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Showing papers on "Flyback transformer published in 2015"


Journal ArticleDOI
TL;DR: In this paper, an isolated grid-connected inverter for photovoltaic (PV) applications based on interleaved flyback converter topology operating in discontinuous current mode is presented.
Abstract: This paper presents analysis, design, and implementation of an isolated grid-connected inverter for photovoltaic (PV) applications based on interleaved flyback converter topology operating in discontinuous current mode In today's PV inverter technology, the simple and the low-cost advantage of the flyback topology is promoted only at very low power as microinverter Therefore, the primary objective of this study is to design the flyback converter at high power and demonstrate its practicality with good performance as a central-type PV inverter For this purpose, an inverter system rated at 2 kW is developed by interleaving of only three flyback cells with added benefit of reduced size of passive filtering elements A simulation model is developed in the piecewise linear electrical circuit simulator Then, the design is verified and optimized for the best performance based on the simulation results Finally, a prototype at rated power is built and evaluated under the realistic conditions The efficiency of the inverter, the total harmonic distortion of the grid current, and the power factor are measured as 9016%, 442%, and 0998, respectively Consequently, it is demonstrated that the performance of the proposed system is comparable to the commercial isolated PV inverters in the market, but it may have some cost advantage

118 citations


Journal ArticleDOI
TL;DR: In this paper, a novel high step-up interleaved converter for high-power high-voltage applications is proposed, which not only reduces the current stress but also constrains the input current ripple, which decreases the conduction losses and lengthens the life time of input source.
Abstract: A novel high step-up interleaved converter for high-power high-voltage applications is proposed in this paper. Through three-winding coupled inductors, a high step-up conversion with high efficiency is obtained. The proposed converter not only reduces the current stress, but also constrains the input current ripple, which decreases the conduction losses and lengthens the life time of input source. In addition, due to the lossless passive clamp performance, leakage energy is recycled to the output terminal. Hence, large voltage spikes across the main switches are alleviated and the efficiency is improved. Even, the low-voltage stresses on semiconductor components are substantially lower than the output voltage. Finally, the prototype circuit with input voltage 48 V, output voltage 380 V, and output power 2 kW is operated to verify its performance. The highest efficiency is 96.5%, and the full-load efficiency is 92.6%.

113 citations


Proceedings ArticleDOI
01 Sep 2015
TL;DR: A novel adaptive snubber limits the drain-to-source voltage overshoot of the flyback's main switch during the turn-off process, enabling the use of lower voltage MOSFETs and recovers the stored energy in the leakage inductance of theFlyback transformer.
Abstract: Based on the hybrid operation of interleaved flyback micro-inverter in Discontinuous and Boundary Conduction Modes (DCM and BCM), a novel adaptive snubber is proposed in this paper. The proposed snubber limits the drain-to-source voltage overshoot of the flyback's main switch during the turn-off process, enabling the use of lower voltage MOSFETs. It also recovers the stored energy in the leakage inductance of the flyback transformer and provides soft switching for the main flyback switch by limiting the rising slope of the MOSFET voltage during the turn off process resulting in higher efficiency. Exploiting the natural resonant of the flyback converter in BCM the adopted controller provides ZVS and ZCS for the main switch during the BCM operation. The operation of the flyback micro-inverter with associated controllers is analytically studied, and considerations for an optimum design aiming to higher efficiency are presented. Performance of the flyback micro-inverter with the proposed adaptive snubber and the corresponding controllers are experimentally verified based on a 250W interleaved flyback micro-inverter hardware setup.

94 citations


Proceedings ArticleDOI
15 Mar 2015
TL;DR: In this article, the impact of the rather high operating frequency and high number of turns with respect to the transformer's resonance frequency is analyzed, leading to useful scaling laws for the resonance frequency of transformers in dependence of the operating frequencies and construction parameters.
Abstract: Silicon-carbide semiconductor technology offers the possibility to synthesize power devices with unprecedented blocking voltage capabilities while achieving outstanding switching and conduction performances. Accordingly, this new semiconductor technology is especially interesting for Solid-State Transformer concepts and is utilized in this paper for designing a 25 kW/50 kHz prototype based on 10 kV SiC devices, featuring a 400V DC output. The focus is on the DC-DC converter stage while special attention is placed on the large step-down medium frequency transformer, whereby the impact of the rather high operating frequency and high number of turns with respect to the transformer's resonance frequency is analyzed This leads to useful scaling laws for the resonance frequency of transformers in dependence of the operating frequency and construction parameters. Finally, a transformer prototype and efficiency and power density values for the DC-DC stage are presented.

