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Contribution: This article proposes a comprehensive graduate course on magnetic design that addresses existing gaps in current power electronics (PEs) education, provides theoretical foundations and hands-on skills, and matches syllabi coverage with current societal needs for electronic energy conversion. Background: A growing worldwide interest in electronic energy conversion in recent years has led to a remarkable development of the PEs knowledge field. Currently, PEs are at the heart of popular applications, such as wireless energy transference for electrical vehicles or energy conversion associated with renewable energies. Environmental and economic factors contribute to this trend. Magnetic elements are an inherent part of PEs converters, and some experts have expressed the need for specific magnetic design courses, to supplement PEs curricula. Intended Outcomes: A comprehensive approach to magnetic design education, mainly focused on filling identified gaps in PEs curricula at the graduate level. Application Design: The design of the proposed course includes lectures, laboratory sessions, and a wireless inductive power transfer (IPT) project as a representative application of electronic energy conversion. Topics include a review of electromagnetism principles, magnetic materials, loss mechanisms, and the design of inductors, transformers, and IPT systems. Societal needs (such as those demanded by the PEs industry, the research sphere, or academia) are addressed through a focus on topic selection, acquisition of specific skills, and developing representative applications pertaining to the electronic energy conversion field. Findings: A learning outcomes assessment proves the validity of the magnetic design course, specifically designed for PEs education. The assessment of the effectiveness of this approach reveals that enhanced skills in magnetic design are acquired in comparison with general PEs courses.

Collaboration between Industry and University is becoming more important in order to improve the competitiveness of the research and development activities. Moreover, establishing synergies to bridge the gap between the academic and industrial spheres has demonstrated to be advantageous for both of them. Nowadays, Industry is moving towards an open innovation structure, in which external agents as universities play a key role. Besides, University is also seeking a more active learning methodology to improve the education of students for the real world. Considering this framework, a special effort should be done to take advantage of the collaborative work between Industry and University. The aim of this paper is to present the collaborative framework and the benefits obtained of the educational activities as a consequence of the long-term collaboration established between the University of Zaragoza and the Bosh and Siemens Home Appliances Group. The key stones of the collaboration are presented, and the positive outcomes for the students are highlighted. The strengths, weaknesses, opportunities, and threats of the proposed program are also discussed. (Contains 2 tables and 7 figures.)

In many applications, efficiency and service quality are improved with an appropriate power control. This paper focuses on a power-measurement method designed to deal with medium/high frequencies (tens to hundreds of kilohertz). It requires a previous knowledge of application and exploits some characteristics of the power topology and control, in this case, a full-bridge series resonant inverter. It is a new method based on a low-cost analog circuit that integrates the high-frequency load current, in order to reduce the computational complexity of measuring power. Harmonic analysis is carried out to determine the A/D converter requirements, and the theoretical results are verified using a digital-signal-processor (DSP)-based experimental setup. The power measurement may be implemented on the microcontroller or low-performance DSP used to control the power stage, with an error below of 2% independent of the load and mains variations. Index Terms--Induction heating, power-conversion harmonics, power measurement, resonant power conversion.

This paper presents the challenges encountered and the solutions adopted during the construction of a versatile voltage-fed high-frequency series-resonant half-bridge inverter module. It is used in the large-signal power generator of an inductive load characterization test-bench operating from 1 kHz up to 1.5 MHz and up to 7-kW output power for a variety of loads. Square wave operation of the module is established slightly above resonance under zero voltage switching conditions. Output power is controlled by means of a variable dc bus while resonant conditions are fixed by means of two adjustable capacitor banks. The control of every test-bench block and the triggering waveform generation is performed digitally with a field programmable gate array. Two prototype modules have been designed, constructed and evaluated for operation in half-bridge and full-bridge configurations showing rugged and stable operation under hazardous conditions such as voltage transients as high as dv/dt = 50 kV/[micro]s at 1 MHz during the characterization of domestic induction heating loads. Index Terms--High-frequency amplifiers, high-frequency resonant inverters, impedance measurement, induction heating, large-signal inductive load characterization.

This paper presents the use of frequency modulation as a spread spectrum technique to reduce conducted electromagnetic interference (EMI) in the A frequency band (9-150 kHz) caused by resonant inverters used in induction heating home appliances. For sinusoidal, triangular, and sawtooth modulation profiles, the influence of peak period deviation in EMI reduction and in the power delivered to the load is analyzed. A digital circuit that generates the best of the analyzed modulation profiles is implemented in a field programmable gate array. The design is modeled in a very-high-speed integrated circuits hardware description language (VHDL). The digital circuit, the power converter, and the spectrum analyzer are simulated all together using a mixed-signal simulation tool to verify the functionality of the VHDL description. The spectrum analyzer is modeled in VHDL-analog and mixed-signal extension language (VHDL-AMS) and takes into account the resolution bandwidth stipulated by the EMI measurement standard. Finally, the simulations are experimentally verified on a 3.5 kW resonant inverter operating at 35 kHz. Index Terms--Electromagnetic interference (EMI), field programmable gate arrays (FPGAs), hardware design languages, induction heating, switching frequency modulation.

