Patents by Inventor Dwarakanath V. Simili

Dwarakanath V. Simili 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: 10396696
    Abstract: A current regulator is provided for an electric machine drive system for driving an electric machine. The current regulator includes an adjustable damping module that has a value of virtual damping resistance that is applied at the current regulator. The value of virtual damping resistance is adjustable as a function of sampling frequency. A controller can control the current regulator by determining whether the sampling frequency has changed since a previous execution cycle of the current regulator, and when the sampling frequency has changed since the previous execution cycle, the controller can modify the damping value as a function of the sampling frequency to allow the damping value to change with the sampling frequency. The damping value has a new value of virtual damping resistance that is applied at the current regulator after modifying the damping value. The controller can then execute the current regulator in accordance with the modified damping value to generate the voltage commands.
    Type: Grant
    Filed: February 21, 2018
    Date of Patent: August 27, 2019
    Assignee: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Brent S. Gagas, Dwarakanath V. Simili, Caleb W. Secrest
  • Publication number: 20190260319
    Abstract: A current regulator is provided for an electric machine drive system for driving an electric machine. The current regulator includes an adjustable damping module that has a value of virtual damping resistance that is applied at the current regulator. The value of virtual damping resistance is adjustable as a function of sampling frequency. A controller can control the current regulator by determining whether the sampling frequency has changed since a previous execution cycle of the current regulator, and when the sampling frequency has changed since the previous execution cycle, the controller can modify the damping value as a function of the sampling frequency to allow the damping value to change with the sampling frequency. The damping value has a new value of virtual damping resistance that is applied at the current regulator after modifying the damping value. The controller can then execute the current regulator in accordance with the modified damping value to generate the voltage commands.
    Type: Application
    Filed: February 21, 2018
    Publication date: August 22, 2019
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Brent S. Gagas, Dwarakanath V. Simili, Caleb W. Secrest
  • Patent number: 10355631
    Abstract: A current regulator is provided for an electric machine drive system for driving an electric machine. The current regulator is configurable to operate in a first configuration or a second configuration depending on a synchronous speed of the electric machine. A controller can configure an operational mode of the current regulator by selecting, based on the synchronous speed of the electric machine, either the first configuration of the current regulator or the second configuration of the current regulator as a currently active configuration, and can then execute the current regulator in accordance with the currently active configuration. The first configuration of the current regulator comprises a first set of elements and cross-coupling gain blocks, whereas the second configuration of the current regulator can include the first set of elements without the cross-coupling gain blocks.
    Type: Grant
    Filed: February 21, 2018
    Date of Patent: July 16, 2019
    Assignee: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Caleb W. Secrest, Brent S. Gagas, Dwarakanath V. Simili
  • Patent number: 10295599
    Abstract: A method in a motor controller for an electric motor is disclosed. The method includes receiving a motor current measurement, a motor reference voltage or measured voltage, and an estimated temperature from the electric motor, determining a reference flux linkage estimate (?pm,ref) from a lookup table based on the motor current measurement and the estimated temperature, determining a back-EMF (electromotive force) estimate based on the motor current measurement, the motor voltage and the estimated temperature, determining an observed flux linkage estimate (?pm,obs) from the back-EMF estimate, determining a magnetic strength as a ratio of the observed flux linkage estimate to the reference flux linkage estimate, and determining that a rotor magnet has been demagnetized to an unacceptable level when the magnetic strength is below a threshold level.
    Type: Grant
    Filed: August 11, 2017
    Date of Patent: May 21, 2019
    Assignee: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Gilsu Choi, Anno Yoo, Dwarakanath V. Simili
  • Publication number: 20190049517
    Abstract: A method in a motor controller for an electric motor is disclosed. The method includes receiving a motor current measurement, a motor reference voltage or measured voltage, and an estimated temperature from the electric motor, determining a reference flux linkage estimate (?pm,ref) from a lookup table based on the motor current measurement and the estimated temperature, determining a back-EMF (electromotive force) estimate based on the motor current measurement, the motor voltage and the estimated temperature, determining an observed flux linkage estimate (?pm,obs) from the back-EMF estimate, determining a magnetic strength as a ratio of the observed flux linkage estimate to the reference flux linkage estimate, and determining that a rotor magnet has been demagnetized to an unacceptable level when the magnetic strength is below a threshold level.
