Patents by Inventor Fred C. Lee

Fred C. Lee has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20190239980
    Abstract: Provided herein are systems, devices, assemblies, and methods for localization of a tag in a tissue of a patient. For example, provided herein are systems, devices, and methods employing a detection component that is attached to or integrated with a surgical device, where the detection component detects a signal from a tag in a patient, where the tag is activated by remote introduction of a magnetic field.
    Type: Application
    Filed: March 18, 2019
    Publication date: August 8, 2019
    Inventors: Daniel W. van der Weide, Fred T. Lee, JR., Robert C. Stewart, Lee G. Wilke
  • Patent number: 10333353
    Abstract: In one example, an omnidirectional wireless power transfer system includes high frequency power generator configured to generate a supply of high frequency oscillating power, a number of transmitter-side resonant tank circuits electrically coupled to the high frequency power generator, a receptacle including a number of coils arranged for omnidirectional power transfer to an electronic device placed in the receptacle, and a controller configured to activate individual ones of the transmitter-side resonant tank circuits to wirelessly transmit power to the electronic device through near-field resonant inductive coupling. In one example, the receptacle can be embodied as a bowl, and the controller can activate individual ones of the transmitter-side resonant tank circuits over time to generate an omnidirectional field distribution for wireless power transmission. In other aspects, various transmitter-side and receiver-side tank circuits for coupling independent resonance and ZVS operation are described.
    Type: Grant
    Filed: January 27, 2017
    Date of Patent: June 25, 2019
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Junjie Feng, Qiang Li, Fred C. Lee, Minfan Fu
  • Patent number: 10312805
    Abstract: A power converter using constant on-time (COT) or ramp pulse modulation (RPM) control achieves more rapid resumption of steady-state operation after a step-up load transient by extending an on-time of a switching pulse by interrupting a ramp voltage waveform that is compared with a threshold that equals a threshold voltage at the termination of a switching pulse or increasing a voltage with which the ramp voltage is compared. These techniques are applied to both single-phase and multi-phase power converters.
    Type: Grant
    Filed: March 21, 2016
    Date of Patent: June 4, 2019
    Assignee: VIRGINIA TECH INTELLECTUAL PROPERTIES, INC.
    Inventors: Virginia Li, Pei-Hsin Liu, Qiang Li, Fred C. Lee
  • Patent number: 10307291
    Abstract: A vitrectomy apparatus is provided, including a pressure source, a cut valve connected to the pressure source, the cut valve configured to be turned on and off to provide pressure to selectively extend and retract a vitrectomy cutting device, a sensor configured to sense pressure provided from the cut valve, and a controller configured to control operation of the cut valve based on pressure sensed by the sensor. The controller is configured to monitor pressures encountered and alter cut valve timing based on pressure conditions previously encountered.
    Type: Grant
    Filed: November 17, 2016
    Date of Patent: June 4, 2019
    Assignee: Johnson & Johnson Surgical Vision, Inc.
    Inventors: Fred C. Lee, James B. Gerg, Kyle E. Lynn, Zheng Zhang, Lauren M. Hickey
  • Patent number: 10291109
    Abstract: Critical-mode soft-switching techniques for a power converter are described. In one example, a power converter includes a converter electrically coupled between an alternating current (AC) power system and a direct current (DC) power system, where the converter includes a number of phase legs. The power converter can also include a control system configured, during a portion of a whole line cycle of the AC power system, to clamp a first phase leg of the converter from switching and operate second and third phase legs of the converter independently in either critical conduction mode (CRM) or in discontinuous conduction mode (DCM).
    Type: Grant
    Filed: January 11, 2018
    Date of Patent: May 14, 2019
    Assignee: VIRGINIA TECH INTELLECTUAL PROPERTIES, INC.
    Inventors: Zhengrong Huang, Zhengyang Liu, Fred C. Lee, Qiang Li, Furong Xiao
  • Patent number: 10217559
    Abstract: A power factor correction (PFC) power converter, particularly of a multiphase totem-pole or other topology presenting a switching bridge that can potentially provide bi-directional power transfer control, reduces a nominal switching frequency and achieves zero voltage switching over an increased portion of a half line cycle by providing positive or inverse coupling of inductors in an inductor structure that can be formed of a multi-layer printed circuit board such that at least three different inductances are presented during each half line cycle period; allowing increased switching frequency and simplifying EMI filtering arrangements. Parasitic capacitances can be balanced with additional coupled windings to reduce differential mode and common mode noise. The PFC power converter is particularly applicable to provide bi-directional power control from an on-board battery charger in an electrically powered vehicle.
    Type: Grant
    Filed: April 11, 2017
    Date of Patent: February 26, 2019
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Yuchen Yang, Mingkai Mu, Fred C. Lee, Qiang Li
  • Patent number: 10109404
    Abstract: 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 conductive cladding on the body of magnetic material or material covering the magnetic material body. Variation of inductance with load current and other operational or environmental parameters is reduced to any desired degree by forming a slot that removes all or a portion of the magnetic material between the locations of the vias.
