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This article presents a 6.78-MHz wireless power transfer (WPT) system, which is configured to automatically cancel the reactance in primary and secondary. In the WPT system, the detuning caused by the parameter variation, the implementation of the frequency control, and components tolerance will decrease a lot the system performance, especially in very low coupling (k = 0.06) and low power applications. The delivered power is sensitive to the reactance under low coupling and high-frequency conditions, accordingly, a novel self-adaptive WPT system to automatically retune the resonance is proposed. The proposed concept uses a synchronous series compensator (SSC) instead of a capacitor in series with the secondary to tune it, which can automatically cancel the reactance caused by the inductor, nonresistive load or frequency variation, hence increases the system performance in terms of delivered power and efficiency. A prototype has been built and tested experimentally to validate the feasibility of the proposed concept. A constant power of 1.8 W can be transmitted with 50% overall efficiency at a coil separation distance of 1.5 cm between the printed-circuit-board transmitter (3 × 3 cm2) and receiver (1 × 2 cm2) under wide detuning conditions, being 0.95 the ratio between distance and the equivalent diameter of receiver. [ABSTRACT FROM AUTHOR]

Several boost-derived topologies are analyzed and compared for an aerospace application that uses a 100 V voltage bus. All these topologies have been designed and optimized considering the electrical requirements and the reduced number of space-qualified components. The comparison evaluates the power losses, mass, and dynamic response. Special attention has been paid to those topologies that may cancel the inherent right half plane zero (RHP) zero of the boost topology. Experimental results of the less common topologies are presented. [ABSTRACT FROM AUTHOR]

In this paper, a multiphase converter where the phases are coupled by transformers is proposed to implement a minimum energy-storage converter. Advantages and drawbacks of this topology are analyzed and validated by means of three prototypes. The two main advantages of the minimum energy-storage concept are that the converter can be operated at very low frequency since the transient response is not affected by the switching frequency, thus achieving very high efficiency while at the same time, providing a fast energy transfer between the input and the output. Since this topology operates (ideally) with no energy storage, energy flow into the magnetic elements of the topology needs to be adequately controlled. The main application of this topology is a “dc–dc transformer” for two-stage power architectures. [ABSTRACT FROM AUTHOR]

The nonlinear and linear controls proposed by Alou and Soto provide very fast transient response (voltage step from 1 to 1.5 V in 2 \mu\s). This nonlinear control is based on hysteretic control of Cout current. This system is very sensitive to effects, like aging, temperature, input and output voltage variation, etc., that modify the switching frequency. This paper proposes a frequency loop to avoid the frequency variation and to adjust the switching frequency to the nominal value by changing the hysteretic band. A 5-MHz buck converter is developed, and experimental results validate the loop design, obtaining the same fast transient response (from 1.5 to 2.5 V in 2 \mu\s) while keeping switching frequency constant in steady state. [ABSTRACT FROM AUTHOR]

Presents a study which proposed a driving circuit that overcomes the limitations of the traditional driving schemes. Traditional driving approach; Description of the proposed single winding self-driven synchronous rectification approach; Simulation of a low-voltage converter to analyze the influence of the main parameters on the performance of the single winding self-driven synchronous rectification technique.

A multi-level boost topology based on a flying capacitor is compared in this work with the hybrid, multi-level, partial power processing topology already presented in the literature for use as a highly efficient and compact dc/dc stage in 1500-V, two-stage, grid-connected PV systems. Different variations of the resonant stage of the hybrid topology are analyzed and compared in terms of losses, volume and complexity. Full multivariable optimization is conducted for the multi-level boost topology with different number of levels and for all the analyzed variations of the resonant stage of the hybrid topology. Appropriately rated new classes of 650-V and 900-V WBG devices are included in the optimization algorithm. It is concluded that due to the dominant conduction losses and gap in the voltage rating of the commercially available WBG devices between 650V and 200V, increase of the number of levels over 4 leads to the deteriorated loss and volume performances. All the analysis related to the resonant stage of the hybrid topology is confirmed by detailed and comprehensive measurements of two prototypes of 4kW of nominal and 7kW of maximal power. Additionally, all the loss models applied in the optimization algorithms presented in this paper are confirmed by detailed measurements, thermal calibration and finite element thermal simulations of the wide bandgap devices and inductor designs employed in this work. [ABSTRACT FROM AUTHOR]

