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To boost the dynamic performance of the full-bridge (FB) dc–dc converter, some model-based controls have been recently proposed in the literature. However, in terms of dynamic performance, these methods have failed to reveal the potential of this converter since the inherent relationship among the duty ratio, the input voltage, the output voltage, and the load resistor is not adopted in the controller, and the dynamic performances are still relayed on the fuzzy adjustment based on the disturbances of output voltage as the single-voltage-loop control method. In this article, based on this inherent characteristic of the FB dc–dc converter, an accurate transferred current modulation method is presented first. Based on this modulation method, a simple direct current control (DCC) scheme is proposed for a fast dynamic response with the feedback values of input voltage and load current. Moreover, the model uncertainties such as the power losses and control delay may influence the control performance. Therefore, a compensation operation is also presented to reduce the impact caused by these uncertainties to ensure the dynamic performance of the proposed strategy. In addition, since the circuit parameters including the leakage inductance and the output capacitor should be employed to implement the proposed DCC strategy with compensation operation, inaccurate circuit parameters may influence the performance of these proposed strategies. Therefore, the circuit-parameter estimation methods for these two circuit parameters are also proposed to ensure the dynamic performance of the FB dc–dc converter. Finally, the simulation and experiment results have verified the correctness and effectiveness of the proposed DCC strategy.

An active-clamp resonant power factor correction converter with output ripple suppression is proposed and analyzed. It combines a buck power factor correction (PFC) unit and a resonant dc-dc unit by sharing one active switch. With another active-clamp switch, a recycling path is built to recover the leakage inductance energy of transformer, which improves the efficiency and the voltage stress of active switch. The effect of voltage ripple of dc link on output can be suppressed by fast voltage mode control loop. Therefore, low output current or voltage ripple can be achieved. With small voltage ripple across output of buck unit, the turn on time of active switch is almost constant in a half line cycle. Therefore, power factor correction can be achieved with inductor current of buck unit operating in discontinuous conduction mode (DCM). Finally, a 65W high power factor (PF) converter prototype for LED driver application with 91.08% peak efficiency and low output current ripple is built to verify the analytical results.

In this paper, an integrated transformer design methodology for dual-active-bridge (DAB) converters, which basically utilize leakage inductance so as to substitute a cumbersome inductor in the conventional DAB converters, is newly proposed. The proposed integrated transformer with integrated leakage inductance inherently includes leakage inductance and magnetizing inductance, whose values can be appropriately selected by modulating the number of turns and the center-core air-gap. Based on the theoretical analysis of the DAB converters, the major parameters, i.e., primary and secondary current levels and its phase difference, can be derived, and these values are utilized for magnetic analysis of the proposed integrated transformer. Considering core loss and copper loss of the proposed integrated transformer in the DAB converters, optimal values of the center-core air-gap $l_{g}$ and the optimal number of turns $N_{\mathrm {1,}op} ~\&~ N_{\mathrm {2,}op}$ can be determined so that high power efficiency is achieved at a normal operating point of the DAB converters. The 20W prototypes of the DAB converter with EER2834 and EER3019 of the ferrite cores were fabricated and verified by simulation and experiment. The design results showed that the optimal number of turns at $l_{g} =2.0$ mm are found to be 11 and 10, for the EER2834 and EER3019, respectively. Compared to 94.5% and 96.3% of AC efficiencies for the conventional transformer and inductor set, the proposed integrated transformer achieved 95.8% and 96.9% of AC efficiencies at maximum power transfer point of $\theta _{p} = \pi $ /2 for EER2834 and EER3019, respectively.

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.