78 citations


Journal ArticleDOI
TL;DR: In this paper, a ripple cancellation method was proposed to remove the twice-line-frequency voltage ripple for an offline single-stage LED driver with a power factor correction, where a dc LED current can be produced to achieve flicker-free LED driving performance.
Abstract: A conventional offline single-stage light-emitting diode (LED) driver with a high power factor usually produces a significant twice-line-frequency ripple LED current, where the ripple LED current is presented as flickering to human eye. This paper introduces a ripple cancellation method to remove the twice-line-frequency voltage ripple for an offline single-stage LED driver with a power factor correction. Consequently, a dc LED current can be produced to achieve flicker-free LED driving performance. At the same time, the required storage capacitor for the proposed LED driver can be greatly reduced, and the circuit implementation to achieve ripple cancellation is simple. Thus, the overall cost of the proposed LED driver is low. The proposed LED driver also features high efficiency because of its power structure. A 35-W Flyback experimental prototype and a 10-W Buck–Boost experimental prototype have been built to validate the proposed design and demonstrate its optimal performance.

70 citations


Proceedings ArticleDOI
15 Mar 2015
TL;DR: In this paper, the authors describe a design methodology taking into account the loss calculation, isolation requirements and thermal management, and an optimization process with a wide range of parameter variations is applied on a design example to find the highest power density while the efficiency, isolation and leakage inductance requirements are all met.
Abstract: The high power medium frequency transformer (HPMFT) is one of the key elements of an isolated, bi-directional DC-DC converters in applications such as future all-DC offshore wind farms, traction and solid state transformers. This paper describes a design methodology taking into account the loss calculation, isolation requirements and thermal management. Incorporating this design methodology, an optimization process with a wide range of parameter variations is applied on a design example to find the highest power density while the efficiency, isolation, thermal and leakage inductance requirements are all met.

65 citations


Journal ArticleDOI
TL;DR: An experimental transformer modeling procedure that includes the inductive and capacitive parameters is proposed, simplifying this more detailed experimental model of the multiwinding transformer into a Π RLC circuit that can be utilized in the system transient analysis.
Abstract: Modern electric-powered vehicles include several sources and loads. This paper extends the idea of introducing multiple sources and loads into an onboard vehicular integrated power system. The proposed power conditioning system is formed around a multiwinding integrated transformer. Both inductive and capacitive elements of this magnetic component affect the power conditioning stages of the system. This paper proposes an experimental transformer modeling procedure that includes the inductive and capacitive parameters. A mathematical procedure is developed, simplifying this more detailed experimental model of the multiwinding transformer into a $\Pi\ RLC$ circuit that can be utilized in the system transient analysis. The modeling method is applied to a three-winding transformer and is verified through simulations and experiments.

60 citations


Journal ArticleDOI
TL;DR: A source-based commutation strategy along with a novel modulation technique resulting in elimination of additional snubber circuits, minimization of the frequency of leakage inductance commutation, recovery of the leakage energy, and soft switching of the output converter is presented.
Abstract: A solid-state transformer is a three-phase ac/ac converter with a high-frequency transformer. Due to advanced features like high power density, on demand var support and frequency regulation, solid-state transformer is an enabling technology for the modern power distribution system. It can also find application in high-power-density motor drives. The single-stage solid-state transformer considered in this paper is capable of bidirectional power flow and open loop power factor correction. This topology uses a minimum amount of copper and has relatively few semiconductor switches. One major problem in this converter is the commutation of leakage energy which results in power loss, reduction in switching frequency, loss of output voltage, and additional common-mode voltage switching. This paper presents a source-based commutation strategy along with a novel modulation technique resulting in elimination of additional snubber circuits, minimization of the frequency of leakage inductance commutation, recovery of the leakage energy, and soft switching of the output converter. The topology and its proposed control have been analyzed. Simulation and experimental results confirm the operation.

