Now showing items 1-14 of 14

    • Accelerated commutation for passive clamp isolated boost converters 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Lai, Jih-Sheng; Zhu, Lizhi (United States Patent and Trademark Office, 2005-04-05)
      An efficient and cost effective bidirectional DC/DC converter reduces switch voltage stress via accelerated commutation allowing use of a low-cost passive clamp circuit in boost mode. The converter includes a primary ...
    • Circuit and method for driving synchronous rectifiers for high-frequency flyback converters 

      Virginia Tech Intellectual Properties, Inc.; Li, Qiang; Lee, Fred C.; Huang, Xiucheng (United States Patent and Trademark Office, 2017-11-07)
      A voltage waveform similar to a waveform of a magnetizing current of an isolation transformer and immune to high frequency oscillatory resonant behavior is developed across a capacitor of a series resistor and capacitor ...
    • Half-bridge zero-voltage switched multi-resonant converters 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Tabisz, Wojciech A.; Jovanovic, Milan M. (United States Patent and Trademark Office, 1989-08-22)
      A half-bridge zero-voltage-switched multi-resonant converter. The converter basically comprises a device for converting an input voltage signal to a DC output signal to be imposed across a load. The device includes input ...
    • High input voltage, high efficiency, fast transient voltage regulator module (VRM) 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Zhou, Xunwei (United States Patent and Trademark Office, 2003-07-08)
      A high input-voltage push-pull forward voltage regulator module (VRM) has high efficiency and fast transient response. The VRM has a primary side wherein two switches and two primary transformer windings are alternately ...
    • Method and apparatus for reduction of energy loss due to body diode conduction in synchronous rectifiers 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Xu, Ming Gang (United States Patent and Trademark Office, 2004-08-24)
      A method and apparatus for preventing current flow through the integral body diode of an electronic switch (e.g. MOSFET) in the secondary circuit of a synchronous rectifier. In a conventional synchronous rectifier, body ...
    • Multi-element resonant converters 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Xu, Ming Gang; Liu, Ya; Fu, Dianbo (United States Patent and Trademark Office, 2010-06-22)
      A resonant switched power converter having switching frequency controlled in response to an output voltage thereof achieves over-current protection such as at start-up or under short circuit conditions using a resonant ...
    • Multi-step simplified optimal trajectory control (SOTC) based on only Vo and I load 

      Virginia Tech Intellectual Properties, Inc.; Li, Qiang; Lee, Fred C.; Fei, Chao; Feng, Weiyi (United States Patent and Trademark Office, 2018-09-11)
      A resonant power converter is disclosed with a driving circuit generating a switching signal connecting power to a resonant tank circuit, with a voltage monitoring circuit measuring a voltage output and a load current. A ...
    • Phase compensation driving scheme for synchronous rectifiers 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Fu, Dianbo (United States Patent and Trademark Office, 2009-10-13)
      Phase compensation of a voltage appearing on physical terminals of a synchronous rectifier switching element such as a MOSFET is used to substantially eliminate effects of package inductance of the synchronous rectifier ...
    • Power converters having capacitor resonant with transformer leakage inductance 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Xu, Ming Gang; Ren, Yuancheng (United States Patent and Trademark Office, 2007-03-27)
      Power converters having reduced body diode conduction loss, reduced reverse recovery loss and lower switching noise, among other benefits, have a resonant capacitor Cr connected across an unfiltered output. The resonant ...
    • Power converters having output capacitor resonant with autotransformer leakage inductance 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Xu, Ming Gang; Ren, Yuancheng; Sun, Ju-Lu (United States Patent and Trademark Office, 2007-08-07)
      Power converters having reduced body diode conduction loss, reduced reverse recovery loss and lower switching noise, among other benefits, have a resonant capacitor Cr connected across an unfiltered output. The resonant ...
    • Self-driven circuit for synchronous rectifier DC/DC converter 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Xu, Ming Gang; Ren, Yuancheng (United States Patent and Trademark Office, 2006-03-21)
      A power converter having a primary circuit (e.g. full bridge) and a secondary circuit (e.g. current doubler) has switches in the secondary circuit that are controlled by a drive circuit. The drive circuit is connected to ...
    • Self-driven circuit for synchronous rectifier DC/DC converter 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Xu, Ming Gang; Ren, Yuancheng (United States Patent and Trademark Office, 2004-11-16)
      A power converter having a primary circuit (e.g. full bridge) and a secondary circuit (e.g. current doubler) has switches in the secondary circuit that are controlled by a drive circuit. The drive circuit is connected to ...
    • Universal system structure for low power adapters 

      Virginia Tech Intellectual Properties, Inc.; Li, Qiang; Lee, Fred C.; Huang, Xiucheng (United States Patent and Trademark Office, 2017-12-19)
      A two-stage power converter architecture including an isolation transformer and rectification of the isolation transformer output by an LLC resonant circuit and methodology for operating the same feeds an output voltage ...
    • Zero-voltage-switched multi-resonant converters including the buck and forward type 

      Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Tabisz, Wojciech A. (United States Patent and Trademark Office, 1989-08-15)
      A multi-resonant-switching network that operates under switching conditions that are favorable to both the active switch and the diode that constitute the switch. In a zero-current multi-resonant switch, the resonant circuit ...