This article presents a control linearization technique for a single-phase single-stage inverter with multiple modulation strategies. The power topology is based on an flying capacitor multi-level (FCML) inverter, and the control is based on the plant inversion. The proposed technique allows decoupling the control of the input current and the output voltage, which simplifies the control in two ways: first, the control of both variables is independent and second, the controllers are independent of the modulation applied, thanks to the plant inversion. This control is implemented in an field-programmable gate array. Since the converter operates at variable frequency, two different data acquisition alternatives are explored: sampling at variable frequency (once per switching cycle) or sampling at constant frequency (higher than the switching frequency).The proposed control is validated by simulation and experimental results with a 1-kVA prototype. [ABSTRACT FROM AUTHOR]

This paper introduces the $v^1$ concept that explains how by only measuring the output voltage, designers have information about almost every signal of the power stage. Following the $v^1$ concept, it is explained how to design a traditional type-III voltage-mode control to behave like a current-mode control with near time-optimal response under load transients. This study is validated in simulations and experimentally on a 300-kHz buck converter. [ABSTRACT FROM AUTHOR]

This paper presents a primary-parallel secondary-series multicore forward microinverter for photovoltaic ac-module application. The presented microinverter operates with a constant off-time boundary mode control, providing MPPT capability and unity power factor. The proposed multitransformer solution allows using low-profile unitary turns ratio transformers. Therefore, the transformers are better coupled and the overall performance of the microinverter is improved. Due to the multiphase solution, the number of devices increases but the current stress and losses per device are reduced contributing to an easier thermal management. Furthermore, the decoupling capacitor is split among the phases, contributing to a low-profile solution without electrolytic capacitors suitable to be mounted in the frame of a PV module. The proposed solution is compared to the classical parallel-interleaved approach, showing better efficiency in a wide power range and improving the weighted efficiency. [ABSTRACT FROM AUTHOR]

This study is related to the improvement of the output impedance of a multiphase buck converter with peak current mode control (PCMC) by means of introducing an additional power path, which virtually increases the output capacitance during transients. Various solutions that can be employed to improve the dynamic behavior of the converter system exist, but nearly all solutions are developed for a single-phase buck converter with voltage mode control, while in the voltage regulation module applications, due to the high currents and dynamic specifications, the system is usually implemented as a multiphase buck converter with current mode control to ensure current sharing. The proposed circuit, output impedance correction circuit (OICC), is used to inject or extract a current n – 1 times larger than the output capacitor current, thus virtually increasing n times the value of the output capacitance during the transients. Furthermore, the OICC concept is extended to a multiphase buck converter system and the proposed solution is compared with the system that has n times bigger output capacitor in terms of dynamic behavior and static and dynamic efficiency. The OICC is implemented as a synchronous buck converter with PCMC, thus reducing its penalty on the system efficiency. [ABSTRACT FROM AUTHOR]

In this article, a series–series wireless power transfer (WPT) system combined with an inverse coupled current doubler rectifier (ICCDR) is proposed, as a very appropriate WPT topology for high current applications. The ICCDR uses an autotransformer to reduce the losses on the rectifier stage, which is suitable for high-current low-voltage output applications. Furthermore, a comprehensive comparison between the proposed WPT system with ICCDR and the traditional WPT system with full-bridge rectifier is presented. In the proposed WPT system, the primary parameter configuration and circuit behavior keep the same, while the secondary side altered, contributing to a volume reduction on the resonant capacitor. The system overall efficiency and power density are improved significantly. Accordingly, a 10 kW 400 V/48 V WPT prototype for battery charging is constructed and tested to validate this proposal. The output voltage is in the range between 38 and 55 Vdc, and the rated output current is 200 A. The overall efficiency of the proposed system reaches 94%, improving 2% efficiency with 220 W energy saving with respect to the traditional diode-rectifier system, when 9.5-kW output power is delivered. Theoretical analysis and experimental results have verified that the proposed system shows great advantages in high-power WPT applications. [ABSTRACT FROM AUTHOR]

V2Ic is a ripple-based control with an excellent performance for load transients and reference voltage tracking because it exhibits a feedforward of the load current and the error of the output voltage. However, if V2Ic is modulated with constant frequency, constant on-time or constant off-time, its dynamic response is hindered by delays in the response. This paper proposes a technique that synchronizes the clock of the converter to initialize the duty cycle when a worst-case load transient occurs using the current through the output capacitor to detect load transients. It is exemplified on a V2Ic control but it is applicable to most of controllers as it only acts on the modulator. [ABSTRACT FROM AUTHOR]

