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In this article, an optimal structure for a high step-up nonisolated dc–dc converter is proposed. In this topology, the required high voltage gain can be obtained with a low number of elements. Furthermore, by implementing an auxiliary circuit, zero-voltage switching condition for the switches is provided, input current ripple has been reduced to almost zero, and all of the power diodes turn off and on under zero-current conditions. In the proposed structure, to regulate voltage gain, the extendable number of diode–capacitor voltage multiplier (DCVM) stages are combined with a coupled inductor. The voltage stresses across the semiconductors can be regulated by the number of the DCVM stages and the turns ratio of the coupled inductor. Thus, it provides two degrees of freedom for the designer to use low-rated semiconductors, which increases the converter efficiency. In this article, the performance of the proposed converter, in terms of voltage stress, voltage gain, and efficiency, has been analyzed, and a comprehensive comparison between the presented topology and other similar topologies presented. Finally, to verify the performance of the proposed topology, a 500 W (40 V/400 V) laboratory prototype has been developed and tested. The experimental results confirm its superiority and suitability. [ABSTRACT FROM AUTHOR]

A single-input dual-output (SIDO) converter with a coupled inductor is a widely used converter to generate two outputs from a single input. The analysis presented in the literature is for continuous conduction mode, where the converters are operating in heavily loaded conditions. While operating, the load may reduce, leading to the discontinuous conduction mode (DCM) of the converter. A coupled inductor SIDO (CI-SIDO) boost converter is analyzed in this article. As this converter combines two boost converters with a common input and a coupled inductor, the DCM operation of one boost affects the other. Due to coupling, it is found that the body diode of the mosfet turns on in the DCM operation of the CI-SIDO boost converter. This article finds the conditions to turn on body diode and its effect on the average values of the inductor current, diode current, and input current. The article also analyzes the CI-SIDO boost when the body diode is not turned on. This article finds the effect of change in input voltage, load current, and duty ratios on the DCM operation of the CI-SIDO boost. Simulations verify all the obtained conditions in MATLAB/Simulink and experiments using a laboratory prototype. This article is accompanied by a supplementary online document with additional illustrative diagrams and experimental results. [ABSTRACT FROM AUTHOR]

A high step-up coupled-inductor single-ended primary-inductor converter (SEPIC) DC–DC converter with input current ripple cancellation is presented in this study. The proposed converter is based on the structure of a SEPIC but also has a coupled inductor. In the proposed converter, two coupled inductors are used to increase the voltage gain and remove the input current ripple. The voltages of the main switch and all diodes are clamped to prevent high-voltage surges caused by the leakage inductance of the coupled inductor. Hence, a dissipative snubber circuit or an active clamping circuit is not required. As a result of the reduction of voltage stress, a MOSFET with low drain-to-source on-state resistance RDS(ON) can be used as the main switch. To demonstrate the performance of the proposed converter, a prototype converter with an input voltage of 24 V, an output voltage of 300 V, and output power of 100 W is implemented. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency of high gain DC-DC converter using MOSFET as switching device, a novel zero-voltage soft-switching high gain DC-DC converter is presented. A main switch tube is used to replace the output diode in the conventional boost converter, and an auxiliary network is added to make the two switches realise true ZVS soft turn-on and all diodes realise true ZCS soft turn-off, which improves the efficiency and effectively suppresses the negative effect of diode reverse recovery. Furthermore, the output end of the converter is composed of three output capacitors in series, which avoids the converter working at the limit duty cycle, increases the voltage gain and reduces the switch voltage stress. Therefore, MOSFET with low voltage level and low on resistance can be selected as switching devices. The resonant capacitor and leakage inductance are used to reduce the current at the turn-off time of the switch. The operating principle and steady-state characteristics of the converter are analysed in detail. The design idea of the main parameters is given, and the efficiency and loss of the converter are evaluated. Finally, the experimental results on a 100 W prototype show that the efficiency reaches 95.79% at rated power. [ABSTRACT FROM AUTHOR]

