Design power electronic converters, generators, motors, circuits, components and systems for renewable energy, motor drives, electric vehicles, sustainable technologies and energy efficiency.
SUMMARY OF CAPABILITIES
Power Converters (DC-AC, DC-DC) design, prototyping and testing, ZVS, high voltage, high frequency designs using SiC MOSFETs, embedded control using Altera FPGAs. Power electronics modeling, feedback control, complete switching converter simulation. Permanent magnet alternator / motor design, analytical modeling, 3-D Electromagnetic simulations (FEA). Field oriented control of motors. Measurement of motor/generator parameters, testing of entire drive train. B/H curve, permeability, loss test of magnetic materials. EMI/EMC compliance, Power magnetics design, troubleshooting inverters. UL, IEC, FCC certification testing of grid interactive inverters, generators/insulation systems. Lightning protection design, analysis for electronics housed in wind turbines. Optoelectronic, RF design up to 40GHz. Strong research, analysis, mathematical, troubleshooting skills. Electromagnetic theory, concepts. Ability to visualize things that are not tangible. Track record of reliable, innovative product design. Follow ISO9001 quality policies.
Software: MATLAB/Simulink, SPICE, JMAG, Solidworks, C, Altera Quartus II, DSP Builder, Altium Designer.
Google Little Box Challenge (Sept 2014 – present)
Summary: Analyzed, designed and built a 2kW inverter occupying a volume of 45 cubic inch. Converter boosts 400-450V DC input voltage to 700V and then inverts it to 240V, 60Hz, split single phase. Converter uses wide bandgap semiconductors in synchronous boost and buck configurations with Zero Voltage Switching at high frequency, up to 500kHz. Housekeeping power supplies use a variety of topologies such as Cuk converter, asymmetrical half bridge, charge pumps. Converter uses a novel current sensing and ZV detection and feedback control circuits (original designs). Magnetics were self-designed. Control is implemented using both op amps and FPGA. Converter was modelled in LTSpice and MATLAB/Simulink. Converter is highly reliable with >96% efficiency, does not use electrolytic capacitors, meets relevant safety standards and other Google’s specifications. Testing is continuing.
Electrical Engineering Consultant, Xzeres Corporation (May 2014)
Summary: Created detailed work instruction and BOM (meeting UL insulation system requirements) for manufacture of 2.6kW slotless permanent magnet generator for wind turbine.
Electrical Engineering Consultant, Eocycle Technologies (Feb 2014-April 2014)
Summary: Performed detailed loss analysis, recommended design changes for improved torque, voltage constant, lower loss operation of a PM transverse flux generator for a 25kW wind turbine.
Electrical Engineering Consultant, Electric Torque Machines (etmpower.com), formerly Motor Excellence, Flagstaff, AZ (May 2011 – Jan 2014)
Summary: Motor control for reduced torque ripple; Motor design for improved efficiency. Established in-house magnetic material testing ensuring reliable magnetic characteristic data.
- Analytical torque model based on Self/Mutual/Leakage Inductances of 3-phase permanent magnet Transverse Flux Machines with unequal mutual coupling. Measurement of d-, q-, self, mutual (position dependent) and leakage inductances.
- MATLAB/Simulink model of the 900W high torque dense Transverse Flux bike motor with PWM signal input, including core loss. Model captured asymmetrical stator inductances of the machine. Model helped the design of motor control to reduce torque ripple.
- Field oriented control of 900W transverse flux permanent magnet synchronous motors driven by 3-phase full bridge inverter (for use in electric bicycles) with inherent stator asymmetry. Incorporation of asymmetrical mutual inductances of motor in embedded software and implementing FOC using a,b,c to d,q flux transformation. Original algorithm allowed current amplitudes to be adjusted in the individual phases of a 3-ph motor (no neutral).
- Review TFM motor designs; Reduced excessive rotor, stator leakage resulting in increased voltage constant. Optimize pole count, flux concentrator shape to get max torque minimizing magnet volume for given speed, dimensions. Increased motor efficiency by 10-20%.
- Measure, characterize magnetic materials (Powder metals, Si Steel, Fe-Co, Fe-Ni, Metglas, nano-crystalline tape wound, etc.) using toroidal cores per ASTM standards. Resulted in improved motor models, better designs and saved the company up to $100k in about one year.
- Troubleshoot 3-phase inverters connecting battery to electric motor used in electric bicycles.
Electrical Engineer, Southwest Windpower, Flagstaff, AZ (Jan 2006 – June2010)
Summary: Design, implement EMI compliance circuitry for a 2.5kW grid connected inverter for the Skystream 3.7 wind turbine; successfully lead, complete its UL / IEC certification enabling its entry into the US and international markets bringing in $1.5M monthly revenue, plus immediately attracting $10+ Million in venture capital. PM Generator design for low wind-speed turbine.
- Slotless radial flux permanent magnet alternator design (for lower RPM operation) for the next generation Skystream wind turbine with integrated inverter with the help of analytical models and commercially available 3D Electromagnetic Flux simulation (JMAG). Included thermal modeling. Design compliant with UL1004-1. Worked with UL engineers in Northbrook, IL, towards recognition of both Skystream 3.7 and this next generation alternator.
- Design, implementation of EMI compliance circuitry in single phase (and split single phase) grid interactive wind turbine converter / inverter for Europe (CE) and USA (FCC) regulations for conducted and radiated emissions.
