Induction Heating Applications Research Articles

Multiple-Output ZVS Resonant Inverter Architecture for Flexible Induction Heating Appliances

Flexible cooking surfaces have changed the domestic induction heating product paradigm enabling the use of a wider range of cookware materials, shapes, and positions. In order to implement such systems, multiple-output resonant inverters featuring high-performance and high-efficiency operation while achieving a cost-effective implementation are required. This paper proposes a multiple-output zero-voltage-switching resonant inverter for flexible induction heating appliances. The proposed converter features a matrix structure, enabling a cost-effective implementation with a reduced number of power devices while achieving high performance and low switching losses. It has been tested by means of an experimental prototype featuring 48 induction heating coils, proving the feasibility of the proposed approach.

Full Bridge Resonant Inverter for Blade Induction Heating Application

This paper presents blade induction heating application using full bridge resonant inverter including six parts: step-down transformer, full wave bridge rectifier, Pulse Width Modulation PWM signal, full-bridge Inverter by using power MOSFETs, high frequency transformer, and workpiece. The workpiece is 2.5-cm width and 15-cm length with 6-turns coil. The result shows that the blade is heated for 60 seconds with the temperature not less than 657.2 ºC. The output power of heating is generated appropriately 1.10 kW, at full load.

Development of Series Resonant Inverters for Induction Heating Applications

This paper proposes a cost-effective series resonant inverter employed in applications of induction heating. The proposed inverter operates with high-frequency pulse-density modulation strategy for soft-switching. The high-frequency operation (20 kHz – 100 kHz) of this inverter results in a nearly sinusoidal output that is suitable for relatively fixed output applications such as induction heating. The series resonance circuit comprises an inductor and a capacitor that are in series with the load. The small size of resonating components is due to the high-frequency switching operation. The practical effectiveness of induction heating power supply is substantially proved by implementing a prototype series resonant inverter. To analyze the performance, comparison between the simulation and experimental results is done by using PSIM program

Development of Series Resonant Inverters for Induction Heating Applications

This paper proposes a cost-effective series resonant inverter employed in applications of induction heating. The proposed inverter operates with high-frequency pulse-density modulation strategy for soft-switching. The high-frequency operation (20 kHz – 100 kHz) of this inverter results in a nearly sinusoidal output that is suitable for relatively fixed output applications such as induction heating. The series resonance circuit comprises an inductor and a capacitor that are in series with the load. The small size of resonating components is due to the high-frequency switching operation. The practical effectiveness of induction heating power supply is substantially proved by implementing a prototype series resonant inverter. To analyze the performance, comparison between the simulation and experimental results is done by using PSIM program

A Single Switch Parallel Quasi Resonant Converter Topology for Induction Heating Application

In this paper 32 KHZ Single phase Single switch Parallel Resonant converter topology (SSPR) using power MOSFET is simulated using MATLAB simulink for the different duty cycle and the THD, Power with respect to change in duty cycle is compared . The workingcoil is the combination of R, L in parallel with C which produces the output power of 1.7KW to 3KW with variation in duty cycle at higher value in duty cycle we get less THD and more power. The operating frequency is selected nearer to the resonant frequency for the improvement performance. The experimental set up of this SSPR Inverter in the induction heating application for the domestic purpose is implemented is depicted and this validates the implementation of quasi resonant using IGBT for domestic applications.

FPGA-Based Resonant Load Identification Technique for Flexible Induction Heating Appliances

Resonant power conversion provides high-efficiency and high-power-density power converters that have boosted the performance of many applications, including induction heating (IH). One of the main challenges of such converters is the fine tuning and operation monitoring of the resonant tank, especially when it is highly variable. This paper proposes an field-programmable gate array (FPGA)-based load identification technique based on measuring the resonant capacitor voltage and calculating its spectral components. This approach proposes an accurate and cost-effective implementation, since the sensing, conditioning, and analog-to-digital conversion systems can be significantly simplified to a single low-harmonic-content signal. The proposed approach has been tested using a wide range of IH loads and operating conditions, proving the feasibility of this proposal.

