Patents by Inventor Mehrdad Ehsani

Mehrdad Ehsani 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: 8022586
    Abstract: According to one embodiment of the present invention, an electric machine comprises a stator and a rotor. The stator has at least one stator pole with a first leg and a second leg. The rotor has at least one rotor pole. The rotor rotates relate to the stator. The at least one rotor is configured to rotate between the first leg and the second leg of the at least one stator pole.
    Type: Grant
    Filed: February 15, 2010
    Date of Patent: September 20, 2011
    Assignees: The Texas A&M University System, StarRotor Corporation
    Inventors: Mark T. Holtzapple, George A. Rabroker, Babak Fahimi, Mehrdad Ehsani
  • Publication number: 20100213786
    Abstract: According to one embodiment of the present invention, an electric machine comprises a stator and a rotor. The stator has at least one stator pole with a first leg and a second leg. The rotor has at least one rotor pole. The rotor rotates relate to the stator. The at least one rotor is configured to rotate between the first leg and the second leg of the at least one stator pole.
    Type: Application
    Filed: February 15, 2010
    Publication date: August 26, 2010
    Applicants: The Texas A&M University System, StarRotor Corporation
    Inventors: Mark T. Holtzapple, George A. Rabroker, Babak Fahimi, Mehrdad Ehsani
  • Patent number: 7663283
    Abstract: According to one embodiment of the present invention, an electric machine comprises a stator and a rotor. The stator has at least one stator pole with a first leg and a second leg. The rotor has at least one rotor pole. The rotor rotates relate to the stator. The at least one rotor is configured to rotate between the first leg and the second leg of the at least one stator pole.
    Type: Grant
    Filed: April 18, 2006
    Date of Patent: February 16, 2010
    Assignees: The Texas A & M University System, StarRoter Corporation
    Inventors: Mark T. Holtzapple, George A. Rabroker, Babak Fahimi, Mehrdad Ehsani
  • Publication number: 20060279155
    Abstract: According to one embodiment of the present invention, an electric machine comprises a stator and a rotor. The stator has at least one stator pole with a first leg and a second leg. The rotor has at least one rotor pole. The rotor rotates relate to the stator. The at least one rotor is configured to rotate between the first leg and the second leg of the at least one stator pole.
    Type: Application
    Filed: April 18, 2006
    Publication date: December 14, 2006
    Inventors: Mark Holtzapple, George Rabroker, Babak Fahimi, Mehrdad Ehsani
  • Patent number: 7095205
    Abstract: A controller (72) for a switched reluctance machine (20) implements a model of at least one active phase representing dynamic magnetic machine characteristics. The controller (72) determines machine control signals based on rotational position obtained by numerically solving the model with measured machine operating parameters. The model may be implemented as the sum of orthogonal functions relating active phase voltage and current with constants derived from phase inductance to obtain the rotor angle.
    Type: Grant
    Filed: March 29, 2001
    Date of Patent: August 22, 2006
    Assignee: The Texas A&M University System
    Inventors: Mehrdad Ehsani, Suresh Gopalakrishnan
  • Patent number: 6922036
    Abstract: According to one embodiment of the invention, a method includes generating, by a computer, a phase current profile, generating a phase current according to the phase current profile, and applying the phase current to the switched reluctance motor drive. Generating the phase current profile includes initializing one or more first profile parameters which define at least a first portion of the phase current profile. Generating the phase current profile also includes determining whether a first performance criterion is satisfied based on operation of the switched reluctance motor drive using the first profile parameters. Generating the phase current profile also includes updating at least one the first profile parameters if the first performance criterion is not satisfied.
    Type: Grant
    Filed: November 30, 2001
    Date of Patent: July 26, 2005
    Assignee: The Texas A&M University System
    Inventors: Mehrdad Ehsani, Babak Fahimi
  • Publication number: 20040251860
    Abstract: Systems and methods for determining the position of the rotor of brushless DC motor drives over a wide speed range from near zero to high speed without additional hardware. This sensorless method and system provides continuous rotor position information with good accuracy and resolution even at very low speed operation, making them suitable for high performance applications. Motor current is detected from two of three motor phases and is compared with reference values. A speed-independent function is calculated to generate continuous rotor position information that covers almost all speed ranges from near zero to high speed. Suitable control of current and speed may then be provided to the motor.
    Type: Application
    Filed: January 9, 2004
    Publication date: December 16, 2004
    Inventors: Mehrdad Ehsani, Taehyung Kim
  • Publication number: 20040124806
    Abstract: A controller (72) for a switched reluctance machine (20) implements a model of at least one active phase representing dynamic magnetic machine characteristics. The controller (72) determines machine control signals based on rotational position obtained by numerically solving the model with measured machine operating parameters. The model may be implemented as the sum of orthogonal functions relating active phase voltage and current with constants derived from phase inductance to obtain the rotor angle.
    Type: Application
    Filed: April 15, 2003
    Publication date: July 1, 2004
    Inventors: Mehrdad Ehsani, Suresh Gopalakrishnan
  • Patent number: 6472842
    Abstract: A system and method for controlling a switched-reluctance motor, in which a control variable is selected for controlling a figure of merit of the motor. The motor is then operated at a first value of the control variable. The control variable is adjusted to a second value, and the motor is operated at the second value of the control variable. A first indicator indicative of the figure of merit of the motor operating at the first value of the control variable is compared to a second indicator indicative of the figure of merit of the motor operating at the second value of the control variable. Thereafter, a new value is selected as the first value of the control variable in response to the comparison of the first indicator first to the second indicator.