LLC resonant converter has the advantages of high frequency and high efficiency, and has been developed rapidly and widely used in recent years. However, due to the presence of multiple magnetic components in the circuit, the improvement of power density is limited. To solve this problem, integrated magnetic transformer is usually designed to replace the discrete magnetics. While, the leakage inductance of the transformer cannot be controlled, the loss of the converter increases. In this paper, a magnetic integrated LLC resonant converter with independent inductance winding is proposed. The resonant inductance and magnetizing inductance are integrated with the transformer in the same magnetic core by using the decoupling integration method. Compared with the existing solution of magnetic integrated LLC resonant converter, this method can reduce the leakage inductance between the transformer windings and decrease the magnetic saturation of the integrated magnetics, thereby reducing the magnetic core loss and improving the efficiency of the converter. Compared with the discrete magnetics, the volume and weight of the magnetic components are reduced by 25.68% and 43.82% respectively, making the power density of the converter effectively improved. Finally, an experimental prototype of integrated magnetic LLC resonant converter with operating frequency of 350kHz and output power of 400W is built. The experimental results verify the correctness of the design scheme.

The magnetic field of end windings affects the leakage reactance of end windings and the eddy current losses of end structures in the large electrical machine. With the rising of single-machine capacity, such effect becomes more obvious. However, due to the complexity of end structures of large electrical machine, it will cause difficulty in meshing and long calculation time to calculate the magnetic field of end windings by using 3-D finite element method (FEM). In order to calculate the magnetic field of end windings quickly and accurately, an improved analytical algorithm (IAA) is proposed based on the mirror image principle, which takes into account the influence of stator back core and air-gap on the magnetic field of end windings by adding the fictitious boundary current and air-gap current, respectively. Taking a 300Mvar synchronous condenser (SC) as an example, the boundary current, air-gap current and magnetic field of end windings are calculated. Then, the influence of stator back core and stator involute segment current on the magnetic field of end windings are analyzed, which provides a theoretical support for the design and optimization of SC. To validate the accuracy of IAA, the calculation result is compared with 3-D FEM.

Funding Information: This work was supported by FinElib, Finland, through the FinELib consortium's agreement with IEEE. Publisher Copyright: © 2013 IEEE. In this paper, a new family of ultra-high step-up DC-DC converters based on a center-tapped coupled inductor (CI) is proposed. These single-switch converters employ different inductive and capacitive power transfer techniques by utilizing multi-winding CIs, intermediate capacitor links and simple switched-capacitors to improve the transferred power rate, harvest magnetizing and leakage inductance energies, and enhance power density. Achieving high voltage gain in low duty cycle values enables the proposed converters to operate under wide output voltage ranges; meanwhile, distributing the output voltage on two or three output ports alleviates the voltage stress on output terminal components. Low input current ripple, simple pulse width modulation control, low switch voltage stress and operation without circulating current can be listed as other features. In this paper, the proposed family is introduced, theoretically analyzed and compared with other state-of-the-art researches. Finally, the accuracy of analyses are evaluated with some experimental tests of a 1.25 kW experimental prototype.

Recent studies on compact and lightweight electronic devices have demonstrated that the LLC resonant converter (LRC) can facilitate achieving high efficiency and high power density. Moreover, employing a planar transformer can further improve the overall system power density. Although the planar transformer can assist in reducing the size of the converter, its high magnetic coupling makes the leakage inductance too small for a resonant inductor in the LRC. Therefore, an extra inductor must be employed separately, leading a considerable decrease in the power density. From this reason, significant research on integrated magnetics has been conducted to combine a transformer and external inductor into a single core. However, they require additional wires or magnetic sheets, and their structures are complex and costly. To overcome these limitations, the integrated magnetics planar transformer (IMPT) for a high power density LRC is proposed in this paper. In the proposed approach, since the primary wire is split into each side leg of the EE-type magnetic core and each operates as a transformer and a resonant inductor alternatively, an external inductor or additional wires are unnecessary. In addition, since the magnetic flux density of the IMPT is approximately equivalent to that of conventional transformer, the core size and the number of turns are almost the same. Therefore, the proposed IMPT features higher efficiency and power density without additional size and costs. To confirm the validity of the proposed IMPT, the operational principles, theoretical analysis, design considerations, and experimental results from a 350 W prototype are presented.

