Resonant transformer theory pdf

A ferroresonant transformer is a threewinding transformer, having one winding in parallel with a capacitor see fig. The equivalent circuit of llc resonant tank for secondary winding. The proposed method allows an easy design of the integrated transformer and the calculation of the losses of all. This is the same problem caused by the series capacitors used in distribution systems 70 years ago. In resonance condition, the current through test object is very large and that is limited only by the resistance of the circuit. The ferroresonant transformer has air gap in the core that can radiate relatively large time varying magnetic field.

Analytic model inclusive transformer for resonant converters. It is a high voltage transformer that consists of two high q coils primary and secondary that are wounded on either same ferrite or air core with capacitors are connected across the windings. This specific transformer is named after nikola tesla, a serbianamerican pioneer of electrical apparatus, methods. A simplified schematic of the parallel resonant converter is given in fig. In theory, the onoff transitions occur at a time in the resonant cycle where the switch current is zero, facilitat3329 ing zero current, hence zero power switching. The charger output is derived from the saturated winding of the transformer and is relatively independent of supply. Resonant power conversion bill andreycak abstract the technique of zero voltage switching in modern power conversion is explored.

A transformer operates on the principals of electromagnetic induction, in the form of mutual induction. Multielement resonant topology based on lclc circuit. At this point, the phase angle of the impedance which can be measured using the angl test is zero. Resonant charging does not only apply to systems incorporating a rotary spark gap. Antennas and resonant circuits tank circuits basic. A parallel resonant circuit is formed where the reactive current drawn by the load. Various kinds of characters of the llc resonant transformer are needed to understand in this study. Here the shortcircuit inductance value is an important parameter that determines the resonance frequency of the resonant transformer. Grounding system theory and practice ced engineering. A unified design theory for classe resonant dcdc converter topologies article pdf available in ieee access pp99. They are also used in some types of switching power supplies. Pdf a partial core transformer has been designed such that its magnetising. Resonant transformer is one of the best choice for high voltage generation which operates on resonance phenomenon xl xc.

Theory of operation of singlephase transformers custom. And9408 basic principles of llc resonant half bridge. Analysis, design, and implementation of improved llc resonant. Operation and design 4 application note an 201209 v1. The regulation of a constantvoltage transformer can be designed to be better than a few percent. Wireless power transfer using resonant inductive coupling.

A resonant transformer of this type is often used in analog circuitry as a bandpass filter. Highvoltage partialcore resonant transformers simon colin bell a thesis presented for the degree of. This example is an actual laboratory measurement of a small 1. Integrated transformers of resonant converters using extended. The tesla coil is a resonant, highfrequency stepup transformer used to produce extremely high voltages. An introduction to llc resonant halfbridge converter. It also performs this with the help of mutual induction between two windings. Design and implementation the llc resonant transformer. Pdf a resonant transformer for high voltage testing of generator. Devices sensitive to magnetic field should be kept some distance away from the transformer. Anderson the classic tesla coil a dualtuned resonant circuit november 24, 2000 1 preface the tesla coil is a high voltage twocoil resonant transformer. Tesla experimented with a number of different configurations consisting of two, or sometimes three, coupled resonant electric circuits tesla used these circuits to conduct.

These are referred to as simply resonant converters. Resonant transformer the equivalent circuit of a highvoltage testing transformer consist of the leakage reactances of the windings, the winding resistances, the magnetizing reactance and the shunt capacitance across the output terminals due to the bushing of the high voltage terminal and also that of the test object. Aeries resonant converter and b its ideal equivalent circuit. The charge is displaced in a time equal to onefourth the resonant period. The classic tesla coil a dualtuned resonant transformer by barton b. Resonant inductive coupling is also being used in wireless power.

The used model is based on the extended fundamental frequency analysis which is explained in principle in the following. The transformer does this by linking together two or more electrical circuits using a common oscillating magnetic circuit which is produced by the transformer itself. As known, tesla transformer presents a phenomenon of high voltage obtained through resonance of lc circuit, where the inductor l is a secondary of transformer with primary excited by a pulsed voltage square wave above. Pdf a unified design theory for classe resonant dcdc. Analysis and design of resonant dcdc converters for. One of teslas dreams was to employ his coil technology to distribute electric power without the need for wires, simply broadcasting it in the form of radio waves which could be received and conducted to loads by means of antennas. The frequency at which the inductive impedance equals the capacitive impedance x l x c is known as the selfresonant frequency srf of the component. Following the curve of its circuit model has different behaviour, analysis to the entity, and then designs the convert circuit of the llc resonant transformer. Morgan lacey in 1925, based on a series of pamphlets entitled transformer abstracts that were. Instrument transformer theory and testing steve hudson, pe engineering manager 10737 lexington drive knoxville, tn 37932 phone. A seriesparallel resonant converter for electrochemical wastewater treatment kathryn m. An induction coil a buzzing device constructed of a selfinterrupting relay and stepup transformer winding to generate a continuous pulsing waveform of high voltage provided an extremely noisy i. It is used to produce highvoltage, lowcurrent, high frequency alternatingcurrent electricity. For example, we need to calculate the core loss and conduction loss for a resonant transformer.