Fuzzy Logic-Based Pulse Density Modulation Scheme for Mitigating Uncertainties in AC–AC Resonant Converter Aided Induction Heating System

Induction heating (IH) applications aided by power electronic control system have become very attractive in the recent past. The power electronics circuits succumb to severe switching loss, lower power density if proper switching methodology is not adhered. A state of uncertainty is indispensable in IH application as the power required by the load varies depending upon the nature of work piece. This uncertain issue makes the selection of the control algorithm and controller very vital. The mundane controllers may not be compatible to combat the uncertainties and leads to exhibit dynamic problems say transients, peak overshoot and poor response. Henceforth, the IH system requires a superlative converter topology and control scheme in order to have reduced switching loss and to improve the system performance there by negating the uncertainties. Here, in this work, a direct AC–AC boost resonant converter fed by pulse density modulation (PDM) is realized in a single stage mode. A fuzzy logic-based PDM control technique improves the efficiency and provides the versatile power control with reduced time domain specifications for dynamic changes in load. The proposed system has been studied using MATLAB/SIMULINK and validated using a hardware prototype employing dsPIC30F4011 microcontroller. The results reveal that efficient control over power can be accomplished by varying the density of the switching pulses, and thereby the efficiency is enhanced even with reduced component count. Also, the single-stage conversion is effective than its two-stage counterpart.

Fast 3D simulation of various applications of induction heating

In this paper, we present some advances in 3D finite element modeling of the induction heating process. Lighten finite element models are used for fast simulation of Carbone Fiber Reinforced Polymers and massive metals at high frequencies. The lightening methods include the use of degenerated hexahedral Whitney elements for very thin anisotropic layers and the impedance boundary condition with external electrical circuit constraint.

Induction Heating Technology for Steel Wire Processing

This article discusses the induction heating application features in metallurgical industry for previously unused objects, such as wire coils and wire rod bundles. The analysis of international trends and a forecast of the induction heating application shows a steady expansion of the induction technologies in the metallurgical industry. The article considers the advantages of induction heating in comparison to other competitive technologies. Heat treatment in electrotechnological induction plants is determined by the interconnected electric and thermophysical processes taking place in them, the complex nature of the internal heat sources distribution, the dependence of the distribution pattern of the induction plant on the temperature of the products being processed. It is shown that the investigation results of the induction heating method influence the temperature and time factors in the formation of the structure, the increase in the uniformity of heating, and the quality of the heat treatment of steel wire and wire rod buntle, taking into account the stated technological task. The efficiency estimation of application of medium and high-frequency induction heating of steel wire of various diameters is given. Evaluation of the efficiency improving of the induction heating device, when the heat treatment simultaneous multiple strands of steel wire of equal diameter, united in a bundle, is given.

A Flexible Cooking Zone Composed of Partially Overlapped Inductors

Domestic induction cookers are evolving from fixed cooking areas to flexible surfaces in such a way that the pot can be placed at any position. This implies the use of a larger number of reduced-sized inductors, which present a lower efficiency. As a solution to increase the efficiency while maintaining the flexibility, we propose the use of partially overlapped inductors of a larger size. This concept is currently in use in wireless power transfer systems, where the transmitter arrangement consists of several overlapped coils. The aim of this paper is to evaluate this concept applied to domestic induction heating appliances, with special emphasis in analyzing the effects of introducing the multicoil system with dissipative media. Moreover, the losses in the winding will be studied in detail. The system will be prototyped and tested, delivering up to 3.7 kW.

