Asymmetrical Modulation Strategies for Partially Covered Inductors in Flexible Induction Heating Appliances

Cost-effective multi-output resonant inverter topologies are a key enabling technology for the development of flexible surfaces for induction heating appliances. These topologies present several challenges when applied to a wide range of IH-loads simultaneously. In this paper, two asymmetrical modulations are proposed as an alternative solution to control output power. The proposed approach has been verified using an experimental prototype featuring 2 induction heating loads up to 3.6 kW with output power control in the whole operating range

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

GaN-based matrix resonant power converter for domestic induction heating

Flexible-surface induction cooktops must operate with a variety of induction heating loads with different behavior and power setpoints to be heated simultaneously. In this context, multi-output inverter topologies aim at achieving independent power management while featuring low power-device count and high power density. However, they suffer from limitations when applying classical modulation strategies to ensure soft switching, which is required to reduce transistor losses and achieve efficient operation. In this scenario, wide band-gap devices reduce switching losses, opening a new paradigm in power conversion where soft switching is not mandatory in order to achieve high efficiency. This paper proposes an implementation of a multi-output resonant inverter based on GaN HEMTs and evaluates various modulation strategies in terms of efficiency under different switching modes. The proposed approach is designed and experimentally validated by means of a 2-coil 2000 W prototype implementation

Asymmetrical Noncomplementary Modulation Strategies for Independent Power Control in Multioutput Resonant Inverters

Domestic induction heating (IH) design trends aim at improving user experience by increasing the cooking surface flexibility while maintaining a cost-effective implementation. The design of multioutput topologies is a key development for this purpose. However, due to their complexity, output power control usually relies on low-frequency pulse density modulations that, in addition to the slow response due to significant power averaging times, present severe restrictions as a consequence of power pulsation regulations. This article proposes two different noncomplementary asymmetrical modulation strategies that allow continuous operation avoiding both flicker and heating performance issues and obtaining a fast-response load power control. In order to prove the feasibility of the proposed modulations, a prototype featuring 12 IH loads of 2000-W maximum rated power has been built, and both strategies have been tested

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

New designs systems for induction cooking devices for heating performances improving

In order to give a temperature distribution at the bottom of the induction cooking, and moderate reduction the temperature outside the useless areas of these systems. This paper is dedicated to the study of the induction heating systems, which involves coupled electromagnetic and thermal phenomena and where new topologies are proposed. The modelling of the problem is based on the Maxwell's equations and the heat diffusion equation. We present a numerical simulation method based on parameterization of thermal electromagnetic coupling phenomena taking into account the changing of the physical characteristics of the body during the induction heating process. The purpose of this new optimum perforation topology is based on improving the thermal performances of the system, which allows improved dissipation by heat exchange. The results are obtained from a two-dimensional calculation code developed and implemented on Matlab software where CVM the finite volume method was adopted as a method of solving partial differential equations with partial derivatives characteristics of physical phenomena

Strongly Coupled Outer Squircle-Inner Circular Coil Architecture for Enhanced Induction over Large Areas

This paper reports a newly designed class of strongly coupled planar coil structures for the purpose of enhanced induction over large areas. These new architectures feature a squircle shape at the outer rim with rounded corners and straight sides evolved into a fully circular shape in the inner side, which proves to be essential to achieve high efficiency in arrays and all-surface inductive heating. As a proof-of-demonstration, a simple inductive heating system composed of a pair of side-by-side placed coils was constructed together with a ferrite layer. Experiments were repeated for 0° and 180° phase differences between coil currents. Here, the system efficiency was shown to be increased overall by 37.4% using outer squircle-inner circular coils instead of conventional circular coils. This comparative study indicates that the proposed coil architecture offers the potential for large-area, fast, and phase-insensitive inductive heating with high efficiency. © 1982-2012 IEEE

A single-coil multi-tapped PDM-based induction heating system for domestic applications

The conventional heating system is inefficient as the major part of the heating coil lies out-side the vessel it is placed on. This research article proposes a new single-coil multi-tapped induction heating system. This novel induction heating system is facilitated by a half-bridge resonant converter controlled by zero-voltage switching (ZVS). The multi-tapping winding system ensures an effective heat transfer between the coil and the working vessel with the windings of the induction coil segmented to an equivalent size of the vessel. The pulse density modulation (PDM) scheme employed here as the control proves to be the most versatile one. The whole system is duly simulated for an 850 W IH setup in MATLAB Simulink and implemented as a hardware prototype using a half-bridge resonant converter. The control pulses are developed through the PDM in a PIC16F877A controller. The simulation and experimental results prove the credibility of the proposed induction heating (IH) scheme, and during heavy loading conditions, it outperforms the single-coil IH system by gaining an efficiency of 89.29

An Efficient Power Control Technique for High-Frequency Resonant Inverter in Induction Heating System

An efficacious and reliable power control technique has been developed which can be used to regulate the output power of a high-frequency full bridge series resonant inverter (HF-FBSRI) in an induction heating (IH) system. In this paper, a modified buck-boost converter is presented to control the DC link/bus voltage which maintains the IH system under resonant mode and optimizes the performance of the IH system. Controlled DC link/bus voltage has been applied to this HF- FBSRI to control the average output power in the IH system. Using this aimed control technique, a wide range of output powers has been controlled and consistent performance of the IH system has been achieved. ZVS switching technique has been used to reduce the switching losses. Varying average power has been obtained at different duty cycles ranging from 0.2 to 0.8 with variable DC link voltage and it has been corroborated using PSIM environment for an IH system rated at 5500W

An amplifier-less acquisition chain for power measurements in series resonant inverters

Successive approximation register (SAR) analog-to-digital converter (ADC) manufacturers recommend the use of a driver amplifier to achieve the best performance. When a driver amplifier is not used, the conversion speed is severely penalized because of the need to meet the settling time constraint. This paper proposes a simple digital correction method to raise the performance (conversion speed and/or accuracy) when the acquisition chain lacks a driver amplifier. It is intended to reduce the cost, size and power consumption of the conditioning circuit while maintaining acceptable performance. The method is applied to the measurement of the output power delivered by a series resonant inverter for domestic induction heating