Induction Heating Applications Research Articles

A Novel LCLC Parallel Resonant Circuit for High-Frequency Induction Heating Application

A Novel LCLC Parallel Resonant Circuit for High-Frequency Induction Heating Application

Semisynthetic ferritin-based nanoparticles with high magnetic anisotropy for spatial magnetic manipulation and inductive heating.

The human iron storage protein ferritin represents an appealing template to obtain a semisynthetic magnetic nanoparticle (MNP) for spatial manipulation or inductive heating applications on a nanoscale. Ferritin consists of a protein cage of well-defined size (12 nm), which is genetically modifiable and biocompatible, and into which a magnetic core is synthesised. Here, we probed the magnetic response and hence the MNP's suitability for (bio-)nanotechnological or nanomedical applications when the core is doped with 7% cobalt or 7% zinc in comparison with the undoped iron oxide MNP. The samples exhibit almost identical core and hydrodynamic sizes, along with their tunable magnetic core characteristics as verified by structural and magnetic characterisation. Cobalt doping significantly increased the MNP's anisotropy and hence the heating power in comparison with other magnetic cores with potential application as a mild heat mediator. Spatial magnetic manipulation was performed with MNPs inside droplets, the cell cytoplasm, or the cell nucleus, where the MNP surface conjugation with mEGFP and poly(ethylene glycol) gave rise to excellent intracellular stability and traceability within the complex biological environment. A magnetic stimulus (smaller than fN forces) results in the quick and reversible redistribution of the MNPs. The obtained data suggest that semisynthetic ferritin MNPs are highly versatile nanoagents and promising candidates for theranostic or (bio-)nanotechnological applications.

Performance Enhancement in LC Series Resonant Inverters with Current-Controlled Variable-Transformer and Phase Shift for Induction Heating

This article presents an analysis of a converter based on an LC resonant inverter for induction heating applications. It employs a current-controlled variable transformer (VT) in conjunction with phase shift regulation (PS) to operate at a fixed frequency close to the resonance frequency. The converter maintains a small switching angle, enabling substantial load variations without sacrificing zero voltage switching (ZVS) for the transistors. This innovative method enhances the inverter’s performance across the entire operating range. Additionally, a new design of the transformer structure with a variable ratio will be analyzed, enabling mathematical modeling. The obtained results demonstrate a performance exceeding 99%. Both the inverter and variable transformer designs were experimentally validated using a 15 kW, 200 kHz converter for induction heating applications with silicon carbide (SiC) MOSFETs.

Efficient conversion of ethanol to acetaldehyde with induction heating at low temperature

The application of induction heating (IH) to provide heat for chemical reactions has received great attention due to its potential to electrify chemical reactions. Biomass-based production of acetaldehyde from ethanol has gained rising interest since it provides an alternative sustainable method instead of the fossil-fuel-based output using acetylene and formaldehyde in the presence of a catalyst. The dehydrogenation of ethanol can be catalyzed by supported copper catalysts. The reaction is typically carried out at high temperatures, around 250–300 °C, without oxygen. The resulting product mixture usually contains acetaldehyde, as well as other byproducts such as ethylene and hydrogen gas. The acetaldehyde can be separated from the other components using distillation or other separation techniques. In this work, we studied the catalyst activity with IH for the first time and achieved high ethanol conversion and acetaldehyde selectivity at a temperature of 30 ˚C lower than that with conventional furnace heating (CFH). A transport model was applied to design the catalyst bed configuration and improve the catalyst activity, stability, and energy efficiency by minimizing the temperature gradient. Our work suggests that the temperature distribution and the fast compensation of heat loss through IH are critical for the catalyst behavior. Both high production efficiency and energy efficiency can be achieved with IH, such that it can be an efficient and environment-friendly heating method for the chemical industry.

Analysis of the Effects of Microwave Combined Induction Heating on Steamed Pork with Rice Powder.

