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

EMI Reduction Via Resonator Coils in Glassless Integrated Domestic Induction Systems

This paper explores the magnetic flux emissions of induction heating systems compared with inductively coupled heating systems. Inductively coupled heating uses a resonator coil attached to the ferromagnetic load in order to improve energy transfer from the appliance to the load. The magnetic flux emissions of both kinds of systems are simulated, and their dependence on coil current and turn number is outlined. The paper focuses on emitted near field, whose measurement and limits are determined by norm. Several prototypes are developed and tested to verify the simulation

Modeling and design of cookware for induction heating technology with balanced electromagnetic and thermal characteristics

Improving the cooking experience of induction-heating users involves, among other factors, an optimized power distribution at the bottom of the cooking vessel. Conventional ferromagnetic cookware presents high efficiency but unequal temperature distribution with flat inductors, which subsequently leads to uneven cooking results. In this work, we propose an alternative to the traditional cookware arrangement by inserting some aluminum pieces in the ferromagnetic bottom of cookware. This arrangement combines the optimal inductive performance of the ferromagnetic iron an the high thermal conductivity of aluminum. The performance of the proposed arrangement is analyzed by means of a multiphysics tool including electromagnetic and heat transfer sub-models which is applied to predict both the equivalent electrical circuit and the temperature distribution in cookware. As a result, a balanced trade-off between efficiency and temperature distribution is evidenced with the proposed solution. Experimental results also corroborates the predictions of the proposed solution. Autho

Analysis and optimization of the efficiency of induction heating applications with litz-wire planar and solenoidal coils

Optimization of the efficiency of an induction heating application is essential in order to improve both reliability and performance. For this purpose, multi-stranded cables with litz structure are often used in induction heating applications. This paper presents an analysis and optimization of the efficiency of induction heating systems focusing on the optimal copper volume of the winding with respect to different constraints. The analysis is based on the concept of a one-strand one-turn coil, which captures the dissipative effects of an induction heating system and reduces the number of variables of the analysis. An expression for the efficiency of the induction heating system is derived. It is found that, with the geometry and the other parameters of the system fixed, efficiency depends on the copper volume of the windings. In order to use this result to optimize the efficiency of an application, volume restrictions, the packing factor and the window utilization factor are also considered. The optimum frequency for an induction heating system is also studied in this work. An experimental verification for both planar and solenoidal cases is also presented

Wireless Inductive Charging for Low Power Devices

Currently wireless charging for most consumer electronics is still evolving in the mainstream market. This technology has taken a slow adoption. I n a world faced with variety of handheld devices demand for a shorter charging time is constantly being explored. Wireless charging has its challenges and successes The goal of this project was to design a prototype through research and design that would critically address and analyze the major design challenges that bring about longer charging periods of the new inductive wireless charging compared to the old fashioned, wired charging method and provide probable solutions. All the sections of the prototype namely transmitter, receiver and coil arrangement were designed and tested. The entire circuit was finally simulated and later fabricated on a PCB to come up with a prototype. Results were compared. This study showed that proper choice of coils must be made during design in order to minimize power losses and therefore increase efficiency

Improving multiphase induction-heating systems: several configurations and resonant control show promise

This article presents a new configuration for multiphase induction-heating (IH) systems and their control schemes. Instead of using separate voltage inverters to supply the required current to the inductors in each phase, we specifically configured the inverters to reduce the number of power switches. A modification of the inverter-setting parameters ensured the proper operation of the system. We obtained the best references through a specific optimization procedure and tested several solutions for neutral current minimization, including a new arrangement of the coils. In addition, proportional-resonant (PR) controllers allowed us to achieve current control in the different phases. We developed the application on a reduced-power, three-phase coupled resonant test bench, which provided simulation and experimental results

Analysis and design of tubular coils for wireless inductive power transfer systems

We evaluate copper tubes as alternative of litz wire for planar coils of inductive power transfer (IPT) systems. For this purpose, a design methodology focused on maximizing the product of the magnetic coupling and the quality factor is proposed. The methodology is based on a combination of FEA simulations and analytical calculations of the skin and proximity losses in the tube. Analytical calculations are based on solutions of Maxwell''s equations for a tubular geometry. These solutions are oriented to extract both skin and proximity losses in the tube. Performance of a prototype of 1.5 kW is evaluated and compared with a conventional litz-wire implementation