A fast and accurate model of the transformer leakage inductance is crucial for optimization-based design of galvanically isolated converters. Analytical models are fastly executable, and therefore, especially suitable for such optimizations. This article compares several analytical leakage inductance per unit length models with respect to the accuracy and computational effort. The considered models are applicable to E-Core and U-Core transformers. 2D FEM simulations are used as a benchmark to evaluate the model accuracy, whereas the computation time is extracted as an indicator for computational effort. Six different transformer prototypes provide the geometries for the comparison. Based on the conducted comparisons, Roth's model is the most accurate. Rogowski's model is the fastest low-error model. Margueron's model is the most versatile as it takes the finite permeability of the core into account. The conducted comparisons lay the foundation for accurate and fast Double-2D modeling of the transformer leakage inductance as it is executed for the two main cross sections of E-core and U-core transformers: inside the transformer window, and outside the transformer window. This article is accompanied by a supplementary document summarizing the equations of Roth's and Margueron's model. ISSN:0885-8993 ISSN:1941-0107

This article presents an efficient interleaved soft switching dc–dc converter for high step-up applications. In the proposed converter, two multifunction coupled inductors are employed to increase the voltage gain, accomplish soft switching operation for all semiconductors in a wide range of load variations, and smooth the input current. Besides, the leakage inductance energy is recovered to enhance the voltage gain and efficiency while assisting soft switching condition for the switches and diodes. In addition, no auxiliary switch or extra magnetic element is employed in the proposed converter while the voltage stress of switches and diodes is rather low. These have led to simple structure, high density, low cost, and improved efficiency. Theoretical analysis and design considerations for the proposed converter are presented. Moreover, the experimental results of a 48 to 500 V laboratory prototype approve the effectiveness of the proposed topology.

This paper proposes a high-performance isolated single-ended primary inductor converter (SEPIC) that is integrated with a non-dissipative snubber for a light-emitting diode (LED) driver. The proposed LED driver employs the snubber circuit to minimize any switching overvoltage caused by parasitic leakage inductance of the high-frequency transformer in the isolated SEPIC converter. This paper also presents a detail theoretical analysis of the proposed LED driver including its operating modes and design calculation. The experimental results of the proposed LED driver at the rated power of 18 W shows that it has a high-power factor, low harmonics, employs non-electrolytic capacitors, low switching stress, high reliability and high efficiency.

Flyback converters are widely used in low power applications due to the simple topology and isolation. However, severe EMI problem occurs because of the rapid switching. Along with the presence of transformer, which makes it difficult to analyze the propagation routes of the noise current. In this letter, a developed common mode noise modeling approach for flyback converters is proposed. Regarding to the transformer model, this investigation not only analyzes the stray capacitance but also takes leakage inductance into consideration, which had been ignored in the previously published models. Besides, the switching voltage waveform is captured and decomposed at time domain. This hypothesis could simplify the following Fourier analysis calculation in frequency domain. Meanwhile, the proposed method could also improve the model accuracy as high frequency ringing has been taken into considerations. The experimental results demonstrated the effectiveness and feasibility of the proposed modeling method.

In this article, a new single-switch buck converter (without considering the synchronous rectifier) with extended duty cycle and continuous output current is proposed. The presented converter employs a self-driven synchronous rectifier with gate energy recovery, which leads to efficiency improvement and simplicity of the converter and the gate drive circuit. The extended duty cycle results in lower current stress of the high-side MOSFET and reduced voltage stress across the synchronous rectifier. Furthermore, the reverse recovery losses of synchronous rectifier are dramatically decreased due to the applied coupled inductors. The introduced converter also provides shoot-through protection and load protection when the high-side MOSFET remains on . In order to clamp the drain–source voltage spikes of the main switch and recover the leakage inductance energy, a lossless snubber circuit is added, which reduces the turn- off drain–source voltage and consequently decreases the turn- off switching losses of the main MOSFET . Moreover, the main switch turns on under zero current switching (ZCS), which results in efficiency improvement. A 150-W prototype of the proposed converter is implemented to verify the theoretical analysis and confirm its efficiency improvement and advantages.