    Type: Application
    Filed: August 11, 2017
    Publication date: February 14, 2019
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Gilsu Choi, Anno Yoo, Dwarakanath V. Simili
  • Patent number: 9973120
    Abstract: An electric machine assembly includes an electric machine having a stator configured to have a stator current and a controller configured to receive a torque command (T). The controller stores a modulation flag (Fm) and a six step active flag (FS), each having a respective status. The controller has a processor and tangible, non-transitory memory on which is recorded instructions for executing a method of controlling a six step pulse width modulation operation in the assembly. The controller is programmed to determine the respective status of a six step active flag (FS) based at least partially on the torque command (T) and the respective status of the modulation flag (Fm). The controller is configured to control at least one operating parameter of the electric machine based at least partially on the respective status of the six step active flag (FS).
    Type: Grant
    Filed: April 20, 2017
    Date of Patent: May 15, 2018
    Assignee: GM Global Technology Operations LLC
    Inventors: Dwarakanath V. Simili, Anno Yoo, Yo Chan Son
  • Patent number: 9774287
    Abstract: An electric machine assembly includes an electric machine having a stator configured to have a stator current and a controller configured to receive a torque command (T). The controller has a processor and tangible, non-transitory memory on which is recorded instructions for executing a method of modifying the stator current for enhanced flux weakening. The controller is programmed to obtain a base stator current [IdLU, IqLU] from a look-up table based at least partially on the torque command (T). The controller is programmed to obtain a characteristic angle (?i, i=1, 2, 3) based at least partially on a value of the torque command (T) and the base stator current [IdLU, IqLU]. A stator current modifier [?Id, ?Iq] is obtained based at least partially on the characteristic angle (?i, i=1, 2, 3) and a flux weakening factor (?IS) such that: ?Id=(?IS*cosine (?i)) and ?Iq=(?IS*sine (?i)).
    Type: Grant
    Filed: July 14, 2016
    Date of Patent: September 26, 2017
    Assignee: GM Global Technology Operations LLC
    Inventors: Dwarakanath V. Simili, Bon Ho Bae, Aayush Gupta
  • Patent number: 9755567
    Abstract: An electric machine assembly has an electric machine having a stator and a rotor. The rotor has a rotor temperature and is configured to rotate at a rotor speed (?). The stator has stator windings at a stator winding temperature (tS) and the electric machine defines a number of pole pairs (P). A controller is operatively connected to the electric machine and is configured to receive a torque command (T*). The controller has a processor and tangible, non-transitory memory on which is recorded instructions for executing a method for determining a total permanent magnetic flux (?T) as a function of the rotor temperature. Execution of the instructions by the processor causes the controller to determine a high-speed magnetic flux factor (?H) and a low-speed magnetic flux factor (?L).
    Type: Grant
    Filed: November 4, 2015
    Date of Patent: September 5, 2017
    Assignee: GM Global Technology Operations LLC
    Inventors: Dwarakanath V Simili, Jihoon Jang
  • Patent number: 9647602
    Abstract: An electric machine assembly includes an electric machine having a stator and a rotor. The stator has stator windings at a stator winding temperature (tS) and the rotor is configured to rotate at a rotor speed (?). A controller is operatively connected to the electric machine and has a processor and tangible, non-transitory memory on which is recorded instructions for executing a method for determining stator winding resistance. The controller is configured to determine a high-speed resistance factor (rH) which is based at least partially on the torque command (T*), the stator winding temperature (tS), the rotor speed (?), a characterized torque error and the number of pole pairs (P). The controller may determine a total resistance value (R) based on a weighting factor (k), the high-speed resistance factor (rH) and the low-speed resistance factor (rL).