Due to the advantages of small size and low cost, single-inductor dual-output converters are attractive choices to provide simultaneous step-up and step-down (SUSD) outputs in engineering applications. However, they also suffer from several limitations, including reverse port polarity, large number of conducting components, or limited output power range. Aiming to eliminate these undesired shortcomings, this article proposes a single coupled inductor dual-output converter, which can work in two modes depending on whether the secondary side of coupled inductor takes part into operation. With the mixed modes, the proposed converter cannot only provide SUSD outputs over whole load range since a new energy transfer pathway is added by using the coupled inductor, but also achieves low conduction losses owing to the reduced number of conducting components. Moreover, no additional magnetic component is required, and the negative terminals of input and outputs are connected together in the proposed converter. Its operation principle and small-signal model are also detailed introduced in the article, followed by the design of closed-loop control to improve the dynamic stability. Finally, a prototype circuit with 24 V input and 12, 48 V outputs is built to experimentally verify the converter performance. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, one of the very first 800-V fuel cell DC–DC converter (FDC) is developed for the next-generation fuel cell electric vehicles. The higher boost gain ratio and switching loss associated with increasing dc-link voltage, along with gradually increasing power density and efficiency demanded in the next-generation EV power converters, make the conventional boost converter not suitable for 800-V FDC. This article proposes a new design approach in which a zero voltage transition (ZVT) high step-up dual floating output boost converter (DFOBC) is introduced. Due to higher voltage gain, the operating duty cycle of DFOBC is reduced and lies in the vicinity of D = 0.5, which reduces filter size. The ZVT cells greatly reduce switching losses at 300 kHz, which enables using only a single discrete SiC mosfet for the main switch of 25-kW module, contributing to volume and cost reduction. Moreover, the proposed converter successfully demonstrates the possibility of using planar core and printed circuit board (PCB) windings at 100-kW power level, which is rarely seen in previous works. Finally, a 25-kW prototype of the proposed ZVT DFOBC is built and test. The power density of 63 kW/L excluding heatsink is achieved. The peak and full-load efficiency are measured to be 99.0% and 97.7%, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a new type of interleaved high step-up converter including a coupled inductor is proposed. The proposed converter has an interleaved configuration on the input side to reduce the ripple of the input current and increase the power level. Moreover, a stacked structure on the output side provides a high input/output (I/O) voltage gain. In addition, the proposed converter can avoid an extreme duty cycle, causing larger conduction losses, by combining a coupled inductor and a lossless clamp circuit with an interleaved method. These increase the efficiency by making the semiconductor device a low voltage stress and allowing the use of components with low voltage ratings. Also, the energy stored in the leakage inductor in the coupled inductor can be recycled to the output side, the MOSFETs can be partially ZCS turned ON, and the diode reverse recovery problem can be alleviated. Finally, a laboratory prototype circuit with an input voltage of 24V, an output voltage of 400V and an output of 500W was implemented to demonstrate the performance of the proposed converter.

In this paper, in order to study the relationship among different converters, a novel concept—modular high step-up converter—is proposed, which is composed of one basic converter, one Nc step-up cell (Nc-SUC), and one M-source passive lossless clamped circuit (PLCC). Nc means the number of capacitors in step-up cell and M-source represents the number of capacitors in PLCC. Nc-SUCs composed of many voltage lift cells (VLCs) and many constant voltage lift cells (CVLCs) are proposed and their general voltage gain formula is deduced. Each type of Nc-SUCs has Nc+1 different structures and the same voltage gain formula. Different Nc-SUCs can converse each other by adding or removing VLC and CVLC. Then, the general voltage gain formula of the proposed converters with Nc-SUCs is deduced, which is an additive combination of the voltage gain of Nc-SUCs and basic converter. Besides, a novel clamp circuit called M-source PLCC which is consisted of M+1 capacitors and one diode is presented. M capacitors of the M-source PLCC come from the Nc-SUC of converter, so only one capacitor and one diode are added. In comparison with classical PLCC, it makes the converters with Nc-SUCs not only possible to recycle the energy stored in the leakage inductor, but also further reduce the voltage stresses of the switch and the output capacitor, further improve the voltage gain, and even realize a three-level converter. Compared with the classical PLCC, the cost in M-source PLCC is unchanged. As M increases, the number and the variety of M-source PLCCs will also increase. Therefore, different M-source PLCCs can be chosen for the same converter to recycle the energy stored in the leakage inductor. If adopting converse thinking, based on the general voltage gain formula, removing basic converter and M-source PLCC, then, the number and the combination way of VLC and CVLC of different Nc-SUCs will expose the relationship among different high step-up converter to researcher. Finally, an improved converter based on 3-SUC as a representative of the deduced converters is proposed and analyzed in detail in the laboratory to verify performances.

A high step-up integrated coupled inductor-capacitor DC-DC converter for renewable energy applications has been proposed in this paper. Because of relative low output voltage of renewable energy systems, a high step-up converter is necessary. In this paper, a new configuration has been given by integrating coupled inductor-capacitor to get the desire voltage gain. The voltage gain dramatically boosted up by using a coupled inductor to charge a capacitor and the voltage across the switch are clamped inherently. The proposed converter possesses of only six components, which makes it uncomplicated and more efficient. The derivation of the steady state operation's principles has been analyzed in detail, this paper. Prototype hardware is implemented in the laboratory and the experimental results are given to verify the theoretical analysis.

Inductors are cornerstone components in power electronics converters. Since winding loss is the dominant loss mechanism in these components, its accurate measurement is fundamental for the validation of the inductor’s operation and design. The techniques for the winding resistance $R_{w}$ measurement in power inductors can be classified into two groups, indirect and direct. Both techniques use coupled inductors to separate winding and core power losses. If coupled inductors with non-zero winding mutual resistances $R_{w,m}$ are used, invalid results are obtained with these techniques. Understanding the meaning of $R_{w,m}$ in coupled inductors is complex. In this paper, the impact of $R_{w,m}$ on the inductor $R_{w}$ measurement techniques is demonstrated and practical guidelines for the design of the zero $R_{w,m}$ coupled inductors are given. Particularly, the location of the auxiliary winding for the direct technique is investigated. In order to compare the $R_{w}$ measurement techniques and to validate the coupled inductor’s $R_{w,m}$ impact, two different inductors are built and tested. The results are compared with the values for $R_{w}$ calculated by FEA simulation. It is found that only the direct technique with an auxiliary winding carefully designed and located following the guidelines given in this paper makes the accurate measurement of $R_{w}$ in power inductors possible.

