Patents by Inventor Julu Sun

Julu Sun 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).

  • Patent number: 8587965
    Abstract: A current-input-type parallel resonant DC/DC converter and a method thereof are provided. The converter includes an inverter-circuit for inverting/converting an input DC current into a positive-and-negative alternating square-wave-current, a resonant-network for converting the square-wave-current into a sine-voltage, a transformer for realizing the isolation of the power transmission, a full-wave rectifier-circuit for rectifying the sine-voltage, and an output-filter-circuit for producing a DC output-voltage.
    Type: Grant
    Filed: August 12, 2011
    Date of Patent: November 19, 2013
    Assignees: FSP-Powerland Technology Inc., FSP Technology Inc.
    Inventors: Ming Xu, Julu Sun
  • Publication number: 20120039092
    Abstract: A current-input-type parallel resonant DC/DC converter and a method thereof are provided. The converter includes an inverter-circuit for inverting/converting an input DC current into a positive-and-negative alternating square-wave-current, a resonant-network for converting the square-wave-current into a sine-voltage, a transformer for realizing the isolation of the power transmission, a full-wave rectifier-circuit for rectifying the sine-voltage, and an output-filter-circuit for producing a DC output-voltage.
    Type: Application
    Filed: August 12, 2011
    Publication date: February 16, 2012
    Applicants: FSP TECHNOLOGY INC., FSP-POWERLAND TECHNOLOGY INC.
    Inventors: Ming Xu, Julu Sun
  • Publication number: 20120039103
    Abstract: A single-stage AC/DC converter is provided, and which includes a power-frequency follow-current circuit, an isolated transmission circuit (ITC), a high-frequency chopper modulation circuit (HFCMC), a power-frequency and high-frequency AC rectifying-circuit and a filter-circuit. The input of the ITC is connected to the output of an external power-frequency power source, the current-modulating side of the ITC is connected to the input of the HFCMC, the output of the ITC is connected to the input of the power-frequency and high-frequency AC rectifying-circuit, the output of the HFCMC is connected to the input of the external power-frequency power source through the power-frequency follow-current connected in series with the HFCMC , and the output of the power-frequency and high-frequency AC rectifying circuit is connected to a load through the filter circuit connected in series with the power-frequency and high-frequency AC rectifying-circuit.
    Type: Application
    Filed: August 11, 2011
    Publication date: February 16, 2012
    Applicants: FSP TECHNOLOGY INC., FSP-POWERLAND TECHNOLOGY INC.
    Inventors: Ming Xu, Julu Sun, Chao Sun
  • Patent number: 7872886
    Abstract: Improved regulation and transient response are provided by a power supply architecture providing both unregulated and regulated voltage converters in parallel but deriving input power from separate power supplies connected in series wherein regulated and unregulated branches each provide a substantially fixed and constant proportion of the output current. The series connection of input power sources may provide a further feedback mechanism in addition to feedback for regulation which enhances overall performance. As a perfecting feature of the invention, inductor-less resonant converters which are switched in an interleaved fashion may be used in the unregulated branch while substantially cancelling the characteristic large output voltage ripple thereof.
    Type: Grant
    Filed: February 20, 2008
    Date of Patent: January 18, 2011
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Ming Xu, Julu Sun, Ya Liu, Fred C. Lee
  • Patent number: 7746041
    Abstract: A voltage converter having four switches Q1, Q2, Q3, Q4, connected in series and operated in pairs in a complementary fashion. An input voltage is provided across the four switches. A middle capacitor is connected in parallel with two middle switches Q2, Q3. Voltage output is provided across switches Q3 and Q4 (i.e. at a midpoint of the four switches). Series-connected output capacitors can be connected in parallel with the set of four switches. The middle capacitor alone or in combination with parallel connected capacitors, when connected to the input voltage or output terminals functions as a capacitive voltage divider for voltage conversion and/or regulation with extremely high efficiency and which can provide either step-down or step-up function. Also, an output inductor can be provided as a perfecting feature to further increase efficiency. Alternatively, two of the four switches can be replaced with rectifying diodes.
