Patents by Inventor Rangarajan Tallam

Rangarajan Tallam 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: 20130119901
    Abstract: A distributed motor drive system includes a power management module and multiple inverter modules integrated with the motors and located on a machine or process remote from the power management module. The power management module distributes DC voltage and command signals to each of the inverters. The DC voltage is distributed between modules via a DC link cable. The integrated inverters execute switching routines to convert the DC voltage to an AC voltage suitable for controlling the motor. Each of the power management module and the inverters includes a portion of the DC bus capacitance. The distributed motor drive system also includes a link inductance between the power management module and the inverters to limit the amount of reactive current generated by the inverters.
    Type: Application
    Filed: November 14, 2011
    Publication date: May 16, 2013
    Inventors: Mark A. Gries, Mark R. Cooper, Rangarajan Tallam, Garrett B. Rodrigues
  • Patent number: 8319466
    Abstract: The present invention relates generally to systems and methods for detecting ground faults (i.e., line-to-ground faults) in electrical power conversion systems. In particular, the embodiments described herein include a common mode voltage booster module configured to calculate a common mode voltage boost factor and a common mode voltage boost function based on a plurality of voltage commands for the system. The common mode voltage boost factor and/or the common mode voltage boost function may be applied to the voltage commands to generate boosted voltage commands which, when applied to an inverter or converter, source current indicative of ground faults in the system. More specifically, the common mode voltage boost factor may be multiplied by a common mode voltage calculated by a common mode voltage calculator and summed with the voltage commands.
    Type: Grant
    Filed: February 21, 2011
    Date of Patent: November 27, 2012
    Assignee: Rockwell Automation Technologies, Inc.
    Inventors: Carlos Rodriguez Valdez, Russel J. Kerkman, Rangarajan Tallam
  • Publication number: 20120212172
    Abstract: The present invention relates generally to systems and methods for detecting ground faults (i.e., line-to-ground faults) in electrical power conversion systems. In particular, the embodiments described herein include a common mode voltage booster module configured to calculate a common mode voltage boost factor and a common mode voltage boost function based on a plurality of voltage commands for the system. The common mode voltage boost factor and/or the common mode voltage boost function may be applied to the voltage commands to generate boosted voltage commands which, when applied to an inverter or converter, source current indicative of ground faults in the system. More specifically, the common mode voltage boost factor may be multiplied by a common mode voltage calculated by a common mode voltage calculator and summed with the voltage commands.
    Type: Application
    Filed: February 21, 2011
    Publication date: August 23, 2012
    Applicant: ROCKWELL AUTOMATION TECHNOLOGIES, INC.
    Inventors: Carlos Rodriguez Valdez, Russel J. Kerkman, Rangarajan Tallam
  • Publication number: 20120187883
    Abstract: The present invention relates generally to systems and methods for detecting ground faults (i.e., line-to-ground faults) in motor drive systems. In particular, the embodiments described herein include a common mode choke of a motor drive system having additional (i.e., secondary) turns wound around a core of the common mode choke. These secondary turns are in addition to and separate from a plurality of sets of primary turns wound around the core of the common mode choke, each set of primary turns corresponding to a phase of AC power to which the common mode choke is directly coupled. The secondary turns terminate in series with a burden resistor. Ground faults may be detected by monitoring the voltage across the burden resistor.
    Type: Application
    Filed: January 26, 2011
    Publication date: July 26, 2012
    Applicant: Rockwell Automation Technologies, Inc.
    Inventors: Carlos Rodriguez Valdez, Rangarajan Tallam, Russel Kerkman
  • Patent number: 8107267
    Abstract: Control systems, methods and fully regenerative power conversion systems are presented for mitigating common mode voltages in AC loads by employing inverter and/or active rectifier PWM control using switching sequences with only active vectors where a first vector of each switching sequence differs by one phase switching state from a last vector of a switching sequence of an adjacent sector.
    Type: Grant
    Filed: April 24, 2009
    Date of Patent: January 31, 2012
    Assignee: Rockwell Automation Technologies, Inc.