This paper proposes a non-isolated three-port converter which integrates the input port, battery port, and load port into one converter for renewable energy applications. The coupled inductor and switched capacitor are used to achieve high voltage gain and three power switches can be utilized to realize the power flows between the sources, the battery, and the load. The energy stored in the leakage inductance is recycled to reduce the voltage stress of the power switch. In addition, various operating stages are analyzed and design considerations are presented. Compared to the relevant converters, the proposed converter can realize power flows and achieve high voltage gain by using few components. Finally, a laboratory prototype of the proposed converter with input port voltage 24 V, battery port voltage 48 V, and output voltage 400 V with 200 W rated power is implemented to validate the feasibility and effectiveness of the theoretical analyses.

This paper presents an integrated single-phase bidirectional ac–dc converter based on a dual-active-bridge (DAB) topology. The primary side is based on a multi-state switching cell (MSSC) with a T-type (TNPC) cell, which is composed of two three-level interleaved legs and coupled inductor, while the secondary side is a single-phase full-bridge (FB). Moreover, a comparative analysis between an isolated ac–dc converter with a neutral point clamped (NPC) converter on the primary side is presented. The basic converter operating principles and experimental results of a 850 W prototype are presented in order to validate the theoretical analysis. The control strategy is implemented on the TMS320F28379D DSP. The proposed topology achieves a maximum efficiency of 91.40% at 300 W output power, and 89.40% at rated power. From the experimental results, it can be stated that the converter based on the T-type topology is more efficient than the structure based on the NPC.

Three-port converters with high voltage gain are desirable solutions for integrating renewable energy and energy storage devices into high voltage dc bus. A high gain three-port converter with soft switching is proposed in this paper, which can realize zero voltage switching for all switches and zero current switching for all diodes in various operating modes. Single coupled inductor is used to achieve high voltage gain and to reduce the voltage stress of switches so that switches with low on-resistance can be selected to reduce the conduction loss. In addition, the advantages of fewer components, higher voltage gain, and very low switch voltage stresses make the proposed converter more suitable for application in renewable energy systems than similar solutions. Various operating modes, performance analysis, design considerations, efficiency analysis, and control method of the proposed converter are discussed. A laboratory prototype with 30 V renewable energy source, 48 V energy storage device and 400 V output is designed to verify the performance of the proposed three-port converter. [ABSTRACT FROM AUTHOR]

This article investigates reluctance-based dynamic models for multiphase coupled inductor buck converters. A reluctance-based state-space model is derived based on the inductance dual model of the coupled inductor. The physical core geometry is explicitly related to the circuit's dynamic properties to provide useful insights for coupled inductor design, especially if the number of phases is large. The transfer functions of multiphase coupled inductor buck converters with an arbitrary number of phases are derived based on the inductance dual model. It is shown that a symmetric multiphase coupled inductor buck converter can be modeled as a second-order dynamic system when perturbed with a common-mode duty cycle change, and the duty-cycle-to-output-voltage and duty-cycle-to-output-current transfer functions are determined by the leakage flux path of the coupled inductor. The differential-mode current balancing mechanisms of the multiphase coupled inductor buck converter are decoupled from other system dynamics and are determined only by the winding resistance and the magnetizing flux path. The applicability of the model in cases with structural asymmetry is discussed, with the results supporting the feasibility of scaling the coupled inductor structure to a large number of phases with tolerance for asymmetry. The dynamic models are verified by SPICE simulations and experimental results. [ABSTRACT FROM AUTHOR]

High step-up, high efficiency, low cost DC/DC converters have operated as an interface to make use of the renewable energy system generated power. In order to obtain desired output voltage, the DC/AC voltage conversion to AC mains voltage is an important consideration mainly achieved through inverters. Taking into acoount the performance of the non-isolated high step-up DC/DC converters for the renewable energy systems, the substantial amount of topologies studied in past years are the non-isolated high step-up DC/DC converters. Based on proposed and generalized configurations, the non-isolated high step-up DC/DC converters are classified into several categories and reviewed in this paper. So, to clarify the distinguishing solutions, the key features; topological variations, merits and demerits of these converters are discussed and compared. This review work aims to give a well-informed and a well-detailed general framework about these converters and facilitates to derive the new well topologies in the future. [ABSTRACT FROM AUTHOR]

