Isolated high-output current DC/DC converters are critical for future data center power architecture. LLC with matrix transformer suitable these applications due to its high efficiency and density. Different structures investigated in this paper. To improve the design practice, a high-frequency loss model is developed detailed methodology proposed. Moreover, novel structure proposed integrate four elemental transformers into one magnetic core simple four-layer print circuit board windings...

The totem-pole bridgeless power factor correction (PFC) rectifier has recently been recognized as a promising front-end candidate for applications like servers and telecommunication supplies. This paper begins with discussion of the advantages using emerging high-voltage gallium-nitride (GaN) devices in PFC rectifiers rather than traditional rectifiers. critical-mode operation is used order to achieve both high frequency efficiency. Then, several high-frequency issues detailed design...

This paper presents a high-frequency modular medium-voltage AC (4160 VAC or 13.8 kVAC) to low-voltage DC (400 VDC) system that is scalable in order be used for different scale microgrids. A 15 kW, 500 kHz DC/DC converter demonstrated as the most important stage of overall, which can 225 kW 4160 400 VDC system. Motivation CLLC resonant and its design parameters determination carefully illustrated. The transformer key element converter. Then, focuses on realize high-voltage insulation, high...

This paper proposes a novel two-stage topology for 6.6-kW on-board charger. The first stage, employing an interleaved bridgeless totem-pole ac/dc in critical conduction mode to realize zero-voltage switching, is operated at over 300 kHz. A bidirectional CLLC resonant converter operating 500 kHz chosen the second stage. variable dc-link voltage adopted track wide battery range, so that can always operate its most efficient point. 1.2-kV SiC devices are stage and primary side of dc/dc while...

A widebandgap-based bidirectional on-board charger (OBC) has been proposed with a variable dc-link voltage, which tracks the battery voltage fluctuation. Although this approach is deemed most efficient for resonant dc/dc stage, it posts significant challenges rectifier/inverter operates in critical mode to realize zero-voltage switching (ZVS), while subjecting large variations of input and output voltages. Design considerations ac/dc stage are presented paper, including: evaluation 1.2-kV...

Recently, omnidirectional wireless power transfer systems have been studied intensely due to their improved flexibility when compared with planar counterparts. In this paper, a novel charging bowl multiple transmitter coils is proposed portable devices. The bowl-shaped coil optimized provide sufficiently strong and nearly uniform field distribution. Inside the bowl, receiver can be charged free-positioning arbitrary orientation. This unique benefit particularly attractive for low-power...

A solid-state transformer can directly convert medium voltage to low (e.g., 400 V) with minimized power-conversion stages. The in the dc–dc module not only provides medium-voltage insulation but also significantly affects power density of module. In this article, an innovative compact structure is proposed handle using coordination epoxy, bobbin, shielding layer, and stress-control layer. brand-new bobbin design related fabrication process ensures a partial-discharge-free insulation. Besides...

Magnetic core loss is an important concern for power converters. As the switching frequency increases and converter size reduced, will have significant impact to efficiency temperature. Accurate evaluation magnetic design estimation. The classic two-winding method limited low frequencies (usually below 1 MHz) because it sensitive phase discrepancy. In this paper, a new proposed high-frequency measurement that utilizes capacitive cancellation, which suitable HF VHF measurement. greatly...

This paper presents a high-frequency high-efficiency GaN device-based interleaved critical current mode (CRM) bidirectional buck/boost converter with an inverse coupled inductor. The switching frequency is continually driven to megahertz range devices due their small loss and driving loss, which greatly reduces the size of passive components. inductor further core volume certain dc flux reductions. equivalent inductance impact on CRM buck-boost are analyzed in detail. resonant period less...

The momentum toward high power density high-efficiency converters continues unabated. key to reducing the size of is high-frequency operation and bottleneck magnetic components. With emerging widebandgap devices, switching frequency increases significantly, hundreds kilohertz, which provides us opportunity adopt printed circuit board (PCB) winding planar magnetics. Compared with conventional litz-wire-based magnetics, magnetics can not only effectively reduce converter size, but also offer...

The two-stage 48 V-12 V-1.8 V voltage regulator module (VRM) structure is gaining more and attention in high-end server applications. LLC converter the preferred choice for first conversion stage because it provides isolated 12-V output efficiently, which then converted to 1.8 by multiphase Buck converter. Since CPU works sleep-mode most of time, light-load efficiency very important energy saving. This paper proposes change primary side from full-bridge (FB) configuration into half-bridge...

This paper analyzes the outage performance of cooperative protocols for two-way relaying model in which a half-duplex relay assists bi-directional communication two terminals. We first define events and derive closed form results probabilities conventional nonadaptive Amplify-and-Forward (AF) Decode-and-Forward (DF) protocols.We then consider simple adaptive protocol scenario, switches between AF DF depending on decodability data streams at relay. also probability this scheme expressions,...

