Patents by Inventor Charles S. Kerfoot

Charles S. Kerfoot 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: 5831409
    Abstract: An electric vehicle propulsion system having a motor with first and second electrically isolated windings and a system control unit for controlling the motor, wherein the system control unit includes a first power bridge for driving the first windings and a second power bridge for driving the second windings.
    Type: Grant
    Filed: February 28, 1997
    Date of Patent: November 3, 1998
    Assignee: Northrop Grumman Corporation
    Inventors: Frank A. Lindberg, David L. Schantz, Jr., Brian H. Smith, Charles S. Kerfoot, Joseph J. Springer, Patricia A. O'Donnell, James H. DeOms, Ronnie L. Starling, Michael J. Ankrom, James L. Munro, Geoffrey B. Lansberry, Beth A. Herman, William B. Hall, Marshall G. Jones, William B. Winkel, Brian A. DeAbreu, Thomas C. Underwood, Todd M. Zaranski, Aaron D. Valdivia, Richard M. Young, Frank E. Altoz, Ngon B. Nguyen, Eric L. Mohler
  • Patent number: 5634262
    Abstract: An easy to assemble transformer for use in an electronics module of an electric vehicle. The transformer can be assembled from the "top down," thus alleviating the need to build the transformer as a subassembly unit. During manufacture of the transformer, windings are wound onto a thermally conductive coil form. Next upper and lower E-shaped core members are inserted into openings in the top and bottom of the form so that the side legs and the center legs of the E's touch and are in alignment. The thermally conductive coil form has a portion that touches a cold plate when the transformer is mounted on the cold plate. The transformer is further secured to the cold plate by a mounting bracket.
    Type: Grant
    Filed: June 9, 1995
    Date of Patent: June 3, 1997
    Assignee: Northrop Grumman Corporation
    Inventors: Patricia A. O'Donnell, Charles S. Kerfoot, Joseph J. Springer
  • Patent number: 5581171
    Abstract: An on-board electric vehicle battery charger includes a surge limiter circuit, a power factor control circuit, and a resonant inverter circuit. The power factor control circuit includes a boost regulator circuit providing a fixed voltage on an output capacitor. The resonant inverter circuit uses a resonance capacitor and the leakage inductance of an output transformer to establish a resonance frequency at least 500 times the AC input power frequency.
    Type: Grant
    Filed: June 10, 1994
    Date of Patent: December 3, 1996
    Assignee: Northrop Grumman Corporation
    Inventors: Charles S. Kerfoot, Patricia A. O'Donnell, David L. Schantz, Jr.
  • Patent number: 5469124
    Abstract: An easy to assemble transformer for use in an electronics module of an electric vehicle. The transformer can be assembled from the "top down," thus alleviating the need to build the transformer as a subassembly unit. During manufacture of the transformer, windings are wound onto a thermally conductive coil form. Next upper and lower E-shaped core members are inserted into openings in the top and bottom of the form so that the side legs and the center legs of the E's touch and are in alignment. The thermally conductive coil form has a portion that touches a cold plate when the transformer is mounted on the cold plate. The transformer is further secured to the cold plate by a mounting bracket.
    Type: Grant
    Filed: June 10, 1994
    Date of Patent: November 21, 1995
    Assignee: Westinghouse Electric Corp.
    Inventors: Patricia A. O'Donnell, Charles S. Kerfoot, Joseph J. Springer
  • Patent number: 5283463
    Abstract: In one embodiment, the invention is a packaged high power electronic switch in the form of a semiconductor chip having metalized planar cathode and anode terminals and a gate terminal. A refractory annular ring has planar open end faces and side walls having stepped portions. A pair of thermally and electrically conductive planar substrates is bonded to the opposite end faces of the annular ring and is maintained in spaced relation thereby, forming an enclosed space. At least one conductive strap within the space is supported by the stepped portion of the internal side wall and extends to one of the substrates forming an electrical and thermal path. One of said conductive substrates receives one of the planar terminals of the chip in intimate electrical and thermal contact. The strap is electrically coupled to the other of said terminals, for forming a high current path between the substrates via the strap.
