondary winding peak current of the isolation transformer, and output current ripple, are analyzed and compared with the conventional current‐doubler rectifier. In this paper, a zero‐voltage‐switching phase‐shift full‐bridge converter with the proposed rectifier with an input voltage of 400 V, output voltage of 12 V, and full load power of 500 W has been implemented and verified, and experimental results have shown that 90% conversion efficiency could be achieved at full load. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

ZVS DC/DC converter with series half‐bridge legs for high voltage application

This paper presents a new DC/DC converter with series half‐bridge legs for high voltage application. Two half‐bridge legs connected in series and two split capacitors are used in the proposed circuit to limit the voltage stress of each active switch at one‐half of input voltage. Thus, active switches with low voltage stress can be used at high DC bus application. In the proposed converter, two circuit modules are operated with an interleaved pulse‐width modulation scheme to reduce the input and output ripple currents and to achieve load current sharing. In each circuit module, two resonant tanks are operated with phase‐shift one‐half of switching cycle such that the frequency of the input current is twice the frequency of the resonant inductor current. Based on the resonant behavior, all MOSFETs are turned on at zero voltage switching with the wide ranges of input voltage and load conditions. The rectifier diodes can be turned off at zero current switching if the switching frequency is less than the series resonant frequency. Thus, the switching losses on power semiconductors are reduced. The proposed converter can be applied for high input voltage applications such as three‐phase 380‐V utility system. Finally, experiments based on a laboratory prototype with 960‐W rated power are provided to demonstrate the performance of proposed converter. Copyright © 2011 John Wiley & Sons, Ltd.     

Three‐stage multiphase‐switched‐capacitor boost DC‐AC inverter

A closed‐loop scheme of a three‐stage multiphase‐switched‐capacitor boost DC‐AC inverter (MPSCI) is proposed by combining the multiphase operation and sinusoidal‐pulse‐width‐modulation (SPWM) control for low‐power step‐up DC‐AC conversion and regulation. In this MPSCI, the power unit contains two parts: MPSC booster (front) and H‐bridge (rear). The MPSC booster is suggested for an inductor‐less step‐up DC‐DC conversion, where three voltage doublers in series are controlled with multiphase operation for boosting voltage gain up to 2³ = 8 at most. The H‐bridge is employed for DC‐AC inversion, where four solid‐state switches in H‐connection are controlled with SPWM to obtain a sinusoidal AC output. In addition, SPWM is adopted for enhancing output regulation not only to compensate the dynamic error, but also to reinforce robustness to source/loading variation. The relevant theoretical analysis and design include: MPSCI model, steady‐state/dynamic analysis, voltage conversion ratio, power efficiency, stability, capacitance selection, total harmonic distortion (THD), output filter, and closed‐loop control design. Finally, the closed‐loop MPSCI is simulated, and the hardware circuit is implemented and tested. All the results are illustrated to show the efficacy of the proposed scheme. Copyright © 2011 John Wiley & Sons, Ltd.