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.     

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 of quasi-resonant converters using a state plane method

In this paper a state plane method has been used to analyse flyback and buck quasi-resonant converters (QRCs). By using the state plane method, the DC voltage conversion ratio and the voltage and current stresses of the active switch, the diode and the resonant capacitor have been derived graphically. the DC voltage conversion ratio and the current stress of the active switch have been used to design QRC circuits. A flyback QRC has been designed, simulated, built and tested. the experimental results have been found to be in good agreement with PSpice simulations.     

Unified subharmonic oscillation conditions for peak or average current mode control

This paper is an extension of the author's recent research in which only buck converters were analyzed. Similar analysis can be equally applied to other types of converters. In this paper, a unified model is proposed for buck, boost, and buck–boost converters under peak or average current mode control to predict the occurrence of subharmonic oscillation. Based on the unified model, the associated stability conditions are derived in closed forms. The same stability condition can be applied to buck, boost, and buck–boost converters. Based on the closed‐form conditions, the effects of various converter parameters including the compensator poles and zeros on the stability can be clearly seen, and these parameters can be consolidated into a few ones. High‐order compensators such as type‐II and PI compensators are considered. Some new plots are also proposed for design purpose to avoid the instability. The instability is found to be associated with large crossover frequency. A conservative stability condition, agreed with the past research, is derived. The effect of the voltage loop ripple on the instability is also analyzed. Copyright © 2014 John Wiley & Sons, Ltd.     

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     

Single‐Inductor Dual‐Output DC–DC Converter Design Using RC Ripple Regulator Method

In this paper, we have proposed Single‐Inductor Dual‐Output (SIDO) buck–buck and boost–boost dc–dc converter using improved RC ripple regulator control. The proposed SIDO buck–buck converter has the characteristics of low‐ripple and high control frequency. RC ripple regulator control cannot be applied to SIDO boost–boost converter because RC ripple regulator undergoes self‐excited oscillation and two self‐excited oscillating controllers make the SIDO converter unstable. Thus we proposed the priority circuit for RC ripple regulator control. The proposed control circuit improves response characteristic and simplicity of the control circuit. Simulations are performed to verify the validity of the proposed SIDO converter. Simulation results indicate good performance of the proposed SIDO converter.     

一种可以建立软开关PWM变换器的系统方法

以结合开关理论为基础,提出了一种可以建立软开关PWM变换器的系统方法。应用这种方法,许多种无源和有源软开关PWM变换器家族中所派生出的变换器,如：Buck—Boost变换器、Cuk变换器、Sepic变换器和Zeta变换器都能够通过Buck变换器和Boost变换器这两种最基本的变换器得到,不仅对变换器家族可以进行更加深入的了解,还可以揭示出软开关变换器之间的内在联系。通过对结合开关理论的具体介绍,在对有源PWM软开关变换器中的零电压转换（ZVT）PWMDC／DC变换器的派生变换器电路拓扑的建立原理和得出过程重点阐述的同时。将有源软开关PWM变换器进一步分成了Buck和Boost家族两大类,并证明了所提出的这种建立软开关PWM变换器的方法的正确性和可行性。     

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.     

Investigations of the usefulness of average models for calculations characteristics of buck and boost converters at the steady state

This paper deals with the problem of the analysis of boost and buck converters at the steady state with the use of the method of average models. The usefulness of this method is examined by comparing the boost and buck converters characteristics at the steady‐state obtained both with the transient analysis with physical models of semiconductor devices and the examined method as well. The accuracy of the method of the average models is investigated with respect to the values of the circuit load resistance, the pulse‐duty factor and the frequency of the signal controlling the power switch. Copyright © 2009 John Wiley & Sons, Ltd.     

DC analysis and design of a PWM buck converter operated as a dynamic power supply

Modern energy transmission and signal reproduction techniques rely upon power amplifiers that must operate with high efficiency. An increasingly popular technique for addressing this problem involves replacing the fixed power amplifier supply voltage V _{D D} with a controlled, variable voltage provided by a dynamic power supply. Although pulse‐width modulated dc‐dc buck converters typically function as fixed‐output supplies, this paper provides new theoretical dc analysis for operation wherein the output voltage is controlled and continuously variable over a wide range. A design procedure for the variable‐output buck converter is derived. Key device parameters affecting converter speed and efficiency are identified. The dc analysis and design procedure are verified experimentally, with calculated and measured parameters shown to be in good agreement. Copyright © 2016 John Wiley & Sons, Ltd.     

A Multi-Functional Single-Stage Power Electronic Interface for Plug-In Electric Vehicles Application

This paper proposes a Zeta-derived non-isolated single-stage power electronic interface for on-board application of plug-in electric vehicles, which provides all modes (plug-in charging, propulsion, and regenerative braking) of vehicle operation. In addition, the proposed converter can charge the battery through universal input voltage range, i.e., 90–260 V due to buck/boost operations in plug-in charging mode. In propulsion and regenerative braking modes, the proposed converter operates as conventional boost and buck DC/DC converter, respectively. Compared to existing single-stage converters, the proposed converter has least components to those converters which have buck/boost operation in plug-in charging mode. A voltage/current stresses and loss analysis of the converter have been investigated for each mode of converter operation. Detailed simulation and experimental results are given to show the effectiveness of the proposed converter.     

