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Induction heating appliance operation is constrained by the nonlinear pot material behavior under the generated magnetic field. The equivalent load seen by the inverter varies with the intensity of the field, meaning that this variation is dependent on the mains voltage. In flexible-surface induction cooktops, this fact is combined with a high coil number and different pots to be powered simultaneously, increasing the complexity to control the transmitted power while maintaining proper mains current consumption. In this article, two noncomplementary asymmetrical modulations with in-cycle parameter variation are proposed for improved power factor correction while avoiding the need for switching frequency variation and intermodulation noise in multiload systems. The proposed strategies are analyzed and experimentally tested using a 3.6 kW multi-inverter prototype featuring five induction coils. [ABSTRACT FROM AUTHOR]

Electroporation is a phenomenon that increases the permeability of cells by applying an electric field. This technique has relevant applications to cancer treatment using both electrochemotherapy and tumor ablation using irreversible electroporation. In order to carry out these treatments, new power converters are needed to apply of output voltages of several kV and output currents of tens of A in pulses of a width of μs. In addition, to achieve safe and relapse-free treatments, it is necessary to generate a controlled and uniform electric field. A challenge in current treatments is to ensure effective treatments despite tissue heterogeneity. In this context, this article proposes a new pulse generator that allows the use of a multielectrode structure that enables the application of a uniform electric field in multiple directions to avoid issues related to tissue heterogeneity. The proposed generator also allows the continuous monitoring of the treatment to adequately control the generator and apply a safer and more effective treatment. An 18-output 1500-V experimental prototype was designed, implemented, and tested using vegetal tissue, proving the feasibility of this proposal. [ABSTRACT FROM AUTHOR]

Multi-output inverters have become a key enabling technology to increase surface flexibility in domestic induction heating appliances. The most commonly used power converter topologies are based on electromechanical relays in order to multiplex the connected loads and obtain a proper heat distribution. This solution, which is used in combination with other modulations such as square waveform, relies on the thermal inertia of the pot as it needs long power-averaging periods to reduce the reiteration of the switching noise. However, it presents a significant limitation in terms of acoustic noise, reliability, and thermal performance. To overcome these limitations, complete solid-state inverters that can be operated at higher frequencies are proposed. This change in the design paradigm of the pulse density modulation strategies leads to improved thermal control in the pot and better user experience, but at the same time increases challenges due to design constraints imposed by electromagnetic compatibility regulations. This article analyzes the possibilities of a new mains-synchronized pulse density modulation applied to a flexible induction cooktop that uses a multiple-output ZVS resonant inverter topology. The feasibility of the control strategies has been tested by means of a prototype featuring 12 2-kW induction heating loads. [ABSTRACT FROM AUTHOR]

Domestic induction heating appliances have improved the final user experience due to the advantages that this technology offers, such as flexibility, fast heating, cleanness, and safety. Currently, these appliances are implemented using several isolated electronic boards to be able to be powered from one or several mains phases, enabling their use in regions with different connections. In order to enhance this approach, a multiphase power factor correction rectifier is proposed in this article, improving significantly induction heating cookers. The topology is described, and a wide variety of modulation strategies are presented and analyzed, discussing their main advantages and disadvantages according to the conduction mode, operating frequency, switching mode, and control strategy. In order to validate this proposal, an 11 kW and up-to three-phase high power-density converter for domestic induction heating applications is implemented and experimentally analyzed, including its main waveforms and efficiency. Finally, a comparative evaluation is performed to enable the selection of the optimum modulation strategy for each specific application. [ABSTRACT FROM AUTHOR]

Litz wire has been widely utilized in power transformers and inductors as a wire with low copper loss at high-frequency operation. The Litz wire is commonly made of many thin isolated strands twisted in multiple levels. Due to its complicated structure, the copper loss prediction of the Litz wire has been difficult, hindering the design optimization of the Litz wire structure. To overcome this difficulty, preceding studies have investigated the analytical copper loss models of the constituting elements of the Litz wire, i.e., the strands and the bundles of strands. The purpose of this article is to propose an analytical copper loss model of the Litz wire by utilizing these preceding knowledge. The proposed model is formulated only with parameters that can be measured by basic testing instruments. Besides, the proposed model considers the bundle structure of the Litz wire, which affects the local ac current distribution, and the twisting pitch, which causes the inclination of the Litz wire strands. The proposed model was tested by comparing the analytical prediction and experimental measurements of the ac resistance of commercially available Litz wires. As a result, the predicted ac resistance showed good agreement with the measured ac resistance, suggesting the appropriateness of the proposed model. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this work is to assess the ability of sine waves to perform electrochemotherapy (ECT) and to study the dependence of the frequency of the applied sine wave on the treatment efficacy. Methods: A subcutaneous tumor model in mice was used, and the electric field was delivered in combination with bleomycin. Sinusoidal electric fields of different frequencies, amplitudes, and durations were compared to square waves. Computer simulations were additionally performed. Results: The results confirmed the ability of a sinusoidal electric field to obtain successful ECT responses. A strong dependence on frequency was obtained. The efficacy of the treatment decreased when the frequency of the sine waves was increased. At low sinusoidal frequency, the efficacy of the treatment is very similar to that obtained with a square wave. The collateral effects such as skin burns and muscle contractions decreased for the highest frequency assayed. Conclusion: The use of sine wave burst represents a feasible option for the treatment of cancer by ECT. Significance: These results could have important implications for the treatment of cancer in the clinical world where ECT is performed with dc square pulses. [ABSTRACT FROM AUTHOR]

