Query: High frequency bus converter with low loss  integrated  matrix  transformer

Candidate papers:

abstract: The trend in isolated DC/DC converters is increasing output power demands and higher operating frequencies. Improved topologies and semiconductors can allow for lower loss at higher frequencies. A major barrier to further improvement is the transformer design. With high current levels and high frequency effects the transformers can become the major loss component in the circuit. High values of transformer leakage inductance can also greatly degrade the performance of the converter. Matrix transformers offer the ability to reduce winding loss and leakage inductance. This paper will study the impact of increased switching frequencies on transformer size and explore the use of matrix transformers in high current high frequency isolated applications. This paper will also propose an improved integrated matrix transformer design that can decrease core loss and further improve the performance of matrix transformers.
author_names: David Reusch

Fred C Lee
title: High frequency bus converter with low loss integrated matrix transformer
venue: 2012 Twenty Seventh Annual IEEE Applied Power Electronics Conference and Exposition (APEC)
year: 2012

abstract: 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 an LLC allows operation at very high frequencies. In addition, the size of the magnetic components is reduced without sacrificing the efficiency. In this article, a novel magnetic structure that integrates a matrix transformer and inductor with minimum winding and a single magnetic core is proposed, to allow a high density and high efficiency LLC converter design for a bus converter. A 40 60 V input and regulated 12 V output converter is developed to deliver a 1 kW output power in a quarter brick form factor. The designed converter can achieve a power density of 700 W/in3 with a maximum efficiency of 97.82% at half load, dropping to 97.7% at full load operation.
author_names: Mohamed Hassan Ahmed

Ahmed Nabih

Fred C Lee

Qiang Li
title: Low Loss Integrated Inductor and Transformer Structure and Application in Regulated LLC Converter for 48 V Bus Converter
venue: IEEE Journal of Emerging and Selected Topics in Power Electronics
year: 2020

abstract: The trend in intermediate bus architectures is increasing output power demands and higher operating frequencies. Improved topologies and semiconductors can allow for lower loss at higher frequencies. A major barrier to further improvement is the transformer design. With high current levels and high frequency effects the transformers can become the major loss component in the circuit. High values of transformer leakage inductance can also greatly degrade the performance of the converter. Matrix transformers offer the ability to reduce winding loss and leakage inductance. This paper will study the use of matrix transformers for a 600 W, 12 V/50A bus converter and identify the optimal number of matrix transformers. This paper will also propose an improved integrated matrix transformer design that can decrease core loss and further improve the performance of matrix transformers.
author_names: David Reusch

Fred C Lee
title: High frequency bus converter with integrated matrix transformers for CPU and telecommunications applications
venue: 2010 IEEE Energy Conversion Congress and Exposition
year: 2010

abstract: A DC DC converter is an essential component in Hybrid Electric Vehicle (HEV) to achieve power transfer from High Voltage bus (HV) to Low Voltage bus (LV) and vice versa. Very high current on the LV side of the high power DC DC converter in a heavy duty hybrid vehicle makes its design extremely challenging. Dual Active Bridge with an integrated matrix planar transformer is considered due to its advantages over other existing topologies, such as the ability to handle very high current on the LV side, bi directional power flow, high power density, zero voltage switching capability, and high modularity. An integrated planar Matrix transformer is chosen for galvanic isolation, as it helps in handling very high current on the LV side efficiently. Multi Objective Design Optimization, with low converter loss and low converter volume as its objectives, is used as a basis of parameters and components design. Current mode control is implemented to achieve a fast response and avoid transformer saturation due to the DC flux injection during the transients. The design algorithm and control scheme has been experimentally verified.
author_names: Shubham Mungekar

Akash Dey

Ghanshyamsinh Gohil
title: High Efficiency Bidirectional DC DC Converter with Matrix Transformer for Heavy Duty Hybrid Electric Vehicles
venue: 2020 IEEE Energy Conversion Congress and Exposition (ECCE)
year: 2020

abstract: The trend in isolated DC/DC converters is increasing output power demands and higher operating frequencies. Improved topologies combined with gallium nitride (GaN) transistors can allow for lower loss at higher frequencies. A major barrier to further improvement is the transformer design. With high current levels and high frequency effects the transformers can become the major loss component in the circuit. This paper will study the impact of increased switching frequencies on transformer size, the ability of GaN transistors to increase switching frequency in high frequency resonant topologies, and propose an improved integrated transformer design that can decrease core loss and further improve the performance of traditional matrix transformers. The final demonstration being a Vin=48V, Vo=12V, Io=30A, 1.6MHz GaN converter with an improved integrated transformer offering a power density of 900W/in3.
author_names: David Reusch

Fred C Lee
title: High frequency isolated bus converter with gallium nitride transistors and integrated transformer
venue: 2012 IEEE Energy Conversion Congress and Exposition (ECCE)
year: 2012

abstract: In a global and growing society, it is necessary to rethink strategies in order to minimize the environmental impact resulting from the progressive increase of energy consumption and the misuse of energy resources. Energy power system converters must be considered as a global way to spare most of the wasted energy. Today, in the power distribution infrastructure, including modern residential buildings, most equipment have power supplies with imbedded AC DC power converters which may have overall losses as high as 25% regarding the equipment output. Therefore, common DC buses for residential applications are being studied to increase equipment efficiency. This paper presents and designs an AC DC isolated converter that uses a full bridge matrix topology with high frequency isolation transformer and non electrolytic capacitors to integrate into the future residential buildings DC bus, presenting a reliable alternative to AC power. Non linear control techniques (sliding mode control and backstepping control) are employed to guarantee stability and disturbance robustness to the output DC low voltage, while enforcing sinusoidal input AC current and power factor correction. Control strategies are described and simulation results are presented and discussed.
author_names: Nelson Santos