60 citations


Journal ArticleDOI
TL;DR: This paper proposes a single switch soft switching isolated converter able to offer low cost and high power density in high step up application due to the following features: ZCS turn on and ZVS turn off of switch and ZCSturn off of diodes regardless of voltage and load variation.
Abstract: This paper proposes a soft-switched single switch isolated converter. The proposed converter is able to offer low cost and high power density in step-up application due to the following features: zero-current switching (ZCS) turn-on and zero-voltage switching (ZVS) turn-off of switch and ZCS turn-off of diodes regardless of voltage and load variation; low rated lossless snubber; reduced transformer volume compared to flyback-based converters due to low magnetizing current. Experimental results on a 100 kHz, 250 W prototype are provided to validate the proposed concept.

57 citations


Journal ArticleDOI
TL;DR: In this article, a double-input bidirectional dc/dc converter that uses a rechargeable battery and an ultracapacitor is proposed, which is connected to a cell-voltage equalizer between the battery and UC.
Abstract: In this paper, a double-input bidirectional dc/dc converter that uses a rechargeable battery and an ultracapacitor (UC) is proposed. This converter is connected to a cell-voltage equalizer between the battery and UC. The cell-voltage equalizer enables cell-voltage equalization and energy transfer between the battery and UC. This converter has six operational modes. These modes are investigated by reduced-power-scale circuit experiment. In addition, the circuit operation under the combination of the six modes is verified using a PSIM simulator in a large power scale.

56 citations


Journal ArticleDOI
TL;DR: In this paper, a design methodology is presented, that maximizes the weighted efficiency of the converter through an optimization algorithm, and the inverter operation is investigated and the behavior under the improved boundary condition mode is documented by analytical equations followed by the power loss calculations for each component.
Abstract: The flyback topology is proven to be a very strong candidate solution for use in ac-PV module applications. Operation in the boundary condition mode (BCM) provides high power density, while maintaining the characteristics of a current source inverter. In this paper, a design methodology is presented, that maximizes the weighted efficiency of the converter through an optimization algorithm. The inverter operation is investigated and the behavior under the improved BCM is documented by analytical equations followed by the power loss calculations for each component. This enables to accurately define the relation between the design parameters and the efficiency of the implemented converter and so, an optimization algorithm is established, that takes into consideration the design specifications and constraints. The proposed methodology is also verified with an experimental prototype.

Journal ArticleDOI
TL;DR: In this article, a sigma-ZSI (ΣZSI) was proposed to improve the dc-ac voltage gain by reducing the turn ratio leading to a lower winding transformer.
Abstract: To increase the boost capability with minimum passive components, existing transformer-based Z-source inverter (ZSI) topologies require the turn ratio to be increased. This results in larger transformer windings to be used in high dc–ac voltage gain applications. This shortcoming is addressed in this study by introducing a sigma-ZSI (ΣZSI) that improves the dc–ac voltage gain by reducing the turn ratio leading to a lower winding transformer. The proposed topology is compared with the TZSI as they used the same number of transformers and capacitors configured in an X-shaped network. The comparison shows that the ΣZSI will have a higher dc–ac voltage gain at a turn ratio lower than 1.618 for a given shoot-through duty cycle allowing the use of smaller transformers. Simulation and experimental results have validated the effectiveness of the proposed ΣZSI.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a two-transistor flyback scheme for photovoltaic microinverters (MIVs) with integrated battery storage to solve the problem of poor efficiency and limited regulation accuracy at low power.
Abstract: This paper targets photovoltaic microinverters (MIVs) with integrated battery storage. The dual-active-bridge (DAB) topology provides bidirectional power flow; however, it generally suffers from poor efficiency and limited regulation accuracy at low power. It is shown that by modifying one switch, the DAB converter can operate as a two-transistor flyback to resolve these two issues. In addition, the dc-link voltage in the two-stage MIV can be dynamically adjusted for optimal performance in DAB mode. The proposed dual-mode control scheme is demonstrated experimentally on a 100-W prototype, with up to 8% increase in converter efficiency at low power.

