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This paper proposes a novel synchronous rectifier (SR) driving scheme for resonant converters. It is very suitable for high-frequency, high-efficiency, and high-power-density dc--dc resonant converters with SRs. In this paper, an LLC resonant converter with the proposed synchronous rectification is designed and analyzed. With the proposed driving scheme, the SR body diode conduction is reduced to almost zero. The driving scheme eliminates the reverse-recovery problem of SRs. Both current and voltage stresses are greatly decreased, and the conduction loss and switching loss of SRs are also reduced considerably. The experimental results show that the proposed LLC resonant converter with SRs can achieve low stress, high efficiency, and high power density. Index Terms--High frequency, resonant converter, synchronous rectification.

Extending battery life is a big challenge for today's laptop, and light-load efficiency is very important for battery life extension. In this paper, adaptive ON-time control is proposed to achieve higher efficiency when the buck converter is running in continuous current mode. A novel nonlinear inductor is then proposed to improve discontinuous-current-mode efficiency. A control method with a thorough analysis is proposed for the nonlinear inductor to achieve high efficiency, the required output voltage ripple, and sufficient transient response. The experimental results demonstrate the benefits of the proposed methods. Index Terms--Light-load efficiency, nonlinear inductor, voltage regulators (VRs).

In this paper, effects of parasitic parameters on the electromagnetic interference (EMI) filter performance are first discussed. The parasitic cancellation techniques for both self-and mutual parasitics are then reviewed and their constraints are identified. The possibilities of integrating parasitic cancellation techniques into one EMI filter are analyzed. It is found that three parasitic cancellation techniques can be integrated into one EMI filter to improve both differential-mode and common-mode filter performances without any conflicts and compromises. Experiments are finally carried out to verify the integration of these three cancellation techniques. Index Terms--Electromagnetic interference (EMI) filter, equivalent parallel capacitance (EPC), equivalent series inductance (ESL), mutual coupling, parasitic cancellation.

Interleaved multichannel power factor correction (PFC) converter is very popular today because of its ability to reduce input and output current ripples. In this paper, the common-mode (CM) electromagnetic interference noise emission model of the multichannel PFC converter is studied. A balance technique is introduced to reduce CM noise emission. To improve the high-frequency balance, a novel topology with coupled-inductor structure is proposed. Its CM noise model is derived and balance condition for minimizing CM noise is calculated. Effects of phase shift and channel shedding on this solution are also studied. The proposed topology has effectively reduced CM noise under any phase shift and channel shedding conditions. A two-channel PFC converter is built to verify the proposed balance technique. Experimental results show that CM noise can be reduced up to 20 dB between 150 kHz and 7 MHz. Index Terms--Electromagnetic interference (EMI), power factor correction (PFC).

This paper proposes a variable-frequency zero-voltage-switching (ZVS) three-level LCC resonant converter that is able to utilize the parasitic components of the high turns-ratio transformer. By applying a three-level structure to the primary side, the voltage stress of the primary switches is half of the input voltage. Low-voltage MOSFETs with better performance can be used in this converter, and zero-current-switching (ZCS) is achieved for rectifier diodes. By applying a magnetic integration technique, only one magnetic component is required in this converter. The power factor concept of resonant converters is proposed and analyzed, and a novel constant power-factor control scheme is proposed. Based on this control strategy, the circulating energy of resonant converters is considerably reduced. High efficiency can be obtained for high-voltage high-power charging applications. The operation principle of the converter is analyzed and verified on a 700-kHz, 3.7-kW prototype, with which a power density of 72 W/[inch.sup.3] is achieved. Index Terms--Constant power factor control, high power density, resonant converter, three-level converter.

In the past few years, coupled inductors have become more and more popular in microprocessor voltage regulators (VRs) for they can increase the VRs' steady-state and transient performances. In this paper, twisted core coupled inductors are proposed to reduce the winding path of coupled inductors. Next, the reluctance model of the twisted core coupled inductors is proposed. After that, based on the proposed reluctance model, the design procedure of the twisted core coupled inductors is shown. Finally, experimental results verify the proposed twisted core coupled inductors and the reluctance model. Index Terms--Coupled inductor, twisted core, voltage regulator (VR).

The goal of this paper is to study the possibility of minimizing common mode (CM) noise emission in bridgeless power factor correction (PFC) converters. Two approaches are proposed. In the first approach, the bridgeless PFC is modified to achieve symmetry. A CM noise model for symmetric topology is derived and the conditions for symmetry are summarized. Parasitics critical to the symmetrical condition are studied and carefully controlled. As a result, CM noise can be minimized with good cancellation. The second approach is to introduce a balance technique to bridgeless PFC converters. The topology is modified so that the balance technique can be applied so as to minimize CM noise. Experimental results validate that both approaches can greatly reduce CM noise up to 30 dB[micro]V. The two approaches are compared in terms of both its effects on CM noise and their implementations. Index Terms--Balance, bridgeless power factor correction (PFC) converter, common mode (CM) noise, symmetry.