Flyback converter, transformer design the author would like to thank dr. For example, we need to calculate the resonant curve of its circuit model with different behavior analysis to the entity, and then design the convert circuit of the llc resonant transformer. Capability for handling a short circuit is an inherent feature of a constantvoltage transformer. Resonant transformers are also used in electronic ballasts for gas discharge lamps, and high voltage power supplies. An ipos llc resonant converters contains multiple dcdc modules, and each module requires a transformer, and these transformers can account for a large part of. The resonant circuit cs, ls and cp of the series parallel resonant converter is fed by a square wave input voltage vab which usually has a varying frequency. An electrical power transformer is a static device, which transforms electrical energy from one circuit to another without any direct electrical connection. It can be seen that the instantaneous voltage vtt applied across the tank circuit is equal to the difference between the switch voltage vst and the rectifier voltage vrt. Special transformers and applications transformers. Resonant converters can he broadly classified as 1. The hf transformer can also be connected after the lclc filter, if necessary, and can also be used to.

Mutual induction is the process by which a coil of wire magnetically. This article covers a wide range of transformer theory and voltechs testing capability. Subintervals and modes the series resonant converter, fig. The voltage waveform vtt, as well as the tank capacitor and inductor. An introduction to llc resonant halfbridge converter introduction although in existence for many years, only recently has the llc resonant converter, in particular in its halfbridge implementation, gained in the popularity it certainly deserves. A highvoltage transformer in which the secondary circuit is tuned to the frequency of the power supply. It is assumed the modern, experienced technician has access to storage type oscilloscopes, inductance and capacitance bridges, q factor meters, waveform analyzers, and. Resonant circuit inside the cvt has a fixed tuned oscillating frequency. A tesla coil is an electrical resonant transformer circuit designed by inventor nikola tesla in 1891. We design a resonant transformer which the conduction. Resonant charging is the means by which a wide static gap can fire and give good performance.

Resonant inductive coupling or magnetic phase synchronous coupling is a phenomenon with inductive coupling where the coupling becomes stronger when the secondary loadbearing side of the loosely coupled coil resonates. A new design of partialcore resonant transformer is arrived at, having an alternative. A potential transformer is a conventional transformer having primary and secondary windings. Transformer book is still in demand is a tribute to the publishers and to the authors who have carried the torch to light our way for 75 years. As a result of this connection, the transformer core is driven into saturation by the resonant tank circuit. Resonant inductive coupling, however, uses this capacitance to resonate with the inductors, increasing the flux linked between transmitter and receiver. If the constant voltage transformer is subjected to a line voltage frequency change the output voltage will vary, as shown in figure 115. Analytic design method for integrated transformers of. In highlyresonant wireless power transfer systems, the system resonators must have a high quality. Vorperian, senior engineer, power and sensor electronics group, jet propulsion laboratory jpl, richard ozenbaugh of linear magnetics and kit sum, senior consultant, for their help with the flyback design equations. However, the operating principles of a llc resonant half bridge converter are far from apparent and intuitive 1.

Here the load is a part of the resonart circuit so that either it carries the resonant crrent or the resonant capacitors voltage appears across it. This combination of an inductor with capacitor makes two coupled lc circuits. Experimental results obtained for a resonant converter with resonant frequency fg 35. Ferroresonance and subsynchronous resonance can arise in power system circuits when capacitance is connected in series and less commonly when connected in parallel with nonlinear inductive circuits such as transformers and reactors and when the voltage is sufficient to drive the nonlinear inductance to near the knee point of the bh curve. Partialcore resonant transformers are then introduced and their characteristics are. The frequency at which the inductive impedance equals the capacitive impedance x l x c is known as the self resonant frequency srf of the component. A closely spaced static spark gap will fire at a relatively low voltage, causing the tank capacitor to be recharged many times per supply cycle. Following the curve of its circuit model has different behaviour, analysis to the entity, and. Basic principles of llc resonant half bridge converter and dcdynamic circuit simulation examples introduction llc resonant half bridge converters are widely used in consumer electronics, like powering the display panel of lcd tv. Kolar abstract the seriesparallel resonant converter and its magnetic components are analysed by fundamental frequency techniques. A general design methodology for partialcore resonant transformers with. As a result, the left leg transition time is given by.