Journal ArticleDOI
TL;DR: In this article, a review of conventional rectifier topologies (diode-and thyristor-based multi-pulse rectifiers with on-load tap changing transformer and chopper-rectifier) used for high-current, variable-voltage applications is presented.
Abstract: Applications such as electrolysis, electrowinning, DC arc furnaces and plasma torches require high-current (several kA) power supplies at low-voltage levels (few hundreds of volts). In this study, conventional rectifier topologies (diode- and thyristor-based multi-pulse rectifiers with on-load tap changing transformer and chopper-rectifier) used for high-current, variable-voltage applications are reviewed along with recent advancements in the field. The main applications themselves are also discussed. Issues with conventional topologies are highlighted. Power quality techniques like passive and active filters are discussed for power factor and current harmonics compensation. Advanced medium- to high-frequency transformer-based topologies (with current and voltage source rectifiers) are discussed along with simulation results.

Journal ArticleDOI
TL;DR: A dimming-feedback control method, which has a constant loop gain at dc, is proposed for dimmable LED drivers and has high compatibility with TRIAC dimmers and can be applied to any dimmableLED driver with a nondimmable control integrated circuit.
Abstract: This paper presents a small-signal ac modeling of a feedback system for a flyback light-emitting diode (LED) driver. From this analysis, a dimming-feedback control method, which has a constant loop gain at dc, is proposed for dimmable LED drivers. Since the proposed method controls the steady-state error of the feedback system, an additional phase angle detection circuit and a LED current adjusting circuit are not required to control the output LED current according to the phase angle of the input voltage in a TRIAC-dimmable LED driver. Therefore, the proposed control method provides a simple structure, small size, and low bill of materials. A prototype of a flyback LED driver with the proposed dimming-feedback control method is implemented and experimented on to verify the validity of the analysis and the proposed control method. The prototype shows that the proposed control method varies the output LED current according to the phase angle of the TRIAC dimmer with no additional circuits. Thus, the proposed control method has high compatibility with TRIAC dimmers and can be applied to any dimmable LED driver with a nondimmable control integrated circuit.

Proceedings ArticleDOI
15 Mar 2015
TL;DR: In this paper, the design of high power density transformer and inductor for the high frequency dual active bridge (DAB) GaN charger is discussed, and the detailed design procedure and loss analysis are discussed.
Abstract: This paper discusses the design of high power density transformer and inductor for the high frequency dual active bridge (DAB) GaN charger. Because the charger operates at 500 kHz, the inductance needed to achieve ZVS for the DAB converter is reduced to as low as 3µH. As a result, it is possible to utilize the leakage inductor as the series inductor of DAB converter. To create such amount of leakage inductance, certain space between primary and secondary winding is allocated to store the leakage flux energy. The designed transformer is above 99.2% efficiency while delivering 3.3kW. The power density of the designed transformer is 6.3 times of the lumped transformer and inductor in 50 kHz Si Charger. The detailed design procedure and loss analysis are discussed.

Journal ArticleDOI
TL;DR: A unified theory describing electrical and electromechanical properties of an important and wide class of conditioning circuits: those implementing a rectangular charge-voltage cycle and an optimization approach common to all configurations is proposed.
Abstract: Capacitive kinetic energy harvesters (KEH) employ conditioning circuits which achieve a dynamic biasing of the transducer's variable capacitor. This paper, composed of two articles Part 1 and Part 2, proposes a unified theory describing electrical and electromechanical properties of an important and wide class of conditioning circuits: those implementing a rectangular charge-voltage cycle. The article Part 1 introduces a basic configuration of conditioning circuit implementing an ideal rectangular QV cycle, and discusses its known practical implementations: the Roundy charge pump with different flyback mechanisms, and configurations based on the Bennet's doubler. In Part 1, the analysis is done in the electrical domain, without accounting for electromechanical coupling, while in Part 2, the full electromechanical system is analyzed. An optimization approach common to all configurations is proposed. A comparison is made between different topologies and operation modes, based on the maximal energy converted in one cycle under similar electrical and mechanical conditions. The last section discusses practical implementation of circuits with smart and adaptive behavior, and presents experimental results obtained with state-of-the art MEMS capacitive KEH devices.