The naturally commutated current-fed dual-active-bridge (CF-DAB) dc/dc converter is a suitable solution for the distributed generation system with low input current ripple and convenient current control. However, the efficiency under light load conditions is still a challenging issue with existing modulation schemes. In this article, a decoupled dual-pulse width modulation (PWM) control strategy is proposed to enhance the efficiency within a wide load range. The proposed modulation adjusts turn-on moments of secondary-side switches flexibly and charges the leakage inductor properly based on the instantaneous input current. The peak leakage inductor current, primary-side rms current, and the corresponding losses are reduced effectively compared to existing methods. Meanwhile, the proposed modulation strategy avoids the interactions between the primary-side duty cycle and the secondary-side duty cycle so as to decouple the voltage conversion ratio with leakage inductance and load conditions and simplify the control-loop design. The design process, power loss analysis, and implementation of the proposed modulation strategy are presented in detail. The impacts of deviations in parameters of input inductor and leakage inductor are also analyzed. Based on parameter estimation, a specific compensation loop without an additional current sensor is proposed to further improve the stability of the closed-loop control for the converter. The experimental results are given to verify the theoretical analysis and validity of the proposed modulation.

Recently, transformers with toroidal core have received much attention. The compactness and weight of these kinds of transformers make them suitable for power electronics applications. In some areas, it is necessary to have a toroidal transformer with particular parasitic elements such as leakage inductance. So, there is a need for a precise method to calculate the exact amount of leakage inductance for designing the desired system. This article presents a pure analytical method based on Maxwell’s equations to accurately determine the leakage inductance of a toroidal transformer which its windings are wounded separately. The proposed expression for the leakage inductance calculation considers the influence of the core specifications, such as dimensions and material. In order to validate the presented method, 3-D finite-element simulation and experimental results of the prototype transformer have been done.

A zero voltage switching (ZVS) interleaved high step-up converter with coupled inductor and built-in transformer voltage multiplier cell is introduced in this study. A more flexible design is provided by increasing the voltage conversion ratio by utilising the turns ratios of the coupled inductor and built-in transformer. The ZVS operation of the metal-oxide-semiconductor field-effect transistors (MOSFETs) and absorption of the leakage current are realised through active clamp circuits. Furthermore, the voltage stress across the switching devices is minimised that give rises to implementation of low voltage rated MOSFETs and consequently low conduction losses. Meanwhile, the diode reverse current problem is alleviated by the leakage inductance of the coupled inductor and built-in transformer. All of the abovementioned advantages make the proposed converter as a high efficiency candidate for high current and high step-up applications. Finally, a 600 W, 48–700 V voltage conversion with the conversion efficiency of 97% is fabricated to probe the merits of the proposed converter.

Boost dc/dc converters are widely used in renewable energy systems. With growing demand for high efficiency and high voltage gain, many new topologies have been published. This article proposes a novel zero current switching (ZCS) boost converter with a tapped inductor and active edge-resonant cell (AERC). To achieve high voltage gain, the tapped inductor was implemented in the structure of the converter, and by employing an AERC, ZCS of transistors was attained. Subsequently, by employing a resonant operation current, overshoots by leakage inductance were eliminated. This article presents an analysis, mathematical derivations, and laboratory test results. Finally, a 30–50 V input, 380 V output, and 750 W output power laboratory model operating with 45–100 kHz switching frequency was built and tested. The maximum reported efficiency was 96.6%. Soft switching of semiconductors was achieved in the whole output power range.

