Design considerations for high frequency co-axial winding power transformers
28 Sep 1991-pp 946-952
TL;DR: In this paper, the important loss aspects of the design of co-axial winding transformers such as the influence of skin effect on winding resistance, the variation of the core loss caused by nonuniform core flux density, and the choice of the principle dimensions and aspect ratios for maximum efficiency are examined.
Abstract: An examination is made of the important loss aspects of the design of co-axial winding transformers such as the influence of skin effect on winding resistance, the variation of the core loss caused by nonuniform core flux density, and the choice of the principle dimensions and aspect ratios for maximum efficiency. Experimental measurements on a 50 kVA 50 kHz unit are included to confirm portions of the analytical results and suggested design procedures. >
Citations
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Patent•
19 Oct 1993TL;DR: In this paper, a contactless recharging system and method for recharging a battery storage device onboard an electric vehicle is described, where the vehicle has a primary converter station (20, 102, 202, 304) for converting power from a power source into high frequency power at a selected charging rate.
Abstract: A contactless recharging system (10, 100, 200, 300) and method for recharging a battery storage device (12) onboard an electric vehicle (14, 106, 302) has a primary converter station (20, 102, 202, 304) for converting power from a power source (16) into high frequency power at a selected charging rate The vehicle has a secondary converter (32, 150, 306) for converting high frequency power into DC power to charge the battery The converters are coupled together by a contactless coupling of a conductor loop (30, 104, 308, 420, 430) and a coupling link (25, 25', 110, 205, 310, 310', 310') forming a coaxial winding transformer The coupled link and loop carry a communication indicating the selected charging rate of the battery The link has a magnetic core (40; 50; 112; 318, 320, 322 and 324) and a core-mounted conductor (45; 55; 120; 326, 328, 330 and 332) at least partially surrounded by the core The core-mounted conductor selectively at least partially surrounds a portion of the loop to transfer power therebetween The core-mounted conductor is coupled to one of the converters, and the loop is coupled to the other converter
384 citations
Patent•
20 Oct 1992TL;DR: In this paper, a submersible contactless power transfer system, especially for powering underwater electric loads, including movable loads, such as underwater vehicles, elevators, or worksite equipment, is described.
Abstract: A submersible contactless power transfer system, especially for powering underwater electric loads, including movable loads, such as underwater vehicles, elevators, or worksite equipment. A converter supplies high frequency power to a conductor loop. A coupling sheath or link has a core-mounted conductor at least partially surrounded by a magnetic core which slidably receives a portion of the conductor loop within the link. An optional secondary converter converts power from the core-mounted conductor to meet the load requirements. A contactless power distribution system is submersible to deliver power to underwater loads through clamped-on or captive links attached at any location along the conductor loop. Methods are also provided of powering loads submersed in water, including seawater, or other non-magnetic liquid mediums.
182 citations
TL;DR: In this paper, a lumped-component equivalent circuit has been developed to model the electric behavior of any two-winding transformer, which is suitable in a wide frequency range: from dc up to one decade beyond the maximum working frequency of the transformer.
Abstract: A lumped-component equivalent circuit has been developed by our team to model the electric behavior of any two-winding transformer. This circuit is general: its topology is independent of shape, sizes, and technology chosen. Changing the sample results only in a change of numerical values. Moreover, this circuit is suitable in a wide frequency range: from dc up to, at least, one decade beyond the maximum working frequency of the transformer. The aim of this paper is to present an experimental method which allows all the component values of this equivalent circuit to be determined, using only external impedance measurements. The method is illustrated by one example and, to conclude, Bode plots related to the circuit are compared to the experimental ones. >
93 citations
01 Jan 1995
TL;DR: In this paper, a lumped-component equivalent circuit has been developed to model the electric behavior of any two-winding transformer, which is suitable in a wide frequency range: from dc up to one decade beyond the maximum working frequency of the transformer.
Abstract: A lumped-component equivalent circuit has been developed by our team to model the electric behavior of any two-winding transformer. This circuit is general: its topology is independent of shape, sizes, and technology chosen. Changing the sample results only in a change of numerical values. Moreover, this circuit is suitable in a wide frequency range: from dc up to, at least, one decade beyond the maximum working frequency of the transformer. The aim of this paper is to present an experimental method which allows all the component values of this equivalent circuit to be determined, using only external impedance measurements. The method is illustrated by one example and, to conclude, Bode plots related to the circuit are compared to the experimental ones. >
86 citations
TL;DR: In this article, a novel soft-switched inverter topology was derived from the passively clamped quasi-resonant link (PCQRL) circuit, where the number of auxiliary switches can be reduced from two to one, and only a single magnetic core is required for the resonant DC link.