This study investigates the application of microwave combined induction heating (MCIH) to steam ready-to-eat pork with rice powder, emphasizing the advantages of rapid and uniform heating. The experimental setup included a mixture of 180 g pork strips, 30 g rice powder, and 10 g water in a CPET tray using MCIH with 1080 W microwave (MW) and 130 °C induction heating (IH) for 150 s. The results showed a quick temperature increase rate of 0.56 °C/s that achieved pasteurization against a variety of pathogenic bacteria, such as Listeria monocytogenes, but not Clostridium botulinum, by lethality calculation. Compared to typical electric cooker steaming, MCIH significantly shortened cooking time (8.6 times faster). To address rice starch gelatinization, two-stage heating techniques to steam pork with rice powder were MCIH: 150 s, and then IH: 60 s (MW1), and MCIH: 180 s, and then IH: 30 s (MW2), with no significant differences seen in color or the nine-point taste scale between treatment groups. MCIH groups had smaller shear forces than control. After MCIH cooking, no microbial counts were detected in the MW1 and MW2 groups initially, and the pork with rice powder had a shelf life of 14 days at 4 °C based on aerobic plate count assay.

Phase-shifted third harmonic modulation technique for induction heating applications to improve soft switching capability

Phase-shifted third harmonic modulation technique for induction heating applications to improve soft switching capability

Hybrid Modulation Technique of Series Resonant Inverter for Induction Heating Applications to Reduce Audible Noises and Switching Losses

Hybrid Modulation Technique of Series Resonant Inverter for Induction Heating Applications to Reduce Audible Noises and Switching Losses

A Self Tuning Fuzzy Control Based Dual Input Nine-Level Self Balancing Switched-Capacitor Inverter for Induction Heating Applications

A Self Tuning Fuzzy Control Based Dual Input Nine-Level Self Balancing Switched-Capacitor Inverter for Induction Heating Applications

Study of magnetic nonlinearities in materials with low Curie temperature applied to domestic induction heating

The analysis of the magnetic properties of alloys with low Curie temperature used in domestic induction heating is presented. These alloys allow the development of cookware with additional benefits with respect to regular cookware oriented to improve temperature control and the user’s safety. Firstly, an experimental method to characterize the magnetic permeability with respect to the magnetic field strength and temperature in the material is presented. Secondly, a finite element simulation method is proposed which, considering the previous characterization, allows the calculation of the electrical equivalent of an inductor-load system as a function of temperature and magnetic field. This method makes possible the application of finite element simulation in the frequency domain with nonlinear materials, which is of interest for the design of electronics associated with domestic applications of induction heating. Simulation results are experimentally verified with various ferromagnetic alloys with low Curie temperature at different power, temperature, and operating frequency ranges.

A new efficiency figure of merit for induction heating appliances operating under highly variable operating conditions

Induction heating is an efficient and high-performance heating method which already has a significant market penetration and economic impact due to its benefits inherent to contactless energy transfer systems such as quickness, cleanness, and safety. Efficiency is a key design parameter since it determines not only the appliance performance but also its environmental impact, with significant socio-political implications. However, it is not easy to determine and compare the actual power converter efficiency operating under highly variable conditions typical of IH. This paper proposes an averaged efficiency parameter elaborated based on technical and typical IH usage conditions that offers a useful value to compare power converters operating under realistic operation conditions. The proposed parameter has been evaluated in some of the most significant power converter topologies used in reported state-of-the-art induction heating systems.

Possibility of application of a low frequency inductive heating to selected ferromagnetic objects

Possibility of application of the low frequency inductive heating for heating ferromagnetic has been considered and discussed. On the basis of simulations and investigated results the heater structure for railway rails was developed.

Thermophysical model of a thermonic cathode with induction heating

A thermophysical model was built and the temperature field of a cylindrical thermionic cathode with induction heating was calculated, taking into account the initial and boundary conditions, based on the adoption of assumptions to simplify the mathematical model. During the induction heating of the cathode, a non-stationary heat conduction process is established, which is described by the differential equation of heat conduction with internal sources of Joule heat. The distribution of internal heat sources in the volume of the cathode is determined by the distribution of the ring induced current. The cylindrical design of the inductive thermionic cathode, due to spatial symmetry, allows to reduce the number of spatial variables, significantly simplify functional dependencies, and limit the algorithm for solving the problem. The problem was solved in the cylindrical coordinate system. The obtained approximate solutions were assessed for the correctness of the accepted simplifications when finding the distribution of the temperature field with a sufficient degree of accuracy. Despite the high thermal conductivity of the cathode material, when the cathode is inductively heated, there can be a significant temperature difference between its outer and inner surfaces. The article shows the permissible temperature difference on the surface of the cathode, which limits the choice of geometric dimensions of the cathode. The temperature difference on the surfaces of the induction thermionic cathode is most affected on the end (annular) surfaces of the cathode, so it is better to apply emitting coatings to the side surfaces of the cylindrical cathode, thus complicating the design of the cathode. The application of induction heating of the thermionic cathode allows to simplify the heating unit, increase the reliability and service life of powerful electronic devices. The obtained results are planned to be used in further research as test data for the analysis of more complex problems of numerical calculation of the thermal regimes of the cathode unit with heat shields and focusing elements of thermoelectron flows.