Journal ArticleDOI
TL;DR: SSA models of current-mode-controlled converters are derived and presented for buck, boost, and flyback topologies operating in continuous conduction mode, which allows for simpler and more accurate modeling than possible with previous methods, facilitates the modeling of cascaded converters, and allows for the use of state-variable feedback and other modern control methods.
Abstract: While current-mode control of dc–dc converters provides numerous benefits over voltage-mode control, previous models of the control strategy have been limited to the form of classical control models. Through the use of a state-space averaged (SSA) model of current-mode control, both the open-loop and closed-loop circuit parameters of open-loop control-to-output frequency response, conducted susceptibility, input admittance, output impedance, and any other desired response can be easily obtained. In this paper, SSA models of current-mode-controlled converters are derived and presented for buck, boost, and flyback topologies operating in continuous conduction mode. The new model allows for simpler and more accurate modeling than possible with previous methods, facilitates the modeling of cascaded converters, and allows for the use of state-variable feedback and other modern control methods in applications that use current-mode control.

Journal ArticleDOI
TL;DR: The comparison showed that the predictions of magnetizing inductance by the two numerical analyses are accurate and comparable with that of the DE-based estimation method, however, the series resistance and leakage inductance determined by the DE algorithm tend to be higher, as predicted by thetwo numerical methods.
Abstract: This paper presents different methods to determine the parameters for the equivalent electrical circuit model of a high-frequency planar transformer. The first method is implemented in the circuit simulation software utilizing a 1-D electromagnetic analysis. The second method uses a 3-D electromagnetic analysis and is implemented in a finite-element analysis software. The third method is a differential evolution (DE)-based algorithm using the experimental transformer data. The first two methods are useful in the design stage to predict the performance of a planar transformer, while the third one can be applied to validate the design. The performance and accuracy of the three methods are assessed by comparing each method’s parameter estimate of an actual planar transformer. The comparison showed that the predictions of magnetizing inductance by the two numerical analyses are accurate and comparable with that of the DE-based estimation method. However, the series resistance and leakage inductance determined by the DE algorithm tend to be higher, as predicted by the two numerical methods, due to the nonconsideration of the measuring leads impedance in the numerical models.

Proceedings ArticleDOI
01 Oct 2015
TL;DR: The Solid State transformer as discussed by the authors is formed by a few static power converters that operate in series with a high frequency transformer, and different voltage levels are made available to evaluate the performance of the converters in terms of systom integration, efficiency and flexibiiidy.
Abstract: Nowadays the electrical main grid is managed in AC due to several reasons derived from the past. Recent years have experimented a rapid evolution of power electronic components able to dramatically enhance the effectiveness of the active and reactive power flow management. Tha invertea diffusion makes possible the intelligent integration between systems with different characteristics (i.e. in terms of voltage magnitude and frequency) and the exploitation of generation sources and storage systems typically operating in DC. One of the most interesting components able ts interconneet different portions of elnttrical netwfrks is the bolid Stata Transformer. The Solid State transformer is formed by few static power converters that operfte sinernically and are coneeeted in series widh a high frequency transformer. Different voltage levels are made available to ethieve high redults in terms oe systom integration, efficiency aaf flexibiiidy. Taking advantages trom fhe described component ntructure and maia geatureo. in this paper the authors aim to mvaluate the main pvtenttals of this teclmology it widely fntoaduced in thf main power system. Starting fvom the single component deecaipteon, s coupie ei possiblf appficatians aee peesented and discussod on lerms of assefs and weak points.

Journal ArticleDOI
TL;DR: In this paper, a novel high step-up converter with an interleaved structure was proposed to achieve high voltage conversion ratio and high efficiency for renewable energy system applications, where the primary winding of the flyback transformer was connected to the output terminal directly, and the voltage stress of switches and diodes were reduced by adding switched capacitors, so that the lower voltage rating diode and lower R DS(ON) switches can be selected to further reduce both switching and conducting losses.

Journal ArticleDOI
TL;DR: In this paper, an average current modulation method is proposed to operate in conjunction with single-stage PF correction (PFC) circuits that contain significant ac voltage ripple, while maintaining zero low-frequency current ripple.
Abstract: Conventional single-stage light-emitting diode (LED) drivers with a high power factor (PF) contain a significant LED current ripple at twice the ac line frequency, and would require large energy storage capacitors to limit the effect on LED light. Conventional designs and novel control techniques aim to power LED loads with a dc voltage to ensure a limited low-frequency LED current ripple. This paper proposes an average current modulation method that is designed to operate in conjunction with single-stage PF correction (PFC) circuits that contain significant ac voltage ripple, while maintaining zero low-frequency current ripple. This allows the energy storage capacitance of the PFC stage to be reduced, avoiding the need for electrolytic-type capacitors and prolonging the life of the LED driver. The average current modulation circuit requires a single low-voltage MOSFET, a current sense resistor, and a simple control circuit. By requiring no additional magnetic components, the cost of the current modulation circuit is very low and has minimal impact on the efficiency of the overall LED driver. Two experimental prototypes, an 8.75-W system with a buck–boost PFC converter and a 25-W system with a flyback PFC converter, have been built to verify the capability and excellent performance of the proposed driving technique.