This study proposes a new high step-up DC–DC converter based on a novel super-lift structure and coupled inductor. The energy stored in the leakage inductance of the coupled inductor is recovered to the converter output, which leads to a snubber-less operation and consequently a fewer-component, lower-cost and more-efficient converter. This feature also reduces voltage stress and the current peak of the active switch without using a snubber circuit. Analysis of continuous current mode of the proposed converter considering the leakage inductance has been demonstrated. Moreover, a comparison between several converters has been done for further information about similar research works. Experimental results such as voltage and current waveforms and efficiency curve have been presented to show the practical characteristics of the proposed converter.

This article presents a novel direct single-power-conversion bidirectional grid-connected inverter for solving the commutation problem and a control strategy for it. The proposed inverter directly interfaces with a low-voltage battery and grid with only one power conversion stage and performs a bidirectional power conversion. The reliability of the proposed inverter is improved because the commutation capacitor eliminates the commutation problem by providing commutation paths in any switching case. The frequency compensation method converts the nonlinear power transfer characteristic into linear and makes grid current control easy. Furthermore, the interdependence of three control variables enables the control of the grid current using a simple equation. The proposed dual-mode control strategy increases the power capacity of the proposed inverter without increasing the turns ratio and decreasing the leakage inductance. The conduction losses can be reduced using this strategy. Additionally, the ZVS capability reduces the switching losses. These features of the proposed inverter and its control strategy enable the proposed inverter to achieve high efficiency and power quality with a simple structure. The theoretical concepts of the proposed inverter were experimentally verified using a 1-kW prototype.

La humanidad está generando un crecimiento tecnológico no sólo continuo sino exponencial, una idea que abre la posibilidad a imaginar un futuro emocionante, cada vez el ser humano se interesa más por lograr mayor eficiencia en sus dispositivos de tal manera que se pueda aprovechar la energía lo máximo posible pues no se desconoce que la demanda energética es cada vez mayor. Puntualmente hablando de dispositivos, los transformadores de energía son más que comunes, la utilidad prestada por los mismos es muy alta dada la diversidad de tensiones que son demandadas, por lo tanto, lograr que la eficiencia de estos sea cada vez mejor, lograr que las pérdidas energéticas sean las mínimas posibles, lograr que un dispositivo de poco tamaño alcance grandes rendimientos, no solo garantiza mejoras tecnológicas, significa a su vez menos contaminación y mejor aprovechamiento del recurso eléctrico. La tecnología planar es una amplia puerta a todas esas posibilidades mencionadas gracias a su disminuido tamaño, su alta eficiencia, sus bajos componentes parásitos y su versatilidad a la hora de diseñar. Humanity is generating a technological growth not only continuous but exponential, an idea that opens the possibility to imagine an exciting future, every time the human being is more interested in achieving greater efficiency in their devices so that you can take advantage of the energy as much as possible because it is not unknown that energy demand is increasing. Specifically speaking of devices, power transformers are more than common, the utility provided by them is very high given the diversity of voltages that are demanded, therefore, make the efficiency of these is getting better, make energy losses losses to be as low as possible, to make a small device reach high performance, not only guarantees technological not only guarantees technological improvements, but also means less pollution and better use of the electrical resource. better use of electrical resources. Planar technology is a wide door to all of these possibilities possibilities thanks to its small size, high efficiency, low parasitic components and versatility. parasitic components and its versatility in design. Ingeniero Electronico Pregrado

Nowadays the use of electronic equipment finds a progressive development in the modern world. Hence it becomes a mandate to check whether the harmonic content of line current of any electronic device which is connected to the ac supply meets the appropriate standards. This demand is satisfied by implementing the Power Factor Correction (PFC) circuit in order to make the input current to be in sinusoidal in nature and in-phase with the input voltage. Numerous solutions are available to make the line current almost sinusoidal. This paper describes an isolated power factor corrected power supply that utilizes the leakage inductance of the isolation transformer to provide boost inductor functionality. The bulk capacitor is in the isolated part of the power supply allowing for controlled startup without dedicated surge limiting components. A control method based on switch timing and input/output voltage measurements is developed to jointly achieve voltage regulation and input power factor control.