- Common, Differential mode choke magnetic design for 2.4kW converter in Skystream turbine.
- UL1741, IEEE1547 (Safety, Grid Compatibility, EMC) testing, certification for the Skystream 3.7 (2.4kW) single phase wind turbine inverters in USA (for 120/240V and 120/208V grid types), including anti-islanding. Worked with UL renewable energy team from Northbrook, IL.
- IEC 61400-2 certification of 2.4kW wind turbine with grid interactive inverter (responsible for electrical part of the system). Worked with GL team in Hamburg, Germany.
- Lightning protection analysis of Skystream 3.7 wind turbine installations per IEC 61400-24. Included tower earthing and Skystream 3.7 grounding design.
- Installation of multiple 2.4kW wind turbines with integrated inverters for a wind/PV/diesel island grid system in the Maldives. Ensuring their successful operation in the system. Also dealt with leakage current issues and proper installation of GFI device in the system.
- Troubleshooting of single phase inverters consisting of IGBTs and MOSFETs.
- Efficiency testing of Skystream 3.7 wind turbine inverter per the CEC regulations. Worked with ETL/Intertek team from Cortland, NY. Included thermal back-off protection.
- Conducted all tests per AS4777.2/3 to achieve Australian C-Tick certification for Skystream 3.7. Certification agency was ITACS.
- Ensured that Skystream 3.7 met all requirements for CE marking. Worked with GL to complete the effort. Created CE technical file.
- Skystream 3.7 installation for UK’s PME (TN-C-S) DNO supply (grid) in compliance with BS7671 requirements. Worked with GL and UK authorities for installation compliance.
- Review, comment, propose changes in NEC Small Wind Article 694 adopted in 2011.
JDS Uniphase Corporation (JDSU), West Trenton, NJ (April 1994 – April 2005)
Summary: Instrumental in success, growth of company by innovative design of 10Gb/s receivers.
Applications Engineer (April 2003 – April 2005)
Help customers design-in JDSU’s electro-absorptive and directly modulated lasers and fiber optic receivers. Provide technical response to customer RFQ’s.
Senior Engineer III (April 1994 –April 2003)
Design high-speed InGaAs photodiode (p-i-n and APD) receivers and for SONET / SDH standards up to 40Gb/s and analog CATV. Microwave feed-through, transmission line design. Hands-on testing of optoelectronic components. Select accomplishments:
- 10Gb/s: Led the development of the JDSU’s (formerly Epitaxx) first 10Gb/s receiver in the K-connector package. This platform was the backbone of all the various 10Gb/s receiver products offered by JDSU in the “coplanar” and “K”-connector packages.
- 40 Gb/s: Electrical lead in the development of the JDSU’s first hermetically sealed 40Gb/s p-i-n transimpedance amplifier receiver in a MSA coplanar package with differential outputs.
- CATV: Low intermodulation distortion, low-noise CATV receiver design (10-900MHz) and manufacturing. Broadband RF transformer design, RF matching circuits.
- Advanced Components and Sub-System solutions for 40Gb/s Transmission, Richard DeSalvo et. al., IEEE Journal of Lightwave Technology, Vol.20, No.12, December 2002; Invited paper.
- Equivalent circuit modelling of a p-i-n Photodiode for 40Gb/s Receivers, Andrew H. Steinbach, et. al., European Conference on Optical Communication (ECOC), Sept. 8-12, 2002, Copenhagen, Denmark.
- Packaging of High Speed Optical Receivers, Nitish Agrawal, et. al., IEEE LEOS, Nov. 2000.
- High Performance 10Gb/s PIN and APD Optical Receivers, Rue, M. Itzler, Nitish Agrawal, S. Bay, W. Sherry, IEEE Electronics Components and Technology Conference, ECTC, June 1999, San Diego, CA.
EDUCATION AND TRAINING
- Power Electronics for Electric Drive Vehicles, University of Colorado, Boulder, Fall 2013
- Certificate in Power Electronics, University of Colorado, Boulder, May 2012. Courses included in the certificate were:
- Resonant and Soft Switching Techniques in Power Electronics, Spring 2012.
- Modeling and Control of Power Electronic Systems, Spring 2011.
- Introduction to Power Electronics, Fall 2010.
- Feedback Control Design, Stanford University, Summer 2011.
- Fluid Mechanics I, Northern Arizona University, Fall Semester 2008.
- Electromagnetic Design of AC Machines (700 level course), University of Wisconsin, Madison, Spring semester 2006.
- Electrical Machinery, California State University, Los Angeles, Summer 2005. Audited 300 level course (3-phase circuits, transformers, induction, synchronous, DC machines).
- Wind Energy Workshop, Solar Energy International, Guemes Island, WA. October 18-23, 2004. Installed an AWP 1kW wind generator atop a 160ft. free standing tower.
- Certified Quality Engineer, 1998, American Society for Quality.
- Master of Science in Electrical Engineering; specialization in Microwave and Lightwave Engineering, New Jersey Institute of Technology, Newark, NJ; August 1994.
Thesis: Artificial Dielectrics, Characterization at low and microwave frequencies.
- Bachelor of Engineering Electrical and Electronics, Manipal Institute of Technology, Manipal, Karnataka, India; May 1992.
Final Year Project: Microprocessor based system for on-line monitoring and characterization of power factor of synchronous motors.
English, Hindi, Bangala, Bahasa Indonesia (very basic)