Now showing items 1-20 of 33

    • A diffusion-viscous analysis and experimental verification of defect formation in sintered silver bond-line 

      Xiao, Kewei; Ngo, Khai D. T.; Lu, Guo-Quan (Cambridge University Press, 2014-04-01)
      The low-temperature joining technique (LTJT) by silver sintering is being implemented by major manufacturers of power electronic devices and modules for bonding power semiconductor chips. A common die-attach material used ...
    • Anti-islanding detection for three-phase distributed generation 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Dong, Dong; Boroyevich, Dushan; Mattavelli, Paolo (United States Patent and Trademark Office, 2017-04-25)
      Wobbling the operating frequency of a phase-locked loop (PLL), preferably by adding a periodic variation is feedback gain or delay in reference signal phase allows the avoidance of any non-detection zone that might occur ...
    • Avoiding internal switching loss in soft switching cascode structure device 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Li, Qiang; Lee, Fred C.; Huang, Xiucheng; Du, Weijing (United States Patent and Trademark Office, 2017-08-15)
      In a cascode switching device, avalanche breakdown of a control transistor and loss of soft switching or zero voltage switching in a high voltage normally-on depletion mode transistor having a negative switching threshold ...
    • Colossal tunability in high frequency magnetoelectric voltage tunable inductors 

      Yan, Yongke; Geng, Liwei D.; Tan, Yaohua; Ma, Jianhua; Zhang, Lujie; Sanghadasa, Mohan; Ngo, Khai; Ghosh, Avik W.; Wang, Yu U.; Priya, Shashank (2018-11-27)
      The electrical modulation of magnetization through the magnetoelectric effect provides a great opportunity for developing a new generation of tunable electrical components. Magnetoelectric voltage tunable inductors (VTIs) ...
    • Correlation between tunability and anisotropy in magnetoelectric voltage tunable inductor (VTI) 