This article analyses the fundamental aspects of the principal resonant network topologies for inductive power transfer systems. From the analytical derivation, different features, such as the variation of the coupling factor or load changes, are studied. Based on this study, a resonant series–series topology is selected, which cancels the leakage inductance. Due to the specifications, the air gap distance and its tolerance ( $\pm \text{12}\%$ ) produce a wide variation of the coupling factor of the inductive link. Therefore, through fast three-dimensional simulations by finite elements, the inductive link is designed so that this variation is minimized. This maintains the resonance and the designed system, in turn, behaves like a voltage source regardless of power, and thus, evades the implementation of a control stage. A dc–dc converter is constructed where the distance between the primary and secondary side vary from 35 to 45 mm, and the power ranges from 0 to 5 kW. The output voltage range goes from 38 to 55 $V_{\text{DC}}$ . Experimental results for the dc–dc converter report an efficiency of over 94%.

In this article, a novel dual-input isolated converter (DI2C) is proposed, which can process two different kinds of clean energy and possesses the features of galvanic isolation and high voltage gain. A dual-charge-pump cell is also proposed in this article and then immersed into the power stage to achieve a high step-up voltage ratio and recycle the energy of leakage inductance. Based on the configuration of the DI2C, even if either of the input sources is interrupted, the converter still can function and keep the high step-up feature. The DI2C only requires two active switches and two coupled inductors. Therefore, the power stage is concise, avoiding complicated control design and simplifying driver mechanism as well. The operation principle, theoretical analysis, and mathematical derivation are thoroughly described. A 200-W prototype is built and then tested to corroborate the correctness of the theoretical analysis and the feasibility of the proposed converter. The measured efficiency is 92.4% at full load.

A comprehensive design methodology is required to maximize the power capacity, the efficiency, and the power density of medium-frequency transformer (MFT), while complying with material, insulation, leakage inductance, and temperature limits. Different from the previous work, an analytical expression for the optimum conductor size of rectangular litz-wire conducting harmonic currents, which ensures best use of the available copper is proposed. A method to tune the leakage inductance with different winding configurations is presented. An insulation design scheme considering the influence of short-term power frequency sinusoidal wave and long-term square wave voltage excitations is put forward. Method to acquire the optimal dimension of fin array heat exchanger under forced air-cooling condition is presented. On this basis, the design methodology is established using the multiobjective nondominated sorting genetic algorithm II. A 1 kV, 200 kVA, 10 kHz nanocrystalline core MFT is designed and prototyped for a 10 kV, 2.5 MW solid-state transformer. The optimal design achieves an efficiency of 99.45%, a power density of 8 MW/m3, and a forced air-cooling temperature of 62 °C.

A stator winding tap changer has been studied for a permanent magnet synchronous motor (PMSM) drive for speeds exceeding the base speed range. At low speeds, all stator windings are configured to fulfill the high output torque; at high speeds, a portion of the stator windings are configured to relieve the burden of the stator winding turns, i.e., large inductive impedance, back electromotive force (BEMF), and field-weakening current. The conventional solid-state tap changers for the PMSMs require snubber capacitors and bleeder resistors. The snubber capacitor is necessary for providing an inductor current path during the stator winding tap-change period. However, it induces long transition times and energy losses. In this article, a snubberless solid-state tap changer is proposed for PMSMs. The proposed mechanism is composed of only three-switches for each tap and controls the leakage inductance current by employing an appropriate switching sequence. With the proposed tap changer, the transition period is reduced and energy loss by bleeder resistance is eliminated. The results of a simulation and an experiment are used to validate the proposed scheme.

