Improving system reliability using FRFET&amp;#x00AE; in LLC resonant converters

Choi, Wonsuk; Young, Sungmo

doi:10.1109/pesc.2008.4592292

Cited by 5 publications

(3 citation statements)

References 13 publications

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“…On rectifier diodes limited to two times output voltage, low voltage stress with no regulation range, (2) At the switching loss with low turn-off current and ZVS capability in the entire load range is very low, (3) to achieve ZVS the use of all extremely important elements, and (4) zero current switching (ZCS) on secondary rectifier and low voltage stress. On rectifier diodes limited to two times output voltage, low voltage stress with no secondary inductor [29,30]. In high current, low voltage application, LLC resonant converter is widely done and also for low current, high voltage application [31].…”

Section: Introductionmentioning

confidence: 99%

LLC resonant DC-DC converter for high voltage applications

Azura

Iqbal

Taib

2014

2014 IEEE Conference on Energy Conversion (CENCON)

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In this paper, an LLC resonant dc-dc converter is proposed for high voltage applications. Full bridge inverter, LLC resonant tanks, high voltage transformer and full bridge rectifier are comprised in the proposed converter circuit. In operating frequency of proposing converter, output voltage regulation is achieved by narrow varying. The energy trapped in leakage inductance of the transformer and to achieve ZVS feature, LLC resonant circuit is utilized to retrieve. It also increases conversion efficiency. A high voltage transformer is used to step up AC voltage which is then refined by the rectifier. With the equivalent circuit derived by first harmonic approximation (FHA method, input-output response and DC characteristics in frequency domain are obtained. The theoretical equations of the circuit operations are studied in detail to infer. Finally, a design example is implemented out to establish the feasibility of the proposed LLC resonant converter. The simulation results on the essential switching and circuit operation are presented. The robustness of this study is verified by the simulation results of the proposed converter with 300V input and 3.5kV/0.35A output.

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Section: Introductionmentioning

confidence: 99%

LLC resonant DC-DC converter for high voltage applications

Azura

Iqbal

Taib

2014

2014 IEEE Conference on Energy Conversion (CENCON)

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“…Regarding capacitive switching, MOSFETs are more sensitive than IGBTs and can be more easily destroyed, as explained in [28] and [29]. However, during normal operation (switching above resonant frequency) some failures have been reported for ZVS converters with light loads in [30][31][32][33].…”

Section: Power Semiconductorsmentioning

confidence: 99%

“…Therefore, special care has to be taken regarding the reverse recovery time and current of the antiparallel diode in case of using MOSFETs. Authors recommend using MOSFETs with fast diodes, most of them using fastrecovery epitaxial diode field-effect transistors (FREDFET), as in [30][31][32][33][34].…”

Section: Power Semiconductorsmentioning

confidence: 99%

Induction heating converter's design, control and modeling applied to continuous wire heating

Segura¹

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Induction heating is a heating method for electrically conductive materials that takes advantage of the heat generated by the Eddy currents originated by means of a varying magnetic field. Since Michael Faraday discovered electromagnetic induction in 1831, this phenomena has been widely studied in many applications like transformers, motors or generators' design. At the turn of the 20th century, induction started to be studied as a heating method, leading to the construction of the first industrial induction melting equipment by the Electric Furnace Company in 1927. At first, the varying magnetic fields were obtained with spark-gap generators, vacuum-tube generators and low frequency motor-generator sets. With the emergence of reliable semiconductors in the late 1960's, motor-generators were replaced by solid-state converters for low frequency applications. With regard to the characterization of the inductor-workpiece system, the first models used to understand the load's behavior were based on analytical methods. These methods were useful to analyze the overall behavior of the load, but they were not accurate enough for a precise analysis and were limited to simple geometries. With the emergence of computers, numerical methods experienced a tremendous growth in the 1990's and started to be applied in the induction heating field. Nowadays, the development of commercial softwares that allow this type of analysis have started to make the use of numerical methods popular among research centers and enterprises. This type of softwares allow a great variety of complex analysis with high precision, consequently diminishing the trial and error process. The research realized in last decades, the increase in the utilization of numerical modeling and the appearance and improvement of semiconductor devices, with their corresponding cost reduction, have caused the spread of induction heating in many fields. Induction heating equipments can be found in many applications, since domestic cookers to high-power aluminum melting furnaces or automotive sealing equipments, and are becoming more and more popular thanks to their easy control, quick heating and the energy savings obtained. The present thesis focuses on the application of induction heating to wire heating. The wire heating is a continuous heating method in which the wire is continuously feeding the heating inductor. This heating method allows high production rates with reduced space requirements and is usually found in medium to high power industrial processes working 24 hours per day. The first chapters of this study introduce the induction heating phenomena, its modeling and the converters and tanks used. Afterwards, a multichannel converter for high-power and high-frequency applications is designed and implemented with the aim of providing modularity to the converter and reduce the designing time, the production cost and its maintenance. Moreover, this type of structure provides reliability to the system and enables low repairing times, which is an extremely interesting feature for 24 hours processes. Additionally, a software phase-locked loop for induction heating applications is designed and implemented to prove its flexibility and reliability. This type of control allows the use of the same hardware for different applications, which is attractive for the case of industrial applications. This phase-locked loop is afterwards used to design and implement a load-adaptative control that varies the references to have soft-switching according to load's variation, improving converter's performance. Finally, the modeling of a continuous induction wire hardening system is realized, solving the difficulty of considering the mutual influence between the thermal, electromagnetic and electric parameters. In this thesis, a continuous process is modeled and tested using numerical methods and considering converter's operation and influence in the process.

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