High‐efficiency transformerless buck–boost DC–DC converter

A novel high‐efficiency transformerless buck–boost DC–DC converter is proposed in this paper. The presented converter voltage gain is higher than that of the conventional boost, buck–boost, CUK, SEPIC and ZETA converters, and high voltage gain can be obtained with a suitable duty cycle. The voltage stress across the power switch is low. Hence, the low on‐state resistance of the power switch can be selected to decrease conduction loss of the switch and improve efficiency. The input current ripple in the presented converter is low. The principle of operation and the mathematical analyses of the proposed converter are explained. The validity of the presented converter is verified by the simulation results in PSCAD/EMTDC software and experimental results based on the prototype circuit with 250 W and 40 kHz. Copyright © 2017 John Wiley & Sons, Ltd.     

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.     

A high efficiency input/output magnetically coupled interleaved buck–boost converter with low internal oscillation for fuel-cell applications: Small signal modeling and dynamic analysis

Dynamic behavior of DC–DC converters plays a crucial role in stability of renewable energy exploitation systems. This paper presents small signal modeling of an input/output magnetically coupled interleaved buck–boost converter for fuel-cell applications to help the designers with the better understanding of converter dynamics. Aiming to have a continuous converter transfer function for a smooth transition between the operation modes and an improved inner dynamics, a damping network and an input/output coupling have been added to the interleaved structure of well-known cascaded buck–boost converter. Having the same step-up/step-down voltage transfer ratio, smooth transition and improved inner dynamics make this converter quite suitable for renewable energy applications. The paper presents a small signal ac equivalent circuit model of the proposed converter based on state space averaging (SSA) method. Simulation results show remarkable improvements in converter dynamic behavior in both time and frequency domains. Prototype setup of 360 W and 36 V output voltage for a fuel cell with a brand of “FCgen 1020ACS” Ballard Power Systems, Inc. was implemented. Experimental results are presented to verify the theoretical model and its expected merits.     

Extend output voltage range of AC/AC converters using a reversible indirect matrix converter

This paper proposes a reversible indirect matrix converter that expands the output voltage range. The proposed circuit has two operation modes. A buck mode that supplies an output voltage lower than the input voltage, and a boost mode that supplies an output voltage higher than the input voltage. In the boost mode, the proposed circuit has the characteristics of the current type inverter therefore, it is possible to obtain an output voltage with less harmonics. The proposed system is validated with a 2 kW prototype. The proposed circuit shows that the input/output voltage ratio of AC/AC direct conversion obtained is 0 to 1.2 or more. Moreover, the conversion efficiency of the proposed circuit is 92.8%.     

Multi-input battery-integrated single-stage DC-DC converter for reliable operation of solar photovoltaic-based systems

Solar photovoltaic (PV) systems are emerging progressively due to their wide compatibility range, ease of installation, and environmental friendliness. The module mismatch (MM) losses and module open circuit (MOC) fault can cause the power mismatch between different PV modules. This significantly affects the energy output from the PV module. Also, the intermittent nature of solar PV power makes the solar PV systems unreliable; to compensate for this, conventional PV systems utilize a battery storage system (BSS) with separate bidirectional converter. These bidirectional converters require two-stage power conversion and massive battery bank connected at the DC link. This leads to the further reduction in overall efficiency. To address these issues, this paper proposed a multi-input PV battery system (MIPBS) that uses nonisolated buck and boost converter combinations. It requires single-stage power conversion to extract maximum power from each PV module along with BSS charging and discharging. Its modular design allows it to function across a wide range of voltage, power, and BSS choices. The proposed system is capable of mitigating the MM loss and sustaining the MOC fault. This paper discusses the operation, steady-state analysis, and dynamic analysis of the proposed MIPBS. The performance of the proposed MIPBS is validated using a state-of-the-art experimental setup with two PV modules, each having a rating of 60.53 W.     