    Type: Grant
    Filed: March 5, 1992
    Date of Patent: February 1, 1994
    Assignee: Westinghouse Electric Corp.
    Inventors: Ngon B. Nguyen, Franklin B. Jones, Charles S. Kerfoot, Gene A. DiGennaro
  • Patent number: 5162965
    Abstract: A high-speed high-voltage FET current interrupter which opens the cathode circuit of microwave tubes when internal tube arcing occurs. By removing the detrimental fault current which causes degradation to the microwave tube body and grid, the longevity of the microwave tube and the pulse energy storage capacitor is greatly increased over those transmitters which use dissipative crow bar circuits. Even more important is that the transmitter reset time after an arc occurs is orders of magnitude faster than transmitters using crow bars or primary power interrupters when arcing occurs--an important feature when engaged in a "dog fight".
    Type: Grant
    Filed: June 28, 1991
    Date of Patent: November 10, 1992
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Walter E. Milberger, Franklin B. Jones, Charles S. Kerfoot
  • Patent number: 5122730
    Abstract: The high voltage regulator employs a field effect transistor (FET) amplifier and a shielded wide band frequency compensated RC voltage divider. The device comprises a FET amplifier used as a current source in a 20 KV power supply. The negative output of the supply is sensed by the voltage divider consisting of two resistors in parallel with two capacitors for frequency compensation. The voltage divider output is applied to the non-inverting input of an operational amplifier whose reference is set to affect the linear operation of an inverting operational amplifier. In the voltage divider, a variable high voltage quartz glass piston capacitor is used to set the RC product of the high level arm equal to that of the low level arm.
    Type: Grant
    Filed: July 15, 1991
    Date of Patent: June 16, 1992
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Walter E. Milberger, Charles S. Kerfoot, Franklin B. Jones
  • Patent number: 5111382
    Abstract: A high power, high frequency inverter has series/parallel resonant inverter elements and employs MOS controlled thyristors (MCTs) in the switching circuit. The resonant inverter elements include a split inductor for reducing peak voltage across the switches. A fault protection circuit cause the power interruption for a short interval before restarting the circuit. High current density is achieved by means of multilayer ceramic chip capacitors and gap ferrite planar inductors.
    Type: Grant
    Filed: October 23, 1990
    Date of Patent: May 5, 1992
    Assignee: Westinghouse Electric Corp.
    Inventors: Franklin B. Jones, Ray S. Kemerer, Charles E. Carter, Charles S. Kerfoot
  • Patent number: 5070538
    Abstract: The high voltage regulator employs a field effect transistor (FET) amplifier and a wide band frequency compensated RC voltage divider. The device comprises a FET amplifier used as a current source in a 20 KV power supply. The negative output of the supply is sensed by a voltage divider consisting of two resistors in parallel with two capacitors. The voltage divider output is applied to the non-inverting input of an operational amplifier whose reference is set to affect the linear operation of an inverting operational amplifier. A no load to full load and line regulation of 0.1% is provided to a microwave tube. For a 16-KV regulated output the inverting amplifier must have a dc operation point of 4 KV to accommodate a 20% storage capacitor voltage droop and a .+-.5% line change. At this level the inverting amplifier provides a swing of .+-.4 KV. This range allows for a large line voltage variation and storage capacitor voltage droop.
    Type: Grant
    Filed: January 2, 1990
    Date of Patent: December 3, 1991
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Walter E. Milberger, Charles S. Kerfoot, Franklin B. Jones
  • Patent number: 5032799
    Abstract: A cascode radio frequency amplifier in which a control amplifier stage is provided and any number of clone amplifier stages are connected in series (cascode) with the control amplifier. The cascode amplifiers provide equal voltage and power since each of the clone stages provides unity gain. The device can operate from low frequencies to high frequencies.
    Type: Grant
    Filed: November 26, 1990
    Date of Patent: July 16, 1991
    Assignee: Westinghouse Electric Corp.