An Effective Switching Algorithm for Single Phase Matrix Converter in Induction Heating Applications

Prevalent converters for induction heating (IH) applications employ two-stage conversion for generating high-frequency magnetic field, namely, AC to DC and then DC to high-frequency AC (HFAC). This research embarks upon a direct conversion of utility AC to high frequency AC with the design of a single-phase matrix converter (SPMC) as a resonant converter using a modified switching technique for IH application. The efficacy of the proposed approach is validated through different attributes such as unity power factor, sinusoidal input current and low total harmonic distortion (THD). The developed prototype-embedded system has high pragmatic deployment potential owing to its cost effectiveness using Arduino mega 2560 and high voltage/current as well as low switching time IXRH40N120 insulated-gate bipolar transistor (IGBT). Different results of the prototype-embedded system for IH application have been verified using Matlab Simulink environment to corroborate its efficacy.

Pulse Density Modulation Based Series Resonant Inverter Fed Induction Heater System

This paper deals with implementation of a multi-output Series Resonant Inverter(SRI) for induction heating applications, which uses pulse density modulation(PDM) control for full bridge Series resonant inverters for output voltage and power control. It ensures better efficiency performances than conventional control strategies. The proposed converter can be considered as a two output extension of a full bridge inverter. This full bridge inverter can control the two outputs, simultaneously and independently, up to their rated powers, which reduces the usage of number of components as compared with conventional method. It also ensures higher utilization of switches used for its operation. A two output full bridge series resonant inverter is simulated and implemented. The Experimental results are compared with the simulation results.

Single Stage Boost Integrated High-Frequency Full Bridge Inverter for Induction Heating System

This paper proposes a new single-stage boost high frequency ac series resonant power inverter for high frequency induction heating (IH) applications. The proposed ac-ac converter consist of a single stage boost (SSB) converter and full-bridge ac series resonant inverter integrated circuit with a ac source voltage control strategy by controlling the inverter switches. The Simulink model is developed using MATLAB simulation software and the simulated results are examined. The output power is maintained to the required level by using phase shift control strategy and the simulated results are validated.

Application of inductive forced heating as a new approach to food industry heat exchangers

Heat exchangers are one of the main equipment used in food industry because of their convenience to transfer energy to both auxiliary facilities and various food products. In food industry, there are several reasons for heat transfer such as pre-heating, pasteurizing and sterilizing in which heat exchangers require high amount of energy. On the other hand, as being a unique quality assurance unit heat exchangers should be cleaned easily and extensively. Having high operating costs due to energy consumption and requiring high investment cost due to ensure a reliable hygienic design make heat transfer units an expensive and energy-consuming unit. Therefore, developing new approaches to generate energy and transferring it hygienically with minimum loses will be an opportunity for the food industry. With the view of developing new equipment for industry, induction-driven heating system was investigated in this study and energy and exergy efficiencies were calculated and compared with conventional heat exchanger system. Selected food system was the tomato paste sterilization/pasteurization which is a part of tomato paste production line. After assumptions and theoretical calculations for both conventional application and inductive heating, it was found that inductive heating system has 95.00% energy efficiency and 46.56% second law efficiency while the conventional heating system with electric boiler has 75.43% energy efficiency and 16.63% exergy efficiency. As a consequence, inductive method was found more beneficial compared to a commercial method having higher energy and exergy efficiencies.

Improved Time Responses of PI & FL Controlled SEPIC Converter based Series Resonant Inverter fed Induction Heating System

This work deals with the Power Factor Corrected Single-Ended Primary Inductor Converter (PFC-SEPIC) based voltage fed closed loop full bridge series resonant induction heating system for household induction heating applications. The output voltage of the front end PFC-SEPIC converter fed series resonant inverter governs the controllers, which may be PI controller or Fuzzy Logic Controller (FLC). The analysis and comparison of time responses are presented in this paper. The PFC-SEPIC converter is used to improve the output power and the THD of source side current are compared for PI and FLC controllers. PFC-SEPIC converter maintains improved current and voltage at unity power factor through the input mains. The SEPIC converter based Voltage Fed Full Bridge Series Resonant Inverter (VFFBSRI) converts the voltage at a frequency of 10 kHz to a level suitable for household induction heating. A 1 kW SEPIC converter based VFFBSRI with RLC load is designed and simulated using MATLAB/ Simulink and hardware is fabricated.

