Step‐up/step‐down DC‐DC converter with near zero input/output current ripples

A novel single switch two diode wide conversion ratio step down/up converter is presented. The proposed converter is derived from the conventional single‐ended primary inductor converter (SEPIC) topology, and it can operate as a capacitor‐diode voltage multiplier, which offers simple structure, reduced electromagnetic interference (EMI), and reduced semiconductor voltage stress. The main advantages of the proposed converter are the continuous input/output current, higher voltage conversion ratio, and near‐zero input and output current ripples compared with the conventional SEPIC converter. The absence of both a transformer and an extreme duty cycle permits the proposed converter to operate at high switching frequencies. Hence, the overall advantages will be: higher efficiency, reduced size and weight, simpler structure and control. The theoretical analysis results obtained with the proposed structure are compared with the conventional SEPIC topology. The performance of the proposed converter is verified through computer simulations and experimental results. Copyright © 2012 John Wiley & Sons, Ltd.     

具有低输入电流纹波带耦合电感的双向DC-DC变换器

针对燃料电池发电系统输出电压低和输入电流纹波大的问题,本文设计了一种新型带耦合电感的双向DC-DC变换器。该变换器利用超级电容器减少电流纹波对燃料电池的冲击从而提高燃料电池的发电效率,同时通过改变占空比和耦合电感的匝数比来提高输出电压增益。在Matlab/Simulink软件中创建仿真模型,采用平均电流模式搭建控制电路,并详细地分析升压和降压模式下变换器的开关状态与工作特性。仿真结果为：变换器的输入电流纹波约为1%,在耦合电感变比为1时升压电压增益最高为16。结果表明本文所提变换器可以在满足燃料电池发电系统对低频电流纹波的要求同时实现高电压增益,验证了所提出拓扑的可行性。     

A new non‐isolated free ripple input current bidirectional DC‐DC converter with capability of zero voltage switching

In this paper, a new nonisolated free ripple input current bidirectional dc‐dc converter with capability of zero voltage switching (ZVS) is proposed. The free ripple input current condition at low voltage side is achieved by using third winding of a coupled inductor and a capacitor for the whole range of duty cycles. In the proposed structure, the voltage conversion ratio can be more increased by adding the turn ratio of the second winding of the coupled inductor for the whole range of duty cycles. By adjusting the value of an auxiliary inductor in the topology of the converter, according to the power, the ZVS operation of the implemented 2 switches can be achieved throughout the whole power range. The mentioned features of proposed converter are validated theoretically for both boost and buck operations. In this paper, the proposed converter is analyzed for all operating modes. Moreover, all equations of the voltages and currents of all components, voltage conversion ratio, the required conditions for ZVS operation of switches, and also required conditions for canceling input current ripple at low voltage side are obtained. Finally, the performance of the proposed converter is reconfirmed through experimental and EMTDC/PSCAD simulation results.     

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.     

Soft switching DC/DC converter with high voltage gain and less current ripple

A new soft switching three‐level converter with two DC/DC circuits in the primary side and current double rectifiers in the secondary side is presented to realize the zero‐voltage switching operation, reduce the transformer secondary winding turns and the output current ripple, and lessen the voltage rating of rectifier diodes. Two DC/DC pulse‐width modulation circuits sharing same power switches with interleaved half switching cycle are adopted in the proposed converter to reduce the current rating of transformer primary windings. Two inductors and four diodes are adopted in the secondary side to achieve current double rectifier, reduce output ripple current, and decrease the transformer secondary winding turns. Based on the pulse‐width modulation scheme, the power switchers can be turned on at zero‐voltage switching operation. Laboratory experiments with a 1.44 kW prototype are provided to verify the theoretical analysis. Copyright © 2016 John Wiley & Sons, Ltd.     

Output current ripple reduction of LED driver using ceramic‐capacitor‐input circuit and buck‐boost converter

This article proposes an LED driver that consists of a ceramic‐capacitor‐input rectifier and a buck‐boost converter. The LED driver has an advantage of long life because it does not contain any electrolytic capacitors. However, the issue with electrolytic capacitor‐less LED driver is that the ripple of the smoothed voltage becomes large due to insufficient capacitance of the smoothing capacitor. The proposed method, which uses the discontinuous current mode of a buck‐boost converter, reduces the output current ripple under such conditions. Experimental results using a 5.7 W LED driver prototype demonstrate that the proposed method reduces the output current ripple and that the percent flicker becomes 4.4%, which is smaller than the recommended upper limit of 8%.     