Abstract: A novel soft-switched inverter topology is derived from the passively clamped quasi-resonant link (PCQRL) circuit. By introducing magnetic coupling between the two resonant inductors, the number of auxiliary switches can be reduced from two to one, and only a single magnetic core is required for the resonant DC link. An analysis of this novel PCQRL topology with coupled inductors is presented to reveal the various soft-switching characteristics. In comparison with the conventional passively clamped, continuously resonant DC link inverter, this soft-switched inverter can reduce voltage stresses from more than 2 per unit (pu) to 1.1-1.3 pu. It can also provide soft-switched pulse-width modulated (PWM) operation. Simulations and experiments are performed to backup the analysis.
83 citations
References
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07 Oct 1990
TL;DR: In this article, the performance of a high-power, high-density DC-to-DC converter based on the single-phase dual active bridge (DAB) topology is described.
Abstract: The performance of a high-power, high-power-density DC-to-DC converter based on the single-phase dual active bridge (DAB) topology is described. The dual active bridge converter has been shown to have very attractive features in terms of low device and component stresses, small filter components, low switching losses, high power density and high efficiency, bidirectional power flow, buck-boost operation, and low sensitivity to system parasitics. For high output voltages, on the order of kilovolts, a cascaded output structure is considered. The effects of snubber capacitance and magnetizing inductance on the soft switching region of control are discussed. Various control schemes are outlined. Coaxial transformer design techniques have been utilized to carefully control leakage inductance. The layout and experimental performance of a prototype 50 kW 50 kHz unit operating with an input voltage of 200 V DC and an output voltage of 1600 V DC are presented. >
1,311 citations
11 Jun 1990
TL;DR: In this paper, the authors investigated various design considerations for high-power (multikilowatt), high-frequency transformers for DC-DC power converters and investigated the influence of leakage flux distribution in the window region on the copper losses.
Abstract: Various design considerations for high-power (multikilowatt), high-frequency transformers for DC-DC power converters are investigated Although Ferrite (PC40) is lossier than Permalloy80 (05 mil) at the frequencies of interest (25-50 kHz) the use of the former is justified on the basis of cost, weight, and wide ranges of shapes The influence of the leakage flux distribution in the window region on the copper losses has been demonstrated for various conventional winding arrangements However, it is seen that in conventionally wound transformers a considerable amount of leakage flux enters the core, resulting in localized core saturation and hot-spots This becomes a very critical issue for high-power, high-frequency transformers Coaxially wound transformers are seen to be a viable alternative, in that the leakage flux is contained with the interwinding space, with very little or none of it permeating the core Such transformers can also realize multiple benefits of a low distributed and controllable leakage inductance, robust construction, low electromechanical forces, and low core and copper losses Test results on two coaxially wound transformers with different tube geometries, designed for 50 kW, 50 kHz, primary voltage of 200 V, and secondary voltage of 1000 V (two windings), are presented Finally the concept of coaxial winding technique for three-phase transformers is also presented >
77 citations
24 Jun 1991
TL;DR: In this article, a load side resonant, high power density, DC-to-DC converter is proposed, which is based on a half-bridge topology with zero voltage switching (ZVS) characteristics.
Abstract: A load side resonant, high power density, DC-to-DC converter is discussed. The proposed converter features a constant current source output characteristic while utilizing all component parasitics. The converter is based on a half-bridge topology with zero voltage switching (ZVS) characteristics, feeding an isolation transformer and output rectifiers. The converter's resonant action is based on the leakage inductance of the isolation transformer and the output rectifier capacitance. This output side resonance resets the energy normally dissipated in the Schottky capacitance and also enables a buck-boost condition for the output voltage. The converter demonstrates current source output characteristics which are applied to a battery charging application. Coaxial winding techniques for the isolation transformer are also investigated. These winding characteristics are shown to be unique and favorable when applied to DC-to-DC converters and especially the dual resonant converter topology. >
15 citations