Stabilizing Control for Nonlinear Switched Systems in Two Dimensions with a Geometric Approach

The purpose of this paper is to give a sufficient condition for the existence and stability of a hybrid limit cycle for the stabilizing control of a class of switched dynamical systems in . This is then illustrated on a Induction Heating Appliance.

Dynamics of inductors for heating of the metal under deformation

Current issues of creating powerful systems for hot sheet rolling with induction heating application in mechanical engineering and metallurgy were discussed. Electrodynamical and vibroacoustic problems occurring due to the induction heating of objects with complex shapes, particularly the slabs heating prior to rolling, were analysed. The numerical mathematical model using the method of related contours and the principle of virtual displacements is recommended for electrodynamical calculations. For the numerical solution of the vibrational problem, it is reasonable to use the finite element method (FEM). In general, for calculating the distribution forces, the law of Biot-Savart-Laplace method providing the determination of the current density of the skin layer in slab was used. The form of the optimal design of the inductor based on maximum hardness was synthesized while researching the vibrodynamic model of the system "inductor-metal" which provided allowable sound level meeting all established sanitary standards.

Investigations on stability and performance of a varia-ble frequency based fuzzy logic controller for induction cooking system

Load variability and perturbation is an important issue in the induction cooking applications as it hinders the performance of the heating system considerably .Therefore a precise power control technique is required for induction heating applications by considering the stability issues and dynamic response of the system. Also, the safety operating ranges need to be confirmed to ascertain the competency of the controller. In this paper, a Fuzzy logic based power control scheme is introduced by considering the load uncertainties. The suggested power control technique uses variable frequency control of the inverter for reaching the target power level. Also, a detailed stability study is done for investigating stability range within which the system operation is safe and stable. The said work is simulated in MATLAB/Simulink environment and realized as a prototype where advanced FPGA controller renders its hand .The simulation and hardware results reveal that the suggested technique is versatile.

High performance full-bridge multi-inverter featuring 900-V SiC devices for domestic induction heating applications

Induction heating is nowadays a key technology due to its advantages in terms of performance and efficiency which has boosted its adoption. Recent developments in domestic induction heating includes flexible cooking surfaces with multiple output power converters. Furthermore, advances in wide bandgap devices allow new design possibilities such as high power density and high efficiency power electronics converters. These facts open the possibility to new high-performance induction heating systems. In this paper, a novel improved full-bridge series resonant multi-inverter with 900-V SiC MOSFET is presented. The proposed converter and the modulation strategies allowing to obtain proper output power control are detailed. Finally, in order to prove the feasibility of this proposal, a multiple-output experimental prototype is implemented, showing the main results and the advantages of the converter.

A novel method of measurement of loss in a track of a turn of a planar transformer for induction heating applications

The new trend in power converters is to design planar magnetic components aimed at low profile. However, at high frequencies, the AC losses induced in the planar inductor and transformer windings become significant due to skin and proximity effects. This paper presents the design of a high-frequency planar transformer (HFPT) for an induction heating system. The aim of this design is to adapt the levels of voltage and current from the inverter to the resonant tank characteristics. We propose a planar structure of Litz in the primary of our HFPT to reduce the AC resistance of the planar conductor. The Litz structure is obtained with a technique of the turn’s division in four tracks and their intersection so that the current passes all over the turn.For the single secondary turn, the choice of the section is based on an analytical study compared to a 2D finite element modeling (FEM), and is determined according to the shape that represents fewer losses and responds to our needs.2D finite element modeling (FEM) was performed for three different primary turns’ structures; full coil, a turn with four parallel tracks and our Litz planar turn; to minimize losses. Simulation results show that the planar Litz conductor can lead to a lower AC resistance. The performance of this Litz structure is also verified by measurements on experimental prototypes.