Rengang Chen

Integrated magnetic for LLC resonant converter

A new LLC resonant converter is proposed for front end DC/DC conversion in a distributed power system. This converter shows some potential benefits in this application. This paper proposes several integrated magnetic designs for LLC resonant converter. This converter has three magnetic components. With magnetic integration, first, a number of components can be reduced; secondly, flux ripple cancellation is achieved so that core loss is reduced. From these benefits, higher power density can be achieved. In design of the integrated magnetic structure for LLC resonant converter, a general model of four winding integrated magnetic structure is derived which can be used to derive integrated magnetic structure for different topologies. Finally, the test result is shown.

Improving the Characteristics of integrated EMI filters by embedded conductive Layers

Discrete electromagnetic interference (EMI) filters have been used for power electronics converters to attenuate switching noise and meet EMI standards for many years. Because of the unavoidable structural parasitic parameters of the discrete filter components, such as equivalent parallel capacitance (EPC) of inductors and equivalent series inductance (ESL) of capacitors, the effective frequency range of the discrete filter is normally limited. Aiming at improving high frequency performance and reducing size and profile, the integrated EMI filter structure has been proposed based on advanced integration and packaging technologies , . Some improvements have been made but further progress is limited by EPCs of the filter inductors, which is restricted by dimension, size and physical structure. In this paper, a new structural winding capacitance cancellation method for inductors is proposed. Other than trying to reduce EPCs, a conductive ground layer is embedded in the planar inductor windings and the structural capacitance between the inductor winding and this embedded layer is utilized to cancel the parasitic winding capacitance. In order to obtain the best cancellation effect, the structural winding capacitance model of the planar spiral winding structure is given and the equivalent circuit is derived. The design methodology of the layout and area of the embedded ground layer is presented. Applying this method, an improved integrated EMI filter is designed and constructed. The experimental results show that the embedded conductive layer can effectively cancel the parasitic winding capacitance, hence ideal inductor characteristics can be obtained. With the help of this embedded conductive layer, the improved EMI filter has much smaller volume and profile and much better characteristics over a wide frequency range, compared to the former integrated EMI filter and the discrete EMI filter.

Design of planar integrated passive module for zero-voltage-switched asymmetrical half-bridge PWM converter

Integrated L-L-C-T (inductor-inductor-capacitor-transformer) technology has been the subject of intensive research over the last few years. Its application to resonant power electronic converters has been reported by many previous publications. This paper presents the application of a planar L-L-C-T module to the integration of passive module for a zero-voltage-switched asymmetrical half bridge PWM converter for application in distributed power systems. Two output transformers, two current doubler inductors, the ZVS resonant inductor and the transformer DC decoupling capacitor are integrated into a single module. The design procedure is discussed and some special considerations of the L-L-C-T module in nonresonant applications are addressed. A 1 kW 300 V-400 V input, 48 V output asymmetrical half bridge PWM converter (AHBC) employing the L-L-C-T module is constructed. A comparison of the AHBC using the integrated passive module and the same circuit using discrete components is given.

Integrating active, passive and EMI-filter functions in power electronics systems:a case study of some technologies

Assemblies of power semiconductor switches and their associated drive circuits are at present available in modules. Upward into the multi-kilowatt range, mixed mode module construction is used. This incorporates monolithic, hybrid, surface mount, and wirebond technology. However, a close examination of the applications in motor drives and power supplies indicates that there has been no dramatic volume reduction of the subsystem. The power semiconductor modules have shrunk the power switching part of the converter, but the bulk of the subsystem volume still comprises the associated control, sensing, electromagnetic power passives (inductors, transformers, capacitors) and interconnects. This paper addresses the improvement of power processing technology through advanced integration of power electronics. The goal of a subsystem in a module necessitates this advanced integration, incorporating active switching stages, electromagnetic interference (EMI) filters, and electromagnetic power passives into modules by integration technology. The central philosophy of the technology development research in the National Science Foundation Engineering Research Center for Power Electronic Systems is to advance the state of the art by providing the concept of integrated power electronics modules (IPEMs) for all these functions. The technology underpinning such an IPEM approach is discussed.

Planar electromagnetic integration technologies for integrated EMI filters

Planar electromagnetic integration technology has been the topic of research over the last few years. Its applications to the resonant and nonresonant switch mode power supplies (SMPS) have been reported in the past. However, this technology was mostly applied in the integration of power electromagnetic components, such as HF transformers, resonant/choke inductors and resonant/blocking capacitors, for SMPS circuits. Very little work has been done on the subject of filter integration. Since an EMI filter has different functions and has different requirements, accordingly special technologies are required. To bridge this gap, technologies to improve the high frequency performance of the integrated EMI filter are proposed, which include reducing the equivalent series inductance (ESL), reducing equivalent parallel capacitance (EPC) and increasing the high frequency noise damping factor. Based on these technologies, an improved integrated EMI filter structure is developed. The effectiveness of these technologies has been evaluated by finite element analysis (FEA) simulation results. Experimental results are also given.