Industrial electronics (IEs) comprise a wide range of transversal and multidisciplinary technologies and applications that have enabled human progress since they emerged during the 20th century. The field poses many challenges, among which biomedical applications are one of the most important and rewarding because of the complexity and magnitude of the problems to be solved and their inherent relation to the most important aspects of human beings' hierarchy of needs: health and well-being. [ABSTRACT FROM AUTHOR]

Industrial induction heating (IH) is a key manufacturing process due to its benefits in terms of efficiency, accurate output power control, and high performance. These features have made possible the extension of this technology to a wide range of industries from automotive to aeronautic, domestic, or renewable energies. One of the main challenges still present is the design of a high-performance and cost-effective process for those induction targets with complex geometries exposed to the magnetic field, being the most representative example gears present in most mechanical systems. Usually, in order to optimize the heating process, multifrequency IH systems are used, being often expensive and/or difficult to tune and control. The aim of this paper is, consequently, to propose a family of power converters able to supply the inductor system with two simultaneous frequencies in order to improve the heating process of the induction target. The proposed converter takes advantage of a multiresonant network allowing full control of the output power delivered at each frequency and, at the same time, a compact and cost-effective implementation. The proposed converter is analyzed, designed, and implemented, and experimental verification of its operation is provided in this paper. [ABSTRACT FROM AUTHOR]

Flexible cooking surfaces represent the most innovative and high-performance induction heating appliances nowadays. This paper presents a multiple-output resonant inverter for multicoil systems featuring high efficiency and flexible output power control for modern induction heating appliances. By adopting a matrix structure, the number of controlled devices can be significantly reduced while high control versatility is ensured. The proposed converter is first analyzed and, in order to prove the feasibility of the proposal, a multiple-output prototype is designed and implemented. The experimental results prove the correct converter operation and output power control with multiple induction heating loads, validating the proposed approach. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Induction heating is nowadays a key technology due to its advantages in terms of performance and efficiency, which has boosted its adoption in industrial, domestic, and medical applications, among others. Recent developments in domestic induction heating are focused on flexible cooking surfaces with higher output power. The design requirements of this cooktops are more restrictive due to electromagnetic compatibility (EMC), power density, efficiency, control complexity, and cost. In order to overcome these issues, the use of active power factor corrector (PFC) rectifiers is proposed. This paper proposes and analyzes a complete set of modulation strategies for a single-phase boost-type PFC applied to domestic induction heating. A comparative analysis is performed taking into account the device stress, efficiency, operating frequency, control complexity, and EMC performance. This discussion reveals the advantages and disadvantages of each modulation strategy according to the final implementation requirements and the application area. [ABSTRACT FROM AUTHOR]

Induction heating has become the most advance heating process due to benefits, such as efficiency, performance, cleanness, and safety. In this process, the electromagnetic coupling between the induction coil and the induction target is a key, determining the heating performance as well as the resonant power converter operation. This letter proposes an accurate and cost-effective resonant tank identification method applied to induction heating systems. It is based on monitoring the resonant capacitor voltage in order to calculate the resonant tank quality factor. The proposed methodology has been tested using a versatile power electronics test bench applied to domestic induction heating, proving the feasibility of this proposal. [ABSTRACT FROM PUBLISHER]

Induction heating (IH) has become the technology of choice in many industrial, domestic, and medical applications due to its high efficiency and performance. This paper proposes an interleaved resonant boost inverter featuring SiC three-phase module to achieve high efficiency and performance IH power supply. The proposed converter achieves high efficiency by reducing the current through the devices, while the use of an interleaved full-bridge configuration reduces input current ripple and provides additional control degrees. The proposed converter has been designed, implemented, and tested experimentally, proving the feasibility of this proposal. [ABSTRACT FROM PUBLISHER]

Thermal management is a key design aspect of power converters since it determines their reliability as well as their final performance and power density. Cooling technologies have been a research area in electronics since the 1940s and, in the last 15 years, the number of articles related to this field has grown significantly. At present, thermal management is essential in new disciplines and it is a critical enabling technology in the development of power electronic systems. This paper aims at presenting a review of the state-of-the-art technology and provides future design guidelines for high efficiency power electronic converters. The main design trends are focused on the need to develop cooling systems able to manage high local density heat fluxes due to two converging trends: higher power dissipation and smaller module size. Considering the latest advances in thermal management, as well as the huge improvement in power electronics in the last decades, a review and classification of the main thermal management techniques is presented. Besides, they are compared considering important parameters such as peak power dissipation, efficiency, cost/complexity, power density or technical maturity, and a design example for an ultrahigh efficiency converter is presented. [ABSTRACT FROM PUBLISHER]