V2Ic control provides very fast dynamic performance to the Buck converter both under load steps and under voltage reference steps. However, the design of this control is complex since it is prone to subharmonic oscillations and several parameters affect the stability of the system. This paper derives and validates a very accurate modeling and stability analysis of a closed-loop V2Ic control using the Floquet theory. This allows the derivation of sensitivity analysis to design a robust converter. The proposed methodology is validated on a 5-MHz Buck converter. The work is also extended to V2 control using the same methodology, showing high accuracy and robustness. The paper also demonstrates, on the V2 control, that even a low bandwidth-linear controller can affect the stability of a ripple-based control. [ABSTRACT FROM AUTHOR]

Over the past few years, RF power amplifiers are taking advantage of the switched dc–dc converters to use them in several architectures that may improve the efficiency of the amplifier, keeping a good linearity. The use of linearization techniques such as envelope elimination and restoration and envelope tracking requires a very fast dc–dc power converter to provide variable voltage supply to the power amplifier, but theoretically, the efficiency can be much higher than using the classical amplifiers belonging to classes A, B, or AB. The purpose of this paper is to analyze the state of the art of the power converters used as envelope amplifiers in this application where a fast output voltage variation is required. The power topologies are explored and several important parameters such as efficiency, bandwidth, and output voltage range are discussed. Some of these topologies are compared in terms of efficiency for a particular set of specifications. [ABSTRACT FROM AUTHOR]

In this article, analysis and design of a 3.3-kW isolated single-stage three-phase buck-type rectifier for aircraft applications is presented. The operating principle and modulation method of the proposed rectifier are introduced. The advantageous zero-voltage switching (ZVS) feature in all of the switching transitions is analyzed. A comparison with the VIENNA Rectifier III is done, being different both in the phase-leg implementation and the modulation sequence. A detailed rectifier design guideline is discussed and losses estimations are provided aiming at reaching 93.7% overall efficiency, including the EMI (electromagnetic interference) filter. Simulation waveforms are presented. Finally, experimental results obtained with the designed 3.3-kW hardware demonstrator are provided. The results verify achievement of ZVS in all of the switching transitions from full load down to 50% of nominal load, while exhibiting 1.9% THD $_I$ (total harmonic distortion) and 0.9996 PF (power factor) at nominal power, ultimately showing very good agreement to the simulation results. This article is accompanied by a video demonstrating experimental operation of the proposed rectifier at nominal input voltage, output voltage, and output power. [ABSTRACT FROM AUTHOR]

This study is related to the improvement of the output impedance of the buck converter by means of introducing an additional power path that virtually increases the output capacitance during transients. It is well known that in voltage regulation module applications, with wide load steps, voltage overshoots and undershoots may lead to undesired performance of the load. To solve this problem, high-bandwidth high-switching-frequency power converters can be applied to reduce the transient time or a big output capacitor can be applied to reduce the output impedance. The first solution can degrade the efficiency by increasing switching losses of the MOSFETS, and the second solution is penalizing the cost and size of the output filter. The output impedance correction circuit, as presented here, is used to inject or extract a current n−1 times larger than the output capacitor current, thus virtually increasing n times the value of the output capacitance during the transients. This feature allows the usage of a low-frequency buck converter with smaller capacitor but satisfying the dynamic requirements. [ABSTRACT FROM PUBLISHER]

The energy consumption in mobile systems has be- come a big challenge that limits high performance and autonomy in mobile systems. The dynamic voltage scaling (DVS) is a recent technique that reduces energy consumption varying dynamically the supply voltage of the system accordingly to the clock frequency. The Buck topology is a good candidate to supply step variations of the output voltage meeting the DVS requirements. In this paper, it is analyzed which is the fastest output voltage evolution that can provide the Buck topology. The minimum time state transition in the Buck converter and its corresponding control law are obtained applying the Maximum Principle or Pontryagin's Principle. Design criteria for the Buck topology are derived from this result. The analysis is extended to a multiphase Buck converter. The minimum time control law is validated in a prototype. The measurements are in good agreement with the theoretical results. [ABSTRACT FROM AUTHOR]

Presents a study that examined the performance of an alternating current/direct current (ac/dc) converter with low output voltage and low input current harmonic content. Design of the output stage; Experimental results; Conclusion.