    Inventors: Walter E. Milberger, Charles S. Kerfoot, Daniel C. Buck, Franklin B. Jones
  • Patent number: 4939450
    Abstract: A high voltage pulse regulator which is capable of measuring and correcting voltage perturbations on the top of a high voltage square wave pulse is disclosed. The regulator uses: a rectifying diode, an oscilloscope, a variable zener diode, a variable biasing current source and pulse capacitor. The rectifying diode receives and rectifies the high voltage square wave pulse from a high voltage pulse source to produce a rectified square wave pulse. The rectified square wave pulse is received and regulated to a voltage level acceptable to the oscilloscope by the variable zener diode pulse capacitor, and current source, which are connected together in a parallel circuit and act as follows. The variable zener diode is activated by the biasing current.
    Type: Grant
    Filed: March 17, 1989
    Date of Patent: July 3, 1990
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Walter E. Milberger, Franklin B. Jones, Charles S. Kerfoot
  • Patent number: 4897617
    Abstract: This high voltage linear FET amplifier operates at voltage levels of ten's of thousand's of volts with power dissipation capabilities in the kilowatt range. It is a broadband device which features power amplification from DC to frequencies well in excess of 100 KHz. The amplifier uses a unity-gain inverting amplifier as its basic building block. N-number of these building blocks are stacked to accommodate whatever voltage stand-off level is desired. To operate stacked high voltage amplifiers, it is necessary to provide a bias shift (reference) progressively increasing in equal increments from the ground reference stage to the highest voltage level stage while preserving the fidelity of the signal applied to the first stage. This is done by establishing a phantom ground at all amplifiers for each progressive bias level.
    Type: Grant
    Filed: February 28, 1989
    Date of Patent: January 30, 1990
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Walter E. Milberger, Franklin B. Jones, Charles S. Kerfoot
  • Patent number: 4893070
    Abstract: A High Voltage Regulation apparatus which uses an amplifier having an arbitrarily large number of stacked MOSFETs to provide low impedance shunt regulation with a "domino effect". Voltages of many kilovolts can be conveniently regulated. voltage sharing among the devices is assured by the domino arrangement. External capacitances are added to optimize low impedance voltage regulation, including an external capacitor connected between the drain and gate of each stage to equalize the drain to gate and gate to source capacitances. There may also be an external capacitor connected between the drain and source of each stage to provide low amplifier impedance at high frequency, or a lumped external capacitor connected across the entire amplifier string, to provide low amplifier impedance at high frequency. The amplifier uses a unity-gain inverting amplifier as its basic building block. N-number of these building blocks are stacked to accommodate whatever voltage stand-off level is desired.
    Type: Grant
    Filed: February 28, 1989
    Date of Patent: January 9, 1990
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Walter E. Milberger, Charles S. Kerfoot, Franklin B. Jones
  • Patent number: 4743785
    Abstract: A high-voltage FET pulser for a synthetic aperture radar transmitter includes an FET ON switch and a tail biter switch both on the floating deck and coupled to a pulse driver circuit through a transformer having a quartz glass tube isolating the secondary winding from the core and primary winding. An active shunt regulator circuit is connected to the output of the FET ON switch to provide a flat output pulse free of ringing.
    Type: Grant
    Filed: March 4, 1987
    Date of Patent: May 10, 1988
    Assignee: Westinghouse Electric Corp.
    Inventors: Walter E. Milberger, Charles S. Kerfoot
  • Patent number: 4721900
    Abstract: The reduction of non-monotonic degradation characteristics induced in the output signals in high-power applications of a transformer which has a primary winding and n secondary windings which have a total of N turns, where n and N are integers, is accomplished by replacing the n secondary windings with m replacement windings, where m is an integer less than n. When the replacement windings have a total of N turns, they produce an output signal with reduced degradation normally caused by stray capacitance and inductance leakage in the secondary windings.