A new topology for nonisolated multiport zero voltage switching dc‐dc converter

In this paper, a new multiport zero voltage switching dc‐dc converter is proposed. Multiport dc‐dc converters are widely applicable in hybrid energy generating systems to provide substantial power to sensitive loads. The proposed topology can operate in 3 operational modes of boost, buck, and buck‐boost. Moreover, it has zero voltage switching operation for all switches and has the ability to eliminate the input current ripple; also, at low voltage side, the input sources can be extended. In addition, it has the ability of interfacing 3 different voltages only by using 3 switches. In this paper, the proposed topology is analyzed theoretically for all operating modes; besides, the voltage and current equations of all components are calculated. Furthermore, the required soft switching and zero input currents ripple conditions are analyzed. Finally, to demonstrate the accurate performance of the proposed converter, the Power System Computer Aided Design(PSCAD)/Electro Magnetic Transient Design and Control(EMTDC) simulation and experimental results are extracted and presented.     

Analysis of a novel four-level DC/DC boost converter

In this paper, novel two-quadrant buck/boost and one-quadrant boost four-level DC/DC power converters are introduced. The primary application for these converters is that of interfacing a low-voltage DC source, such as a fuel cell or battery, to a high-voltage four-level inverter. One important feature of the four-level DC/DC power converters proposed is the ability to perform the power conversion and balance the inverter capacitor voltages simultaneously. With the capacitor voltage balancing, it is possible to obtain the full voltage from the inverter. For the boost converter, the steady-state and nonlinear average-value (NLAM) models are developed. The NLAM is verified against a detailed simulation of a four-level converter/inverter drive system. The proposed converter is experimentally verified using an 18 kW converter/inverter system     

单级组合式不间断高功率因数AC/DC变换器研究

提出了一类基于Boost-Flyback变换器的单级组合式不间断高功率因数AC/DC变换器电路结构与拓扑族。这类变换器由二极管整流桥和具有功率因数校正、不间断供电、输出电压快速调节等功能的Boost-Flyback变换器构成，可以将1种交流电压变换成所需要的输出直流电压。分析研究了这类变换器的3种工作模式(正常工作模式、后备工作模式、充电工作模式)、稳态原理特性、控制策略和关键电路参数设计准则，并给出了原理试验结果。这类变换器具有单级功率变换、不间断供电、网侧功率因数高、蓄电池与电网或负载高频电气隔离、输出电压调节速度快、体积重量小、成本低等优点。     

A new interleaved bidirectional dc/dc converter with zero voltage switching and high voltage gain: analyses,design and simulation

In this paper, a new interleaved non‐isolated bidirectional dc–dc converter with capability of zero voltage switching and high voltage gain is proposed. In the proposed converter by using two coupled inductors and one capacitor, the voltage gain is extended. Moreover, by using only an auxiliary circuit that includes an inductor and two capacitors, the zero voltage switching (ZVS) of two used switches in the first phase of converter can be achieved. The ZVS operation of two used switches in the second phase is always obtained without using any extra auxiliary circuit. This converter similar to other interleaved converters has low input current ripple and low current stress on switches. In this paper, the proposed converter is analyzed in all operating modes, and also the voltage gain, required conditions for ZVS operation of switches, voltage and current stresses of all switches, and the value of input current ripple in both boost and buck operations are obtained. Finally, the accuracy performance of the proposed converter is verified through simulation results in EMTDC/PSCAD software. Copyright © 2017 John Wiley & Sons, Ltd.     

Application of duality principle to synthesis of single‐stage power‐factor‐correction voltage regulators

The duality principle is applied to derive new single‐stage power‐factor‐correction (PFC) voltage regulators. This paper begins with an application of duality transformation to conventional discontinuous‐conduction‐mode buck, buck‐boost and boost converters. The resulting dual converters operate in the discontinuous capacitor voltage mode. These new converters provide the same PFC property, but in the dual manner. It is proved that in the practical case of the input being a voltage source, the mandatory insertion of inductance between the voltage input and the ‘dual PFC converter’ does not affect the power‐factor‐correcting property. A new single‐stage PFC regulator is derived by taking the dual of a well‐known circuit based on a cascade of conventional boost and buck converters. Analytical design expressions are derived, illustrating the relation between current stress and component values. Experiments are performed to confirm the operation of the circuit and its power‐factor‐correcting capability. Copyright © 2003 John Wiley & Sons, Ltd.     