In this article, a novel ultrahigh voltage gain dc–dc boost converter with expandable diode-capacitor voltage multiplier (VM) cells is presented. The diode-capacitor VM cells and coupled inductors are employed in the presented topology to provide a higher voltage gain. Also, the main and the auxiliary power switches of the presented converter operate with zero voltage switching. The coupled inductors' leakage inductances control the rates of the current drop in the voltage multiplier diodes, which decreases their reverse recovery losses markedly. Moreover, the voltage stresses on all capacitors and semiconductors are reduced significantly. In this converter, the number of voltage multiplier cells, and the coupled inductors turn ratios provide three degrees of design freedom. These degrees of freedom are used to set the desired voltage stresses of the semiconductors within the desired range and to provide a high voltage gain at optimum duty cycles. The design and theoretical analysis of the presented converter are discussed. Finally, the performance of the presented converter is validated using a 500 W, 40 V/380 V laboratory prototype converter, and the experimental results confirm the theoretical calculation. [ABSTRACT FROM AUTHOR]

Magnetic core inductors with a sufficiently high coupling factor ${k}$ are critical for interleaved dc–dc converters. In current work, solenoid coupled inductors with a joint magnetic core were designed and fabricated to boost ${k}$ while preserving the hard-axis excited characteristic. Devices were optimized based on a closed-loop magnetic reluctance model. Test results evidence a high coupling coefficient of 0.42. Meanwhile, a large ${L}/{R}_{dc}$ ratio of 295 nH/ $\Omega $ and a high saturation current of 1.87 A have been achieved. The performance of the coupled inductor has been calculated for a standard 1.8–0.9-V interleaved converter and a high efficiency ~96% can be obtained across a wide range of phase currents between 0.3 and 1.6 A. [ABSTRACT FROM AUTHOR]

In order to improve the step-up capability of the Zeta converter, the method of topology combination and coupled voltage doubler is used to combine the Zeta converter with a diode-capacitor multiplier while adding a coupled inductor structure. A high-gain combined Zeta converter with coupled inductor is proposed. This converter has a higher voltage gain, and the shared capacitor-diode structure in the structure absorbs the leakage inductance energy for the passive clamp branch. The working principle of the converter is analyzed, and the voltage gain expression of the converter and the voltage stress expression of the device are derived. The results show that the proposed converter has the highest voltage gain and the lower voltage stress. The capacitor-diode structure in the shared structure acts as a passive clamping branch, absorbing the leakage inductance energy without adding additional devices. The correctness of the theoretical analysis is verified by setting up 150 W experimental prototype. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a new voltage multiplier with a small number of components, composed of a coupled inductor and a switched capacitor cell, which allow four different configurations. To evaluate these configurations, these cells were integrated into the boost converter, thus generating four new high voltage gain topologies. These topologies have different characteristics: thus, the principle of operation, voltage gain, voltage and current stress, and design guidelines of each converter were evaluated. Finally, four prototypes of 30 V/400 V and 200 W were built and evaluated experimentally. [ABSTRACT FROM AUTHOR]

Due to increased demand for electricity and to curtail large consumption of fossil fuels, researchers are more focused on renewable energy sources, particularly solar photovoltaic (PV). In general, grid-tied PV systems require a high voltage boosting stage, leading to reduced efficiency. A converter is proposed along with the high gain and soft-switching capabilities by using an active-clamped circuit to the coupled inductor for grid-tied PV system applications. In this circuit, high gain is achieved by incorporating switched capacitors (SCs) in conjunction with the coupled inductor and regenerative diodes. The SCs are connected in such a way that, they store the energy in parallel and deliver the energy in a series. By using the active-clamped circuit, the switching overvoltages are diminished and also improvement in converter efficiency with the zero-voltage switching (ZVS). The operating principle of the converter and its design procedure is presented. Finally, to validate the theoretical analysis, the obtained experimental results from a laboratory prototype of 500 W rated at 100 kHz with the variation of input voltage, 36–48 V, and output voltage 400 V are presented. [ABSTRACT FROM AUTHOR]

Circuit models for multiphase coupled inductors are summarized, compared, and unified. Multiwinding magnetic structures are classified into parallel-coupled structures and series-coupled structures. For parallel-coupled structures used for multiphase inductors, the relationships between: 1) inductance-matrix models, 2) extended cantilever models, 3) magnetic-circuit models, 4) multiwinding transformer models, 5) gyrator-capacitor models, and 6) inductance-dual models are examined and discussed. These models represent identical physical relationships in the multiphase coupled inductors, but emphasize different physical aspects and offer distinct design insights. The circuit duality between the series-coupled structure and the parallel-coupled structure is explored. Design equations for interleaved multiphase buck converters based on these models are streamlined and summarized, and a simplified equation showing the relationships between current ripple with and without coupling is presented. The models and design equations are verified through theoretical derivation, SPICE simulation, and experimental measurements. [ABSTRACT FROM AUTHOR]

This letter demonstrates an on-silicon integrated thin film coupled inductor using a novel cascade matrix concept to suit multiphase integrated voltage regulator (IVR) applications. The novel cascade matrix coupled (CMC) stripline inductor facilitates all-phase-coupled configuration to reduce the phase ripple current in IVRs. It also shows excellent scalability and neat floor planning. Moreover, the proposed CMC inductor uses double layer metal scheme for windings and interconnects, which significantly reduces the ac winding resistance. A four-phase CMC inductor has been successfully fabricated on-silicon substrate and characterized, which uses conventional thin film magnetic core deposition process to achieve in-plane magnetic uniaxial anisotropy. The device occupies 3.2 × 1.7 mm2 floor area and provides 19.5 nH phase inductance with 120 mΩ dc resistance. The saturation current for each phase is up to 0.4 A when the phase inductance drops by approximately 20%. The coupling coefficient between any two phases of the proposed CMC inductor is 0.27, much higher and more controllable than that of toroid core-based coupled inductors. [ABSTRACT FROM AUTHOR]

