Coaxially wound transformers for high-power high-frequency applications

Abstract-A bi-directional multi-port converter can accommodate various energy storages and sources. Therefore, a multiport converter will be a good candidate for application as a future universal converter for (hybrid) electrical vehicles or local distribution systems. For the multiport converter proposed in this paper, the main design challenge is the design of its three-phase symmetrical transformer. In this converter, symmetry of the leakage inductances is essential to ensure balanced three-phase currents (transferred power). These currents are interconnected by three single-phase high-frequency link transformers. To realize the equality of the leakage inductances a specific transformer design is necessary. Since conventionally wound three-phase transformer core shapes suitable for high-frequency are expensive and difficult to build, a coaxially wound transformer will be designed in this paper.

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“…Transformers that can provide natural leakage symmetry are either conventionally [4] or coaxially [8] wound, as shown in Fig. 4.…”

Section: Coaxially Wound Transformermentioning

confidence: 99%

Multiport converters for fast chargers of electrical vehicles - Focus on high-frequency coaxial transformers

Waltrich

Duarte

Hendrix

2010

The 2010 International Power Electronics Conference - ECCE ASIA -

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“…This technique offers a feasible solution to contain the leakage flux within the inter-winding space and thus prevents the core from being saturated locally [12]. As a result, the core and copper losses are lower, and localized heating is avoided [12]. Furthermore, from a mechanics point of view, this technique offers reduced forces within the transformer and a robust construction.…”

Section: Symmetrical Transformer Designmentioning

confidence: 99%

“…8 shows the structure of a coaxially wound transformer. This technique offers a feasible solution to contain the leakage flux within the inter-winding space and thus prevents the core from being saturated locally [12]. As a result, the core and copper losses are lower, and localized heating is avoided [12].…”

Section: Symmetrical Transformer Designmentioning

confidence: 99%

“…Furthermore, from a mechanics point of view, this technique offers reduced forces within the transformer and a robust construction. In [12], it has been demonstrated that coaxial windings can lead to low loss, low leakage inductance power transformers in high-frequency softswitched dc-dc and resonant converters. Some of the important loss aspects such as the influence of skin effect on winding resistance, the variation of core loss caused by non-uniform core flux density, and the choice of the principle dimensions and aspect ratios for maximum efficiency were examined in [13].…”

Section: Symmetrical Transformer Designmentioning

confidence: 99%

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High-Power Three-Port Three-Phase Bidirectional DC-DC Converter

Tao

Duarte

Hendrix

2007

2007 IEEE Industry Applications Annual Meeting

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Abstract-This paper proposes a three-port three-phase bidirectional dc-dc converter suitable for high-power applications. The converter combines a slow primary source and a fast storage to power a common load (e.g., an inverter). Since this type of system is gaining popularity in sustainable energy generation systems and electrical vehicles, the proposed topology is of practical interest. The proposed converter consists of three high-frequency inverter stages operating in a six-step mode, and a high-frequency three-port three-phase symmetrical transformer. The converter provides galvanic isolation and supports bidirectional power flow for all the three ports. An arbitrary power flow profile in the system can be achieved by phase shifting the three inverter stages. Thanks to the three-phase structure, the current handling capability of the circuit is larger and the ripple currents at the dc sides are much lower owing to the interleaving effect of the threephase, and thus the VA rating of the filter capacitors is much lower. The operating principle and, in particular, the transformer design which is based on conventionally and coaxially wound structures are presented. Circuit simulation results are included to verify the proposed converter topology and the dual-PI-loop control strategy.

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“…However, for the test and characterization of power switches, coaxial current shunts and Rogowski coils are commonly used [3]. The coaxial current transformer (CCT) [1], [4] is an interesting choice for measurement of the current through power devices since the coaxial structure of the primary circuit leads to extremely low insertion inductance. This paper analyzes the characteristics of the current measurement device and explains how it can be integrated into a test setup for both press-mounted and module packages to achieve high power and high bandwidth measurements.…”

mentioning

confidence: 99%

Co-axial current transformer for test and characterization of high power semiconductor devices under hard and soft-switching

Lyra¹,

John²,

Lipo³

et al.

Conference Record of the 1999 IEEE Industry Applications Conference. Thirty-Forth IAS Annual Meeting (Cat. No.99CH36370)

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Abstract-The use of a coaxial current transformer (CCT) is an interesting choice for pulsed measurement of current through power devices during switching transients. The CCT is used to reflect current for convenient external measurement with minimal insertion impedance in the critical power circuit. This paper analyzes the characteristics of the CCT and explains how it can be integrated into test setups for both press-pack and module packages. Finite-element techniques are applied to the study of the CCT to obtain detailed electrical and magnetic characteristics. Current distribution in the primary and secondary circuits, flux densities, and insertion inductance and resistance are among the design information that can be obtained through finite-element analysis. Analytical and numerical results are obtained for the proposed CCT that is integrated in test setups for MOS turn-off thyristors (press-pack) and high-voltage insulated gate bipolar transistors (module) characterization.

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Coaxially wound transformers for high-power high-frequency applications

Cited by 56 publications

References 5 publications

Multiport converters for fast chargers of electrical vehicles - Focus on high-frequency coaxial transformers

Multiport converters for fast chargers of electrical vehicles - Focus on high-frequency coaxial transformers

High-Power Three-Port Three-Phase Bidirectional DC-DC Converter

Co-axial current transformer for test and characterization of high power semiconductor devices under hard and soft-switching

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