Impedance source converters (ISC) based on the magnetic coupling can enhance their voltage gains by maintaining lower shoot-through duty ratios and reduced passive component count. However, the nonzero leakage inductance in the practical ISC generates high switching voltage spikes resulting in poor voltage regulation. Therefore, an absorbing circuit with additional components is crucial to reduce these voltage spikes and to absorb the energy stored in leakage inductances. This article presents a family of differential-mode Y-source converters (DMYSCs) as an alternative to the latest Y-source converter that mitigates the switching voltage spikes without increasing the number of components. The proposed converters DMYSC-I, DMYSC-II, and improved Γ-type Y-source converter are derived from the original Y-source impedance network by altering the winding orientation. In this article, the respective topologies with their working principles are studied and the characteristics are compared with other Y-source converters. Simulation and experimental results have confirmed the abilities of the proposed converters to mitigate their switching voltage spikes.

Full-bridge zero-current-switching (FB-ZCS) dc–dc converters realize quasi-resonant soft-switching and smooth current commutation by utilizing the leakage inductance of high-frequency transformer and a resonant capacitor. The following two types of resonant capacitor configurations are proposed in the literature: First, shunt-connected across the transformer-secondary and, second, series-connected with the transformer-primary. Shunt-connected capacitor has the drawbacks of storing full-load-rated resonant energy irrespective of converter loading. This results in large duty-cycle loss and consequently regulation loss at light-loads. Series-connected capacitor addresses this issue but suffers from higher peak-voltage stress across components and insufficient voltage for resonance at light-loads. To address these limitations, a dual-capacitor resonant circuit is proposed in this article. Series-capacitor facilitates current-adaptive resonant energy storage and shunt-capacitor is designed only for a fraction of full-load-rated resonant energy, which lowers the duty-cycle loss and supports soft-switching at light-loads. This combination also reduces the series-capacitor voltage required for resonance, thereby reducing the peak-voltage stress. Steady-state analysis of converter operation is presented and the advantages over existing converters are demonstrated through simulations for medium-voltage dc application. Experimental results from a scaled-down prototype are presented to validate the proposed converter.

Magnetically coupled impedance source networks (MCIS) are capable of producing higher voltage gains at the expense of high switching voltage spikes due to the presence of leakage inductance. These voltage spikes decorate the converter efficiency and life expectancy of switches. Therefore, to reduce the voltage spikes, a negative embedded differential mode gamma source inverter (NEDM ${{\Gamma }}$ ZSI) is presented in this brief. The proposed inverter can achieve higher voltage gains with reduced switching voltage spikes and low capacitor voltage stresses compared to other MCIS networks. Also, the proposed inverter draws continuous input current from the dc mains, having a common ground, and uses the minimum number of component in a circuit. The operating principle of the proposed NEDM ${{\Gamma }}$ ZSI is analyzed in electrical and magnetic domains. The ability of the proposed impedance network, in terms of voltage spike suppression has been verified experimentally using DC-DC converter configuration. Finally, the performance of a NEDM ${{\Gamma }}$ ZSI is validated with simulation and experimental verification using a single-phase inverter configuration.

In this article, a soft-switched nonisolated high step-up multi-input dc–dc converter is proposed. The proposed converter has overcome the hard switching problem of the conventional boost three port converter (boost-TPC) by providing zero-voltage-switching condition for all switches at various operating modes. The proposed converter uses coupled inductors technique to enhance the voltage gain and utilizes the leakage inductance energy and the energy storage device power path to provide soft switching condition. In addition, the voltage stress of the main switch is reduced which has led to utilizing low R ds(ON) switches. Various converter operating modes are presented and design considerations are discussed. To evaluate the proposed converter performance, two prototypes of the proposed converter are implemented utilizing the latest generation gallium nitride high electron mobility transistors and the mature Si MOSFETs technology. The results show that the proposed converter efficiency is enhanced in comparison with the conventional boost-TPC converter.