Jelena Popovic-Gerber

Power Electronics Enabling Efficient Energy Usage: Energy Savings Potential and Technological Challenges

Power electronics is a key technology for the efficient conversion, control, and conditioning of electric energy from the source to the load. In this paper, the potential of power electronics for energy savings in four major application fields, buildings and lighting, power supplies, smart electricity grid, and industrial drives, is investigated. It is shown that by wider adoption of power electronics in these areas, the current European Union electricity consumption could be reduced by 25%. The technology challenges for exploiting this potential for all the four areas are identified in the paper.

Comparison of Si and GaN power devices used in PV module integrated converters

Using the newly developed enhancement-mode Galium-Nitride-on-Silicon (eGaN) devices with high conductivity and very fast switching speed a breakthrough in switching performance can be achieved. Multi-megahertz switching frequency capability will significantly reduce the size of passive components, adding the cost benefits and increasing the integration level and power density. As to date, the use of GaN devices in power converters is still in its infancy, but its widespread application is a near reality. PV converter industry is one of the areas which would greatly benefit from the new GaN technology. The most important requirements for a PV converter, efficiency and cost effectiveness, can both be addressed with improved switching devices. This paper presents a performance comparison of a PV module integrated DC-DC converter based on commercially available GaN and Si power devices. The presented results show that the first generation of GaN devices outperforms the best in class Si devices. Since GaN is immature technology, further improvements will be seen in the years to come.

Thermally enhanced SMT power components

The paper introduces new x-dimension (x-dim) components that allow for high components packaging density and automated manufacturing of power converters. The x-dim components are double sided SMT passives, having uniform height (x) and enhanced thermal properties. With stacked converter construction and the x-dim components soldered to two sides, the heat removal from the systems can be significantly improved. This publication presents various methods to manufacture thermally enhanced x-dim components. The thermal behaviour of x-dim components is improved by integrating heat extractors, removing packaging materials and filling the air gaps by potting compounds. In the stacked construction, thermal enhancement of one component improves heat removal from other components, placed in adjacent stack layers. Thermal performance of x-dim components in both standard and stacked converter constructions is evaluated by FEM and analytical simulations. New x-dim components employed in stacked construction play a key role in overcoming current power density limits.

Quantifying the Value of Power Electronics in Sustainable Electrical Energy Systems

Power electronics enables the efficient generation, use, and distribution of electrical energy because it substantially improves energy conversion efficiency. In order to realize the large electrical energy savings potential enabled by power electronics suitable technological solutions at acceptable cost levels are needed. Moreover, public policy and public acceptance must play an increasingly important role. An effective way to quantify the value of power electronics is needed and it must be presented in such a way that it is understood and appreciated by policymakers. In this paper, energy payback time is shown to be a powerful tool for weighing the value of energy savings achieved by using power electronics versus the energy needed to manufacture the systems. A life cycle analysis of two power electronic converters and their parts is performed. The benefits of energy savings versus energy invested in manufacturing and end-of-life management of power converters is analyzed. It is shown that power electronics systems have considerably shorter energy payback time compared to other technologies.

A PCB system integration concept for power electronics

Current passive components construction technologies and power converters manufacturing methods are the main barriers limiting the power density improvement. In this paper a new PCB system integration concept for power converters construction - Power Sandwich, that allows for a high density packaging, effective thermal management and automated manufacturing is introduced. In the Power Sandwich integration concept new passive components, x-dimension components, having the same height (x) and double sided electrical terminations are stacked between planar substrates and soldered on two sides. Depending on the number of stack layers (x-layers) and the components loss density, various arrangements in the Power Sandwich converter is possible. A Power Sandwich demonstrator, 70W flyback converter, is designed and implemented using modified standard components representing the prototype of x-dimension components. The spatial and thermal designs are discussed in detail and the experimental results of the first Power Sandwich demonstrator are shown.

Power Sandwich: An integration technology for manufacturability

This paper presents a novel power electronics construction technology for surface mount technology (SMT) automated manufacturing of power converters– Power Sandwich. The Power Sandwich manufacturing method employs new x-dimension components, having the same height (x) and double sided SMT electrical terminations. The components are stacked between planar substrates and can be soldered on both, top and bottom sides using the multilayer Power Sandwich assembly process. The process is compatible with standard SMT assembly line with some alternations. By arranging the components in different stack layers an increase in power density and better heat removal from the systems can be achieved. Power Sandwich is an enabling integration technology for achieving both SMT automated construction and high power densities of power electronics converters.

Thermal modeling of the module integrated DC-DC converter for thin-film PV modules

This paper presents an investigation into the thermal behavior of a DC-DC converter integrated on the back side of a thin-film photovoltaic (PV) module. Analytical thermal models of the converter and the PV module are made and the results obtained from the models are compared to the results obtained by computational fluid dynamics (CFD) simulations.

Comparison and suppression of conducted EMI in SiC JFET and Si IGBT based motor drives

This paper compares and suppresses the conducted Electromagnetic Interference (EMI) in Silicon Carbide (SiC) JFET and IGBT based motor drive systems. Two inverter prototypes - with SiC JFETs and Si IGBTs as the transistors are built using the same circuit layout and investigated accordingly. The comparisons start from the transient level of the inverter tested under clamped inductive switching conditions by using of a single inverter leg to the system level conditions of all three phases of each of the inverter drives are functioning. The conducted EMI comparisons include with no fiCM filterslter and with conventional CM filters. To identify the exhibited different filtering performance with the identical filters, two inverters are tested in the CM mode. This allows for the identification and analysis of their maximized CM and DM wave shape differences. The comparisons show that the high frequency noise level of SiC JFET drive under filtered condition is much higher than that of the IGBTs. Therefore, two methods of inserting ferrite beads at different current paths are proposed to mitigate the increased EMI. Respectively, the middle and high frequency noise of SiC JFET drive system are effectively suppressed to comply with the standard of IEC61800-3: C2.

Design of a flexible very low profile high step-up PV module integrated converter

Recently, improved PV system architectures were proposed with more granular power processing by means of distributed maximum power point tracking (DMPPT). This is achieved by connecting an MPPT unit to each PV module in the PV array. This paper presents a step further in the distributed power tracking approach, with the optimized, very low profile, high step-up, high frequency power converter suitable for integration into a low cost flexible PV module. Additional problems arise in this approach, specifically in the magnetic design and thermal management, due to the tight thermal coupling and specific mechanical requirements for a flexible converter design. Overcoming these limitations presents a challenge, but can lead to a cost effective, reliable solution for PV systems with improved integration level and power density.

New double sided SMT power inductor

The paper presents the design and construction of new SMT power inductors that allow for high components packaging density and automated manufacturing of power converters. The inductors are double sided SMDs with a uniform profile (14mm), reduced packaging (i.e. no coil former) and enhanced thermal properties. The inductor is implemented with drum and shield magnetic core parts. The thermal behaviour of the inductors is improved by employing heat extractors and filling the air gaps by thermal glue. Several inductor samples for different power levels and applications have been manufactured. The electromagnetic and thermal designs of the inductors are given in details. Because of larger air gaps the inductance value is calculated with the aid of FEM to include fringing field effects. The simulated inductance value match measured inductance value within ±3%. New inductors have reduced size, enable effective heat removal and are necessary building blocks in automated manufacturing of power converters.