A step‐up PWM DC–DC converter for renewable energy applications

A step‐up pulse width modulation (PWM) direct current (DC)–DC converter is presented in this paper, which has its origin in quasi Z‐source inverter. Analysis of this converter in steady state is presented, and relevant expressions are derived for the proposed converter operating in continuous conduction mode. The power loss expressions for each component of the converter are derived, and thereby, obtained expressions for overall converter efficiency are presented. Further, a dynamic model is derived to design an appropriate controller for this converter. The simulation and experimental results are presented to support the theoretical analysis. The advantages such as continuous input current, high step‐up gain at lower duty ratio, and common ground for source, load, and switch makes the converter suitable for renewable energy applications. 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.     

基于上下续电流的功率变换器故障诊断方法

开关磁阻起动/发电系统中功率变化器是核心部件,其故障将会给系统带来不可估量的影响。针对功率变换器的典型电气故障(上下管的开、短路故障)进行了分析,研究了上下续电流的变化,结合电动状态和发电状态的共同点和不同点,基于上下续电流分别提出了一种在线故障诊断方案,利用上下续电流在一个周期内积分值的变化,来进行判断故障类型和故障位置;同时利用数字化的思想,提取了故障特征系数F'_(AB1)、F'_(AB2)和F'_(A12),利用判断特征系数来进行在线的故障诊断;最后搭建了开关磁阻起动/发电系统的故障诊断模型并分别进行了仿真验证。结果表明:该方案在电动和发电状态都能够实现在线的故障诊断,并且实现了故障验证;与相电流故障诊断相比,大大降低了虚警率。     

Performance analysis and calculation of critical inductance and output voltage ripple of a simple non‐isolated multi‐input bidirectional DC‐DC converter

In this paper, a simple non‐isolated multiple input (MI) bidirectional DC‐DC topology is proposed which can operate in buck, boost, or buck‐boost modes. The proposed topology utilizes a battery pack to realize the bidirectional power flow operation especially when the input sources are non‐storable ones. The excess energy of input sources can be stored in the battery and be injected to the load, when required. Simultaneous or independent power transfer of input sources is also provided. For better evaluation, the proposed topology has been compared with several recently presented novel topologies, from view point of number of inductors, capacitors, switches, and diodes. Comparison results show that the proposed topology utilizes less number of components (switches, inductors, capacitors, and current sensors) which can reduce the size, cost, and complexity of converter. Different operational modes of the proposed topology (unidirectional buck, boost, buck‐boost modes, and bidirectional mode) have been presented. Also, boost mode of the proposed topology has been investigated in detail, from design point of view, and generalized relationships have been proposed for calculation of critical inductance (CI) and output voltage ripple (OVR) of proposed n‐input boost topology. To validate proposed theoretical concepts, the proposed topology has been modeled and simulated in PSCAD/EMTDC software, and the 3‐input boost version has been experimentally implemented. Simulation and experimental results confirm appropriate performance of the proposed topology.     

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.     

Study on Improving Precision of Analysis of Boost Ratio and Power Efficiency of Tapped‐Inductor DC–DC Converter Circuit

Analysis precision of boost ratio and power efficiency in boost DC–DC converter circuit is improved by proposing adaptive equivalent circuit of output diode of the circuit. In experiment, boost ratio and power efficiency in high boost ratio circuit were 9.89% and 76.5% respectively with its load resistance of 20 Ω driven by output voltage 10 V. In experimental results, error in theoretical values of boost ratio compared with the measured values of that was reduced to ?3.79% from 57.5% in the conventional circuit. In a tapped‐inductor high boost ratio circuit, error in theoretical values of boost ratio was reduced to 3.54% from 31.8%. Error in theoretical values of power efficiency with the measured values of that was reduced to 5.51% from 33.2% in the conventional circuit. In a high boost ratio circuit, error in theoretical values of power efficiency was reduced to ?3.32% from 17.3%. Power loss of every element in boost DC–DC converter circuits was analyzed with high precision by analysis of inductance current waveforms in those circuits. Error in theoretical values of power loss compared with measured values was reduced to equal or less than 5%.     

