Patents by Inventor Yungtaek Jang

Yungtaek Jang 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: 20070040644
    Abstract: A PFC circuit comprises a first converter and a second converter and a multi-port electromagnetic device. The first converter has a first inductive element and the second converter has a second inductive element. The multi-port electromagnetic device. comprises a first magnetic core having a first closed flux path and a second magnetic core having a second closed flux path, with the first closed flux path being independent of the second closed flux path. The first inductive element of the first boost circuit comprises a first winding that electromagnetically couples the first magnetic core to the second magnetic core and the second inductive element of the second boost circuit comprises a second winding that electromagnetically couples the first magnetic core to the second magnetic core independent of the electromagnetic coupling of the first winding such that current application in one windings does not induce a substantial voltage in the other.
    Type: Application
    Filed: February 17, 2006
    Publication date: February 22, 2007
    Applicant: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan Jovanovic
  • Patent number: 7161458
    Abstract: A multi-port electromagnetic device comprises a first magnetic core having a first closed flux path and a second magnetic core having a second closed flux path, with the first closed flux path being independent from the second closed flux path. At least one first winding electromagnetically couples the first magnetic core to the second magnetic core, and at least one second winding electromagnetically couples the first magnetic core to the second magnetic core independent of the electromagnetic coupling of the at least one first winding such that current application in one of the first or second windings does not induce a magnetic flux in the other one of the first or second windings.
    Type: Grant
    Filed: February 22, 2005
    Date of Patent: January 9, 2007
    Assignee: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan Jovanović
  • Publication number: 20060186981
    Abstract: A multi-port electromagnetic device comprises a first magnetic core having a first closed flux path and a second magnetic core having a second closed flux path, with the first closed flux path being independent from the second closed flux path. At least one first winding electromagnetically couples the first magnetic core to the second magnetic core, and at least one second winding electromagnetically couples the first magnetic core to the second magnetic core independent of the electromagnetic coupling of the at least one first winding such that current application in one of the first or second windings does not induce a magnetic flux in the other one of the first or second windings.
    Type: Application
    Filed: February 22, 2005
    Publication date: August 24, 2006
    Applicant: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan Jovanovic
  • Publication number: 20060152954
    Abstract: The present invention relates to a current control circuit for controlling inrush current through an energy storage capacitor of a power supply having an input voltage. A semiconductor device is coupled in series to the energy storage capacitor; and a control circuit produces a constant current through the semiconductor device during an inrush current period when the energy storage capacitor is charged by the input voltage to reach an energy storage capacitor voltage that causes the semiconductor device to act as a short switch.
    Type: Application
    Filed: January 7, 2005
    Publication date: July 13, 2006
    Applicant: Delta Electronics, Inc.
    Inventors: Milan Jovanovic, Yungtaek Jang, Chi-Hsing Huang
  • Publication number: 20060087295
    Abstract: A non-isolated power conversion system has an input stage and an output stage. A plurality of cascaded switching power converter stages are coupled between the input stage and the output stage. Each of the plurality of switching power converter stages has at least one switch that is activated in accordance with a duty cycle associated with a switching cycle. At least one energy storage device temporarily stores energy that is proportional to the duty cycle during the switching cycle for delivery to the output stage.
    Type: Application
    Filed: October 26, 2004
    Publication date: April 27, 2006
    Applicant: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan Jovanovic
  • Patent number: 6992902
    Abstract: A soft-switched, full-bridge pulse-width-modulated converter and its variations provide zero-voltage-switching conditions for the turn-on of the bridge switches over a wide range of input voltage and output load. The FB PWM converters of this invention achieve ZVS with a substantially reduced duty cycle loss and circulating current. The ZVS of the primary switches is achieved by employing an auxiliary circuit having an inductor and transformer to store energy for ZVS turn-on of the bridge switches.
    Type: Grant
    Filed: August 21, 2003
    Date of Patent: January 31, 2006
    Assignee: DELTA Electronics, Inc.
    Inventors: Yungtaek Jang, Milan M. Jovanović
  • Patent number: 6987675
    Abstract: A soft-switched boost converter includes an active snubber to provide soft switching of all semiconductor components. Specifically, the current (“turn-off current”) in the rectifier is switched off at a controlled rate, the main switch is closed under zero-voltage switching (ZVS) condition, and the auxiliary switch in the active snubber is opened under zero-current switching (ZCS) condition. As a result, switching losses are reduced with beneficial effects on conversion efficiency and EMC performance.
    Type: Grant
    Filed: May 23, 2003
    Date of Patent: January 17, 2006
    Assignee: Delta Electronics, Inc.
