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).
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Patent number: 8022586Abstract: 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: GrantFiled: February 15, 2010Date of Patent: September 20, 2011Assignees: The Texas A&M University System, StarRotor CorporationInventors: Mark T. Holtzapple, George A. Rabroker, Babak Fahimi, Mehrdad Ehsani
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Publication number: 20100213786Abstract: 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: ApplicationFiled: February 15, 2010Publication date: August 26, 2010Applicants: The Texas A&M University System, StarRotor CorporationInventors: Mark T. Holtzapple, George A. Rabroker, Babak Fahimi, Mehrdad Ehsani
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Patent number: 7663283Abstract: 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: GrantFiled: April 18, 2006Date of Patent: February 16, 2010Assignees: The Texas A & M University System, StarRoter CorporationInventors: Mark T. Holtzapple, George A. Rabroker, Babak Fahimi, Mehrdad Ehsani
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Publication number: 20060279155Abstract: 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: ApplicationFiled: April 18, 2006Publication date: December 14, 2006Inventors: Mark Holtzapple, George Rabroker, Babak Fahimi, Mehrdad Ehsani
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Patent number: 7095205Abstract: 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: GrantFiled: March 29, 2001Date of Patent: August 22, 2006Assignee: The Texas A&M University SystemInventors: Mehrdad Ehsani, Suresh Gopalakrishnan
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Patent number: 6922036Abstract: 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: GrantFiled: November 30, 2001Date of Patent: July 26, 2005Assignee: The Texas A&M University SystemInventors: Mehrdad Ehsani, Babak Fahimi
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Publication number: 20040251860Abstract: 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: ApplicationFiled: January 9, 2004Publication date: December 16, 2004Inventors: Mehrdad Ehsani, Taehyung Kim
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Publication number: 20040124806Abstract: 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: ApplicationFiled: April 15, 2003Publication date: July 1, 2004Inventors: Mehrdad Ehsani, Suresh Gopalakrishnan
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Patent number: 6472842Abstract: 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: GrantFiled: August 28, 2000Date of Patent: October 29, 2002Assignee: The Texas A&M University SystemInventor: Mehrdad Ehsani
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Patent number: 5852358Abstract: 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: GrantFiled: December 11, 1996Date of Patent: December 22, 1998Assignee: The Texas A&M University SystemInventor: Mehrdad Ehsani
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Patent number: 5586613Abstract: 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: GrantFiled: September 26, 1994Date of Patent: December 24, 1996Assignee: The Texas A&M University SystemInventor: Mehrdad Ehsani
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Patent number: 5448149Abstract: 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: GrantFiled: June 20, 1994Date of Patent: September 5, 1995Assignee: Texas A&M UniversityInventors: Mehrdad Ehsani, Mohammed S. Arefeen, Thomas A. Lipo
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Patent number: 5410235Abstract: 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: GrantFiled: March 1, 1994Date of Patent: April 25, 1995Assignee: The Texas A&M University SystemInventor: Mehrdad Ehsani
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Patent number: 5291115Abstract: 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: GrantFiled: September 25, 1992Date of Patent: March 1, 1994Assignee: The Texas A&M University SystemInventor: Mehrdad Ehsani
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Patent number: 5287261Abstract: 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: GrantFiled: June 23, 1992Date of Patent: February 15, 1994Assignee: The Texas A&M University SystemInventor: Mehrdad Ehsani
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Patent number: 5208740Abstract: 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: GrantFiled: May 30, 1991Date of Patent: May 4, 1993Assignee: The Texas A & M University SystemInventor: Mehrdad Ehsani
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Patent number: 5072166Abstract: 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: GrantFiled: June 18, 1990Date of Patent: December 10, 1991Assignee: The Texas A&M University SystemInventor: Mehrdad Ehsani