Design and analysis of power‐CMOS‐gate‐based switched‐capacitor DC–DC converter with step‐down and step‐up modes

A unified multi‐stage power‐CMOS‐transmission‐gate‐based quasi‐switched‐capacitor (QSC) DC–DC converter is proposed to integrate both step‐down and step‐up modes all in one circuit configuration for low‐power applications. In this paper, by using power‐CMOS‐transmission‐gate as a bi‐directional switch, the various topologies for step‐down and step‐up modes can be integrated in the same circuit configuration, and the configuration does not require any inductive elements, so the IC fabrication is promising for realization. In addition, both large‐signal state‐space equation and small‐signal transfer function are derived by state‐space averaging technique, and expressed all in one unified formulation for both modes. Based on the unified model, it is all presented for control design and theoretical analysis, including steady‐state output and power, power efficiency, maximum voltage conversion ratio, maximum power efficiency, maximum output power, output voltage ripple percentage, capacitance selection, closed‐loop control and stability, etc. Finally, a multi‐stage QSC DC–DC converter with step‐down and step‐up modes is made in circuit layout by PSPICE tool, and some topics are discussed, including (1) voltage conversion, output ripple percentage, and power efficiency, (2) output robustness against source noises and (3) regulation capability of converter with loading variation. The simulated results are illustrated to show the efficacy of the unified configuration proposed. Copyright © 2003 John Wiley & Sons, Ltd.     

Analysis and experimental verification of the linear correlation of the operation condition among the bifurcation points of current‐mode‐controlled buck–boost converter

The operation parameter of the buck–boost converter is examined for its boundary of the first flip bifurcation. It is found that the parameters exhibit a linear relation for the same parameter at another bifurcation point. The bifurcation parameters also have a linear correlation between them. Theoretical analysis is presented to explain how this can occur. Simulation and experimental results at 20 kHz are used to present these novel results. Copyright © 2005 John Wiley & Sons, Ltd.     

无桥Dual-Sepic PFC变换器分析与设计

研究了一种新型无桥Dual-Sepic功率因数校正(Power Factor Correction,PFC)变换器,该变换器具有升降压功能,且完全消除了传统桥式PFC变换器中的二极管整流桥,减少了电流流通路径中功率器件的数量,提高了变换器的效率。工作于不连续导电模式(Discontinuous Conduction Mode,DCM)的无桥Dual-Sepic PFC变换器具有二极管零电流关断特性,减小了二极管反向恢复损耗和开关损耗,进一步提高了变换器的效率。此外,无桥Dual-Sepic PFC变换器输入电流连续,减小了电磁干扰。对DCM模式无桥Dual-Sepic PFC变换器进行了详细的分析和电路参数设计,仿真和实验结果证实了参数设计的正确性和方案的可行性。     

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.     

Quasi‐V2 hysteretic control boost DC–DC regulator with synthetic current ripple technique

Conventionally, a high accuracy operational amplifier (OPA)‐based current sensor is used for sensing current message under a full load range, which increases the cost characteristic. Instead of a high accuracy OPA‐based current sensor, this paper describes using a switching inductor quasi‐V² hysteretic control boost dc–dc regulator with a proposed current‐sensing technique named emulated‐ramp feedback (ERF), which can improve transfer efficiency under a full load range. Two control systems are presented in this paper. The first system, a hysteretic voltage control switching boost converter with ERF, achieves the hysteretic voltage control in a boost regulator and lowers the cost characteristic without using compensator. The second system, a quasi‐V² hysteretic voltage control switching boost converter with ERF, demonstrates the compatibility of ERF technique in rippled‐based control boost converters. The regulator was implemented with TSMC 0.25‐µm HV CMOS process. Experimental results show the second system can work under the specification of 5–12 V with a 0 to 300‐mA load range. Additionally, this system attained a recovery time is 27/95 µs for step‐up/step‐down in a 100 to 300‐mA continuous conduction mode load current, and a peak efficiency of 92.1% with a chip area of only 1.014 mm². Copyright © 2016 John Wiley & Sons, Ltd.     

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.     

Fast‐scale instability in a PFC boost converter under average current‐mode control

This paper investigates the fast‐scale instability in a power‐factor‐correction (PFC) boost converter under a conventional average current‐mode control. The converter is operated in continuous mode. Computer simulations and theoretical analysis are performed to study the effects of the time‐varying input voltage under the variation of some chosen parameters on the qualitative behaviour of the system. It is found that fast‐scale instability may occur during a line cycle, which can cause distortion to the line current and degrade the practical power factor. The results provide useful information for the design of PFC boost converters to avoid distortion due to fast‐scale bifurcation. Copyright © 2003 John Wiley & Sons, Ltd.