Automatic frequency control of an induction furnace

Khan, Imran; Tapson, Jonathan; Vries, I. De

doi:10.1109/afrcon.1999.821891

Cited by 8 publications

(5 citation statements)

References 9 publications

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“…In order to synchronize the converter and its switching frequency, most authors use phase‐locked loop (PLL) schemes . The phase‐shift between current and voltage is measured through an XOR gate and a low pass filter used to obtain a proportional voltage.…”

Section: Introductionmentioning

confidence: 99%

“…Afterwards, a voltage‐controlled oscillator (VCO) generates the gate signals to the switches. For implementing this control scheme, some authors use integrated circuits like the 4046 family , measuring directly the voltage and current or using gate signals instead of voltage measurements to reduce the cost of the equipment . In the last case, some include a compensator to take into consideration the delays in drivers and switches .…”

Section: Introductionmentioning

confidence: 99%

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All-digital DSP-based phase-locked loop for induction heating applications

Segura

Sala-Perez

Lopez-Mestre³

et al. 2012

Int. Trans. Electr. Energ. Syst.

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Phase-locked loop schemes are widely used in induction heating applications for controlling the converters.\ud Most authors use total or partial analog solutions to implement the control schemes, which are less sturdy\ud and flexible to changes than digital schemes. In this paper, an all-digital DSP-based PLL is presented. It\ud has fewer variations due to the tolerances of the analog components and provides great flexibility in a wide\ud range of conditions just by reprogramming. Moreover, it allows changing dynamically some of the parameters\ud during the process and opens up the possibility of more complex control algorithms. The all-digital\ud PLL has been simulated and experimentally tested, demonstrating the feasibility and reliability of this type of\ud control in a real industrial equipmentPostprint (published version

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

All-digital DSP-based phase-locked loop for induction heating applications

Segura

Sala-Perez

Lopez-Mestre³

et al. 2012

Int. Trans. Electr. Energ. Syst.

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“…Although digital and all-digital PLLs are still widely used, software-PLLs have advantages regarding the integration, flexibility and control's complexity that with classical PLL systems can be difficult to Considering PLLs and IH applications, PLL systems are used to control the phase-shift between two electric variables and reach the resonant frequency. Some examples of authors that make use of similar schemes in IH field are [24,59,[91][92][93][94][95][96][97][98]. In case of VFSRI, the voltage and current phase-shift is close to zero at resonant frequency.…”

Section: Phase-locked Loop Description and Operation Principlesmentioning

confidence: 99%

“…To control this phase-shift, some authors use PLL systems that just measure i tank and use a feedback loop, as shown in Case 1 in Figure 5.3. Some examples of this type of PLL can be found in [93][94][95][96]. In this case, the current i tank is the input signal and the PLL output is a signal that tends to be synchronized with this current.…”

Section: Phase-locked Loop Description and Operation Principlesmentioning

confidence: 99%

“…Regarding the circuits employed, some authors use circuits designed by themselves, like [8, p. 152], but most of them use integrated circuits from the CMOS 4046 circuit family, like [59,[91][92][93][94][95]98]. Nevertheless, most authors use digital PLL systems, in which just the phase detector is digital, but the low-pass filter and the VCO are analog (Figure 5.2).…”

Section: Phase-locked Loop Description and Operation Principlesmentioning

confidence: 99%

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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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Study on the optimum transmission of active power between the source and an induction heating installation

Ioan

Marta

Aurel³

et al. 2015

2015 9th International Symposium on Advanced Topics in Electrical Engineering (ATEE)

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The paper presents several technical considerations related to the optimum transmission of electrical power from a voltage source of the mono phase inverter type with variable frequency to an installation providing the induction heating and melting of certain metallic materials. The oscillating circuit is LC parallel and may operate at a voltage of 100 V a.c. and a frequency falling within the (10÷300) kHz range. The experimental results showed the efficiency of the installation operation up to temperature of 1200°C. Until reaching this temperature, metallic alloys may be obtained, with new mechanic, physical and technological properties.

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Automatic frequency control of an induction furnace

Cited by 8 publications

References 9 publications

All-digital DSP-based phase-locked loop for induction heating applications

All-digital DSP-based phase-locked loop for induction heating applications

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

Study on the optimum transmission of active power between the source and an induction heating installation

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