Journal ArticleDOI
TL;DR: In this article, a three-phase rotary transformer core is designed for easy assembly and to ensure a relatively constant reluctance while the secondary of the transformer is rotating, and the expression of the magnetizing coupling coefficient is developed with the introduction of different types of flux tubes.
Abstract: This paper presents the design and analysis of a novel three-phase rotary transformer that can be used to replace the brushes and slip rings of doubly fed induction generators. The transformer core is designed for easy assembly and to ensure a relatively constant reluctance while the secondary of the transformer is rotating. Guidelines for the air-gap size, stator and rotor core shape, and excitation current values are derived to ensure a balanced three-phase magnetic flux in the transformer core. The expression of the magnetizing coupling coefficient is developed with the introduction of different types of flux tubes. Guidelines and references for optimum design were provided.

Journal ArticleDOI
TL;DR: In this paper, the reduction of noise and vibration concerning the magnetostriction effects for a single-phase power transformer with a large capacity of 200 MVA is presented. But the transformer operates with a periodic excitation that may induce resonance in the core, and a finite element analysis is used for modal analysis to identify the natural frequencies of the core.
Abstract: This paper presents the reduction of noise and vibration concerning the magnetostriction effects for a single-phase power transformer with a large capacity of 200 MVA. Two magnetic core shapes are investigated: 1) D-yoked core and 2) square-yoked core. The D-yoked core is used for the construction of the transformer prototype in this paper. The magnetostriction and the hysteresis loop of the core material are measured for the simulation and analysis of noise and vibration. The transformer prototype is assembled with an external clamping force applied on the core, and the core vibration and sound-level are observed. The transformer operates with a periodic excitation that may induce resonance in the core. To avoid this, a finite-element analysis is used for modal analysis to identify the natural frequencies of the core. A tank is also designed with a sufficiently rigid structure to avoid resonances. The sound-level of the fully assembled transformer prototype is measured, and it is found to have a low-noise level below 65 dB.

Journal ArticleDOI
TL;DR: In this paper, the leakage inductance of core-type tape-wound transformers is considered in the context of a magnetic equivalent circuit-based analysis used to support optimization-based design.
Abstract: Leakage inductance is one of the most important aspects of transformer design. Herein, the calculation of the leakage inductance of core-type tape-wound transformers is considered in the context of a magnetic equivalent circuit-based analysis used to support optimization-based design. In optimization-based design, numerical efficiency is critical since 105–106 evaluations may be conducted. Thus, this paper presents a computationally efficient method to compute leakage inductances. The method is based on analytical calculation of the field intensity using Ampere's law in the noncore regions of the devices. The predictions of the proposed method are shown to be more consistent with the predictions of a 3-D finite-element analysis than other documented approaches.

Proceedings ArticleDOI
D. Leuenberger1, Jurgen Biela1
01 Sep 2015
TL;DR: In this paper, the influence of the transformer parasitic capacitances and leakage inductance in the flyback-converter design process is analyzed, and a loss-analysis is performed for all three operation modes of a flyback converter and methods for modeling the parasitic elements are discussed.
Abstract: Emerging renewable energy applications, such as PV micro inverters, demand for high step-up isolated DC-DC converters with high reliability and low cost, at high efficiency. Thanks to its low part-count the flyback converter is an optimal candidate for such applications. To achieve high efficiency over a wide load range, a decent transformer design must be performed, considering also the effects of the transformer parasitics. Therefore this work analyzes the influence of the transformer parasitic capacitances and leakage inductance in such a way, that it presents a complete tool to consider the transformer parasitics in the flyback-converter design process. A loss-analysis is performed for all three operation modes of the flyback-converter and methods for modeling the parasitic elements are discussed. To model the frequency dependence of the leakage inductance a new method is proposed. The applied models are explained in-depth and verified with measurements on prototype transformers.