In this work, a non-isolated high step up DC-DC converter using coupled inductor and voltage multiplier cell is proposed. The proposed converter conversion ratio is efficiently extended by using a coupled inductor. An interleaved configuration of two diode-capacitor cells is applied to step up the voltage conversion ratio and decrease the voltage stress across the switches. Also, in the suggested converter high voltage gain is provided by low turn ratio of the coupled inductor which decreases the volume of cores. Moreover, the reverse recovery problem of output diode is diminished by recycling the leakage inductance energy of the coupled inductor. It causes to increase the overall system efficiency. Furthermore, the voltage multiplier cells lead to clamp the voltage spikes through the switch, when the switch turns off. The comparison between the suggested converter and similar converters is provided to verify its advantages. To validate the effectiveness of the suggested converter, a 200W laboratory prototype with 20V input and 150V output voltages operating at 25kHz switching frequency is carried out and experimental test consequences are given.

In this paper, a high-efficiency DC/DC converter with low voltage stress is designed for green power applications. The proposed non-isolated high step-up DC/DC converter combines the advantages of switched capacitors, coupling inductors, and voltage multiplier techniques. Adding the cells of the switched capacitor not only increases the voltage gain but reduces the voltage stress of the semiconductor devices. High voltage gain can be achieved by adding a coupled inductor method to adjust the turns ratio. When these are combined with a voltage multiplier circuit, the leakage energy of the coupled inductor is recirculated to the output terminal with lossless passive clamping performance. The leakage inductance of the coupled inductor controls the current dropping rate of the output diode turn OFF so that the reverse-recovery problem is mitigated. The proposed converter integrates these three techniques to achieve high voltage gain without operating at maximum duty cycle. In addition, switching loss reduction is realized through zero current switching turn ON soft switching performance with low voltage stress of semiconductor devices. Finally, this paper verifies the performance of the proposed converter for theoretical analysis by using a 35~45V input, 380V output, and 1kW power prototype circuit.

Application of coupled inductor in designing nonisolated bidirectional dc–dc converter provides flexibility to attain high voltage conversion ratio both in buck and boost mode of operation. In this article, a new coupled inductor bidirectional converter is designed with low winding turns ratio (n = 1). The proposed topology uses two current path inductor structure which improves voltage conversion ratio and shares current in all operating modes. All the active switches in the proposed topology are soft switched utilizing synchronous rectification concept. Higher efficiency operation is possible as no extra circuit elements are required to achieve soft switching. Leakage energy of coupled inductor is successfully stored in a clamped capacitor which is utilized in the circuit topology. The voltage stress and current stress level of main active switches are low. The proposed circuit is simulated and performance parameters are verified through hardware results. Both simulation and experimental results performed on a 250 W prototype confirm to attain a high efficiency of the proposed converter with simple hardware requirement for practical implementation. [ABSTRACT FROM AUTHOR]

In this article, a family of dual-boost bridgeless five-level rectifiers with common-core inductors is proposed, which is composed of two coupled inductors, one bidirectional switch unit, and the dual-boost bridgeless power factor correction (PFC) rectifier. A bidirectional switch unit is embedded in the midpoint between the two capacitors and the bridge arm of the dual-boost bridgeless PFC (DBBL-PFC) to directly generate the five-level waveforms in each line cycle. The proposed topologies have the characteristics of lower voltage/current stresses and low total harmonic distortion. Additionally, the proposed five-level rectifiers employ a pair of common-core coupled inductors at the input side to replace the inherent independent inductors to improve the core utilization and the power density. First, the characteristics of the proposed topologies are analyzed and compared, and one of the topologies is taken as an example to illustrate its operating principle. Second, the modulation strategy with strong topology applicability and control system is designed for the proposed topologies. The advantage of the proposed pulsewidth modulation method is that it only needs to change the pulse distribution of the five-level topology to realize the five-level rectification, and the program debugging is simple. Then, the coupled inductors are designed, compared, and analyzed by the equivalent model in detail. Finally, a rated output of 1 kW/400 V experimental prototype is built, and the experimental results are presented to demonstrate the performance and effectiveness of the proposed topologies. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, a high-gain bidirectional quadratic dc–dc converter is proposed. This converter is studied under step-up and step-down modes. In each power flow direction, two switches and two antiparallel diodes of the other switches operate. Therefore, the switching losses depend only on the operation of two switches in each direction. The use of coupled inductor in the proposed converter significantly reduces the input and output current ripples of the step-up and step-down modes, respectively, at all operating points of continuous and discontinuous conduction modes (CCM and DCM). The voltage gain of the proposed converter in the step-up mode is as high as that of the cascaded boost converter, and in the step-down mode, the converter voltage gain is similar to that of the cascaded buck converter. Thus, the high-voltage conversion ratio with an appropriate duty-cycle in both power flow directions can be achieved. The operating principles and steady-state analysis of the proposed converter in CCM, DCM, and the boundary-conditions between these modes are discussed in detail. Finally, a prototype of the converter is implemented in the laboratory and the experimental results are presented to validate the effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

