Patents by Inventor James Sigamani
James Sigamani 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: 8842451Abstract: A power conversion system for use with a photovoltaic (PV) power source may include a DC/DC converter for converting a first DC voltage into a second DC voltage, an isolation transformer, an inverter for converting DC power to AC power, and at least one controller for controlling the DC/DC converter and the inverter. The controller may be configured to operate the DC/DC converter as a buck converter or a boost converter based, at least in part, on whether the first DC voltage is less or greater than a reference voltage. Additionally, the controller may operate the converter according to a maximum power point tracking algorithm. Further, the controller may be configured to operate the inverter to control the DC voltage at the inverter's input as a function of the AC voltage at the inverter's output. Example embodiments of power systems, DC/DC converters, DC/AC inverters and related methods are also disclosed.Type: GrantFiled: March 4, 2011Date of Patent: September 23, 2014Assignee: Astec International LimitedInventors: Vijay G. Phadke, James Sigamani
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Publication number: 20140268891Abstract: A multiphase DC/DC power converter includes an input, an output, at least a first converter and a second converter coupled in parallel between the input and the output, an inductor coupled to the first and second converters, an output capacitor coupled between the first and second converters and the output, and a control circuit coupled to the first converter and the second converter. The first and second converters each include a power switch. The control circuit is configured to switch the power switches at a frequency with a phase shift therebetween, and to vary the frequency to regulate a voltage at the output. Additionally, the control circuit may be configured to switch power switches at a fixed frequency with substantially no phase shift therebetween during startup of a multiphase DC/DC power converter, and at a variable frequency with a defined phase shift therebetween after startup.Type: ApplicationFiled: March 13, 2013Publication date: September 18, 2014Inventors: James Sigamani, Vijay Gangadhar Phadke
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Publication number: 20140126257Abstract: A control circuit for controlling one or more power switches of a power converter includes a voltage control loop and a current control loop. The control circuit is configured to generate a current reference for the current control loop using the voltage control loop and an AC reference signal. The control circuit is configured to operate in at least a first mode in which a parameter of the voltage control loop is sampled only at every other zero crossing of the AC reference signal and the sampled parameter is used to generate the current reference for the current control loop. The power converter may be an AC-DC converter or a DC-AC converter (i.e., inverter). Alternatively, the voltage control loop may be sampled at every zero crossing of the AC reference signal, and/or more frequently during transient load conditions.Type: ApplicationFiled: January 14, 2014Publication date: May 8, 2014Applicant: Astec International LimitedInventors: James Sigamani, Yancy Fontanilla Boncato
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Publication number: 20130322122Abstract: A control circuit for controlling one or more power switches of a power converter includes a voltage control loop and a current control loop. The control circuit is configured to generate a current reference for the current control loop using the voltage control loop and an AC reference signal. The control circuit is configured to operate in at least a first mode in which a parameter of the voltage control loop is sampled only at every other zero crossing of the AC reference signal and the sampled parameter is used to generate the current reference for the current control loop. The power converter may be an AC-DC converter or a DC-AC converter (i.e., inverter). Alternatively, the voltage control loop may be sampled at every zero crossing of the AC reference signal, and/or more frequently during transient load conditions.Type: ApplicationFiled: May 30, 2012Publication date: December 5, 2013Inventors: James Sigamani, Yancy Fontanilla Boncato
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Patent number: 8488350Abstract: A method of operating a DC-AC inverter to produce AC power having alternating positive and negative half cycles is disclosed. The inverter includes an input connected to a DC power source, an output, a first buck converter coupled between the input and the output and a second buck converter coupled between the input and output. The method includes alternately operating the first buck converter and the second buck converter to alternately produce the positive and negative half cycles at the output.Type: GrantFiled: September 25, 2009Date of Patent: July 16, 2013Assignee: Astec International LimitedInventor: James Sigamani
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Publication number: 20120127764Abstract: A power conversion system for use with a photovoltaic (PV) power source may include a DC/DC converter for converting a first DC voltage into a second DC voltage, an isolation transformer, an inverter for converting DC power to AC power, and at least one controller for controlling the DC/DC converter and the inverter. The controller may be configured to operate the DC/DC converter as a buck converter or a boost converter based, at least in part, on whether the first DC voltage is less or greater than a reference voltage. Additionally, the controller may operate the converter according to a maximum power point tracking algorithm. Further, the controller may be configured to operate the inverter to control the DC voltage at the inverter's input as a function of the AC voltage at the inverter's output. Example embodiments of power systems, DC/DC converters, DC/AC inverters and related methods are also disclosed.Type: ApplicationFiled: March 4, 2011Publication date: May 24, 2012Applicant: Astec International LimitedInventors: Vijay G. Phadke, James Sigamani
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Publication number: 20120075898Abstract: Power converters for photovoltaic (PV) systems and maximum power point tracking techniques are disclosed. One example power converter for a PV system includes an input for coupling to the PV system, an output for providing an output voltage, and a switch coupled between the input and the output. The input is configured to receive an input voltage (Vin) and input current (Iin) from the PV system. The power converter includes a controller configured for controlling operation of the switch using a control signal C. C is a function of at least the input voltage, the input current and a variable (K).Type: ApplicationFiled: September 28, 2010Publication date: March 29, 2012Applicant: ASTEC INTERNATIONAL LIMITEDInventors: James Sigamani, Yancy F. Boncato
