Patents by Inventor Lav Thyagarajan

Lav Thyagarajan 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: 20240136969
    Abstract: A motor control system includes a motor including a plurality of windings, a first sensor configured to sense a first operating parameter of the motor, a second sensor configured to sense a second operating parameter of the motor, and memory hardware configured to store a machine learning model and computer-executable instructions. The machine learning model is trained to generate a winding temperature estimation output based on motor operating parameter inputs. The motor control system includes processor hardware configured to execute the instructions and use the machine learning model to cause the motor control system to generate a winding temperature estimation output using the machine learning model based on the first operating parameter and the second operating parameter, the temperature estimation output indicative of a predicted temperature of the plurality of windings, and control the motor based on the winding temperature estimation output.
    Type: Application
    Filed: October 19, 2022
    Publication date: April 25, 2024
    Applicant: Deere & Company
    Inventors: Lav THYAGARAJAN, Yujiang WU, Zhouyan XU, Abram HAICH, Jared LERVIK
  • Patent number: 11689142
    Abstract: A control module comprises software instructions for execution by an electronic data processor. An inductance estimator is configured to estimate direct inductance and quadrature inductance associated with the electric machine based on a first set of equations that assume constant rotor resistance and constant magnetic flux. A torque estimator is configured to estimate an observed torque associated with a rotor of the electric machine based a commanded direct-axis voltage and a commanded quadrature-axis voltage, where the observed torque is proportional to the observed power consumption of the electric machine. A pulse-width-modulation (PWM) module is configured to provide pulse-width modulated signals to the electric machine based on the commanded direct-axis voltage and a commanded quadrature-axis voltage. A back-electromotive force adjustment is derived from an estimated, observed torque and a commanded torque.
    Type: Grant
    Filed: December 12, 2021
    Date of Patent: June 27, 2023
    Assignee: Deere & Company
    Inventors: Lauren M. White, Long Wu, Lav Thyagarajan, Danielle Li, Scott C. Johnson
  • Publication number: 20230179133
    Abstract: One or more example embodiments provide systems and methods for using impedance separation and impedance shaping.
    Type: Application
    Filed: September 7, 2022
    Publication date: June 8, 2023
    Applicants: Deere & Company, Wisconsin Alumni Research Foundation
    Inventors: Lav THYAGARAJAN, Giri VENKATARAMANAN
  • Publication number: 20220376642
    Abstract: A control module comprises software instructions for execution by an electronic data processor. An inductance estimator is configured to estimate direct inductance and quadrature inductance associated with the electric machine based on a first set of equations that assume constant rotor resistance and constant magnetic flux. A torque estimator is configured to estimate an observed torque associated with a rotor of the electric machine based a commanded direct-axis voltage and a commanded quadrature-axis voltage, where the observed torque is proportional to the observed power consumption of the electric machine. A pulse-width-modulation (PWM) module is configured to provide pulse-width modulated signals to the electric machine based on the commanded direct-axis voltage and a commanded quadrature-axis voltage. A back-electromotive force adjustment is derived from an estimated, observed torque and a commanded torque.
    Type: Application
    Filed: December 12, 2021
    Publication date: November 24, 2022
    Inventors: Lauren M. White, Long Wu, Lav Thyagarajan, Danielle Li, Scott C. Johnson
  • Patent number: 11233473
    Abstract: A sensor is configured to sense current, of one or more output phases of an inverter, associated with back electromotive force (back EMF) of the machine. A converter or electronic data processor is adapted to convert the sensed current into current vectors associated with a stationary reference frame. An estimator or current model is configured to estimate back-EMF vectors from the converted current vectors. A vector tracking observer or the electronic data processor is adapted to mix the back-EMF vectors and applying the mixed back-EMF vectors to a preliminary inertial model. A secondary observer or the data processor is operable to apply the output of the preliminary inertial model to a secondary inertial model in the second speed range to estimate position or motion data for the rotor.
    Type: Grant
    Filed: October 10, 2019
    Date of Patent: January 25, 2022
    Assignee: Deere & Company
    Inventor: Lav Thyagarajan
  • Publication number: 20210165011
    Abstract: At least one example embodiment discloses a system including a memory storing instructions and at least one controller configured to execute the instructions to cause the system to obtain a measured speed of an electric machine and a measured position of the electric machine based on output from a sensor, select an observer based on a speed value, obtain an estimated speed of the electric machine and an estimated position of the electric machine using the selected observer, determine a control output based on the measured speed and the measured position, the control output being the measured speed and the measured position or the estimated speed and the estimated position and control the electric machine using the control output.