An optimized configuration of bidirectional Z-source circuit breaker using a coupled inductor is introduced for the fault isolation in low-voltage dc microgrid. The proposed circuit breaker is designed to operate with a single coupled inductor for bidirectional power flow. Use of the single coupled inductor for the power flow in both the directions reduces the component count. In this article, the operating principle of the breaker is explained for a short-circuit fault condition and breaker design criteria are derived. The performance of the circuit breaker is evaluated by carrying out a MATLAB simulation study. The functional prototype is developed to validate the breaker capabilities. Experimental results show that the fault is cleared within few microseconds. Additionally, the breaker is tested under the step load change condition for a current five times the steady-state rated current of the breaker and results are satisfactory. [ABSTRACT FROM AUTHOR]

There are different low switching stress non-isolated DC-DC power converter structures developed for Photo-Voltaic (PV) applications with a view to achieve high voltage conversion ratio. The work proposed in this research article investigates the performance analysis of a coupled inductor and diode-capacitor multiplier cell based non-isolated high gain single-switch DC-DC conversion scheme with a single-ended primary-inductor on the input side. The presented converter suitable for renewable energy applications has the merits such as continuous input current, high voltage conversion ratio, and reduced voltage stress across the power switch. The multiplier cell consisting of two diodes and two capacitors is mainly used to enhance the converter output voltage level. A MATLAB / SIMULINK model of the suggested topology has been developed to validate its performance. During the simulation of the converter, a DC voltage of 50 V was given at the input side. The load end received a DC voltage of approximately 900 V. Thus, through this study, it was found that the addition of diode-capacitor cell can significantly improve the static gain of the suggested converter. The findings of this research may serve as a base for future studies on improvement of voltage gain of DC-DC converters. [ABSTRACT FROM AUTHOR]

The magnetic coupling of filter inductors is widely utilized in various power electronics application fields, including most commonly implemented dc-dc converters in electric vehicle charger systems, in order to enhance the filtering performance while maintaining the minimal filter size. The optimal distribution of self and mutual inductance of the coupled inductor is regarded as one of the important design tasks with respect to the coupling factor. This article proposes an explicit mathematical form of the optimized coupling factor design of a generalized n-winding coupled inductor, which generates the least size of inductor current ripple in phase-staggered multiparalleled dc-dc converters. The general equations for the n-winding coupled inductor are verified through the example case of the three-winding coupled inductor. The experimental results successfully confirmed the newly proposed method of obtaining the optimal coupling factor. [ABSTRACT FROM AUTHOR]

This paper presents a new soft switching high voltage gain interleaved dc-dc converter with a three-windings coupled inductor for a fuel cell vehicle. Two interleaved and intercoupled boost cells are connected by the input parallel and output series (IPOS) configuration, realizing low input current ripple and high voltage gain simultaneously. All power switches can operate under soft switching conditions by only adding a simple auxiliary circuit composed of one auxiliary inductor and one power switch. Besides, the auxiliary inductor is coupled with the main inductors, which results in a rapid zero convergence of the auxiliary current and a small conduction loss of the auxiliary circuit. The operating principle, steady state characteristic, comparison with other converters, and parameter design are analyzed in this paper. Finally, the main characteristics of the proposed converter are verified by a 1-kW laboratory prototype. [ABSTRACT FROM AUTHOR]

This brief proposes a method to dynamically modeling the coupled-inductor double-boost converter operating in continuous-conduction mode. Such method has the advantage of including the leakage inductance effect on the dynamic behavior of the converter in a simple, straightforward approach. The presence of the leakage inductance is initially neglected and a traditional circuit-averaging technique is used. The averaged models are then refined by accounting the impacts of the reported inductance. Since its major impact is on the damping factor of the system, this dynamic change is modeled by equivalent resistors. Equations for describing the equivalent resistors are derived based on the analysis of the duty cycle loss caused by leakage inductance in the static gain of the converter. The effect on the averaged small-signal model is shown by a closed-form control-to-output transfer function and experimental results demonstrate its accurate performance. [ABSTRACT FROM AUTHOR]

To overcome low output voltage of renewable energy sources such as photovoltaic arrays and fuel cells, a high step up SEPIC-based multi-input converter with dual coupled inductor is proposed. A new structure is presented in this paper, as an improved structure. This converter is based on combination of modified quadratic buck-boost converter, Dickson switched capacitor (DSC), and voltage multiplier modules (VMM). The high voltage gain can be achieved by adjusting the duty cycle and turn ratio of coupled inductor of VMM. This structure inherits all the advantages of the SEPIC converter such as step-up/down capability without inverting the polarity of regulated output voltage and using a bidirectional input port (in which an energy storage system (ESS) can be connected), and several unidirectional input ports. The load power can be flexibly divided among various power sources. Due to the buck-boost characteristics of the presented converter, it is suitable to charge-discharge the ESS. A coupled inductor (CI) is used to couple energy from input to the output equipped with the VMM. The usage of the DSC technique also enables the converter to obtain an additional double voltage gain while reducing the voltage stress on switches. Simulation results verify the performance of the proposed converter and feasibility of the control strategy. [ABSTRACT FROM AUTHOR]