J Fernando Silva

Vasco Soares
title: High Frequency Transformer Isolated AC DC Converter for Resilient Low Voltage DC Residential Grids
venue: DoCEIS
year: 2018

abstract: Both server and telecom power supply prefers LLC resonant converter with matrix transformer as DC/DC stage due to its high efficiency and high power density. With reduced labor intensive and lower profile, print circuit board (PCB) winding based matrix transformer is gaining more and more attention. A 4 layer PCB structure, with two layers for secondary side winding and another two layers for primary side winding, is general practice. In the case with even number of turns in primary side, each layer has half of the turns. However, with odd number of turns in primary side, it is impossible to physically get half of one turn. This paper proposes a novel winding structure that allows odd number of turns arranged in two layer PCB. Besides, four elemental transformers are integrated into a single planar magnetic core by flux cancellation. The winding width and core dimension are optimized to achieve lower loss and footprint. A 3 kW matrix transformer with 4 layer PCB winding is built up. Turns ratio of 3:1 is demonstrated as an example in each elemental transformer. The proposed winding layout method has simple structure, but shows low winding loss and good current sharing. The matrix transformer is demonstrated on a 500 kHz switching frequency wide band gap device based LLC resonant converter. The prototype achieves a peak efficiency of almost 98.5% and a power density of 24.4 kW/L (400 W/in3)
author_names: Shuo Wang

Hongfei Wu

Fred C Lee

Qiang Li
title: Integrated Matrix Transformer with Optimized PCB Winding for High Efficiency High Power Density LLC Resonant Converter
venue: 2019 IEEE Energy Conversion Congress and Exposition (ECCE)
year: 2019

abstract: In this paper, a high efficiency and power density unregulated LLC converter (DCX) is proposed for a first stage converter in two stages 48V voltage regulator module (VRM) for data center applications. An optimized matrix transformer structure including an enhanced termination method for both primary and secondary side winding, in addition, a PCB winding structure for equal current sharing among all transformer parallel layers is proposed, by which a significant reduction in the total conduction loss for the high frequency transformer is achieved. The proposed optimized design is applied for designing two LLC DCX converters with different fixed transformation ratios of (4:1) and (8:1) to study and evaluate the impact of the intermediate bus voltage variation on the overall two stage 48V VRM performance. The designed LLC DCX with GaN devices can provide a continuous output power of 900W with maximum efficiencies of 98.4% for the (4:1) conversion and 98.0% for the (8:1) conversion with high power densities of 1600 W/in3 and 1200W/in3 respectively.
author_names: Mohamed Hassan Ahmed

Fred C Lee

Qiang Li

Michael A de Rooij
title: Design Optimization of Unregulated LLC Converter with Integrated Magnetics for Two Stage 48V VRM
venue: 2019 IEEE Energy Conversion Congress and Exposition (ECCE)
year: 2019

abstract: Efficient dc dc power conversion with wide span voltage regulation is crucial to a sustainable and robust power electronics system. Dual active bridge (DAB) offers straight forward regulation and its transformer enables voltage step up/down required for many applications, such as battery chargers and bus converters for dc distribution systems. However, losing soft switching at light loads or when operating at voltage gains far from the turns ratio severely degrades the efficiency of DAB, especially at high switching frequencies. In this article, we demonstrate an enhanced DAB (E DAB) topology which employs an adjustable tap transformer to extend the soft switching over wider voltage gains and increase the power transfer capability. By a proper tap adjustment and with single phase shift modulation, the proposed gallium nitride (GaN) based converter achieved a peak efficiency of 97.4% with an overall efficiency greater than a conventional DAB for voltage gains of up to 2.8 times higher. Employing a quasi planar matrix transformer with integrated leakage inductance at 300 kHz allowed for an extremely high power density of 10 kW/l (7.5 kW/l with cooling) The tapped transformer did not incur extra losses to the topology. The gain versus power transfer characteristic for soft switching operation was derived for the E DAB and its improvement in efficiency was experimentally verified over a wide power range.
author_names: Armin Jafari

Mohammad Samizadeh Nikoo

Furkan Karakaya

Elison Matioli
title: Enhanced DAB for Efficiency Preservation Using Adjustable Tap High Frequency Transformer
venue: IEEE Transactions on Power Electronics
year: 2020

abstract: A switch mode power supply (SMPS) provides a much more efficient solution to drive the DC power supplies. As the LED driver, SMPS have to get the high efficiency, stability, no hot Spot and high current driving ability. Especially, high brightness LEDs is prominent source of light and has better efficiency and reliability than conventional light sources. Transformer is the major challenge and bottleneck for achieving low profile, high power density converter. Conventional transformers are designed with multiple windings on a ingle core. These winding cause higher leakage inductance, more noises and higher losses. Instead of using multiple windings on a single core, matrix transformer uses a single winding on multiple cores, resulting in a modular structure with many inherent advantages. The secondary winding in a matrix transformer consists of a pair of copper plates that are bonded to the inside surface of square ferrite core. In the present study, the design and analysis of matrix transformer converter for the LED driver which is proposed to reduce volume and easy structure, high current density, and high efficiency of the transformer in 300W SMPS. In this study DS DC converter, matrix transformer is integrated into advanced power conversion application systems. The half bridge converter topology is applied to archive object of the system. We designed and examined 300W DC DC converter to verify the performance of the matrix transformer. As a result, its leakage inductance is highly decreased and it is more suitable for high frequency operation than conventional SMPS.
author_names: Byeong-ho Jeong

Gil Mo Seo

Eun-A Moon

Geum-Bae Cho
title: A Study on High Frequency Matrix Transformer Applied to SMPS Design
year: 2012