I. Josifovic

Modeling and Reduction of Conducted EMI of Inverters With SiC JFETs on Insulated Metal Substrate

This paper presents the suppression of conducted common-mode (CM) electromagnetic interference (EMI) in an inverter for motor drive with discrete silicon carbide (SiC) JFETs attached on top of the insulated metal substrate (IMS). The EMC performance of the IMS inverter is compared with that of a heat sink inverter in a similar circuit layout. Both are under the same influence of parasitic capacitive couplings between the SiC JFET drains and the substrate base plate. It is found that although the application of conventional CM filters effectively suppresses the emitted noise in the low-frequency (LF) range, the influence of this capacitive coupling results in slight or no improvement in the middle-frequency (MF) and high-frequency (HF) ranges. To deal with this problem, a system CM equivalent circuit model with extracted parasitic parameters is proposed. The model is able to evaluate the filter insertion losses over a broad conducted EMI frequency band, which is essential to achieve an optimized filter design balanced between performance and cost. The presented experimental and calculated results form the step-by-step guideline that effectively suppresses the generated EMI to comply with the standard prescribed by IEC61800-3 C2: Qp.

Comprehensive CM filter design to suppress conducted EMI for SiC-JFET motor drives

This paper proposes a comprehensive EMI common-mode (CM) filter design procedure to suppress conducted EMI in silicon carbide (SiC) JFETs based inverter-fed motor drive systems. The first part of this paper is focusing on analyzing the EMC issue arisen from the newly generated power semiconductor device — SiC JFET, where the switching dynamics of SiC JFET and Si IGBT with the same power flowing level are compared. Then the second part towards EMI suppression for the inverter prototype. A comprehensive EMI CM filter design procedure is proposed. The proposed CM equivalent circuit model is able to evaluate the filter insertion loss gains over the whole conducted EMI frequency range, thereby different filter topologies can be compared and optimally selected. The performed experiments form the guideline that exhibits the process how the generated conducted EMI from the built inverter prototype is successfully suppressed to comply with the IEC61800–3 standard step by step.

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.

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.

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.

Thermal management of compact SMT multilayer power converters

This paper presents thermal management considerations for a multilayer stacked converter construction technology - Power Sandwich. The multilayer converters are built using novel x-dim components that have uniform height and double-sided SMT terminals. The SMT terminals of the components are soldered to two substrates and together with the substrate metallisation form copper-conductors reinforced multilayer assembly. Such structure has enhanced thermal performance as is shown in the paper. The concept enable more uniform distribution in the systems with non-uniform power loss distribution as proven by CFD sumulations and experimental demonstrators, thus simplifying the design procedure of power sandwich converters. Analytical thermal models for forced and natural convection heat transfer from

Multilayer SMT high power density packaging of electronic ballasts for HID lamps

This paper presents a method for high power density manufacturing of electronic ballast for HID lamps by utilization of a novel SMT stacked converter construction method, Power Sandwich. A two-stage topology of an HID lamp electronic ballast used in a commercial benchmark is employed as a case study. In Power Sandwich technology, new double-sided SMT x-dim components that have uniform height and enhanced thermal properties are stacked between planar substrates to achieve size reduction and better thermal performance of HID lamp ballast. A Power Sandwich prototype of a 150W HID lamp electronic ballast is developed, which has an electrical performance comparable to the commercially available benchmark counterpart but twice as high power density and better thermal performance.

New Double-Sided SMT Power Inductor

This paper presents the design and construction of new surface-mount technology (SMT) power inductors that allow for high-component packaging density and automated manufacturing of power converters. The inductors have double-sided SMT terminations, uniform profile (14 mm), reduced packaging (i.e., no coil former), and enhanced thermal properties. The inductor is implemented with drum and shield magnetic core parts. The thermal behavior of the inductors is improved by employing heat extractors and filling the air gaps by thermal glue. The electromagnetic and thermal designs of the inductors are given in detail. The method for designing novel x-dim inductors that results in the smallest drum and shield core parts for a given set of design parameters is presented. The designers of shielded drum inductors are provided by one-turn inductance values that include the fringing field effect in the form of fringing factor. New inductors have reduced size, enable effective heat removal, and are necessary building blocks in automated manufacturing of power converters.

Passive components for a 3D environment

Presents a collection of slides covering the following topics: commercial power electronics; power sandwich concept for manufacturability; inductors; capacitors; SMT automated manufacturing; pick and place; soldering; multilayer thermal management concept; temperature distribution analysis; natural convection cooling; and forced convection cooling.