Presents a simple single-stage alternating current/direct current converter based on the flyback topology. Performance of the flyback converter with or without bulk capacitor; Analysis of the line current; Advantages of the converter over the two-stage approach.

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%. [ABSTRACT FROM AUTHOR]

This article studies design guidelines to optimize the inductive coils for electric vehicles by replacing the standard compact ferrite core with a compound of polymers, nanoparticles, and tile-links of ferrite and by reviewing different aspects of the winding to improve mechanical behavior and efficiency. A system composed of the studied vehicle assembly and ground assembly from the society of automotive engineers’ recommended practice is defined. Fast three-dimensional (3-D) finite element simulations are performed by evaluating different geometric aspects of the vehicle assembly. In doing so, the variation of coupling factor and inductance related to the geometry can be observed and compared in order to analyze the performance when the amount of compact ferrite is reduced. The polymer bonded magnetic is, then, incorporated to improve the decreased magnetic behavior due to the reduction in ferrite. In previous works, the modeling of the litz-wire and polymer bonded magnetic were developed to accelerate the simulations. In this article, we include the modeling of the compact ferrite tile-links to further reduce the time consumption of these simulations. Moreover, simple two-dimensional simulations are described to study the windings’ parasitic capacitances. The design guidelines, based on fast 3-D simulations, are detailed and validated with particular prototypes. [ABSTRACT FROM AUTHOR]

The main standard for avionic equipment DO-160G defines a set of tests that require compliance before the employment of a device in aircraft. An important test involves the generator voltage and consequential current distortion of the three-phase load in the variable 360–800 Hz frequency grid. The main purpose of this paper is to present and analyze a systematic design methodology for three-phase boost and buck rectifiers in order to meet with the voltage distortion test requirement. For a given voltage harmonic profile, the current harmonic limits that have to be satisfied are translated into equivalent per-harmonic admittances and a profile of maximum rectifier input admittance versus frequency is obtained. The defined profile, due to normalization, is applicable to arbitrary power level with simple shifting by the base admittance governed by the converter nominal power. It is shown that for boost-type rectifiers there is a tradeoff between current controller bandwidth and input inductor size, while for the buck-type rectifiers main limitation lies in the input LC filter design used for differential electromagnetic interference filtering. The experimental results conducted on an SiC three-phase 10 kW VIENNA rectifier are tightly backing up the proposed theoretical analysis. This paper is accompanied by three videos demonstrating experimental measurement of d-axis open-loop duty cycle to inductor current transfer function, loop-gain of d-axis current controller with 3.8 kHz bandwidth and variable grid frequency 360–800 Hz operation of the converter under 0% and 10% input three-phase voltage total harmonic distortion. [ABSTRACT FROM AUTHOR]

A nonlinear control able to perform voltage and power stability in direct current (dc) microgrids for an efficient renewable energy integration that is capable of providing frequency support to an alternate current grid is introduced in this work. A generic dc microgrid modeling is developed, and the introduced controllers are shown to ensure grid stability, both by a theoretical analysis with a formal proof of stability using Lyapunov techniques, than by simulations performed in MATLAB. A comparison with classical proportional integral control techniques is described to show the performance improvements. [ABSTRACT FROM AUTHOR]

This paper presents an analytical model for input, output, and reverse capacitance of a normally on AlGaN/GaN high-electron mobility transistor (HEMT) with a gate field-plate structure, when the device is in the subthreshold regime. Together with the existing model for the output I–V characteristics, the proposed capacitance model provides the complete set of analytical equations that relate the physical design parameters to the electrical characteristics of the device. The model was verified by the experimental characterization of a HEMT. In comparison to the physics-based models implemented in Finite Element Analysis tools, the obtained capacitance model has substantially lower level of complexity and, therefore, it is more suitable for implementation into iterative design optimization algorithms. In order to verify the proposed model for such usage, the prototype of a high-frequency buck converter was built, using previously modeled GaN HEMT as the main switch. The hybrid analytical-behavioral power loss model of a high-frequency buck converter was implemented into Simplorer simulation tool, using the proposed physics-based model as the device description for the capacitive part. The efficiency measurements showed good agreement with the simulation results, even at 20 MHz of switching frequency in the low range of the output power. [ABSTRACT FROM AUTHOR]