    Inventors: Milan M. Jovanovic, Yungtaek Jang, Yu-ming Chang, Kung-Hui Fang
  • Publication number: 20050243579
    Abstract: The present invention includes multiple power converters for driving one or more loads via an input power source, AC or DC. A first switching power converter has first one or more windings coupled to an input power source, and a second switching power converter having second one or more windings coupled to one or more loads. A magnetic device comprising a single integrated magnetic core couples the first one or more windings to the second one or more windings for reducing switching loss.
    Type: Application
    Filed: April 29, 2004
    Publication date: November 3, 2005
    Applicant: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan Jovanovic
  • Publication number: 20050226012
    Abstract: A soft-switched boost converter includes an active snubber to provide soft switching of all semiconductor components. Specifically, the current (“turn-off current”) in the rectifier is switched off at a controlled rate, the main switch is closed under zero-voltage switching (ZVS) condition, and the auxiliary switch in the active snubber is opened under zero-current switching (ZCS) condition. As a result, switching losses are reduced with beneficial effects on conversion efficiency and EMC performance.
    Type: Application
    Filed: May 23, 2003
    Publication date: October 13, 2005
    Inventors: Milan Jovanovic, Yungtaek Jang, Yu-Ming Chang, Kung-Hui Fang
  • Patent number: 6934167
    Abstract: A contactless electrical energy transmission system includes a transformer having a primary winding that is coupled to a power source through a primary resonant circuit and a secondary winding that is coupled to a load through a secondary resonant circuit. The primary and secondary resonant circuits are inductively coupled to each other. A primary control circuit detects current changes through the primary resonant circuit to control the switching frequency of a controllable switching device for maintaining a substantially constant energy transfer between the primary winding and secondary winding in response to at least one of a power source voltage change and a load change. As a result, excessive circulating energy of the CEET system is minimized providing a tight regulation of the output voltage over the entire load and input voltage ranges without any feedback connection between the primary side and the secondary side.
    Type: Grant
    Filed: May 1, 2003
    Date of Patent: August 23, 2005
    Assignee: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan M. Jovanovic
  • Patent number: 6906930
    Abstract: An isolated boost converter includes first and second switches that are switched simultaneously, a transformer and an energy storage capacitor on the primary side of the transformer for storing energy received from input power source. In one embodiment, when the first and second switches are closed, the energy in the capacitor is transferred to the output load while a boost inductor is charged, and when the first and second switches are open, the boost inductor provides energy from the input voltage source to supply the load and to charge the capacitor, In one embodiment, a third switch is provided to relieve the voltage stress on the secondary side.
    Type: Grant
    Filed: June 26, 2003
    Date of Patent: June 14, 2005
    Assignee: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan M. Jovanovic
  • Publication number: 20050041439
    Abstract: A soft-switched, full-bridge pulse-width-modulated (FB PWM) converter and its variations provide zero-voltage-switching (ZVS) conditions for the turn-on of the bridge switches over a wide range of input voltage and output load. The FB PWM converters of this invention achieve ZVS with a substantially reduced duty cycle loss and circulating current, which optimizes the conversion efficiency. The ZVS of the primary switches is achieved by employing an auxiliary circuit comprising an inductor and transformer to store energy for ZVS turn-on of the bridge switches.
    Type: Application
    Filed: August 21, 2003
    Publication date: February 24, 2005
    Applicant: DELTA Electronics, Inc.
    Inventors: Yungtaek Jang, Milan Jovanovic
  • Publication number: 20040264224
    Abstract: An isolated boost converter includes first and second switches that are switched simultaneously, a transformer and an energy storage capacitor on the primary side of the transformer for storing energy received from input power source. In one embodiment, when the first and second switches are closed, the energy in the capacitor is transferred to the output load while a boost inductor is charged, and when the first and second switches are open, the boost inductor provides energy from the input voltage source to supply the load and to charge the capacitor, In one embodiment, a third switch is provided to relieve the voltage stress on the secondary side.
    Type: Application
    Filed: June 26, 2003
    Publication date: December 30, 2004
    Inventors: Yungtaek Jang, Milan M. Jovanovic
  • Publication number: 20040218406
    Abstract: A contactless electrical energy transmission system includes a transformer having a primary winding that is coupled to a power source through a primary resonant circuit and a secondary winding that is coupled to a load through a secondary resonant circuit. The primary and secondary resonant circuits are inductively coupled to each other. A primary control circuit detects current changes through the primary resonant circuit to control the switching frequency of a controllable switching device for maintaining a substantially constant energy transfer between the primary winding and secondary winding in response to at least one of a power source voltage change and a load change. As a result, excessive circulating energy of the CEET system is minimized providing a tight regulation of the output voltage over the entire load and input voltage ranges without any feedback connection between the primary side and the secondary side.