    Type: Grant
    Filed: March 27, 2007
    Date of Patent: June 29, 2010
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Ming Xu, Julu Sun, Fred C. Lee
  • Publication number: 20090206804
    Abstract: Improved regulation and transient response are provided by a power supply architecture providing both unregulated and regulated voltage converters in parallel but deriving input power from separate power supplies connected in series wherein regulated and unregulated branches each provide a substantially fixed and constant proportion of the output current. The series connection of input power sources may provide a further feedback mechanism in addition to feedback for regulation which enhances overall performance. As a perfecting feature of the invention, inductor-less resonant converters which are switched in an interleaved fashion may be used in the unregulated branch while substantially cancelling the characteristic large output voltage ripple thereof.
    Type: Application
    Filed: February 20, 2008
    Publication date: August 20, 2009
    Inventors: Ming Xu, Julu Sun, Ya Liu, Fred C. Lee
  • Publication number: 20070296383
    Abstract: A voltage converter having four switches Q1, Q2, Q3, Q4, connected in series and operated in pairs in a complementary fashion. An input voltage is provided across the four switches. A middle capacitor is connected in parallel with two middle switches Q2, Q3. Voltage output is provided across switches Q3 and Q4 (i.e. at a midpoint of the four switches). Series-connected output capacitors can be connected in parallel with the set of four switches. The middle capacitor alone or in combination with parallel connected capacitors, when connected to the input voltage or output terminals functions as a capacitive voltage divider for voltage conversion and/or regulation with extremely high efficiency and which can provide either step-down or step-up function. Also, an output inductor can be provided as a perfecting feature to further increase efficiency. Alternatively, two of the four switches can be replaced with rectifying diodes.
    Type: Application
    Filed: March 27, 2007
    Publication date: December 27, 2007
    Inventors: Ming Xu, Julu Sun, Fred C. Lee
  • Patent number: 7265525
    Abstract: A voltage converter uses a component such as a JFET or four-terminal power MOSFET having no body diode and exhibiting no body diode conduction characteristic as a synchronous rectifier to reduce switching losses and body diode conduction losses and to support high frequency switching so that use of smaller components and higher current densities can be achieved. These effects are enhanced by a self-driven circuit utilizing positive feedback to enhance switching speed and reduce switching losses which increase with switching frequency.
    Type: Grant
    Filed: March 31, 2005
    Date of Patent: September 4, 2007
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Ming Xu, Julu Sun, Jinghai Zhou, Fred C. Lee
  • Patent number: 7254047
    Abstract: 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 capacitor Cr resonates with the leakage inductance Lk of the transformer. The resonant capacitor and leakage inductance are selected such that ½ a LC resonance period is equal to an ON time of each secondary switch S1 S2. The resonance provides zero current switching for secondary switches S1 S2, eliminates zero body diode conduction during dead times, and eliminates reverse recovery losses in the secondary switches. The present invention is applicable to many different circuit topologies such as full bridge, active clamp forward, push-pull forward, and center-tap secondary. The present converters provide high energy conversion efficiency and high frequency operation.
    Type: Grant
    Filed: March 31, 2005
    Date of Patent: August 7, 2007
    Assignee: Virginia Tech Intellectual Properties, Inc.
    Inventors: Yuancheng Ren, Julu Sun, Ming Xu, Fred C. Lee
  • Publication number: 20060226819
    Abstract: A voltage converter uses a component such as a JFET or four-terminal power MOSFET having no body diode and exhibiting no body diode conduction characteristic as a synchronous rectifier to reduce switching losses and body diode conduction losses and to support high frequency switching so that use of smaller components and higher current densities can be achieved. These effects are enhanced by a self-driven circuit utilizing positive feedback to enhance switching speed and reduce switching losses which increase with switching frequency.
    Type: Application
    Filed: March 31, 2005
    Publication date: October 12, 2006
    Inventors: Ming Xu, Julu Sun, Jinghai Zhou, Fred Lee
  • Publication number: 20060109696
    Abstract: 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 capacitor Cr resonates with the leakage inductance Lk of the transformer. The resonant capacitor and leakage inductance are selected such that ½ a LC resonance period is equal to an ON time of each secondary switch S1 S2. The resonance provides zero current switching for secondary switches S1 S2, eliminates zero body diode conduction during dead times, and eliminates reverse recovery losses in the secondary switches. The present invention is applicable to many different circuit topologies such as full bridge, active clamp forward, push-pull forward, and center-tap secondary. The present converters provide high energy conversion efficiency and high frequency operation.
    Type: Application
    Filed: March 31, 2005
    Publication date: May 25, 2006
    Inventors: Yuancheng Ren, Julu Sun, Ming Xu, Fred Lee