Investigation of Induction Heating for Sheet Metal with Moving Induction Coil

The efficiency of induction heating is highly dependent on the coil geometry and the air gap between the coil and the workpiece, therefore the aim of this research is to experimentally evaluate the efficiency and uniformity of temperature distribution in induction heating, utilizing an inductor coil, movable in three axes. The experiment is conducted under the condition that the inductor coil is not tailored for the specific workpiece, giving it a higher flexibility compared to the conventional application of induction heating. To achieve this objective, a downscaled test bench was designed, employing a CNC machine for execution. In addition, in this study, a second test bench was built to establish an analytical approach in determining the parameter field between power, air gap and efficiency. The steady-state conditions in this test bench allowed the closure of the energy balances to be calculated analytically, allowing immediate validation of the accuracy of the results. This parameter field was utilized to evaluate the outcomes of the moving inductor experiments.

Enhanced asymmetrical modulation for half‐bridge series resonant inverters in induction heating applications

AbstractThis paper presents a method that improves the reliability of half‐bridge (HB) series resonant inverters (SRI) for high‐frequency induction heating applications. Many industrial processes, like induction heat treatments, are very repetitive. This cyclical operation represents a strong limitation of the inverter's reliability, mainly due to the accelerated stress of the power semiconductors. This method consists in an enhanced asymmetrical pulse width modulation (EAPWM) that allows distributing the losses across the components, thereby reducing the cyclic increase in junction temperature of the power devices, and thus achieves a reliability that is more than twice as high as that achieved using traditional modulation methods. The work methodology includes a theoretical study of the HB inverter and a complete analysis of losses. The presented design rules have been used to implement a 25 kW, 100 kHz inverter. The use of silicon carbide (SiC) MOSFET transistors allows reaching an efficiency greater than 99%. The analytical results obtained have been experimentally validated by testing the inverter on an induction heating test bench.

Design of PLL Controller for Resonant Frequency Tracking of Five-Level Inverter Used for Induction Heating Applications

In this work, the phase lock loop PLL-based controller has been adopted for tracking the resonant frequency to achieve maximum power transfer between the power source and the resonant load. The soft switching approach has been obtained to reduce switching losses and improve the overall efficiency of the induction heating system. The jury’s stability test has been used to evaluate the system’s stability. In this article, a multilevel inverter has been used with a series resonant load for an induction heating system to clarify the effectiveness of using it over the conventional full-bridge inverter used for induction heating purposes. Reduced switches five-level inverter has been implemented to minimize switching losses, the number of drive circuits, and the control circuit’s complexity. A comparison has been made between the conventional induction heating system with full bridge inverter and the induction heating system with five level inverter in terms of overall efficiency and total harmonic distortion THD. MATLAB/ SIMULINK has been used for modeling and analysis. The mathematical analysis associated with simulation results shows that the proposed topology and control system performs well.

Maximum Voltage Gain Tracking Algorithm for High-Efficiency of Two-Stage Induction Heating Systems Using Resonant Impedance Estimation

A boost power factor correction (PFC) circuit has replaced the diode rectifier to improve its poor power factor performance, low efficiency, and output power limitation for conventional induction heating (IH) applications. Accordingly, many studies have been conducted, but they considered only the efficiency of the boost PFC rather than the entire IH system, or their control and design were complicated. In this paper, an algorithm tracking the maximum voltage gain of the resonant network is proposed to improve the entire efficiency of the two-stage IH system based on an exact online resonant frequency estimation. It can make the resonant network operate at the maximum voltage gain point which can improve the efficiency of the series-resonant inverter (SRI) included in the IH system with low circulating current, the minimum switching frequency, and zero voltage switching (ZVS) capability. The proposed algorithm also induces the minimum output voltage of the boost PFC, which can reduce its switching losses and total harmonic distortion (THD). The validity of the proposed algorithm is experimentally verified using a 2.4-kW prototype IH system, including the boost PFC and the IH-SRI controlled by a digital signal processor (DSP).