This paper presents a new isolated single-stage pulse-width modulation rectifier system based on the recently presented Swiss rectifier topology providing the isolation by replacing a buck with a forward converter. The principle of operation and a new modulation technique which compensates the reactive power generated by the input filter at light load and maximizes the power factor are discussed. Furthermore, the analytical equations for the stress in the semiconductor devices useful for the system optimization are derived. The proposed topology and modulation technique are experimentally validated on a 3.3-kW 115 Vac to 270 Vdc prototype demonstrator. [ABSTRACT FROM AUTHOR]

Envelope tracking (ET) and envelope elimination and restoration (EER) are techniques that have gained in importance in the last decade in order to obtain highly efficient radio frequency power amplifier that transmits signals with high peak-to-average power ratio. In this study, a multilevel multiphase buck converter is presented as a solution for the envelope amplifier used in ET and EER. The presented multiphase buck converter generates multilevel voltage using “node” duty cycles and nonlinear control. In this way, the multilevel is implemented using only one simple power stage. However, the complexity of the multilevel converter implementation has been shifted from complicated power topologies to complicated digital control. Detailed discussion regarding the influence of the design parameters (switching frequency, output filter, and time resolution of the digital control) on the performance of the proposed envelope amplifier is presented. The design of the output filter is conducted fulfilling the constraints of the envelope slew rate and minimum driver pulse that can be reproduced. In the cases when these two constraints cannot be fulfilled, they may be relieved by the modified control that is presented and experimentally validated. Finally, in order to validate the concept, a prototype has been designed and integrated with a nonlinear class F amplifier. Efficiency measurements showed that by employing EER, it is possible to save up to 15% of power losses, comparing to the case when it is supplied by a constant voltage. Additionally, adjacent channel power ratio has been measured. The obtained results showed the value higher than 30 dB for signals up to 5 MHz of bandwidth, without using a predistortion technique. [ABSTRACT FROM AUTHOR]

Conventional three-phase rectifiers are controlled to achieve good power factor and low total harmonic distortion in the input. In the case of pulsating power loads, the fast dynamic response implies that the load pulses are reflected in the generator. These pulsating loads affect the lifetime operation of the generator, especially when it is not oversized (as in the case of aircraft applications). In order to smooth the power demanded from the generator, it is preferable to reduce the bandwidth of the output voltage controller for the rectifier but it affects its stability due to the fact that the right-half-plane (RHP) pole given by the negative impedance of a constant power load requires high-bandwidth control loop to compensate it. In this paper, an energy control method is proposed that utilizes the energy stored in the output capacitor of the rectifier to control the output voltage of the rectifier. In such a way, the minimum bandwidth restriction imposed by the RHP pole of the power load is eliminated and the bandwidth of the voltage loop can be defined low enough to demand smooth power from the generator. [ABSTRACT FROM PUBLISHER]

This paper presents a single-stage converter for a high-bandwidth and high-efficiency envelope amplifier. In the proposed application, due to the high peak-to-average-power ratio, high bandwidth, and the power level requirements, the envelope amplifier has low efficiency. Therefore, many efforts have been made to increase the efficiency of the envelope amplifier. To achieve this improvement, the current ripple cancellation technique is applied in this paper to a synchronous buck converter to cancel the output current ripple and to decrease the switching frequency without a reduction in the large signal bandwidth, for open-loop operation and for the envelope elimination and restoration technique. The advantages of the proposed design are presented and validated experimentally. The transfer function of the output filter of the buck converter with a ripple cancellation circuit has been modeled and compared to measurements, showing a good correspondence. Experimental validation is provided at 4 MHz of switching frequency, for dc and for variable output voltage, applying a sinusoidal reference and a 64-QAM signal. Experimental validation of the efficiency improvement is provided, compared to the equivalent design of the conventional buck converter in terms of the output voltage ripple rejection ratio and large signal bandwidth. [ABSTRACT FROM AUTHOR]

This paper presents a theoretical analysis and an optimization method for envelope amplifiers. Highly efficient envelope amplifiers based on a switching converter in parallel or in series with a linear regulator are analyzed and optimized. The results of the optimization process are shown, and these two architectures are compared regarding their complexity and efficiency. The proposed optimization method is based on the knowledge of the transmitted signal type (OFDM, WCDMA…), and it can be applied to any signal type as long as the envelope probability distribution is known. Finally, it is shown that both analyzed architectures have an inherent efficiency limit. [ABSTRACT FROM AUTHOR]