    Type: Application
    Filed: June 16, 2020
    Publication date: June 3, 2021
    Applicant: Deere & Company
    Inventor: Lav THYAGARAJAN
  • Publication number: 20200280276
    Abstract: A sensor is configured to sense current, of one or more output phases of an inverter, associated with back electromotive force (back EMF) of the machine. A converter or electronic data processor is adapted to convert the sensed current into current vectors associated with a stationary reference frame. An estimator or current model is configured to estimate back-EMF vectors from the converted current vectors. A vector tracking observer or the electronic data processor is adapted to mix the back-EMF vectors and applying the mixed back-EMF vectors to a preliminary inertial model. A secondary observer or the data processor is operable to apply the output of the preliminary inertial model to a secondary inertial model in the second speed range to estimate position or motion data for the rotor.
    Type: Application
    Filed: October 10, 2019
    Publication date: September 3, 2020
    Inventor: Lav Thyagarajan
  • Patent number: 10632999
    Abstract: A method of operating a hybrid electric vehicle includes driving an engine to generate mechanical energy, converting the mechanical energy into a first AC voltage, estimating a total DC link current associated with a respective plurality of loads of the hybrid electric vehicle, converting, with a first inverter, the first AC voltage into a DC bus voltage by regulating the DC bus voltage based on the total DC link current, and inverting, with a respective plurality of inverters, the DC bus voltage into a respective plurality of other AC voltages to drive the respective plurality of loads on the hybrid electric vehicle.
    Type: Grant
    Filed: August 21, 2018
    Date of Patent: April 28, 2020
    Assignee: DEERE & COMPANY
    Inventors: Lav Thyagarajan, Jacob Decock
  • Publication number: 20200062260
    Abstract: A method of operating a hybrid electric vehicle includes driving an engine to generate mechanical energy, converting the mechanical energy into a first AC voltage, estimating a total DC link current associated with a respective plurality of loads of the hybrid electric vehicle, converting, with a first inverter, the first AC voltage into a DC bus voltage by regulating the DC bus voltage based on the total DC link current, and inverting, with a respective plurality of inverters, the DC bus voltage into a respective plurality of other AC voltages to drive the respective plurality of loads on the hybrid electric vehicle.
    Type: Application
    Filed: August 21, 2018
    Publication date: February 27, 2020
    Applicant: Deere & Company
    Inventors: Lav THYAGARAJAN, Jacob DECOCK
  • Patent number: 10224849
    Abstract: A voltage difference is determined between the observed voltage and a reference direct current bus voltage. A quadrature-axis (q-axis) voltage command is outputted based on a current difference derived from the voltage difference. A commanded direct-axis (d-axis) voltage is determined based on a measured d-axis current and a determined d-axis reference current derived from a mathematical relationship between d-axis residual voltage, the observed voltage and the commanded q-axis voltage, where residual voltage is proportional to a function of the observed voltage and the commanded q-axis voltage. An inverse Parks transformation module or a data processor provides one or more phase voltage command based on inverse Parks transform of the commanded voltages.
    Type: Grant
    Filed: January 13, 2017
    Date of Patent: March 5, 2019
    Assignee: DEERE & COMPANY
    Inventors: Sumit Dutta, Lav Thyagarajan, Long Wu, Kent D. Wanner
  • Patent number: 10044310
    Abstract: In one example embodiment, a method includes determining a first adjustment value for a slip frequency of a rotor in an induction motor, determining a second adjustment value for an inductance of the induction motor and tuning the slip frequency of the rotor and the inductance of the induction motor based on the first adjustment value and the second adjustment value, respectively.
    Type: Grant
    Filed: March 16, 2015
    Date of Patent: August 7, 2018
    Assignee: Deere & Company
    Inventors: Lav Thyagarajan, Long Wu, Tianjun Fu
  • Patent number: 10014807
    Abstract: A capacitor is connected between the direct current voltage terminals. Switched terminals of a first switch and a second switch are coupled in series, between the direct current voltage terminals. An electric machine or generator has one or more windings and a first phase output terminal associated with the switched terminals. A first set of blocking diodes are cascaded in series and second set of blocking diodes are cascaded in series. A first voltage supply provides a first output voltage level and a second output level switchable to the first control terminal, where the first output level is distinct from the second output level. A second voltage supply provides the first output voltage level and the second output level switchable to the second control terminal.