    Type: Grant
    Filed: November 4, 2015
    Date of Patent: May 9, 2017
    Assignee: GM Global Technology Operations LLC
    Inventors: Dwarakanath V Simili, Jihoon Jang, Sinisa Jurkovic
  • Publication number: 20170126166
    Abstract: An electric machine assembly includes an electric machine having a stator and a rotor. The stator has stator windings at a stator winding temperature (tS) and the rotor is configured to rotate at a rotor speed (?). A controller is operatively connected to the electric machine and has a processor and tangible, non-transitory memory on which is recorded instructions for executing a method for determining stator winding resistance. The controller is configured to determine a high-speed resistance factor (rH) which is based at least partially on the torque command (T*), the stator winding temperature (tS), the rotor speed (?), a characterized torque error and the number of pole pairs (P). The controller may determine a total resistance value (R) based on a weighting factor (k), the high-speed resistance factor (rH) and the low-speed resistance factor (rL).
    Type: Application
    Filed: November 4, 2015
    Publication date: May 4, 2017
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Dwarakanath V. Simili, Jihoon Jang, Sinisa Jurkovic
  • Publication number: 20170126167
    Abstract: An electric machine assembly has an electric machine having a stator and a rotor. The rotor has a rotor temperature and is configured to rotate at a rotor speed (?). The stator has stator windings at a stator winding temperature (tS) and the electric machine defines a number of pole pairs (P). A controller is operatively connected to the electric machine and is configured to receive a torque command (T*). The controller has a processor and tangible, non-transitory memory on which is recorded instructions for executing a method for determining a total permanent magnetic flux (?T) as a function of the rotor temperature. Execution of the instructions by the processor causes the controller to determine a high-speed magnetic flux factor (?H) and a low-speed magnetic flux factor (?L).
    Type: Application
    Filed: November 4, 2015
    Publication date: May 4, 2017
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Dwarakanath V. Simili, Jihoon Jang
  • Publication number: 20170077854
    Abstract: A multi-phase electric machine electrically connected to an inverter is described. A method for controlling the electric machine includes determining an initial current command responsive to a torque command for the electric machine and determining an expected torque ripple associated with operation of the electric machine. A mitigation current command is determined based upon the torque command and the expected torque ripple, and the electric machine is dynamically controlled responsive to the initial current command and the mitigation current command.
    Type: Application
    Filed: September 15, 2015
    Publication date: March 16, 2017
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventors: Yo Chan Son, Brian A. Welchko, Dwarakanath V. Simili, Mohammad Faizul Momen, Aayush Gupta, Chia-Chou Yeh
  • Patent number: 8981692
    Abstract: An electric motor system includes a motor configured to produce a torque signal in response to a torque command. The torque signal has a fundamental frequency component, a first ripple harmonic and a second ripple harmonic. The first ripple harmonic is an integer multiple of the fundamental frequency component. The second ripple harmonic is an integer multiple of the first ripple harmonic. A system and method is provided to generate a ripple reduction signal in response to the torque command that simultaneously cancels the first and the second ripple harmonic in the torque signal. The second ripple harmonic may be canceled with the first ripple harmonic by being projected onto the first ripple harmonic through a transformation matrix.
    Type: Grant
    Filed: July 19, 2012
    Date of Patent: March 17, 2015
    Assignee: GM Global Technology Operations LLC
    Inventor: Dwarakanath V. Simili
  • Publication number: 20140021894
    Abstract: An electric motor system includes a motor configured to produce a torque signal in response to a torque command. The torque signal has a fundamental frequency component, a first ripple harmonic and a second ripple harmonic. The first ripple harmonic is an integer multiple of the fundamental frequency component. The second ripple harmonic is an integer multiple of the first ripple harmonic. A system and method is provided to generate a ripple reduction signal in response to the torque command that simultaneously cancels the first and the second ripple harmonic in the torque signal. The second ripple harmonic may be canceled with the first ripple harmonic by being projected onto the first ripple harmonic through a transformation matrix.
    Type: Application
    Filed: July 19, 2012
    Publication date: January 23, 2014
    Applicant: GM GLOBAL TECHNOLOGY OPERATIONS LLC
    Inventor: Dwarakanath V. Simili