The combination of minimum time control and multiphase converter is a favorable option for dc–dc converters in applications where output voltage variation is required, such as RF amplifiers and dynamic voltage scaling in microprocessors, due to their advantage of fast dynamic response. In this paper, an improved minimum time control approach for multiphase buck converter that is based on charge balance technique, aiming at fast output voltage transition is presented. Compared with the traditional method, the proposed control takes into account the phase delay and current ripple in each phase. Therefore, by investigating the behavior of multiphase converter during voltage transition, it resolves the problem of current unbalance after the transient, which can lead to long settling time of the output voltage. The restriction of this control is that the output voltage that the converter can provide is related to the number of the phases, because only the duty cycles at which the multiphase converter has total ripple cancellation are used in this approach. The model of the proposed control is introduced, and the design constraints of the buck converter's filter for this control are discussed. In order to prove the concept, a four-phase buck converter is implemented and the experimental results that validate the proposed control method are presented. The application of this control to RF envelope tracking is also presented in this paper. [ABSTRACT FROM AUTHOR]

The boost topology with ripple cancellation network allows input and output current ripples attenuation, which means the suppression of the input filter and a high reduction of the output filter. However, to achieve the ripple cancellation, the complexity and the number of components of the converter need to be increased as compared with the conventional boost. A detailed analysis is developed to specify the advantages and disadvantages of this topology. This paper presents the averaged model that derives the complex transfer function of the topology. The theoretical transfer function is obtained. Due to the complexity of the seventh order transfer function that is obtained, a simplified second-order transfer function is calculated to simplify control design calculations. A comparison between the analyzed topology and a conventional boost in terms of weight and losses is carried out. To estimate the current ripple calculation, it is proposed to use the ripple theorem, which allows an estimation of the efficiency of the cancellation network using the averaged model. A prototype to validate ripple cancellation and the dynamic analysis is developed. Measured waveforms and Bode plots are enclosed. Current ripple cancellation at the input and output in both conduction modes of the converter is also validated. [ABSTRACT FROM AUTHOR]

Some of the recent applications in the field of the power supplies use multiphase converters to achieve fast dynamic response, smaller inputloutput filters, or better packaging. Typically, these converters have several paralleled power stages, with a current loop in each phase and a single voltage loop. The presence of the current loops avoids current imbalance among phases. The purpose of this paper is to demonstrate that, in CCM, with a proper design, there is an intrinsic mechanism of self-balance that reduces the current imbalance. Thus, in the buck converter, if natural zero-voltage switching (ZVS) is achieved in both transitions, the instantaneous inductor current compensates partially the different dc currents through the phases. The need for using n current loops will be finally determined by the application but not by the converter itself. Using the buck converter as a base, a multiphase converter has been developed. Several tests have been carried out in the laboratory and the results show clearly that, when the conditions are met, the phase currents are very well balanced even during transient conditions. [ABSTRACT FROM AUTHOR]

Piezoelectric transformers (PTs) provide several advantages compared to magnetic components, which are higher power density, lower radiated noise, and higher voltage isolation capability. PT must be properly designed to benefit the power converter with the aforementioned advantages. Analytical models are widely used for PT design in order to validate it before constructing the prototype. In this paper, the additional usefulness of finite element analysis (FEA) for PT design is shown. With FEA, it is possible to optimize the PT design not only by maximizing the energy transference but also by cleaning the working frequency range of spurious modes (geometrical 2-D/3-D effects). Moreover, FEA tools allow the study of other main aspects of the PT design such as manufacturing tolerances or the influence of the fixing layer on PT performance (which is a critical design point). A method for modeling and designing PTs is proposed, combining analytical 1-D mode!s and FEA results. The proposed method is validated with measurements of a PT design for a 10-W ac/dc converter prototype for mobile phone battery charger. [ABSTRACT FROM AUTHOR]

Presents a review of the solutions for single phase and low power applications. Penalty for the highest quality waveform and tight output voltage regulation; Classification of the solutions; Major advantages and disadvantages of the solutions.