Developing parasitic cancellation technologies to improve EMI filter performance for switching mode power supplies

Electromagnetic interference (EMI) filters have been used for power electronics converters to attenuate switching noise and meet EMI standards for a long time. However, because of the parasitics in the filters, filters cannot attenuate high-frequency noises efficiently. In this paper, critical parasitics, which include both mutual and self-parasitics, are first identified in both differential and common mode filters. Three techniques are then developed to cancel the adverse effects of mutual parasitics. These techniques can effectively cancel the inductive couplings between an inductor and capacitors, between an inductor and trace loops, and between two capacitors. Two additional techniques are further developed to cancel the self-parasitics of components, such as the equivalent series inductance of capacitors and the equivalent parallel capacitance of inductors. Experiments are carried out to verify these developed techniques. It is shown that the high-frequency performance of EMI filters is drastically improved.

Integration of EMI filter for distributed power system (DPS) front-end converter

Integration of power electromagnetic components, such as HF transformers, resonant/choke inductors and resonant/blocking capacitors, for switch mode power supplies (SMPS) has been studied in the past few years to reduce the count, volume and profile of the components so as to increase the power density of the converter. Its applications in resonant and nonresonant SMPS have been reported. However, very little work has been done on the subject of filter integration. To bridge this gap, the integration of an EMI filter for a DPS front-end converter is presented in this paper. The planar integrated L-C technology is used to integrate the filter components. The design issues of the integrated EMI filter are discussed and the experimental results are given.

Technologies and characteristics of integrated EMI filters for switch mode power supplies

Power electronics converters are potentially large EMI noise source to there nearby electrical and electronic equipments because of the switching function. EMI filters are necessary to insure the electromagnetic compatibility. Conventional discrete EMI filters are consisted of a fairly large number of components, with different shapes, sizes and form factors, and they are manufactured by different processing and packaging technologies, of which may include labor intensive processing steps. As a result, discrete EMI filters are usually bulky, high profile, with poor space and material utilization factors. In addition to that, because of the parasitic parameters of the discrete components and the interconnection board layout, the high frequency attenuation of discrete EMI filters is reduced. Hence the effective filter frequency range is limited. Aiming at these issues, integration technologies for EMI filters are studied. Our goal is to accomplish integrated EMI filters with structural, functional and processing integration to achieved smaller size, lower profile, better performance and reduced fabrication time and cost.

Experimental and theoretical characterization of an antiferroelectric ceramic capacitor for power electronics

Capacitance-voltage (C-V) measurements up to 800 VDC were made on a modified lead-zirconate (PbZrO/sub 3/) 20-layer multilayer ceramic (MLC) antiferroelectric power-electronic capacitor, with large energy-density storage capability. For these a precision impedance analyzer was used, in conjunction with a high-voltage capacitor dc-bias circuit configured for voltage-isolation from the analyzer input. A peak effective permittivity /spl epsiv/ /spl sim/ 4300 was derived at the capacitance peak of 133 nF at 400-V dc-bias, yielding an energy density storage of /spl sim/0.5 J/cc in the device volume of 0.022 cc. Modeling of the experimental C-V response was applied to three conceptual series-connected capacitance regions within each grain and grain-boundary region of the MLC. The equivalent capacitance component for the first region was derived from the voltage-dependent polarizations within a ferroelectric and/or antiferroelectric grain. This involved application of differing Langevin functions for modeling the ferroelectric and antiferroelectric polarizations. That for the second region related to the voltage and frequency dependence of the equivalent p-n junction capacitance at opposite sides of a grain-boundary and compensation-region, with Debye-type relaxation constants relating its frequency dependence. The third capacitance region was associated with the insulator-barrier region itself. Agreement between experimental and theoretical C-V-f responses was considered to be good, in view of the number of modeling parameters and variables employed.

Volumetric optimal design of passive integrated power electronics module (IPEM) for distributed power system (DPS) front-end DC/DC converter

In most power electronics converters, the overall footprint and profile of the whole system are in large part determined by the footprint and profile of the passive components and the interconnections between them. Planar magnetics, integrated magnetics, and passive integration have been topics of research for the past few years to reduce the count, footprint, and profile of the passive components and, hence, increase the power density of the whole converter. This becomes especially prominent in distributed power system (DPS) front-end converters, as the trend is moving from the 2U (1U=1.75 in) standard toward the 1U standard. Chen, Strydom, and van Wyk presented an integration technology, which combines the planar magnetics, integrated magnetics, and passive integration techniques, to integrate all the high-frequency passive components in a DPS front-end dc/dc converter into a single passive integrated power electronics module (IPEM) to reduce the size and volume of the overall system. To optimally design the passive IPEM, an ac loss model and a thermal model are needed. Based on these models, the volumetric optimal design algorithm is presented. To evaluate the performance of the optimally designed passive IPEM, a passive IPEM prototype is constructed and tested. Comparisons are made between the passive IPEM and the discrete components from viewpoints of volume, profile, efficiency, and thermal management. The optimal design is verified by experimental results.