    Type: Grant
    Filed: December 2, 2015
    Date of Patent: October 23, 2018
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Yipeng Su, Dongbin Hou, Fred C. Lee, Qiang Li
  • Patent number: 10110122
    Abstract: Response of a variable frequency switching constant on-time or adaptive on-time controlled power converter to a large step-up or step-down change in load is improved with a simple circuit that detects magnitude and polarity of a change in output voltage and initiates, extends or terminates conduction of power pulses from an input source through said power converter. Both the amplitude and duration of undershoot or overshoot of the transient response are reduced or, alternatively, the capacitance of an output filter may be significantly reduced and still provide comparable transient performance. The fast adaptive on-time control is applicable to multi-phase power converters using phase managers or one or more phase-locked loops for interleaving of power pulses.
    Type: Grant
    Filed: March 31, 2015
    Date of Patent: October 23, 2018
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Syed Bari, Fred C. Lee, Qiang Li, Pei-Hsin Liu
  • Patent number: 10075083
    Abstract: 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 micro-controller is operable with a control circuit for multiple step sampling with the switching signal at a switching frequency to settle the resonant circuit determined from the voltage output and load current. A fast load transient response at a high frequency with the resonant circuit provides the multiple step sampling to ensure enough time for micro-controller to calculate. Optimal trajectory control facilitates a burst mode of high frequency with the resonant circuit using adaptive multiple step sampling for an on-time to extend the burst operation range. A soft start-up process uses the micro-controller processing in multiple stages.
    Type: Grant
    Filed: April 1, 2016
    Date of Patent: September 11, 2018
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Chao Fei, Fred C. Lee, Weiyi Feng, Qiang Li
  • Publication number: 20180226182
    Abstract: A matrix transformer particularly suited to large voltage step-down, high current applications achieves increased good current sharing uniformity or air gap and electrical characteristics and reduced or eliminating termination losses, core losses and winding losses with a unitary magnetic core structure featuring sheets of magnetic material and a two-dimensional array of pillars on which windings, oriented in opposite directions on pillars that are adjacent in orthogonal directions, can be formed or placed comprising metallization on or embedded in a printed circuit board (PCB) structure. Magnetic flux density is reduced by at least one-half by dividing the magnetic flux in each pillar into two paths of increased width in the sheets of magnetic material. Magnetic flux density may be further decreased and flux uniformity improved by extending the sheets of magnetic material beyond a periphery defined by the pillar array.
    Type: Application
    Filed: July 21, 2017
    Publication date: August 9, 2018
    Inventors: Chao Fe, Fred C. Lee, Qiang Li
  • Publication number: 20180205306
    Abstract: Critical-mode soft-switching techniques for a power converter are described. In one example, a power converter includes a converter electrically coupled between an alternating current (AC) power system and a direct current (DC) power system, where the converter includes a number of phase legs. The power converter can also include a control system configured, during a portion of a whole line cycle of the AC power system, to clamp a first phase leg of the converter from switching and operate second and third phase legs of the converter independently in either critical conduction mode (CRM) or in discontinuous conduction mode (DCM).
    Type: Application
    Filed: January 11, 2018
    Publication date: July 19, 2018
    Inventors: Zhengrong Huang, Zhengyang Liu, Fred C. Lee, Qiang Li, Furong Xiao
  • Patent number: 10013007
    Abstract: 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 bandwidth output voltage feedback loop, guaranteed stability of the PLL loop and avoidance of jittering and phase cancellation issues are achieved by anchoring the bandwidth at the frequency of peak phase margin. This methodology is applicable to multi-phase power conveners of any number of phases and any known or foreseeable topology for individual phases and is not only applicable to power converters operating under constant on-time control, but is extendable to ramp pulse modulation (RPM) control and hysteresis control. Interleaving of pulses from all phases is simplified through use of phase managers with a reduced number of PLLS using hybrid interleaving arrangements that do not exhibit jittering even when ripple is completely canceled.
    Type: Grant
    Filed: March 31, 2015
    Date of Patent: July 3, 2018
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Pei-Hsin Liu, Qiang Li, Fred C. Lee
  • Publication number: 20180076723
    Abstract: A variable direct current (DC) link power converter is described. In one example, the power converter includes a first converter stage configured to convert power from a power source to power at an intermediate link voltage and a second converter stage configured to convert the power at the intermediate link voltage to power for charging a battery. The power converter further includes a control system having an intermediate link voltage regulation control loop configured, in a first mode of operation, to regulate the intermediate link voltage through the first converter stage based on a voltage of the battery, and a ripple regulation control loop configured to sense a charging current for the battery and regulate a gain of the second converter stage based on the charging current to reduce ripple in the charging current. A new configuration of transformer suitable for use with the power converter is also described.
    Type: Application
    Filed: September 1, 2017
    Publication date: March 15, 2018
    Inventors: Bin Li, Zhengyang Liu, Fred C. Lee, Qiang Li
  • Patent number: 9847710
    Abstract: 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 back to a circuit for generating waveforms for controlling a totem pole circuit to provide output voltage regulation as well as rectification of AC input voltage. The circuit for controlling the totem pole circuit may also be responsive to the AC input power waveform to provide power factor correction (PFC), in which case, the feedback signal provides additional pulse width modulation of the PFC signals. Bus capacitor size may also be reduced by injecting harmonics of the AC input waveform into the feedback signal which also serves to substantially maintain efficiency of the (preferably LLC) resonant second stage.