    Type: Grant
    Filed: August 6, 1986
    Date of Patent: January 26, 1988
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Charles S. Kerfoot, Walter E. Milberger
  • Patent number: 4698742
    Abstract: A high-voltage converter circuit which uses a slip slide power conditioner to reduce non-monotonic non-linearities in the converter output signal is disclosed. The slip slide power conditioner includes: a choke feed D.C. circulator; two radio frequency (RF) power pumps; a phase detector; a phase controller; and a combiner. The choke feed D.C. circulator receives the D.C. input signal and produces therefrom two voltage output signals which are each sent to one of the two RF power pumps. The two RF power pumps produce two out-of-phase square wave output signals which are algebraically combined in the combiner to form an output signal whose amplitude is a function of phase difference. The phase detector and phase controller sample this output signal and adjust the phase of the two power pumps to remove non-linearities due to secondary ranging (resonance) that beats with harmonics of their square wave signals.
    Type: Grant
    Filed: August 1, 1986
    Date of Patent: October 6, 1987
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Franklin B. Jones, Walter E. Milberger, David E. Bulgher, Charles S. Kerfoot
  • Patent number: 4686448
    Abstract: A programmable slewing power supply is used to drive microwave phase shifters according to a command signal from a system controller using: a Milberger converter; a power source; a rectifying circuit; two differential amplifier circuits; and two comparator amplifier circuits. The Milberger converter outputs a combined square wave which it produces by combining two independent square waves which add or cancel. The power source receives the combined square wave and outputs: a reference voltage, a positive voltage signal; and a negative voltage signal. The rectifying circuit produces a rectified command signal by rectifying the command signal from the system controller. The two differential amplifier circuits respectively measure the positive and negative voltage signals with respect to the reference voltage to produce a measured positive voltage signal, and a measured negative voltage signal.
    Type: Grant
    Filed: August 1, 1986
    Date of Patent: August 11, 1987
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Franklin B. Jones, Charles S. Kerfoot, Walter E. Milberger
  • Patent number: 4683387
    Abstract: A field effect transistor (FET) quadrature switch for the control of multi mode microwave phase shifters provides bi-directional random mode switching while using only one power supply. The switch apparatus provides high speed, high voltage, and high-current switching while reducing the stand off voltage requirement of the linear driver, the number of switching elements which are required for mechanization, and reducing the size, weight and the complexity of the apparatus.
    Type: Grant
    Filed: December 3, 1985
    Date of Patent: July 28, 1987
    Assignee: The United States of America as represented by the Secretary of the Air Force
    Inventors: Franklin B. Jones, Walter E. Milberger, Charles S. Kerfoot
  • Patent number: H436
    Abstract: A low voltage trigger pulse is coupled to a three-stage driver which genees therefrom a high amplitude (e.g., 20 amp.) decaying current spike of predetermined width. The current pulse or spike from the driver is coupled to the gates of a multiplicity (i.e., 12) of parallel-connected field effect transistors (FETs) to turn or switch the same to the "ON" state. A laser diode array is series-connected with the parallel connected FETs so that when the latter is switched ON a very high (100 amp.) current pulse is delivered to the laser diode array to enable the same. At the cessation of the pulser current drive, a passive pull-down technique is used to enhance the turn-off of the parallel-connected FETs so that the laser diode array is quickly disabled. A protective overload circuit sets a limit to the average current through the laser diode array without affecting the pulse burst current.
    Type: Grant
    Filed: August 21, 1987
    Date of Patent: February 2, 1988
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Walter E. Milberger, Charles S. Kerfoot
  • Patent number: H575
    Abstract: The light weight non-saturating spaced core inductor that is made of altete layers of magnetic and light weight non-magnetic materials to provide a structure that is light in weight yet has the non-saturating inductor characteristics required for certain circuits that are subject to over-load.
    Type: Grant
    Filed: April 25, 1988
    Date of Patent: February 7, 1989
    Assignee: The United States of America as represented by the Secretary of the Army
    Inventors: Charles S. Kerfoot, Walter E. Milberger