Patents by Inventor Ronald J. Krefta
Ronald J. Krefta 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).
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Patent number: 11423203Abstract: A method for modeling a thermal circuit of power inverter includes setting a first input node of the thermal circuit to a first measured temperature. The method also includes setting a second input node of the thermal circuit to a second measured temperature. The method also includes determining at least one thermal characteristic of the thermal circuit using, at least, the first measured temperature. The method also includes determining an operating temperature of the thermal circuit based on the at least one thermal characteristic.Type: GrantFiled: July 23, 2019Date of Patent: August 23, 2022Assignee: DELPHI TECHNOLOGIES IP LIMITEDInventors: Lijun Zheng, Ronald J. Krefta
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Publication number: 20210026929Abstract: A method for modeling a thermal circuit of power inverter includes setting a first input node of the thermal circuit to a first measured temperature. The method also includes setting a second input node of the thermal circuit to a second measured temperature. The method also includes determining at least one thermal characteristic of the thermal circuit using, at least, the first measured temperature. The method also includes determining an operating temperature of the thermal circuit based on the at least one thermal characteristic.Type: ApplicationFiled: July 23, 2019Publication date: January 28, 2021Inventors: Lijun Zheng, Ronald J. Krefta
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Patent number: 9463713Abstract: A system and method for controlling a rotating E-machine and for correcting a rotational position signal output by an angular position sensor operatively connected to the E-machine in conjunction with a sensor digital converter is disclosed. For each angular operating speed of interest, a set of signals as a function of position is taken such that the harmonics (or sub-harmonics) related to the position sensor may be determined and isolated from errors due to an associated digital converter. From this information, the magnitude and phase of the position sensor harmonics is determined. The effects of the sensor digital converter (or other signal processing equipment) are then determined and accounted for, allowing the control system to apply the total position error signal to the position sensor output signal to determine a corrected position sensor signal for use in controlling the E-machine.Type: GrantFiled: February 12, 2016Date of Patent: October 11, 2016Assignee: Allison Transmission, Inc.Inventors: James E. Walters, Ronald J. Krefta
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Publication number: 20160276969Abstract: A system configured to operate an electric motor and correct for current measurement errors present in current sensors used by the system includes a plurality of voltage drivers, a plurality of current sensors, and a controller. Each of the plurality of voltage drivers is electrically coupled to each phase of a motor. Each of the plurality of current sensors is each configured to measure current in each phase of the motor. The controller is configured to sample a current-signal from each current sensor, and determine a baseline-offset error of each current sensor based on a plurality of samples of the current-signal from each current sensor while the motor is rotating.Type: ApplicationFiled: March 20, 2015Publication date: September 22, 2016Inventor: RONALD J. KREFTA
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Publication number: 20160193941Abstract: A system and method for controlling a rotating E-machine and for correcting a rotational position signal output by an angular position sensor operatively connected to the E-machine in conjunction with a sensor digital converter is disclosed. For each angular operating speed of interest, a set of signals as a function of position is taken such that the harmonics (or sub-harmonics) related to the position sensor may be determined and isolated from errors due to an associated digital converter. From this information, the magnitude and phase of the position sensor harmonics is determined. The effects of the sensor digital converter (or other signal processing equipment) are then determined and accounted for, allowing the control system to apply the total position error signal to the position sensor output signal to determine a corrected position sensor signal for use in controlling the E-machine.Type: ApplicationFiled: February 12, 2016Publication date: July 7, 2016Inventors: James E. Walters, Ronald J. Krefta
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Patent number: 9260036Abstract: A system and method for controlling a rotating E-machine and for correcting a rotational position signal output by an angular position sensor operatively connected to the E-machine in conjunction with a sensor digital converter is disclosed. For each angular operating speed of interest, a set of signals as a function of position is taken such that the harmonics (or sub-harmonics) related to the position sensor may be determined and isolated from errors due to an associated digital converter. From this information, the magnitude and phase of the position sensor harmonics is determined. The effects of the sensor digital converter (or other signal processing equipment) are then determined and accounted for, allowing the control system to apply the total position error signal to the position sensor output signal to determine a corrected position sensor signal for use in controlling the E-machine.Type: GrantFiled: February 13, 2015Date of Patent: February 16, 2016Assignee: Allison Transmission, Inc.Inventors: James E. Walters, Ronald J. Krefta