      Yan, Yongke; Geng, Liwei D.; Zhang, Lujie; Gao, Xiangyu; Gollapudi, Sreenivasulu; Song, Hyun-Cheol; Dong, Shuxiang; Sanghadasa, Mohan; Khai Ngo; Wang, Yu U.; Priya, Shashank (Springer Nature, 2017-11-22)
      Electric field modulation of magnetic properties via magnetoelectric coupling in composite materials is of fundamental and technological importance for realizing tunable energy efficient electronics. Here we provide ...
    • Energy storage for power factor correction in battery charger for electric-powered vehicles 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Wang, Hui; Ngo, Khai Doan (United States Patent and Trademark Office, 2018-03-13)
      Switches of a switching circuit used to control operation of an electric motor such as in an electrically powered vehicle connect respective windings of the electric motor as a single phase inductor during battery charging. ...
    • External ramp autotuning for current mode control of switching converter 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Liu, Pei-Hsin; Lee, Fred C.; Mattavelli, Paolo; Yan, Yingyi (United States Patent and Trademark Office, 2017-06-13)
      Peak current, valley current or average current mode controlled power converters in either digital or analog implementations obtain a stabilized feedback loop and allow high system bandwidth design by use of an external ...
    • High frequency integrated point-of-load power converter with embedded inductor substrate 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Li, Qiang; Lee, Fred C.; Su, Yipeng; Zhang, Wenli (United States Patent and Trademark Office, 2017-02-07)
      A low profile power converter structure is provide wherein volume is reduced and power density is increased to approach 1 KW/in3 by at least one of forming an inductor as a body of magnetic material embedded in a substrate ...
    • Hybrid interleaving structure with adaptive phase locked loop for variable frequency controlled switching converter 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Li, Qiang; Liu, Pei-Hsin; Lee, Fred C. (United States Patent and Trademark Office, 2018-07-03)
      In a multi-phase power converter using a phase-locked loop (PLL) arrangement for interleaving of pulse frequency modulated (PFM) pulses of the respective phases, improved transient response, improved stability of high ...
    • Iaverage current mode (ACM) control for switching power converters 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Mattavelli, Paolo; Yan, Yingyi (United States Patent and Trademark Office, 2016-05-17)
      Providing a fast current sensor direct feedback path to a modulator for controlling switching of a switched power converter in addition to an integrating feedback path which monitors average current for control of a modulator ...
    • Low profile coupled inductor substrate with transient speed improvement 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Li, Qiang; Lee, Fred C.; Su, Yipeng; Hou, Dongbin (United States Patent and Trademark Office, 2018-10-23)
      A low profile inductor structure suitable for use in a high power density power converter has one or more windings formed by vias through a thin, generally planar body of magnetic material forming the inductor core and ...
    • Maximum power point tracking for solar panels 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Materials Science and Engineering (MSE); Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Wang, Feng; Wu, Xinke; Wang, Zijian (United States Patent and Trademark Office, 2017-06-20)
      Approximately one-half of the loss of delivered power from a solar panel having photovoltaic (PV) cells connected in series to form sub-panels due to shading is recovered at low hardware cost by connecting sub-panels in ...
    • Method and apparatus for current/power balancing 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Toyota Motor Engineering & Manufacturing North American, Inc.; Wang, Chi-Ming; Mao, Yincan; Miao, Zichen; Ngo, Khai D. (United States Patent and Trademark Office, 2018-03-20)
      Aspects of the disclosure provide a system having a power circuit. The power circuit includes a first switch circuit having at least a first transistor and a second switch circuit having at least a second transistor. ...
    • Method and apparatus for current/power balancing 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Toyota Motor Engineering & Manufacturing North American, Inc.; Wang, Chi-Ming; Mao, Yincan; Miao, Zichen; Ngo, Khai D. (United States Patent and Trademark Office, 2017-02-28)
      Aspects of the disclosure provide a power circuit that includes a first switch circuit in parallel with a second switch circuit. The first switch circuit and the second switch circuit are coupled to a first driving node, ...
    • Method and apparatus for driving a power device 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Toyota Motor Engineering & Manufacturing North American, Inc.; Wang, Chi-Ming; Shin, Jongwon; Ngo, Khai D. (United States Patent and Trademark Office, 2016-12-27)
      Aspects of the disclosure provide a circuit for driving a power switch. The circuit includes a first circuit configured to provide a charging current to charge a control terminal of the power switch, a second circuit ...
    • Method and apparatus to improve power device reliability 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Toyota Motor Engineering & Manufacturing North American, Inc.; Wang, Chi-Ming; Mao, Yincan; Miao, Zichen; Ngo, Khai D. (United States Patent and Trademark Office, 2017-05-23)
      Aspects of the disclosure provide a power device that includes an upper power module and a lower power module. The upper power module and the lower power module are coupled in series between two supply voltages, and are ...
    • Method for reducing or eliminating conducted common mode noise in a transformer 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Li, Qiang; Lee, Fred C.; Huang, Daocheng; Yang, Yuchen (United States Patent and Trademark Office, 2017-03-07)
      At least one shield member interposed between primary and secondary windings of a transformer and connected to the primary and/or secondary windings forms a distributed parasitic capacitance between the shield member and ...
    • Multi-step simplified optimal trajectory control (SOTC) based on only Vo and I load 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); 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 ...
    • Optimal trajectory control for LLC resonant converter for LED PWM dimming 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Polytechnic Institute and State University; Lee, Fred C.; Ji, Shu; Feng, Weiyi (United States Patent and Trademark Office, 2016-03-01)
      Pulse width modulation is provided for controlling a resonant power converter, particularly for dimming of light emitting diode arrays without loss of efficiency. Dynamic oscillation due to the beginning of a pulse width ...
    • Optimal trajectory control for LLC resonant converter for soft start-up 

      Electrical and Computer Engineering; Center for Power Electronics Systems (CPES); Virginia Tech Intellectual Properties, Inc.; Lee, Fred C.; Feng, Weiyi (United States Patent and Trademark Office, 2016-04-19)
      By setting switching instants of a switching circuit of a resonant power converter based on current in a resonant circuit reaching a current limit of a current limitation band, soft start-up of the power converter can be ...