A switch‐mode boost DC–DC converter for IR‐drop compensation of charging cable

A switch‐mode boost DC–DC converter has been developed to compensate for the IR‐drop because of the finite resistance of a charging cable. The boost ratio of the DC–DC converter is adaptively controlled by an IR‐drop sensing circuit to provide the required voltage level to a battery charger regardless of the cable resistance. Implemented in a 0.18 µm BCDMOS process, the IR‐drop compensating switch‐mode boost DC–DC converter occupies 6.2 mm² active area and shows the 93.2% peak efficiency. The proposed IR‐drop compensating boost converter can be applied to compensate for the IR‐drop of any type of charging cables. Copyright © 2014 John Wiley & Sons, Ltd.     

Global hybrid modeling and control of a buck converter: A novel concept

Several attempts have been made to design suitable controllers for DC–DC converters. However, these designs suffer from model inaccuracy or their inability to desirably function in both continuous and discontinuous current modes. This paper presents a novel switching scheme based on hybrid modeling to control a buck converter using mixed logical dynamical (MLD) methodologies. The proposed method is capable of globally controlling the converter in both continuous and discontinuous current modes of operation by considering all constraints in the physical plant such as maximum inductor current and capacitor voltage limits. Different loads and input voltage disturbances are simulated in MATLAB and results are presented to demonstrate the suitability of the controller. The transient and steady‐state performance of the closed‐loop control over a wide range of operating points shows satisfactory operation of the proposed controller. Copyright © 2008 John Wiley & Sons, Ltd.     

Three-phase buck/boost-type high-power-factor switching converter

The harmonic pollution caused by ac-to-dc converters has been of great concern. To overcome this problem, several power-factor-correction (PFC) converters have been developed and applied in recent years. However, several power converter systems, such as the motor drive system, with a wide V/F control range, uninterruptible power supply system and dc power supply system with universal input voltage range, require an ac-to-dc converter or an off-line converter (preregulator) with a wide output-voltage control range in order to be highly efficient. However, the most conventional PFC converters employ a voltage-fed or current-fed type topology and they have a lower or upper limitation of the output-voltage control range. Thus, they do not realize sufficiently high-system efficiency. On the other hand, a buck/boost converter has a wide control range of the output voltage and acts in PFC operation under an appropriate control technique. Thus, study of the possibility of using the buck/boost ac-to-dc converter with PFC and a wide output-voltage control range is important to the realization of harmonic-free and efficient power conversion systems. In this paper, the author proposes a three-phase bridge-type ac-to-dc converter system with a high input power factor and a wide output-voltage control range. The controller of the proposed system includes the following two new techniques. One is the pulse integral value modulation that compensates modulation errors in conventional pulse-width-modulation caused by dc current ripples or fluctuations of the current pulse amplitude. The other is a switching pulse pattern generator, using the idea of equivalent pulse current source for the bridge as a way to simplify the pulse pattern generation process. This paper describes the proposed converter system, the control and modulation principles, and experimental results that show the reliability and usefulness of the proposed buck/boost converter system. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (2): 41–55, 1997     

无通信互联线储能系统的直流母线协调控制策略

针对无通信互联线的储能系统如何在不增加系统成本和复杂度的前提下维持直流母线功率平衡及电压稳定,提出了一种直流母线协调控制策略,DC/AC变流器采用定直流电压或定交流电压控制,两台DC/DC变换器采用包含电池充放电控制的改进型二阶直流电压偏差控制。通过对系统典型工况的分析,说明了系统中各个装置是如何协调工作的。搭建了微网实验平台对所提出的控制策略进行了实验验证,实验结果证明了该控制策略的有效性和实用性。     

A new single‐phase high‐power‐factor converter with buck and buck–boost hybrid operation

In recent years, a wide variety of high‐power‐factor converter schemes have been proposed to solve the harmonic problem. The schemes are based on conventional boost, buck, or buck–boost topology, and their performance, such as output voltage control range in the boost and buck topology or efficiency in the buck–boost topology, is limited. To solve this, the authors propose a single‐phase high‐power‐factor converter with a new topology obtained from a combination of buck and buck–boost topology. The power stage performs the buck and buck–boost operations by a compact single‐stage converter circuit while the simple controller/modulator appropriately controls the alternation of the buck and buck–boost operation and maintains a high‐quality input current during both the buck and buck–boost operations. The proposed scheme results in a high‐performance rectifier with no limitation of output voltage control range and a high efficiency. In this paper, the principle and operation of the proposed converter scheme are described in detail and the theory is confirmed through experimental results obtained from 2‐kW prototype converter. © 2000 Scripta Technica, Electr Eng Jpn, 131(3): 91–100, 2000     