    Inventors: Rangarajan Tallam, Russel Kerkman, David Leggate
  • Publication number: 20100172161
    Abstract: Control systems, methods and power conversion systems are presented for controlling common mode voltages in AC motor loads driven by inverter PWM control using switching sequences with only active vectors where a first vector of each switching sequence differs by one phase switching state from a last vector of a switching sequence of an adjacent sector, along with enhanced deadtime compensation and reflected wave reduction techniques in providing pulse width modulated switching signals to a switching inverter.
    Type: Application
    Filed: February 27, 2009
    Publication date: July 8, 2010
    Applicant: Rockwell Automation Technologies, Inc.
    Inventors: Rangarajan Tallam, Russel Kerkman, David Leggate
  • Publication number: 20100172162
    Abstract: Control systems, methods and fully regenerative power conversion systems are presented for mitigating common mode voltages in AC loads by employing inverter and/or active rectifier PWM control using switching sequences with only active vectors where a first vector of each switching sequence differs by one phase switching state from a last vector of a switching sequence of an adjacent sector.
    Type: Application
    Filed: April 24, 2009
    Publication date: July 8, 2010
    Applicant: Rockwell Automation Technologies, Inc.
    Inventors: Rangarajan Tallam, Russel Kerkman, David Leggate
  • Patent number: 7738267
    Abstract: Control systems, methods and power conversion systems are presented for controlling common mode voltages in AC motor loads driven by inverter PWM control using switching sequences with only active vectors where a first vector of each switching sequence differs by one phase switching state from a last vector of a switching sequence of an adjacent sector, along with enhanced deadtime compensation and reflected wave reduction techniques in providing pulse width modulated switching signals to a switching inverter.
    Type: Grant
    Filed: February 27, 2009
    Date of Patent: June 15, 2010
    Assignee: Rockwell Automation Technologies, Inc.
    Inventors: Rangarajan Tallam, Russel Kerkman, David Leggate
  • Patent number: 7564703
    Abstract: An apparatus and method for converting DC voltage across positive and negative DC buses to three phase AC voltages on first, second and third AC output lines, the method comprising the steps of providing first and second three phase inverters that include a first subset of inverter switches and a second subset of inverter switches, respectively, linking a first choke in series with the first three phase inverter between the positive and negative DC buses and the AC output lines, linking a second choke in series with the second three phase inverter between the positive and negative DC buses and the AC output lines and synchronously controlling the first and second inverter switch subsets so that switching of first and second inverter switch subsets is substantially synchronized among the three phases.
    Type: Grant
    Filed: April 17, 2007
    Date of Patent: July 21, 2009
    Assignee: Rockwell Automation Technologies, Inc.
    Inventors: Dennis Braun, Rangarajan Tallam, Ajith Wijenayake, Robert J. Johnson
  • Publication number: 20070070660
    Abstract: A rectifier includes a switching circuit and a controller. The switching circuit is coupled between positive and negative buses and a plurality of input voltage sources. The switching circuit includes a plurality of pairs of switching devices. Each pair is associated with one of the input voltage sources. The controller includes first and second control loops operable to generate control signals for operating the pairs of switching devices to generate a potential across the positive and negative buses. The controller is further operable to estimate a line inductance seen by the rectifier based on at least one of the control signals and generate an inductance compensation gain factor for applying to the control loops based on the estimated line inductance.
    Type: Application
    Filed: September 28, 2005
    Publication date: March 29, 2007
    Inventor: Rangarajan Tallam
  • Publication number: 20060067092
    Abstract: The invention includes a method and apparatus for reducing common mode voltage applied to a load by a drive, the drive including a rectifier linked between three AC supply lines and positive and negative DC buses that converts AC supply voltage to DC voltage across the DC buses and an inverter linked between the DC buses and a load, the rectifier providing a DC input voltage to the inverter wherein, during normal operation, the inverter is capable of generating maximum inverter output voltages given a specific DC bus voltage, the method comprising the steps of controlling the inverter to supply output voltages to the load where the output voltages are substantially free of common mode voltage and such that the maximum inverter output voltage is X % less than the maximum inverter output voltage during normal inverter operation and given a specific DC bus voltage and controlling the rectifier to convert the supply voltage to DC voltage across the DC buses and so that the DC bus voltage is boosted to a level mor
    Type: Application
    Filed: September 28, 2004
    Publication date: March 30, 2006
    Inventors: Thomas Nondahl, Rajendra Naik, Rangarajan Tallam