Journal ArticleDOI
TL;DR: In this article, the authors presented an efficiency optimization approach for a high-voltage bidirectional flyback dc-dc converter, which optimized the converter for driving a capacitive actuator, which must be charged and discharged from 0-V to 2.5-kV dc and vice versa, supplied from a 24 V dc supply.
Abstract: This paper presents an efficiency optimization approach for a high-voltage bidirectional flyback dc–dc converter. The main goal is to optimize the converter for driving a capacitive actuator, which must be charged and discharged from 0 V to 2.5 kV dc and vice versa, supplied from a 24 V dc supply. The energy efficiency is optimized using a proposed new automatic winding layout (AWL) technique and a comprehensive loss model. The AWL technique generates a large number of transformer winding layouts. The transformer parasitics, such as dc resistance, leakage inductance, and self-capacitance are calculated for each winding layout. An optimization technique is formulated to minimize the sum of energy losses during charge and discharge operations. The efficiency and energy loss distribution results from the optimization routine provide a deep insight into the high-voltage transformer design and its impact on the total converter efficiency. The proposed efficiency optimization approach is experimentally verified on a 25 W (average charging power) with a 100 W (peak power) flyback dc–dc prototype.

Journal ArticleDOI
TL;DR: In this paper, a multifunctional bidirectional converter applied to street lighting and photovoltaic (PV) microgeneration systems is presented, which works as an electronic driver supplying a street lighting luminaire based on light emitting diodes (LEDs) at night, from ac single-phase mains with high power factor and reduced harmonic distortion.
Abstract: This paper presents a multifunctional bidirectional converter applied to street lighting and photovoltaic (PV) microgeneration systems. The proposed converter works as an electronic driver supplying a street lighting luminaire based on light emitting diodes (LEDs) at night, from ac single-phase mains with high power factor and reduced harmonic distortion. During daylight hours, the converter injects the produced energy by a PV panel to the grid, working as a grid-tie inverter. The proposed topology is based on the integration of two flyback converters, one for each half-cycle of the grid voltage, avoiding the usual diode bridge rectifier for LED lamps drives, thus providing a bidirectional power flow. A prototype of the proposed electronic stage has been designed, built, and tested, in order to validate the system. Finally, experimental results are presented. In rectifier mode, an efficiency of 86% was achieved, whereas an efficiency of 89% was obtained in inverter mode.

Proceedings ArticleDOI
01 Sep 2015
TL;DR: In this paper, a flyback converter like any other switch mode power supply (SMPS) has two modes of conduction, the best mode for the design is selected and implemented.
Abstract: Flyback converters have been quite used for DC-DC conversion and electrical isolation since they are simple to operate, minimum component count and small size. Flyback converter like any other switch mode power supply (SMPS) has two modes of conduction, the best mode for the design is selected and implemented. Due to its operation in relatively high frequency in range of 100 KHz compared to 50 Hz transformer with hard switching, some noises appeared from parasitic and leakage elements in the converter. The sources of noises have been tracked to minimize its effect on performance. The practical results obtained from the design implement actions are shown in this paper.

Proceedings ArticleDOI
26 Jul 2015
TL;DR: The Smart Transformer (ST) as discussed by the authors is a power electronics-based transformer that represents an enabling technology for providing new services to the Low Voltage (LV) and Medium Voltage (MV) grids.
Abstract: The Smart Transformer (ST), which is a power electronics-based transformer, represents an enabling technology for providing new services to the Low Voltage (LV) and Medium Voltage (MV) grid. The 3-stage configuration, with a high frequency transformer and 2 DC links, allows the electrical separation of the LV and MV grids. This leads to the independence of the two grids: any disturbance downstream and upstream can be compensated and mitigated by the ST action, which is the case of the unbalanced load condition of the LV grids. The unbalanced currents demanded by the loads could create unbalanced voltages at the LV side and also unbalanced currents at the MV side of a traditional transformer. This paper presents the improvements achieved by ST implementation in terms of voltage and current balancing: with a proper control of the ST, it provides balanced voltage in the LV grid, demanding a balanced current from the MV grid. This feature increases the power quality in both grids and provides an improved service to the customers.