一种单级隔离型Sepic逆变器

提出了一种新型单级隔离型Sepic逆变器。该逆变器只需三个有源开关和一个高频变压器,结构简单、易于实现。该逆变器由直流Sepic变换器扩展而来,因而具有升降压能力,适于直流侧电压宽范围波动的可再生能源发电系统。介绍了所提逆变器的电路结构和工作原理,采用单周期控制实现了系统的闭环控制;给出了该逆变器的磁集成设计方案;在理论分析的基础上,进行了仿真和实验验证。仿真和实验结果表明,该逆变器具有良好的动、静态性能。     

DSP based proportional integral sliding mode controller for photo-voltaic system

The buck–boost converter is controlled using different algorithms like voltage mode control, current mode control, V² control, enhanced V² control, Sliding Mode Control (SMC), and Proportional Integral (PI) control. In all these algorithms the steady state error is more. On combining PI control and sliding mode control the steady error can be minimized. In industry and commercial applications involving Photo-Voltaic (PV) systems, uses buck–boost converter. In this converter above control algorithms are implemented using hardware circuitry or microcontroller. In industry and commercial applications Digital Signal Processor (DSP) is used for automation purposes and the same DSP can be used to implement control algorithms so as to get maximum electrical energy from solar energy. The efficient utilization of resources such as DSP is achieved as we are using the same DSP for implementing control algorithm. In the proposed study, PI control method and sliding mode control methods are combined to obtain a Proportional Integral Sliding Mode Control (PISMC) and it is used to control the buck–boost converter which is used to drive the electrical loads from solar energy. The buck–boost converter is designed, simulated and implemented. The algorithms PI, SMC and PISMC are simulated in using MATLAB simulink and then implemented in DSP TMS 320 2808. In the proposed study PISMC, a stable and efficient output voltage is obtained in which the steady state error and maximum overshoot are minimum. The PISMC is better in terms of transient and steady state performances as validated by our experiments. The proposed study will work in real-time since DSP is used for implementing the control algorithms and found to be better in terms of speed and regulation. The proposed DSP based PISMC can also be used to control other types of DC–DC converters.     

A structural approach to synthesizing,analyzing, and modeling quasi‐resonant converters

This paper presents a structural approach to synthesizing, analyzing, and modeling quasi‐resonant converters (QRCs) based on the concept of basic converter units (BCUs). Typical QRCs include the well‐known topologies of buck, boost, buck‐boost, Cuk, Zeta, and Sepic. With proper reconfiguration, these QRCs can be synthesized from either buck‐QRC BCU or boost‐QRC BCU plus certain linear networks. Thus, the BCUs and general configurations of the converters can be identified. Analysis of steady state operation and derivation of small‐signal models for the converters then can be conveniently performed from the general configurations, reducing the complexity significantly. Moreover, the proposed structural approach can explore more physical insights into the converters in a family, and can reveal more relationships among converters over conventional approaches. Copyright © 2011 John Wiley & Sons, Ltd.     

一种电源-电容串联型直流变换器

提出了一种电源-电容串联型直流变换器,这种拓扑结构可以同时为两路直流电源升压,并且有效降低了半导体器件的电压与电流应力。与双路Boost型直流变换器相比,该电源-电容串联型直流变换器在不增加功率器件数量的前提下,显著降低了半导体器件的电压与电流应力,适用于分布式光伏并网逆变器的直流变换级。主要涉及该直流变换器的运行方式、电压与电流应力分析、效率对比,并通过实验验证了该直流变换器的可行性。     

倍流整流三电平零电压软开关三相高功率因数整流器

提出一种新型的具有倍流整流的三电平零电压软开关三相高功率因数AC/DC变换器电路,该电路入端电感电流工作在DCM方式,以便实现高功率因数,输出滤波电感工作在CCM方式.与普通零电压三电平变换器比较,该电路在整个负载范围内更易实现功率管的零电压开关,无占空比丢失和二次侧电压尖峰.本文分析了电路工作原理,给出了高功率因数与电路参数的关系曲线,推导了电压增益公式和入端电感与输出滤波电感的设计公式,最后给出了实验结果.