In this article, a coupled inductor common-ground single-phase inverter, well-suited for photovoltaic (PV) applications, is presented. The proposed PV inverter is constructed based on a two-stage topology. At the first stage, a high gain DC-DC structure converts low PV voltage to the high bipolar output voltages. The produced bipolar output voltages are the inputs for the conventional half-bridge inverter in the second stage. It is noteworthy that the parasitic capacitors between the PV panel and its ground provide the path for circulating the leakage current in conventional configurations. This problem is tackled in the proposed topology by making a common-ground structure. Furthermore, the first stage contains only one switch with low voltage stress, which leads to a significant suppression in conduction losses. The proposed DC-AC structure has the ability to reduce the input current ripple and also recycle the leakage energy caused by the coupled inductor. The operation principles of the proposed structure are analyzed in detail, and finally, the experimental results are accomplished to confirm the accuracy of the performed analysis. [ABSTRACT FROM AUTHOR]

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The bidirectional dc-dc converter with high voltage gain and high efficiency plays an important role in the designing of battery charging systems. In this paper, design and development of a battery charging system utilizing coupled inductor based high gain dcdc converter is presented. The converter uses a clamp capacitor network to recover the leakage energy of a coupled inductor. The converter has inherent soft-switching capability during turn ON, which ensures high efficiency at high switching frequency. Design equations to derive value of different passive components are given and a step-wise exclusive design to construct coupled inductor is presented. A 50 kHz, 500 W laboratory prototype has been designed, which can increase the voltage with 10 gain (boost operation) in one direction and can reduce the voltage at (1/10) gain (buck operation) in other direction. The CCCV battery charging algorithm is implemented using generic ARM Cortex-M4 microcontroller. Extensive experiments have been performed and the experimental results are presented in buck, boost, and battery charging operations. [ABSTRACT FROM AUTHOR]

A new non-isolated, coupled-inductor, single-switch boost DC-DC converter for photovoltaic (PV) power application is introduced in this paper. A coupled inductor and voltage multiplier cells is used in the presented converter to obtain a high voltage conversion ratio. Also, a passive clamp circuit is applied in the converter structure to reduce voltage stress of the power switch. This leads to using a power switch with lower on-state resistance in the converter which decreases the conduction loss. In addition, zero current switching (ZCS) condition for the power switch is achieved due to the use of the clamp circuit. Several advantages such as low operating duty cycle, high voltage conversion ratio, reduced voltage stress of semiconductors, low turn ratio for the coupled inductor, leakage inductance reverse recovery and high efficiency operation make the presented converter suitable for renewable energy applications. The steady state operation of the suggested structure in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) is expressed and analyzed. Then, the presented topology is compared with several similar high gain topologies to prove its advantages. Finally, experimental measurement results of a laboratory prototype of the proposed DC-DC converter with about 213W output power and 435V output voltage at 50 kHz switching frequency are presented to corroborate its feasibility and performance.

Fractional order coupled inductor (FCI) was proposed recently which can enrich existing circuit element system. In this paper, the passivity conditions of FCI are discussed. The study shows that different from the traditional passive coupled inductor, passive fractional order coupled inductor (PFCI) can be non-reciprocal. Traditional integer order coupled inductors are special cases of FCI, and the passivity conditions between them have great differences. Based on passivity conditions of FCI, modified multivariate positive real definition is proposed and multivariate passivity of general FCIs also be proved. Finally, this paper proposes passivity criterions of networks with general FCIs in the complex frequency domain and multivariate domain, respectively.

This study mainly develops a high-efficiency single-input triple-outputs dc/dc converter (HSTDC) with a soft-switching technique for high step-up applications. In general, multiple output voltages with only one single input power source is always required for the applications of renewable energy or electric vehicles. At the high step-up operation, the proposed HSTDC has a high voltage conversion ratio to sustain the high-voltage dc bus for the utilization of dc/ac inverter. The proposed HSTDC uses a coupled inductor with lower turn ratios to achieve the high step-up voltage gain and adopts an auxiliary inductor to adjust the voltage of the auxiliary output terminal indirectly. Moreover, the utilization of voltage clamping and zero-current switching (ZCS) in the proposed HSTDC is helpful for accomplishing the goal of high-efficiency power conversion and three output voltage levels. In addition, the effectiveness of the proposed HSTDC is verified by rich experimental results.