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Publication number: 20110075455Abstract: A method of operating a DC-AC inverter to produce AC power having alternating positive and negative half cycles is disclosed. The inverter includes an input connected to a DC power source, an output, a first buck converter coupled between the input and the output and a second buck converter coupled between the input and output. The method includes alternately operating the first buck converter and the second buck converter to alternately produce the positive and negative half cycles at the output.Type: ApplicationFiled: September 25, 2009Publication date: March 31, 2011Inventor: James Sigamani
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Patent number: 7616464Abstract: A reverse current control system for first power converter having a synchronous rectifier and an output inductance includes a reverse current module. The reverse current module monitors a first voltage that is based on an output voltage of the output inductance and a second voltage that is based on an input voltage of the output inductance. The reverse current module anticipates a reverse current condition based on the first and second voltages. When the reverse current condition exists, the reverse current module prevents current from flowing in reverse through the power converter.Type: GrantFiled: August 16, 2005Date of Patent: November 10, 2009Assignee: Astec International LimitedInventors: Vijay Phadke, James Sigamani
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Patent number: 7596007Abstract: A multiphase DC to DC converter includes an input, an output, at least first and second converters, an inductor, an output capacitor, and a drive circuit. The drive circuit is configured for switching the first and second converters with a predetermined phase shift therebetween. The output capacitor is operatively coupled between the first and second converters and the output. The inductor can be placed either at the input side or the output side. When placed at the input side, the inductor is operatively coupled between an input capacitor and the first and second converters. When placed at the output side, the inductor is operatively coupled between the first and second converters and the output capacitor. The multiphase DC to DC converter is capable of achieving lossless switching transitions and negligible ripple current in the output capacitor.Type: GrantFiled: October 13, 2006Date of Patent: September 29, 2009Assignee: Astec International LimitedInventors: Vijay Phadke, James Sigamani, Israel Beltran
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Publication number: 20090085543Abstract: A method of generating at least a first voltage and a second voltage in a power converter including at least one DC-DC converter is disclosed. The method includes operating the DC-DC converter as a full-bridge converter to generate the first voltage and operating the DC-DC converter as a half-bridge converter to generate the second voltage. Power supplies including a DC-DC converter selectively configurable as a full bridge converter to provide a first DC voltage and as a half bridge converter to produce a second DC voltage and controller circuits for such configuration are also disclosed.Type: ApplicationFiled: September 25, 2008Publication date: April 2, 2009Applicant: Astec International LimitedInventors: James Sigamani, Gordon Currie
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Publication number: 20070229047Abstract: A buck dc-dc converter includes a tapped inductor having an active switch connected to the inductor tap and to a ground. A first diode is connected between the inductor and an input voltage source.Type: ApplicationFiled: March 31, 2006Publication date: October 4, 2007Inventors: James Sigamani, Khanderao Gaikwad
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Publication number: 20070133232Abstract: A two-stage converter including a buck converter and a DC-DC converter that receives power from the buck converter. The DC-DC converter generates an output voltage of the two-stage converter. A buck control circuit generates a control signal for the buck converter. The control signal is based on a first signal representing the output voltage, a second signal representing load applied to the buck converter, and a compensation signal. A characteristic of the compensation signal varies based on the output voltage.Type: ApplicationFiled: December 8, 2005Publication date: June 14, 2007Inventor: James Sigamani
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Publication number: 20070086224Abstract: A multiphase DC to DC converter includes an input, an output, at least first and second converters, an inductor, an output capacitor, and a drive circuit. The drive circuit is configured for switching the first and second converters with a predetermined phase shift therebetween. The output capacitor is operatively coupled between the first and second converters and the output. The inductor can be placed either at the input side or the output side. When placed at the input side, the inductor is operatively coupled between an input capacitor and the first and second converters. When placed at the output side, the inductor is operatively coupled between the first and second converters and the output capacitor. The multiphase DC to DC converter is capable of achieving lossless switching transitions and negligible ripple current in the output capacitor.Type: ApplicationFiled: October 13, 2006Publication date: April 19, 2007Inventors: Vijay Phadke, James Sigamani, Israel Beltran
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Publication number: 20070041221Abstract: A reverse current control system for first power converter having a synchronous rectifier and an output inductance includes a reverse current module. The reverse current module monitors a first voltage that is based on an output voltage of the output inductance and a second voltage that is based on an input voltage of the output inductance. The reverse current module anticipates a reverse current condition based on the first and second voltages. When the reverse current condition exists, the reverse current module prevents current from flowing in reverse through the power converter.Type: ApplicationFiled: August 16, 2005Publication date: February 22, 2007Applicant: Astec International LimitedInventors: Vijay Phadke, James Sigamani