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Publication number: 20150158396Abstract: A system and method for controlling a rotating E-machine and for correcting a rotational position signal output by an angular position sensor operatively connected to the E-machine in conjunction with a sensor digital converter is disclosed. For each angular operating speed of interest, a set of signals as a function of position is taken such that the harmonics (or sub-harmonics) related to the position sensor may be determined and isolated from errors due to an associated digital converter. From this information, the magnitude and phase of the position sensor harmonics is determined. The effects of the sensor digital converter (or other signal processing equipment) are then determined and accounted for, allowing the control system to apply the total position error signal to the position sensor output signal to determine a corrected position sensor signal for use in controlling the E-machine.Type: ApplicationFiled: February 13, 2015Publication date: June 11, 2015Inventors: James E. Walters, Ronald J. Krefta
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Publication number: 20140350871Abstract: A method to estimate power dissipation of an inverter configured to control electric energy to an electric machine. The method can estimate both conductive power losses and switched power losses of a transistor or a diode in a power switch or driver stage of the inverter. The estimation includes applying a correction factor (CF) to power dissipation calculations if the modulation index of the inverter is greater than a threshold indicating that the inverter is being over-driven or operated in a non-linear region.Type: ApplicationFiled: May 21, 2013Publication date: November 27, 2014Inventor: RONALD J. KREFTA
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Patent number: 8656890Abstract: A system and method for controlling an injection time of a fuel injector. The system includes a drive circuit configured to output a drive signal having a pulse width, wherein the injection time is influenced by the pulse width and a closing electrical decay of the fuel injector. A controller is configured to determine the closing electrical decay of the fuel injector and adapt the pulse width based on the closing electrical decay to control the injection time. The closing electrical decay includes a closing response. The controller determines the closing response based on an injector signal, such as a coil voltage of the fuel injector. By determining the closing response, the pulse width can be adjusted to compensate for fuel injector part-to-part variability, fuel injector wear, variations in fuel pressure received by the fuel injector, dirt in the fuel injector, and the like.Type: GrantFiled: March 23, 2011Date of Patent: February 25, 2014Assignee: Delphi Technologies, Inc.Inventors: Philippe S. Farah, Ronald J. Krefta, Brent J. Wahba, Eugene A. Kobos, Kevin R. Keegan
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Publication number: 20110251777Abstract: A system and method for controlling an injection time of a fuel injector. The system includes a drive circuit configured to output a drive signal having a pulse width, wherein the injection time is influenced by the pulse width and a closing electrical decay of the fuel injector. A controller is configured to determine the closing electrical decay of the fuel injector and adapt the pulse width based on the closing electrical decay to control the injection time. The closing electrical decay includes a closing response. The controller determines the closing response based on an injector signal, such as a coil voltage of the fuel injector. By determining the closing response, the pulse width can be adjusted to compensate for fuel injector part-to-part variability, fuel injector wear, variations in fuel pressure received by the fuel injector, dirt in the fuel injector, and the like.Type: ApplicationFiled: March 23, 2011Publication date: October 13, 2011Applicant: DELPHI TECHNOLOGIES, INC.Inventors: PHILIPPE S. FARAH, RONALD J. KREFTA, BRENT JACK WAHBA, EUGENE ANTHONY KOBOS, KEVIN RICHARD KEEGAN
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Patent number: 7945374Abstract: A method for equalizing fuel injector flows among a plurality of fuel injectors in an internal combustion engine including the steps of a) characterizing the electrical and/or mechanical performance of each fuel injector; b) imprinting characterization data on each fuel injector; c) reading the imprinted data into a control computer, preferably at the time of engine assembly or sub-assembly; and d) using the characterization data in an algorithm to adjust at least one electrical parameter such as hold current, peak current, and boost time for each fuel injector in an assembled engine during each fuel injection cycle.Type: GrantFiled: December 5, 2008Date of Patent: May 17, 2011Assignee: Delphi Technologies, Inc.Inventors: Kevin R. Keegan, Ronald J. Krefta
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Publication number: 20100145597Abstract: A method for equalizing fuel injector flows among a plurality of fuel injectors in an internal combustion engine including the steps of a) characterizing the electrical and/or mechanical performance of each fuel injector; b) imprinting characterization data on each fuel injector; c) reading the imprinted data into a control computer, preferably at the time of engine assembly or sub-assembly; and d) using the characterization data in an algorithm to adjust at least one electrical parameter such as hold current, peak current, and boost time for each fuel injector in an assembled engine during each fuel injection cycle.Type: ApplicationFiled: December 5, 2008Publication date: June 10, 2010Inventors: Kevin R. Keegan, Ronald J. Krefta