    Type: Grant
    Filed: January 13, 2017
    Date of Patent: July 3, 2018
    Assignee: DEERE & COMPANY
    Inventors: Sumit Dutta, Lav Thyagarajan, Long Wu, Kent D. Wanner
  • Publication number: 20170353135
    Abstract: A voltage difference is determined between the observed voltage and a reference direct current bus voltage. A quadrature-axis (q-axis) voltage command is outputted based on a current difference derived from the voltage difference. A commanded direct-axis (d-axis) voltage is determined based on a measured d-axis current and a determined d-axis reference current derived from a mathematical relationship between d-axis residual voltage, the observed voltage and the commanded q-axis voltage, where residual voltage is proportional to a function of the observed voltage and the commanded q-axis voltage. An inverse Parks transformation module or a data processor provides one or more phase voltage command based on inverse Parks transform of the commanded voltages.
    Type: Application
    Filed: January 13, 2017
    Publication date: December 7, 2017
    Inventors: Sumit Dutta, Lav Thyagarajan, Long Wu, Kent D. Wanner
  • Publication number: 20170353134
    Abstract: A capacitor is connected between the direct current voltage terminals. Switched terminals of a first switch and a second switch are coupled in series, between the direct current voltage terminals. An electric machine or generator has one or more windings and a first phase output terminal associated with the switched terminals. A first set of blocking diodes are cascaded in series and second set of blocking diodes are cascaded in series. A first voltage supply provides a first output voltage level and a second output level switchable to the first control terminal, where the first output level is distinct from the second output level. A second voltage supply provides the first output voltage level and the second output level switchable to the second control terminal.
    Type: Application
    Filed: January 13, 2017
    Publication date: December 7, 2017
    Inventors: Sumit Dutta, Lav Thyagarajan, Long Wu, Kent D. Wanner
  • Publication number: 20160276971
    Abstract: In one example embodiment, a method includes determining a first adjustment value for a slip frequency of a rotor in an induction motor, determining a second adjustment value for an inductance of the induction motor and tuning the slip frequency of the rotor and the inductance of the induction motor based on the first adjustment value and the second adjustment value, respectively.
    Type: Application
    Filed: March 16, 2015
    Publication date: September 22, 2016
    Inventors: Lav THYAGARAJAN, Long WU, Tianjun FU
  • Patent number: 9270223
    Abstract: At least one example embodiment discloses a control device for controlling an alternating current (ac) machine. The control device includes a processor configured to select a modulation mode from a plurality of modulation modes, determine a plurality of present phase voltages corresponding to phases of an inverter based on the selected modulation mode, the determination compensating for deadtimes associated with the selected modulation mode and phases of the inverter, the inverter configured to drive the ac machine and determine an estimated terminal voltage based on the plurality of present phase voltages.
    Type: Grant
    Filed: December 27, 2013
    Date of Patent: February 23, 2016
    Assignee: DEERE & COMPANY
    Inventors: Long Wu, Anthony Weber, Lav Thyagarajan
  • Publication number: 20140306638
    Abstract: At least one example embodiment discloses a control device for controlling an alternating current (ac) machine. The control device includes a processor configured to select a modulation mode from a plurality of modulation modes, determine a plurality of present phase voltages corresponding to phases of an inverter based on the selected modulation mode, the determination compensating for deadtimes associated with the selected modulation mode and phases of the inverter, the inverter configured to drive the ac machine and determine an estimated terminal voltage based on the plurality of present phase voltages.
    Type: Application
    Filed: December 27, 2013
    Publication date: October 16, 2014
    Applicant: DEERE & COMPANY
    Inventors: Long WU, Anthony WEBER, Lav THYAGARAJAN
  • Patent number: 8810169
    Abstract: Position samples are stored from an encoder coupled to a permanent magnet electric machine. A data processor determines first changes in position between successive position samples and second changes between successive first changes in position. A data processor determines whether each first change in position is generally increasing, decreasing or constant. A corrective motion factor is applied to each stored position sample based on whether the first change in position is generally increasing or decreasing. The data processor estimates a final rotor angle of the electric machine based on a particular one of the position samples and a corresponding first change in position associated with the particular one of the position samples corresponding to a respective time.
    Type: Grant
    Filed: October 14, 2011
    Date of Patent: August 19, 2014
    Assignee: Deere & Company
    Inventor: Lav Thyagarajan
  • Publication number: 20130093372
    Abstract: Position samples are stored from an encoder coupled to a permanent magnet electric machine. A data processor determines first changes in position between successive position samples and second changes between successive first changes in position. A data processor determines whether each first change in position is generally increasing, decreasing or constant. A corrective motion factor is applied to each stored position sample based on whether the first change in position is generally increasing or decreasing. The data processor estimates a final rotor angle of the electric machine based on a particular one of the position samples and a corresponding first change in position associated with the particular one of the position samples corresponding to a respective time.
    Type: Application
    Filed: October 14, 2011
    Publication date: April 18, 2013
    Inventor: Lav Thyagarajan