The study proposes a novel integrated three-port bidirectional dc/dc converter for energy storage systems. The converter includes two batteries, namely 24- and 48-V batteries, used as input source and for backup energy, respectively. Each battery can supply to dc load in the normal case. When the grid power fails, 24-V battery input is stepped up to the dc bus through a high step-up converter. The 48-V battery serves as a buffer power supply when the load increases instantaneously. At night, when the 48-V battery is under low power consumption, the dc bus can charge the battery. In addition, the converter can monitor both battery voltages simultaneously; when one battery is used excessively, the other battery can charge it, thus keeping the system power stable. The integrated three-port bidirectional dc/dc converter is a combination of a boost-flyback, forward converter, and voltage doubler and has the following advantages: 1) it operates in input continuous current and low voltage stress; 2) it provides input current recovery; 3) it improves high reverse voltage caused by the transformer; 4) it operates in zero current switching (ZCS); and 5) its doubler circuit can flexibly adjust the dc bus voltage. A 500-W three-port bidirectional dc/dc device was implemented to verify the feasibility and practicability of the proposed converter. The highest efficiency achieved for operation in 24-V battery high step-up mode was 95.3%; it was 94.9% and 95.2% in 48-V battery step-up and step-down mode, respectively.

Coupled inductors can effectively optimize the THD, loss, current ripple, and power density of multiphase interleaved totem-pole PFC converters. However, a coupled inductor will also worsen the zero-crossing distortion process. This paper first introduces the working principle of the interleaved totem-pole PFC converter with a coupled inductor based on a detailed analysis of modes, and then analyzes the influence on the zero-crossing process caused by the coupled inductor. To eliminate the zero-crossing distortion caused by the coupled inductor, an improved control strategy and its digital realization method of the totem-pole PFC converter is presented through the system model. Finally, the validity and correctness of the proposed circuit and control are verified in the 7.7 kW interleaved totem-pole PFC converter.

This paper presents a novel three-port high-step-up/step-down bidirectional DC/DC converter with a coupled inductor for photovoltaic (PV) systems. The proposed converter combines a high-step-up converter, which is used to step-up the PV module to DC bus 200 V, and a battery charge/discharge bidirectional converter to form a three-port bidirectional converter. When sufficient energy is supplied from the PV modules, the converter can step-up the output of the PV modules and provide energy to the DC bus while charging the battery simultaneously. However, when no energy is supplied from the PV modules, the DC bus voltage is provided by the battery. Moreover, the energy stored in the leakage inductor is recycled to the DC-blocking capacitor, and synchronous rectification is conducted in the switch during the step-up mode to reduce switch loss and thereby increase the system’s overall efficiency. Finally, a 500 W three-port bidirectional converter is implemented to verify the feasibility and practicability of the proposed converter. The maximum efficiency of the proposed converter is 95.4%, 94.3%, and 94.7% when operated in the high-step-up mode, battery step-up mode, and step-down mode for the PV modules, respectively.

Summary: This work proposes a kind of DC–DC topology with a higher voltage conversion ratio. The suggested converter utilizes a coupled inductor and a voltage multiplier cell to enhance the voltage conversion ratio. The voltage multiplier cell has the feature of the clamping circuit, which can decrease the maximum voltage of the semiconductors elements. In the presented structure, only one lower ON‐state resistance (RDS‐ON) power switch is utilized that makes the control circuit to be simple. The proposed converter has soft‐switching features such as zero‐current switching (ZCS) and zero voltage switching (ZVS) that lead to decrease the diodes reverse recovery losses and increase the efficiency. Besides, the ripple value of the input current is lower than the other similar works. The high efficiency and low input current ripple make the suggested converter suitable for photovoltaic (PV) applications. In order to approve the technical analysis of the recommended structure, technical investigations and comparison study with some similar structures are carried out. Finally, for demonstrating the advantages of the presented structure, a laboratory circuit is built with 12‐V DC source voltage, 120‐V load voltage, and power rate of 100 W in 50‐kHz operation frequency. [ABSTRACT FROM AUTHOR]

Summary: A single‐switch ultra‐high voltage DC‐DC converter is proposed in this paper. In the introduced structure, a voltage multiplier cell (VMC) and three‐winding coupled inductor (CL) are integrated to obtain an ultra‐large voltage gain. The input current ripple of the presented configuration is very low due to utilizing an inductor in the input part of the converter which is a very important factor in clean energy applications. The CL leakage inductance energy is successfully recovered, and the main power switch voltage stress is clamped because of using a passive clamp circuit. Therefore, a switch with low os‐state resistance can be applied, which declines the conduction losses as well as the cost of the suggested topology. Moreover, the common ground between the input and output of the proposed configuration makes it suitable for many applications such as photovoltaic systems. Some important merits include ultra‐high voltage gain, operating in low duty cycles, reduced voltage stress of semiconductors, continuous input current, and high efficiency, which make the introduced converter very suitable for clean energy applications. The operation principle, steady‐state analysis, design considerations, and theoretical efficiency analysis of the suggested converter are discussed completely in the paper. Also, the superiority of the proposed converter over recently suggested similar most important DC‐DC converters is demonstrated in the comparison study. Finally, the performance and theoretical analysis of the converter are validated with the experimental results at an output voltage of 450 V and an output power of 250 W. [ABSTRACT FROM AUTHOR]