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Publication number: 20040012354Abstract: An electrical machine having a hybrid rotor, i.e., both electrical and permanent magnet excitation, and system and method for controlling such hybrid machine are provided.Type: ApplicationFiled: April 22, 2003Publication date: January 22, 2004Inventors: Ronald J. Krefta, Tillasthanam V. Sriram
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Publication number: 20030193260Abstract: A composite powder metal stator sleeve for placing adjacent the tip-less teeth of a conventional stator core to form a stator assembly in an electric machine. The sleeve includes alternating tooth tip-shaped magnetically conducting segments of sintered ferromagnetic powder metal and magnetically non-conducting segments of sintered non-ferromagnetic powder metal. A stator assembly is also provided in which a stator core, for example, of stamped laminations, includes radially extending tip-less teeth, and the composite sleeve of the present invention surrounds and contacts the teeth of the stator core to form tips extending from the teeth and topsticks/slot wedges between the tips. There is further provided alternative methods of making an annular composite powder metal stator sleeve of the present invention, including a compaction-sintering method, an injection molding method, and a sinterbonding method.Type: ApplicationFiled: April 16, 2002Publication date: October 16, 2003Inventors: Frederick B. Reiter, Brian J. Maskew, Ronald J. Krefta
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Publication number: 20030057789Abstract: An alternating current (AC) generator includes a casing or housing defining an accommodation space therein. A stator assembly is rigidly mounted in the accommodation space in the casing and includes stator slots and a 5-phase winding distributed through and among the stator slots. A rotor assembly is rotatably disposed inside the stator assembly and includes a plurality of pairs of opposed pole members. Pairs of pole members are configured for energization in opposite magnetic polarity. A plurality of rectifiers rectify output voltages generated by the 5-phase windings.Type: ApplicationFiled: September 21, 2001Publication date: March 27, 2003Inventors: Duane Joseph Buening, Gregory R. Holbrook, Michael L. Hull, Ronald J. Krefta
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Multiphase electrical motor, control and method using overlapping conduction periods in the windings
Patent number: 5821722Abstract: A motor has a stationary assembly including three windings in magnetic coupling relation to a rotatable assembly, the position of which is sensed by a position sensor. A converter, adapted to be coupled to a power supply, energizes each of the windings with a voltage. The converter is responsive to the angular position and speed of the rotatable assembly for selectively energizing each of the windings according to a preselected sequence. The converter energizes each winding with the voltage throughout a commutation period when a back EMF induced in such winding has a polarity opposite to a polarity of the voltage energizing such winding, the commutation period for each winding overlapping the commutation period for another winding. Alternatively, the converter energizes each winding with the voltage throughout a commutation period of 180 electrical degrees, the commutation period for each winding overlapping the commutation period for another winding.Type: GrantFiled: June 6, 1995Date of Patent: October 13, 1998Assignee: General Electric CompanyInventors: Franklin L. Forbes, Ronald J. Krefta, Amritlal H. Patel -
Patent number: 4950960Abstract: An electronically commutated motor is disclosed including a stationary assembly having a plurality of winding stages adapted for commutation in at least one preselected sequence and a rotatable assembly having a plurality of permanent magnet elements in magnetic coupling relation with the stationary assembly. The permanent magnet elements are adapated to sequentially apply a magnetic field having a substantially constantly increasing magnetic flux to each respective winding stage during the period that current is supplied to the respective winding stage as the rotatable assembly rotates. The permanent magnet elements are also adapted to sequentially apply a magnetic field having a substantially constantly decreasing magnetic flux to each respective winding stage during a period that current is not supplied to the respective winding stage as the rotatable assembly rotates. A rotatable assembly, a method of operating the motor, and a method of rotating the rotatable assembly are also disclosed.Type: GrantFiled: March 27, 1989Date of Patent: August 21, 1990Assignee: General Electric CompanyInventors: Ronald J. Krefta, Franklin L. Forbes
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Patent number: 4933584Abstract: An electronically commutated motor has substantially constant air gap energy to reduce cogging. A rotatable assembly has permanent magnet elements which rotate about an axis of rotation. The elements are oriented with respect to said axis of rotation to provide a magnetic field with lines of flux along a plane forming a skew angle of s.sub.1 mechanical degrees with respect to the axis of rotation, wherein s.sub.1 is not equal to zero. The elements may be provided with an unmagnetized portion referred to as a phantom skew. A stationary assembly is in magnetic coupling relation with the permanent magnet elements of the rotatable assembly and has t spaced teeth with adjacent teeth defining a slot therebetween, wherein t is positive integer. Each tooth has a surface adjacent the rotatable assembly having one or more notches forming a skew angle of s.sub.2 mechanical degrees with the axis of rotation. Each tooth has winding stages adapted for commutation in at least one preselected sequence.Type: GrantFiled: December 22, 1988Date of Patent: June 12, 1990Assignee: General Electric CompanyInventors: Harold B. Harms, Ronald J. Krefta, John L. Oldenkamp