A Reduced Switch Count High-Frequency Single-Phase 5-L MLI for IH Applications

Nowadays, multilevel inverter (MLI)-based induction heating (IH) technology is the best-suited option in many domestic, commercial and medicinal applications because of its higher efficiency, low cost, fast heating and lower electromagnetic interference (EMI). This paper presents reduced components count high-frequency (HF) single phase five-level (5-L) MLI for IH applications. The working methodology of the proposed system has been analyzed in the multicarrier phase disposition pulse width modulation (MC-PD-PWM) method in high switching frequency i.e., 10[Formula: see text]kHz. In addition, the proposed topology can produce output voltage twice of input voltage without any external source. Moreover, the detailed power loss and reliability analysis have been evaluated for the proposed system. In terms of switch count and efficiency, the single-phase 5-L inverter architecture is compared to some conventional and current topologies. Finally, to validate and justify the operation of the proposed system, the simulation and experimental results of five-level inverter are presented.

高周波IH応用単相ダイレクトAC-ACコンバータの固定周波数電力制御手法

The direct ac-ac converter is an effective circuit topology for high-efficient power conversion in induction heating (IH) applications. The conventional pulse frequency modulation (PFM)-based power control scheme causes audible noises between the adjacent IH loads which operate at different switching frequencies. As a solution for the technical issue, a new fixed-frequency power control methodology for a single-phase direct ac-ac converter is proposed in this paper, featuring a wide range of soft switching operation and robustness for abnormal load conditions. The principle of the proposed pulse modulation is explained in detail with the logic circuit diagram of controller. The performances of the ac-ac converter and power controller are demonstrated by simulation, after which the effectiveness is revealed in terms of the power control range and soft switching operation.

A Comparative Evaluation of Wide-Bandgap Semiconductors for High-Performance Domestic Induction Heating

This paper presents a comparative evaluation of wide-bandgap power semiconductor devices for domestic induction heating application, which is currently a serious alternative to traditional heating techniques. In the induction heating system, the power transferred to the output depends on the equivalent resistance of the load, and the resistance depends on the operating frequency. Due to the switching characteristics of wide-bandgap power semiconductor devices, an induction heating system can be operated at higher operating frequencies. In this study, SiC and Si semiconductor devices are used in the comparison. These devices are compared according to different evaluation issues such as the turn-off energy losses, turn-off times, current fall time, the power losses of the internal diodes, and the conduction voltage drops issues. To perform the proposed evaluation, the series-resonant half-bridge inverter, which is frequently used in state-of-the-art induction heating systems, has been selected. The device suitability in an induction heating system is analyzed with the help of a test circuit. A comparison is made in terms of criteria determined by using the selected switches in the experimental circuit, which is operated in the 200 W to 1800 W power range and 45 kHz to 125 kHz switching frequency range. System efficiency is measured as 97.3% when Si IGBT is used. In the case of using SiC cascode JFET, the efficiency of the system is increased up to 99%.

Comparative analysis and improved design of LLC inverters for induction heating

AbstractThis work presents a comparative analysis and design procedure of a converter based on an LLC resonant inverter used for induction heating applications depending on the transistor technology used and the selected operating frequency. A major objective of the work is to determinate the inverter design requirements leading to the optimal sizing of the components, improving its operation and minimizing power losses. Additionally, it proposes a design to obtain a great insensitivity of the inverter operation against large variations of load impedance. This article analyzes the operation of the inverter where the power regulation is carried out by phase‐shift (PS) modulation. Simple rules are formulated for the design of the resonant circuit components. The design has been verified testing a 25‐kW inverter in an industrial application of induction hardening operating at 500 kHz. Inverter efficiency is around 98.5% when using Silicon Carbide (SiC) MOSFETs.