Wenduo Liu

Optimal design methodology for LLC resonant converter

Although LLC resonant converter can achieve wide operation range with high efficiency, lack of design methodology makes it difficult to be implemented. In this paper, based on the theoretical analysis on the operation principles during normal condition and holdup time, the relationship between converter efficiency and operation range with different circuit parameters has be revealed. An optimal design methodology has been developed based on the revealed relationship. A 1MHz, 1kW LLC converter is designed to verify the proposed method.

Design of integrated passive component for a 1 MHz 1 kW half-bridge LLC resonant converter

The LLC resonant converter has some special characteristics to make it an excellent candidate for front-end DC/DC conversion in a distributed power system. Even with advanced topology, to achieve high power density, the passive component design is still the key issue. Passive integration is used to integrate all the passive components within the resonant tank of the LLC resonant converter into one single component - an integrated L-L-C-T. The design approach and loss estimation of the integrated L-L-C-T component for a 1 MHz 1 kW LLC resonant converter is given in this paper. A prototype is constructed and tested under small signal and in-circuit working conditions.

Embedded solid State heat extraction in integrated power electronic modules

The use of embedded solid-state heat extractors to increase the power densities in power electronic modules seems promising. Cross-sectional geometric optimization was done on heat extraction insert and it was found that the most suitable heat extraction configuration for the dimensional range applicable in power electronics is the use of flat continuous heat extraction layers aiding in conducting heat to externally mounted heat sinks. Theoretically expected thermal enhancement factors were determined and experimentally verified. The adverse influence of interfacial thermal resistances on the effectiveness of heat extraction inserts was also evaluated.

Design of integrated LLCT module for LLC resonant converter

This paper presents the electromagnetic design of integrated L-L-C-T modules with stacked structure for an LLC resonant converter. Based on the one-dimensional magnetic field assumption, both the electromagnetic design and the loss calculation are investigated. A high power density design sample is provided and the test result is presented.

Design and evaluation of integrated electromagnetic power passives with vertical surface interconnections

This paper presents a symmetric planar structure with vertical surface interconnection to construct an integrated electromagnetic power passive module (IEPP), incorporating distributed inductance, capacitance and transformer action. A design procedure is proposed with specific attentions to constructional aspects, electromagnetic constraints and thermo-mechanical characteristics. Loss calculation and one-dimensional thermal modeling are studied and applied in the design. A prototype is built and tested, showing good electromagnetic performance.

High density integrated electromagnetic power passives with vertical interconnect and stacked structure

A stacked-cell structure to construct an integrated electromagnetic power passive (IEPP) module is presented in this paper. Copper is plated on dielectric substrate, such as ceramic strip to realize a so-called L-C-cell. The L-C-cells are stacked symmetrically and encapsulated inside a ferrite as a passive module. With the interconnections on the vertical surface, the module can achieve various energy transfer functions. The 1/sup st/ order approximation circuits of modules with specific interconnections are presented. The construction of interconnections is also discussed. The experimental results show the potential of IEPP as a high-density power passive module. Good correspondence between the first-order models and experimental measurements is demonstrated.

Power density improvement in integrated electromagnetic passive modules with embedded heat extractors

In this paper, heat extractors are embedded into the magnetic materials of the integrated power electronics passive modules. The optimum volume of heat-extracting material may slightly reduce the amount of electromagnetic energy that is processed, but more efficient heat removal yields higher allowable levels of both electromagnetic stress and losses per unit volume in the remaining material. Without influencing the electromagnetic performance, heat extractors provide the potential to improve the power density of passive modules. This paper introduces the mechanism of heat extractors into passive power electronics modules. Theoretical thermal models and simulation are used to investigate factors influencing the module performance and the improvement on power density. Prototypes are built for experimental investigation. The experimental results show great improvement of power density by the application of heat extraction technology. High power density, more than 1 kW/in3 (70 W/cm3), is achieved on the prototype.

Evaluation of embedded heat extraction for high power density integrated electromagnetic power passives

The use of embedded solid-state heat extractors to increase the power densities in power electronic modules seems promising. Cross-sectional geometric optimisation was done on heat extraction insert and it was found that the most suitable heat extraction configuration for application in power electronics is the use of flat continuous heat extraction layers aiding in conducting heat to externally mounted heat sinks. Theoretic expected thermal enhancement factors were determined and experimentally verified. Interfacial thermal resistances adversely influence the effectiveness of heat extraction inserts and should be minimised.

A High-Power-Density Integrated Electronic Ballast for Low Wattage HID Lamps

A high power density integrated electronic ballast for low wattage high intensity discharge (HID) lamp is proposed in this paper. Packaging and integration technologies are explored to fully utilize the three-dimensional space, therefore improve the power density of the system. This paper focuses on the power passive integration, including the integrated EMI filter, and the integrated LC series resonators serving as output filter or ignitor. A prototype with integrated passive components is developed, which achieves almost the same efficiency but doubles the power density of discrete ballast.

High-Power-Density Igniter With Integrated

This paper presents the design of a high-power-density igniter with integrated LC resonator for low-wattage high-intensity discharge lamp ballasts. Electromagnetic integration technology is applied to reduce the number of passive components and the overall volume of the igniter. By applying the interwinding capacitance as the resonant capacitance, the integrated igniter is simply composed of a magnetic core and two magnet wire windings. By selecting the proper terminals and exploiting the advantage of an integrated LC resonant structure, the obtained output voltage is twice as much as an ordinary LC resonator. The design and implementation of the igniter are presented, while the experimental results of a small-signal measurement and a high-voltage test are given. The experiment results show that the application of passive integration technology into low-wattage passive modules is promising.