    Type: Grant
    Filed: August 28, 2000
    Date of Patent: October 29, 2002
    Assignee: The Texas A&M University System
    Inventor: Mehrdad Ehsani
  • Patent number: 5852358
    Abstract: A circuit for controlling power to a capacitive load includes a DC power source coupled in series with an inductor and the capacitive load. The inductor provides for resonant charging of the capacitive load from the DC source. A second inductor is used for resonantly discharging the capacitive load back to the power source. Solid state switches are included for selectively activating the charging and discharging of the capacitive load. An energy absorbing load is selectively coupled across the capacitive load to remove any residual voltage after a discharging process.
    Type: Grant
    Filed: December 11, 1996
    Date of Patent: December 22, 1998
    Assignee: The Texas A&M University System
    Inventor: Mehrdad Ehsani
  • Patent number: 5586613
    Abstract: A series hybrid electric-combustion system is provided which includes an engine (16) operable to generate mechanical energy and translate it to a drive shaft (21). A battery (24) is included that is operable to store electrical energy and to deliver electrical energy. Also provided is a electric machine (18) mechanically coupled to engine (16) and electrically coupled to battery (24). Electric machine (18) has two modes of operations. In the first mode it translates electrical energy from battery (24) into additional mechanical energy at drive shaft (21). In the second mode of operation, electric machine (18) delivers electrical energy to battery (24) for storage. Converter (22) is also included in the system to convert the electrical energy from electric machine (18) for storage and battery (24) and also for converting electrical energy from battery (24) for use by electric machine 18.
    Type: Grant
    Filed: September 26, 1994
    Date of Patent: December 24, 1996
    Assignee: The Texas A&M University System
    Inventor: Mehrdad Ehsani
  • Patent number: 5448149
    Abstract: A discrete position sensor elimination technique for a sinusoidally wound synchronous reluctance motor drive uses induced voltage, phase currents, and excitation frequency to estimate rotor position at all speeds, including zero speed.
    Type: Grant
    Filed: June 20, 1994
    Date of Patent: September 5, 1995
    Assignee: Texas A&M University
    Inventors: Mehrdad Ehsani, Mohammed S. Arefeen, Thomas A. Lipo
  • Patent number: 5410235
    Abstract: Apparatus and method for detecting rotor (12) position in a switched reluctance motor (18) having multiple stator phases (A-A', B-B', and C-C'). A multiplexer (48) intermittently connects a known resistor (54) to a non-conducting stator phase. Circuitry (62 and 68) detects the amplitude of the current passing through the resistor (54) and the phase difference between the varying voltage and the current passing through resistor (54). The resulting signal is proportional to the position of rotor (12).
    Type: Grant
    Filed: March 1, 1994
    Date of Patent: April 25, 1995
    Assignee: The Texas A&M University System
    Inventor: Mehrdad Ehsani
  • Patent number: 5291115
    Abstract: Apparatus and method for detecting rotor (12) position in a switched reluctance motor (18) having multiple stator phases (A--A', B--B', and C--C'). A multiplexer (48) intermittently connects a known resistor (54) to a non-conducting stator phase. Circuitry (62 and 68) detects the amplitude of the current passing through the resistor (54) and the phase difference between the varying voltage and the current passing through resistor (54). The resulting signal is proportional to the position of rotor (12).
    Type: Grant
    Filed: September 25, 1992
    Date of Patent: March 1, 1994
    Assignee: The Texas A&M University System
    Inventor: Mehrdad Ehsani
  • Patent number: 5287261
    Abstract: A zero current soft switching power converter (10) is provided in which a link capacitor (20) is coupled between a source switch S.sub.1 and a source switch S.sub.2. The reversal of voltage polarity across link capacitor (20) allows for zero current switching of switches S.sub.1 and S.sub.2.
    Type: Grant
    Filed: June 23, 1992
    Date of Patent: February 15, 1994
    Assignee: The Texas A&M University System
    Inventor: Mehrdad Ehsani
  • Patent number: 5208740
    Abstract: An inverse dual converter circuit (20) provides continuous voltage step-up or step-down control over a wide range and without the need of a transformer. The converter comprises an input DC voltage source (22) for generating an input DC voltage. An inverse dual converter bridge receives the input DC voltage and comprises a network of source voltage converters (26), an AC link circuit (28), and a network of load voltage converters (32). The source voltage converters (26) and load voltage converters (32) operate at the same frequency, but at a different phase. The AC link circuit (28) stores energy to be transferred from the source voltage converters (26) to the load voltage converters (32) and supplies reverse voltage bias for commutation. The inverse dual DC-DC (20) converter may include circuitry (180) for controlling the output DC voltage and for regulating output current continuity. Topological variations of the basic circuit include transformer coupled (140), multi-phase (80) and multi-pulse derivations.
    Type: Grant
    Filed: May 30, 1991
    Date of Patent: May 4, 1993
    Assignee: The Texas A & M University System
    Inventor: Mehrdad Ehsani
  • Patent number: 5072166
    Abstract: Rotor position information for a switched reluctance (SR) motor drive is obtained indirectly in response to the motor phase inductance. An oscillator generates a signal having a time period that is a function of the inductance. The signal is processed by other circuits to obtain proper instants of commutation. In the preferred motor drive, the energized phase windings are isolated from the oscillator, and periodic signals are obtained which have periods indicating the phase inductances of the unenergized phase windings. The periods are compared to threshold values to obtain position indicating signals, and commutating signals are derived from the position indicating signals.
    Type: Grant
    Filed: June 18, 1990
    Date of Patent: December 10, 1991
    Assignee: The Texas A&M University System
    Inventor: Mehrdad Ehsani