The magnetic field in many magnetic components, namely toroids and EE cores, has a three-dimensional (3-D) distribution. Energy and losses calculation in these particular structures makes necessary the use of 3-D techniques that accounts for all 3-D effects. The calculation of the energy and losses is needed in order to obtain any transformer model. This paper presents a procedure that allows the calculation of energy and losses in 3-D structures using two-dimensional (2-D) approaches. This procedure accounts for 3-D effects, solving each magnetic component by means of two different analyses but using 2-D finite-element analysis (FEA) solvers instead of 3-D. The main advantages of this procedure are that all geometrical and frequency effects are taken into account using 2-D FEA solvers [18]. 3-D FEA solvers [18] are not applicable to analyze most practical cases because of the complexity in the geometry. Therefore, the use of this method is not only advantageous from the point of view of time reduction, but also it is a solution for many cases where 3-D solvers are not a feasible solution. Some experimental results illustrate the application of the methodology, which is especially useful to study the influence of the winding strategy in toroidal structures and to design integrated magnetics in order to adjust the coupling coefficient between each pair of windings before the component construction. [ABSTRACT FROM AUTHOR]

The thermal management of magnetic components for power electronics is crucial to ensure their reliability. However, conventional thermal models for magnetic components are known to have either poor accuracy or excessive complexity. Contrary to these models, the use of Thermal Resistance Matrices is proposed in this paper instead, which combine both accuracy and simplicity. They are usually used to characterize semiconductor devices, but not for magnetic components. The guidelines to apply Thermal Resistance Matrices for magnetic components are discussed in detail. The accuracy of this model is validated by 3D FEA simulations and experimental results, showing an absolute error lower than 5 ∘ C and a relative error between − 6.4 % and 3.9 % , which is outstanding compared to the carried-out literature review. [ABSTRACT FROM AUTHOR]

The volume of magnetic components for space applications, directly related to the launch cost, and their performance are critically influenced by their capability to dissipate the internal electromagnetic power losses. This is the reason why accurate thermal models are required. Furthermore, these models need to be simple and versatile to allow a fast analysis of many different designs. In this study, a specific methodology to analyze inductors and transformers by thermal networks and a simplification based on the Thevenin's theorem leading to a simple equation are proposed. The specific details to address thermal modelling for space magnetic components are discussed. A generic 50 W Flyback transformer for space applications is analyzed in this study and experimental validation is provided, showing that the proposed method leads to a deviation in the temperature estimation between 1 °C and 5 °C, which is considered quite a good result from the literature review carried out. [ABSTRACT FROM AUTHOR]

In modern aircraft designs, following the More Electrical Aircraft (MEA) philosophy, there is a growing need for new high-power converters. In this context, innovative solutions to provide high efficiency and power density are required. This paper proposes an unregulated LLC full-bridge operating at resonant frequency to obtain a constant gain at all loads. The first harmonic approximation (FHA) model is not accurate enough to estimate the voltage gain in converters with high parasitic resistance. A modified FHA model is proposed for voltage gain analysis, and time-based models are used to calculate the instantaneous current required for the ZVS transition analysis. A method using charge instead of current is proposed and used for this ZVS analysis. Using this method, an auxiliary circuit is proposed to achieve complete ZVS within the whole load range, avoiding a gapped transformer design and increasing the efficiency and power density. A 28 Vdc output voltage prototype, with 10 kW peak output power, has been developed to validate the theoretical analysis and the proposed auxiliary circuit. The maximum efficiency (96.3%) is achieved at the nominal power of 5 kW. [ABSTRACT FROM AUTHOR]

This paper provides an exhaustive analysis of the Dual-Active-Bridge with Triple-Phase-Shift (DAB-TPS) modulation and other simpler ones, identifying all the possible switching modes to operate the DAB in both power flow directions, and for any input-to-output voltage range and output power. This study shows four cases and seven switching modes for each case when the energy flows in one direction. That means that the DAB operates up to fifty-six different switching modes when the energy flows in both directions. Analytical expressions for the inductor current, the output power, and the boundaries between switching modes are provided for all cases. Additionally, the combination of control variables to achieve Zero-Voltage-Switching (ZVS) or Zero-Current-Switching (ZCS) is provided for each case and switching mode, by showing which switching modes obtain ZVS or ZCS for the whole power range and all switches—independent of the input-to-output voltage ratio. Therefore, the most interesting cases, switching mode and modulation for using the DAB are identified. Additionally, experimental validation has been carried out with a 250 W prototype. This analysis is a proper tool to design the DAB in the optimum switching mode, reducing the RMS current and achieving to increase efficiency and the power density. [ABSTRACT FROM AUTHOR]