    Type: Application
    Filed: May 1, 2003
    Publication date: November 4, 2004
    Inventors: Yungtaek Jang, Milan M. Jovanovic
  • Patent number: 6504497
    Abstract: The stored energy in the energy-storage capacitors of a power supply during the hold-up time is improved by providing two groups of energy storage capacitors, and by connecting one group of capacitors to the input of a hold-up-time extension circuit that has its output connected to the other group of energy-storage capacitors. Each group of energy-storage capacitors may consist of a single capacitor, or a number of capacitors connected in parallel. The hold-up-time extension circuit is designed so that its output is regulated at a voltage that is lower than the minimum regulation voltage of the output-stage dc/dc converter. As a result, the hold-up-time extension circuit is inactive during the normal operation mode. i.e., when the input voltage is present. In fact, during the normal operation mode both groups of capacitors are effectively connected in parallel so that their voltages are equal.
    Type: Grant
    Filed: May 16, 2001
    Date of Patent: January 7, 2003
    Assignee: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan M. Jovanovic
  • Publication number: 20020071300
    Abstract: The stored energy in the energy-storage capacitors of a power supply during the hold-up time is improved by providing two groups of energy storage capacitors, and by connecting one group of capacitors to the input of a hold-up-time extension circuit that has its output connected to the other group of energy-storage capacitors. Each group of energy-storage capacitors may consist of a single capacitor, or a number of capacitors connected in parallel. The hold-up-time extension circuit is designed so that its output is regulated at a voltage that is lower than the minimum regulation voltage of the output-stage dc/dc converter. As a result, the hold-up-time extension circuit is inactive during the normal operation mode. i.e., when the input voltage is present. In fact, during the normal operation mode both groups of capacitors are effectively connected in parallel so that their voltages are equal.
    Type: Application
    Filed: May 16, 2001
    Publication date: June 13, 2002
    Inventors: Yungtaek Jang, Milan M. Jovanovic
  • Patent number: 6392902
    Abstract: A soft-switched full-bridge pulse-width modulated (“FB PWM”) converter includes a coupled inductor provides ZVS conditions over a wide range of input voltages and output loads. Further, the FB PWM converter of the present invention requires neither a large leakage inductance in the transformer, nor an external inductor, to achieve ZVS.
    Type: Grant
    Filed: August 31, 2000
    Date of Patent: May 21, 2002
    Assignee: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan M. Jovanovic
  • Publication number: 20020044461
    Abstract: A family of soft-switched, full-bridge pulse-width-modulated (FB PWM) converters provides zero-voltage-switching (ZVS) conditions for the turn-on of the bridge switches over a wide range of input voltage and output load. The FB PWM converters of this family achieve ZVS with the minimum duty cycle loss and circulating current, which optimizes the conversion efficiency. The ZVS of the primary switches is achieved by employing two magnetic components whose volt-second products change in the opposite directions with a change in phase shift between the two bridge legs. One magnetic component always operates as a transformer, where the other magnetic component can either be a coupled inductor, or uncoupled (single-winding) inductor. The transformer is used to provide isolated output(s), whereas the inductor is used to store the energy for ZVS.
    Type: Application
    Filed: February 5, 2001
    Publication date: April 18, 2002
    Inventors: Yungtaek Jang, Milan M. Jovanovic
  • Patent number: 6356462
    Abstract: A family of soft-switched, full-bridge pulse-width-modulated (FB PWM) converters provides zero-voltage-switching (ZVS) conditions for the turn-on of the bridge switches over a wide range of input voltage and output load. The FB PWM converters of this family achieve ZVS with the minimum duty cycle loss and circulating current, which optimizes the conversion efficiency. The ZVS of the primary switches is achieved by employing two magnetic components whose volt-second products change in the opposite directions with a change in phase shift between the two bridge legs. One magnetic component always operates as a transformer, where the other magnetic component can either be a coupled inductor, or uncoupled (single-winding) inductor. The transformer is used to provide isolated output(s), whereas the inductor is used to store the energy for ZVS.
    Type: Grant
    Filed: February 5, 2001
    Date of Patent: March 12, 2002
    Assignee: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan M. Jovanovic
  • Patent number: 6353547
    Abstract: Three-level, constant-frequency, soft-switched isolated converters provide zero-voltage-switching (ZVS) conditions for the turn-on of all primary switches over a wide range of input voltage and output load. These converters achieve ZVS with the minimum duty cycle loss and circulating current, which optimizes the conversion efficiency. The ZVS of the primary switches is achieved by the energy stored in an inductor on the primary side of the isolation transformer. The inductor and transformer are arranged so that a change in the phase shift between the outer and inner pair of switches of the series connection of four switches changes the volt-second product on the windings of the transformer and the windings of the inductor in opposite directions. In some embodiments the primary-side inductor is coupled inductor with two windings, whereas in the other embodiments the inductor has only one winding.
    Type: Grant
    Filed: March 29, 2001
    Date of Patent: March 5, 2002
    Assignee: Delta Electronics, Inc.
    Inventors: Yungtaek Jang, Milan M. Jovanovic