Calculation of steady‐state solution of parallel‐connected buck converters with active current sharing and its parameter sensitivity

In this paper, the effect of active current‐sharing control on the steady‐state operation of parallel‐connected buck converters is investigated. The system under study consists of N voltage‐mode‐controlled buck converters connected in parallel. Three kinds of active current‐sharing schemes are considered, namely, master–slave scheme with automatic master, master–slave scheme with dedicated master, and democratic scheme. Using the principle of charge balance, the mechanism of the operating point drift arising from active current sharing is examined. A general formulation of the steady‐state solution under active current sharing is derived. Moreover, detailed parameter sensitivity analysis is performed to evaluate the effect of parameters' variation on the operating point. The results from sensitivity analysis can be used to categorize parameters for facilitating practical design. Computer simulations are presented to verify the analytical results. Copyright © 2010 John Wiley & Sons, Ltd.     

Unified Pulse‐Width Modulation Scheme for Improved Digital‐Peak‐Voltage Control of Switching DC‐DC Converters

Contrast to conventional dependent double‐edge (DDE) pulse‐width modulation (PWM), independent double‐edge (IDE) PWM is investigated and applied to the control of switching dc‐dc converters, with improved digital‐peak‐voltage (IDPV) controlled buck converter in this paper. IDE modulation unifies all the PWM schemes reported up to now and is thus called as unified PWM. It is revealed that conventional trailing‐edge, leading‐edge, trailing‐triangle, and leading‐triangle modulations are special cases of IDE modulation. The control laws of IDPV controlled buck converter with IDE modulation are investigated and compared with those of IDPV with DDE modulation. Their stabilities and robustness are analyzed subsequently. Digital implementation of the unified PWM is also carried out. Steady‐state and transient performances of IDPV controlled buck converters with IDE modulation and DDE modulation are compared and verified by experimental results. It is concluded that steady‐state and transient performances of IDPV with IDE are better than those of IDPV with DDE modulation. Copyright © 2012 John Wiley & Sons, Ltd.     

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.     

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.     

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 new control method of a resonant switched‐capacitor converter and the application for balancing of the split DC voltages in a multilevel inverter

This paper proposes a new voltage‐balancing circuit for the split DC voltages in a diode‐clamped five‐level inverter. The proposed circuit is based on a resonant switched‐capacitor converter (RSCC), which consists of two half‐bridge inverters, a resonant inductor, and a resonant capacitor. A new phase‐shift control of the RSCC is proposed to improve voltage balancing performance. Theoretical analysis reveals the rating of the RSCC and stored energy in the resonant inductor. Experimental results confirm the reduction of the inductor to one‐tenth in volume compared to a conventional voltage‐balancing circuit based on buck‐boost topology. Moreover, the proposed phase‐shift control has demonstrated that it is possible to eliminate the voltage deviation between the DC capacitors. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(2): 69–79, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20719     

A modified dual current mode control method with an adaptive current bandwidth

In this paper, a new adaptive dual current mode control method (ADCMC) is presented, being a result of the modification of existing dual current mode control (DCMC) by introducing an adaptive current bandwidth. The ADCMC offers several important advantages over DCMC, such as no peak‐to‐average error in the inductor current, better transient response of current loop, and improved line regulation. A detailed analysis of the proposed ADCMC is performed for three types of DC–DC power electronics converters: buck, boost, and non‐inverting buck–boost converter. The performances of the ADCMC are tested with simulations and experiments. The obtained results confirm the analysis and validity of the proposed ADCMC method. Copyright © 2015 John Wiley & Sons, Ltd.     

Improved control‐to‐output characteristics of a PWM buck‐boost converter

An indirect control variable for improving the control‐to‐output characteristics of a Pulse Width Modulation (PWM) buck‐boost converter is introduced in this letter. The voltage gain and the small‐signal model of the buck‐boost converter are reviewed. The actual voltage command at one input of the PWM comparator is from the proposed indirect control variable and the peak value of the high‐frequency PWM carrier. The resulted voltage gain function appears proportional to this indirect control command. Also the dependence of the DC gain of the control‐to‐output transfer function on the duty cycle is eliminated. Experimental results conform well to the theoretical analysis. Copyright © 2010 John Wiley & Sons, Ltd.     

Transient analysis of multi‐state dc–dc converters using system energy characteristics

The study of multi‐state dc–dc power conversion techniques is restricted by the complicated inner switching behaviors. This paper presents a general and unified transient analysis for various sorts of multi‐state dc–dc converters from a viewpoint of their system energy characteristics. With the applications to the boost converters, the proposed analytical method has indicated its advantages of high convenience and practicability to the multi‐state converters. The generalized concepts of system energy parameters of dc–dc converters are introduced and applied to the transient analysis. Consequently, the expressions of system model parameters of multi‐state dc–dc converters are deduced. The new 2nd order transfer functions are obtained to describe the large‐ and small‐signal mathematical models accurately. The model simulation and experimental results are provided to support the theoretical analysis. Copyright © 2007 John Wiley & Sons, Ltd.