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The modeling of electrical characteristics of connections is an important stage of the design phase of a structure. Indeed, they have an impact on the current density distributions inside conductors as well as on the current distributions when several components are connected in parallel. In the case of a return plane in the studied structure as for power electronics converters or railway applications, the model of connections has to be improved in order to represent the physics better. For the first application field, the cooling system itself can be a ground plane, and for the second one, the earth has to be modeled. This paper presents different ways to take into account a return plane while modeling the electrical equivalent circuit of connections above it. It starts with the simplest one, the image method, and continues with the use of a complex skin depth result of solving the Carson integral. Index Terms--Electromagnetic interference (EMI) modeling, equivalent impedance, finite-element method (FEM), partial-element equivalent circuit (PEEC) method, railway system, transmission line modeling.

Harmonics are a very important issue in the design and operation of medium-voltage inverter drives, due to restrictions imposed by regulations. This paper studies the harmonics generated by a three-phase multicell cascade inverter, with single-phase pulsewidth modulation rectifiers at the input side of each cell; thus, the entire topology is able to regenerate power to the net. This paper identifies accurately the harmonic generation process in the dc-link voltage, the input current of each cell, and, therefore, at the input side of the inverter. Moreover, this paper proposes a method to reduce and, in some cases, eliminate the input current harmonics, reaching a very high input power factor for any operation condition. Simulation and experimental results are provided to validate the theoretical analysis. Index Terms--Harmonic analysis, power electronics, voltage control.

Predictive control is a very wide class of controllers that have found rather recent application in the control of power converters. Research on this topic has been increased in the last years due to the possibilities of today's microprocessors used for the control. This paper presents the application of different predictive control methods to power electronics and drives. A simple classification of the most important types of predictive control is introduced, and each one of them is explained including some application examples. Predictive control presents several advantages that make it suitable for the control of power converters and drives. The different control schemes and applications presented in this paper illustrate the effectiveness and flexibility of predictive control. Index Terms--Drives, power electronics, predictive control.

Silicone gels are widely used to encapsulate power electronics modules. The objective of this paper is to study the partial discharge (PD) mechanism in a silicone gel, using electrical measurements and fast visualization. Experiments are carried out in a point-plane geometry, using either impulse voltage or ac. Under impulse voltage, the visualization shows that the first discharges recorded in a new sample are due to the initiation and propagation of 'streamers', with features close to those previously reported in viscous liquids. Under ac, a stable PD regime rapidly establishes: a streamer creates a cavity with a long lifetime, and PDs occur in this cavity during the subsequent ac waves. Since slow streamers develop during long times (some ms), classical PD measurements do not provide an adequate evaluation of the actual discharge magnitude: very small PDs (1 pC) are recorded, whereas large cavities with a total charge in excess of 10 pC are actually present in the gel. When PDs are repeated permanent degradations of the gel rapidly occur, showing the limited self-healing capabilities of silicone gels. Index Terms--Partial discharges, streamers, silicone gel and power electronics.

The paper describes a simple treatment for the fringing fields of an air gap in the core of a magnetic component such as an inductor or a transformer. It verifies the derived analytical formulas for the fields by using numerical (finite-element) calculations. It then applies these formulas to the calculation of high-frequency eddy-current losses for two types of winding arrangements, both of which employ thin rectangular conductors. The rectangular conductors are commonly used in flex circuit windings, printed circuit windings, and thin-film windings. The two types of winding configurations are flat and barrel wound. Each behaves in a different way as a function of the position of the conductor. Index Terms--Air gap, fringing field, high frequency, inductor, motors, power conditioning, power conversion, power electronics, transformer, winding loss.

This paper presents a new analytical method for the generalized study of a cluster of single-stage power-factor correctors ([S.sup.2]PFCs). Due to this generalized approach, new topologies have been obtained, and the study of other known topologies has been simplified. The new analytical method simplifies the design of [S.sup.2]PFCs by making it possible to compare a large number of different designs from the same viewpoint in order to identify the best topology. Finally, this research has enabled us to reduce the total size of the additional inductors that are used by a factor of two to three with respect to previous implementations. Index Terms--Current harmonics, IEC 61000-3-2 regulations, nonlinear loads, power-factor correction (PFC).

Zero-current-transition pulsewidth-modulation (ZCT-PWM) boost converters are conventional boost converters that use an active auxiliary circuit to turn off the main power switch with zero-current switching; the operation and properties of these converters are the focus of this paper. In this paper, the general operating principles behind all ZCT-PWM converters are reviewed, and the operation and properties of specific converters are discussed. The strengths and weaknesses of each converter are stated, and a new and improved ZCT-PWM boost converter is proposed and discussed. Experimental results obtained from an experimental ZCT-PWM boost converter prototype implemented with several of the auxiliary circuits discussed in this paper are presented, and the results confirm the superior performance of the proposed converter. Index Terms--Power conversion, power electronics, power supplies, switched-mode power supplies.