    Type: Grant
    Filed: March 30, 2016
    Date of Patent: December 19, 2017
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Fred C. Lee, Xiucheng Huang, Qiang Li
  • Patent number: 9812978
    Abstract: 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 connection connected in parallel with a synchronous rectifier. A simple logic circuit produces a waveform for controlling the synchronous rectifier which is not subject to significant turn on delay or early turn off caused by oscillatory resonances among parasitic inductances and capacitances. Improved timing accuracy of a synchronous converter provides improved power converter accuracy, particularly for flyback converters which are commonly used in converters for supplying power to offline electrical devices but are subject to oscillatory resonant behaviors that cannot be adequately damped at switching frequencies sufficiently high to support miniaturization of adapters.
    Type: Grant
    Filed: March 30, 2016
    Date of Patent: November 7, 2017
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Xiucheng Huang, Fred C. Lee, Qiang Li
  • Publication number: 20170294833
    Abstract: A power factor correction (PFC) power converter, particularly of a multiphase totem-pole or other topology presenting a switching bridge that can potentially provide bi-directional power transfer control, reduces a nominal switching frequency and achieves zero voltage switching over an increased portion of a half line cycle by providing positive or inverse coupling of inductors in an inductor structure that can be formed of a multi-layer printed circuit board such that at least three different inductances are presented during each half line cycle period; allowing increased switching frequency and simplifying EMI filtering arrangements. Parasitic capacitances can be balanced with additional coupled windings to reduce differential mode and common mode noise. The PFC power converter is particularly applicable to provide bi-directional power control from an on-board battery charger in an electrically powered vehicle.
    Type: Application
    Filed: April 11, 2017
    Publication date: October 12, 2017
    Inventors: Yuchen Yang, Mingkai Mu, Fred C. Lee, Qiang Li
  • Patent number: 9735238
    Abstract: 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 voltage and the corresponding losses are avoided by providing additional capacitance in parallel with a parallel connection of drain-source parasitic capacitance of the control transistor and gate-source parasitic capacitance of the high voltage, normally-on transistor to form a capacitive voltage divider with the drain-source parasitic capacitance of the high voltage, normally-on transistor such that the avalanche breakdown voltage of the control transistor cannot be reached. The increased capacitance also assures that the drain source parasitic capacitance of the high voltage, normally-on transistor is fully discharged before internal turn-on can occur.
    Type: Grant
    Filed: August 28, 2014
    Date of Patent: August 15, 2017
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Xiucheng Huang, Weijing Du, Qiang Li, Fred C. Lee
  • Publication number: 20170222483
    Abstract: In one example, an omnidirectional wireless power transfer system includes high frequency power generator configured to generate a supply of high frequency oscillating power, a number of transmitter-side resonant tank circuits electrically coupled to the high frequency power generator, a receptacle including a number of coils arranged for omnidirectional power transfer to an electronic device placed in the receptacle, and a controller configured to activate individual ones of the transmitter-side resonant tank circuits to wirelessly transmit power to the electronic device through near-field resonant inductive coupling. In one example, the receptacle can be embodied as a bowl, and the controller can activate individual ones of the transmitter-side resonant tank circuits over time to generate an omnidirectional field distribution for wireless power transmission. In other aspects, various transmitter-side and receiver-side tank circuits for coupling independent resonance and ZVS operation are described.
    Type: Application
    Filed: January 27, 2017
    Publication date: August 3, 2017
    Applicant: Virginia Tech Intellectual Properties, Inc.
    Inventors: Junjie Feng, Qiang Li, Fred C. Lee, Minfan Fu
  • Patent number: 9685790
    Abstract: 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 series and providing maximum power point tracking control in common for the series connected sub-panels such that the respective sub-panels produce equal voltages even in the presence of shading of a portion of one or more sub-panels. By doing so, the input voltage of respective power converters which control the voltage at which each sub-panel is operated can be placed close to the maximum power point of each sub-panel regardless of shading and maximum total power harvested even though the respective sub-panels are not operated at optimum voltages.
    Type: Grant
    Filed: October 29, 2013
    Date of Patent: June 20, 2017
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Xinke Wu, Zijian Wang, Fred C. Lee, Feng Wang
  • Patent number: 9678521
    Abstract: 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 ramp generator using a slope computation equation or design parameters based on fixing the quality factor of a double pole at one-half of the switching frequency at a desired value The slope of the external ramp waveform is tuned automatically with knowledge of the slope change in the waveform of inductor current of a power converter derived by differentiating a waveform in the current feedback loop. This autotuning of the external ramp generator provides immunity of quality factor change under variations of duty cycle, component values of topological change of the power converter.
    Type: Grant
    Filed: October 10, 2013
    Date of Patent: June 13, 2017
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Pei-Hsin Liu, Fred C. Lee, Yingyi Yan, Paolo Mattavelli