This paper presents a field-programmable gate array (FPGA) implementation of a digital circuit that measures in real time the output power of medium-frequency (25-50 kHz) induction-heated cooking appliances. The voltage and current are sensed using first-order sigma-delta ([SIGMA][DELTA]) analog-to-digital converters. The power-measuring algorithm is very simple while maintaining good accuracy. The algorithm is developed using a hardware description language (VHDL). The digital circuit, the power converter, the signal conditioning circuits, and the [SIGMA][DELTA] modulators are simulated all together using a mixed-signal (analog + digital) simulation tool. The algorithm error is obtained in simulation computing the average power using VHDL-Analog and Mixed-Signal Extension Language (VHDL-AMS), and the influence of different parameters is analyzed. Finally, the digital circuit is implemented in the FPGA, and the simulations are experimentally verified. Index Terms--Analog-to-digital (A/D) conversion, field-programmable gate arrays (FPGAs), hardware design languages, induction heating, power measurement, sigma-delta ([SIGMA][DELTA]) modulation.

This letter presents a powerful tool for the study of the performance of control strategies and consists of a versatile modulator capable of synthesizing triggering signals for various fixed-frequency and pulse width modulation controls based on a digital implementation. Among many other advantages, the approach provides a straightforward, flexible, and rapid means for prototyping because of its reprogramming capability and user-friendly interface. Field programmable gate array was chosen as the hardware platform because of the additional benefits it provides, such as high operating frequency and parallel processing capabilities. Several practical examples of its application demonstrate the utility of this approach. Index Terms--Asymmetrical voltage-cancellation control, control strategies, field programmable gate array (FPGA) digital control, pulsewidth modulation (PWM) control, voltage-fed inverters.

In this paper, the frequency-dependent resistance in Litz-wire planar windings for domestic induction heating appliances is analyzed. For these inductors, in which the size is not an essential constraint, an analytical model is developed based on the superposition of different loss effects in the wire. Eddy current losses, including conduction losses and proximity-effect losses, both internal and external, were considered and modeled. The magnetic field necessary to evaluate the external proximity losses is as well analytically calculated considering the complete winding and load properties. To verify this model and its limitations, several inductors with different wires and numbers of turns were constructed and results with both non-loaded and loaded inductors are compared with theoretical predictions. Index Terms--Frequency-dependent resistance, home appliances, induction heating, Litz wire, resistance measurements.

This paper presents a time-domain analysis and a computerized search algorithm for optimizing the efficiency in zero-voltage switching (ZVS) full-bridge series resonant inverters with asymmetrical voltage-cancellation (AVC) control for different load quality factors. The optimum AVC control found allows all the switches to be turned on with zero voltage with the minimum switching frequency. In order to minimize losses, the switching frequency is kept as close as possible to resonance. The optimum AVC control is compared with previous fixed or narrow frequency range control strategies to show that it improves performance over all the output power range for different loads. The detailed steady-state analysis carried out here increases the precision of the first-harmonic analysis of a previous work, which is especially important with distorted output currents due to low load quality factors or highly asymmetrical modulation strategies. The theoretical results are verified experimentally. Index Terms--Asymmetrical voltage-cancellation (AVC) control, series resonant inverters, steady-state analysis, zero-voltage switching (ZVS).

We present a simple method to calculate the winding resistance of a litz-wire inductor in an induction cooking appliance, taking into account eddy-current losses, including conduction losses and proximity-effect losses. The method, which uses numerical calculation of the magnetic field, can be used to determine the optimum number of strands in the litz wire. The effects of the temperature on the winding total resistance are included in the calculation. We have built a prototype to verify the calculation method and its limitations. We consider the accuracy limits of the method. Index Terms--Home appliances, induction heating, litz wires, resistance measurements, temperature dependence.

This paper presents and analyzes the asymmetrical voltage-cancellation (AVC) control, a generalized control technique for resonant inverters. It is applied to the popular full-bridge series resonant inverter. The proposed control technique achieves better efficiency performances than conventional fixed-frequency control strategies, while considering zero-voltage-switching operation, output power and load variations. The theoretical results are verified experimentally, using a prototype for an induction-heating cooking appliance. Index Terms--Asymmetrical control, induction-heating cooking appliances, resonant inverters, zero-voltage-switching.

Inductive devices are extensively employed in power electronic systems due to their magnetic energy storage and power transfer capabilities. The current trend is towards increasing the frequency of operation in order to reduce the size of the magnetic components, but the main drawback is that the parasitic capacitance effect can become significant, and degrade the performance of the system. This work analyses the influence of this stray capacitance, and considers how to improve the performance of the device. In general, the impact of the stray capacitance on a magnetic component can be reduced by two methods: reducing the parasitic capacitance between turns of the winding or, alternatively, modifying the arrangement of the connection between turns. To evaluate the last option, an approximated expression of the first self‐resonant frequency of the magnetic device is proposed. This gives a rapid assessment of the performance of different devices maintaining the overall equivalent inductance. The proposed expression accounts for the influence of the connection between turns in the bandwidth of the component. Finally, some numerical results are verified with planar coils manufactured on two‐layer printed circuit boards. [ABSTRACT FROM AUTHOR]