For a planar solid-oxide fuel cell (PSOFC)-based power system, the differences in the response times of the PSOFC stack, the power electronics subsystem (PES), and the balance-of-plant subsystem (BOPS) cause low-reactant conditions near the PSOFC electrodes during load transients. Because the BOPS cannot instantaneously provide enough fuel to the PSOFC, the load transients have a detrimental effect on the performance and life of the fuel cell. To alleviate the degrading effects of load transients on PSOFC stacks, the effectiveness of the energy buffering is investigated. Index Terms--Balance-of-plant subsystem (BOPS), distributed generation (DG), energy buffering, load transient, mitigation, planar solid-oxide fuel cell (PSOFC), power conditioning system (PCS), power electronics.

Hardware-in-the-loop (HIL) testing is increasingly recognized as an effective approach in the design of power electronics controls. A high-performance real-time simulation environment is necessary to obtain high-fidelity results in HIL simulations. This paper presents the detailed implementation of a very-low-cost multisolver hard real-time simulation environment, namely the real-time extension of the virtual test bed (VTB-RT). VTB-RT is implemented completely from open-source software and off-the-shelf hardware. Using VTB-RT, this paper proposes an efficient real-time HIL testing approach for control designs in power electronics applications. VTB-RT enables the natural coupling between the simulation environment and the hardware under test and, thus, makes virtual power exchange in HIL simulation possible. For validation purposes, the proposed real-time HIL testing approach is applied in two well-known power electronics application examples, namely a boost converter and an H-bridge inverter with their respective control systems, representing a very-low-cost and a relatively advanced hardware setup, respectively. The consistency of the experimental results with the theoretical results proves the applicability of VTB-RT and the proposed testing approach. Finally, the most recent research progresses in VTB-RT are summarized. Index Terms--Distributed simulation, field-programmable gate array (FPGA), hardware-in-the-loop (HIL), power electronics, real-time simulation (RTS), virtual test bed (VTB).

Technology for a 3-D high temperature integrated power electronics module for applications involving high density, and high temperature (e.g., those over 200 [degrees]C) is described. The high temperature embedded chip module (ECM) technology is proposed to realize a lower stress distribution in a mechanically balanced structure with double-sided metallization layers and material coefficient of thermal expansion match in the structure. This technology for packaging the active component is also proposed for universal use with a flip-over structure and pressure connections. The fabrication process of this high temperature ECM is presented. The forward and reverse characteristics of the high temperature ECM have been measured up to 279 [degrees]C. Thermally induced mechanical stress is reduced to an acceptable level by applying a symmetrical structure with buffering layers. Index Terms--Coefficient of thermal expansion (CTE), embedded chip module (ECM).

Dithering is proposed as a technique for the regulation of the boundary layer for switched systems under sliding-mode control. It is proved that dithering maintains the state of the system close to the ideal sliding manifold and that state error and practical stability depend on the dither amplitude, period, and shape, all by preserving the natural switching mode of the system. Experiments on a dc/dc buck power converter confirm the theoretical results. Index Terms--Dither techniques, power electronics, sliding mode, switched systems.

Optimal control methodology is applied to the design of the feedback loops of a multi-inverter uninterruptible power supplies system. The control signals thus obtained will minimize a performance index, which is a function of the output voltage error, the inductor currents of all inverters and the reference signals. This enables the controller to achieve the desired objectives like minimization of the circulating current and reduction of error of the output voltage. The robustness of the controller has also been investigated. Through frequency-domain analysis, it is shown that variations in the number of paralleled inverters in the system have only small influence on the performance of the system. Therefore, the optimal controller designed for a fixed number of inverters can also work well in systems with variable number of paralleled inverters. Three experimental 110 Vac/l.1 KVA inverters are built and paralleled to verify the analysis and theoretical predictions. Index Terms--Inverters, optimization, power electronics, statespace methods.

We describe the electronics for controlling the independently pulsed polarizing coil in a prepolarized magnetic resonance imaging (PMRI) system and demonstrate performance with free induction decay measurements and in vivo imaging experiments. A PMRI scanner retains all the benefits of acquiring MRI data at low field, but with the higher signal of the polarizing field. Rapidly and efficiently ramping the polarizing coil without disturbing the data acquisition is one of the major challenges of PMRI. With our modular hardware design, we successfully ramp the 0.4-T polarizing coil of a wrist-sized PMRI scanner at up to 100 T/s without causing image artifacts or otherwise degrading data acquisition. Index Terms--Electromagnet power supplies, magnetic fields, magnetic resonance imaging, power electronics.

The heat dissipation in GaN-LGO devices is modeled using a finite element numerical approach along with measurements and calculations of thermal approach conductivity of the LGO and GaN layers. Relatively low-power electronic devices are obtainable if the primary mode of heat dissipation is through the rear of the substrate.