The LLC converter is deemed the most widely used topology as dc/dc in server and telecom applications. To increase output power reduce input current ripples, three-phase interleaved becoming more popular. It has been demonstrated that three can achieve further efficiency improvement at 3-kW level. However, magnetic components for multiphase are complex, bulky, difficult to manufacture a cost-effective manner. In this paper, high-frequency gallium nitride (GaN)-based employed address these...

A high-efficiency, high-power-density Sigma converter for a 48 V rack architecture in data centers is proposed this paper. The quasi-parallel that uses high-efficiency unregulated to deliver the bulk power load. small buck responsible regulating output voltage with prescribed dynamic responses. design guideline integrated magnetics provided an LLC designed printed circuit board (PCB) winding matrix transformer, structure which integrates four elemental transformers into one core. discrete...

Isolated high output current dc/dc converters are critical for power supplies in information technology industries. LLC with a matrix transformer suitable these applications due to their efficiency and density. By pushing switching frequency up MHz GaN devices, planar transformers printed circuit board (PCB) windings advantageous over conventional designs, but the large interwinding capacitance of PCB provides coupling path common-mode (CM) noise. In order analyze CM noise, is analyzed,...

A high efficiency and power density sigma converter for 48/1V voltage regulator module (VRM) is proposed in this paper. The Sigma a quasi-parallel that uses unregulated to deliver most the load with small flowing through buck responsible regulating output voltage. isolated LLC designed matrix transformer structure integrating 4 transformers one core Synchronous Rectifiers (SRs) winding minimize termination losses of so can be achieved. discrete GaN devices PCB inductor regulate 48/1V-80A...

Synchronous rectifiers (SRs) are important for high-output-current LLC converters in order to reduce the secondary conduction loss. Conventional SR driving schemes not suitable high-frequency converters: analog will lose a large portion of duty cycle due parasitic inductance; and digital require much higher cost controllers operation. In this paper, implementation adaptive scheme with cost-effective microcontroller is proposed. The proposed senses drain-source voltage detect body diode...

With ever increasing demands of smaller size, lighter weight for all forms consumer electronics, efficient power conversion with higher operating frequency has always being pursued rigorously. This paper demonstrates high frequency, efficiency and density design active clamp flyback converter adapter application. Both the primary secondary switches are gallium nitride (GaN) devices which can significantly reduce device related conduction switching loss. The procedures, including selection...

Equivalent circuit models are useful design tools for control and have already well served their purposes in pulse width modulation dc-dc converters. However, no simple equivalent model is available yet resonant-type Up to now, the most successful of series resonant converter (SRC) based on extended describing function concept, which was proposed by Yang et al. a complicated fifth order with cross-coupling effect analytical solution provided transfer functions. This paper proposes...

In this article, a high-efficiency and power-density unregulated inductor-inductor-capacitor (LLC) converter (DCX) is proposed for first-stage in two-stage 48-V voltage regulator module (VRM) data center applications. The intermediate bus the architecture evaluated by designing two LLC-DCX converters with fixed transformation ratios of (4:1) (8:1). overall efficiency evaluated, optimal selected. designed using gallium nitride (GaN) devices an optimized integrated magnetic structure. An...

One challenge of on board charger application is bi-directional operation. Due to the absence reverse recovery charge and small junction capacitance, it much easier do bidirectional operation using wide band gap devices. Another very battery voltage range. It difficult optimize converter over whole range efficiency drops either too high or low. In this paper, a novel two stage structure proposed utilizing both SiC GaN Bi-directional power flow as well zero switching achieved with structure....

In this paper, a novel critical-conduction-mode-based modulation is proposed for three-phase bidirectional ac-dc converters. With modulation, the switching frequency variation range shrinks, zero-voltage-switch soft achieved, and switching-related loss reduced, which especially beneficial systems operating above hundreds of kHz high with wide-band-gap power semiconductor devices to achieve both density efficiency. A 25 kW silicon carbide based high-frequency ac- dc converter prototype...

This paper develops a 200-W wide-input-range (64-160-to-24-V) rail grade dc-dc converter based on gallium nitride devices. A two-stage configuration is proposed. The first regulated stage two-phase interleaved buck (>400 kHz), and the second unregulated an LLC (2-MHz) dc transformer. In order to achieve high frequency efficiency, critical-mode operation applied for converter, negative coupled inductors are used reduce conduction losses. Then, systematical methodology proposed optimize...

In this article, an LLC converter using gallium nitride (GaN) transistors is proposed for a 48-V regulated and isolated bus converter. Compared with pulsewidth modulation (PWM)-based topologies, the soft switching capability of allows operation at very high frequencies. addition, size magnetic components reduced without sacrificing efficiency. novel structure that integrates matrix transformer inductor minimum winding single core proposed, to allow high-density high-efficiency design A...

Resonant converters, especiallyLLC are deployed in many applications thanks to their reliability and high efficiency. With the introduction of wide band gap (WBG) devices soft switching feature LLC converter, frequency can be pushed order megahertz, shrink converter size increase power density. However, magnetic design control challenges stand way doing so. This article addresses high-frequency for presents an overview latest solutions on transformer. The matrix transformer is suitable where...