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Design, Development and Control of High-Speed Switched Reluctance Generator for Direct-Coupled Operation with Thermal Turbo-Machinery

Primary Information



Project No.


Sanction and Project Initiation

Sanction No: F.No.3-18/2015-TS-TS.I dtd 29.11.16 (P ID 4548)

Sanction Date: 29/11/2016

Project Initiation date: 1/3/2017

Project Duration: 36

Partner Ministry/Agency/Industry

Ministry of Power


Role of partner: ***


Support from partner: ***

Principal Investigator

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Professor G Narayanan
Indian Institute of Science, Bangalore

Host Institute


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Dr. L Umanand
Indian Institute of Science, Bangalore

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Dr. Pramod Kumar
Indian Institute of Science, Bangalore


Scope and Objectives

1. Experimental characterization of magnetic materials and material selection.
2. Electromagnetic design and verification through finite element analysis.
3. Structural and dynamic analysis of the SRG rotor and experimental validation
4. Cooling system design and validation through computational fluid dynamics
5. Complete design procedure ensuring structural robustness, dynamic stability, thermal compliance and manufacturability of the high-speed machine
6. Fabrication and performance evaluation of three high-speed SRG prototypes (i) 5 kW/10,000 rpm (ii) 5 kW/50,000 rpm (iii) 20 kW/50,000 rpm
7. SiC based 20-kW power converter, switching at 50 kHz
8. Novel control methods for high-speed SRG
9. Industry-ready high-speed SRG based generation system for thermal turbomachinery


1. Working prototypes of high-speed SRG (5 kW, 10,000 rpm SRG; 5 kW, 50,000 rpm SRG; 20 kW, 50,000 rpm SRG)
2. B-H curve measurement technique for high frequency (5 kHz)
3. Knowledge of magnetic materials for high-speed electric machine
4. Electromagnetic design procedure for SRG
5. Test rig for rotor dynamic analysis and balancing
6. Development of modal model for high-speed SR machine rotor
7. Understanding and experimental evaluation of bearings for high-speed operation
8. Efficient liquid cooling for high-power-density electric machines
9. Fabrication procedures for various machine components
10. SiC based high-switching-frequency power electronic converter for SRG (asymmetric Hbridge topology, 3 phase, 800 V DC bus, 20 kW, 50 kHz switching frequency) 11. Novel control schemes for high-speed motoring, generation and back-to-back operation
12. Back-to-back test rig for testing of high-speed and high-power SRG (20 kW circulating power, 50,000 rpm, 20 Nm peak torque measurement)
13. Electrical and mechanical characterization of high-speed SRG prototypes
14. Mitigation techniques for acoustic noise and vibration besides vibration isolation
15. Mechanical and electrical design methodologies for high-speed SRG system

Scientific Output

1. The first prototype (5kW, 10000 rpm) has been designed, manufactured and run at speeds up to 11000 rpm
2. Novel stator design for effective forced air cooling in the first prototype
3. Novel rotor structure, design and fabrication for operation at high speeds and high shaft temperatures
4. Novel method of integration of rotor and position encoder in the first prototype
5. Advanced gate driver circuit with a fast acting protection mechanism for SiC power MOSFETs
6. Improved heat-sink design for the SiC based power converter
7. SiC based asymmetric H-bridge converter with 800 V DC bus voltage, 20kW power and switching frequency of 50 kHz.
8. Rotodynamic test setup for high-speed rotors and bearings
9. Designs of gas bearings for high speed machinery
10. MEMS based pressure and temperature sensor arrays for measurements in and control of thrust gas bearing.
11. Novel characterization approach to switched reluctance machine through injection of constant current, and a current control technique for the same
12. Novel current control scheme for low-speed motoring operation
13. Single pulse based optimal control scheme for motoring and generation
14. Analysis and modeling of voltage build up in switched reluctance generators.
15. Novel liquid cooling method and system for cooling of stator
16. Second prototype being manufactured (10 kW, 40000 rpm)
17. Eight invention disclosures to date on a variety of topics including electric machine design, heat transfer, cooling system design, power semiconductor device, MEMS sensor arrays for pressure and temperature, integrated excitation system for rotodynamic studies, advanced control schemes for SRM in motoring and generating modes and for low and high speed operation
18. Ten research publications (published, accepted or under prepartion) to date. More publications will follow after patent applications are filed on the above invention disclosures.
19. Extensive technical, manufacturing and testing support from industry - Shakti Pumps, Precision Machinekraft, ESCO couplings, ABRO, Triveni Turbines
20. Interest shown by different industries for percolation of the different technologies being developed for different applications - Transflow Cool (fans), Shakti Pumps (pumps), Tata Motors (compressor for fuel cell), Triveni Turbines (high speed generation system) and a startup, Direct Electric Pvt Ltd (gate driver for SiC devices)

Results and outcome till date

1) Preliminary electromagnetic design of SRM
2) Magnetic material testing and selection
3) An invention disclosure on a novel magnetic characterization setup
4) Development of rotor dynamics test rig
5) Rotor dynamics and balancing for first prototype
6) Cooling system design for first prototype
7) Complete design and detailed engineering drawings of SRM first prototype
8) Provisional patent application based on the first prototype
9) Power converters for back-to-back SRM: two SiC based high frequency converters built and tested
10) Invention disclosure on protection of power semiconductor devices
11) Fabrication, light-load testing of first prototype (5 kW, 10,000 rpm)
12) Control method for low-speed motoring and generating operation; an invention disclosure has been submitted
13) Control method for high-speed motoring and generating operation; another invention disclosure has been submitted


Societal benefit and impact anticipated

The main goal of this project is to address an important issue in the domain of energy, namely, to improve electrical power generation from heat energy using certain thermodynamic cycles and high speed turbines. The work is also used for turbochargers. Though the project aims at generation, this has led to a number of motoring applications such as fans, compressors, high speed spindles and electric vehicles.

Next steps

Manufacturing of the second prototype is at an advanced stage. Testing and evaluation of this prototype to achieve a speed of 40000 rpm is one of the goals for the near future. Advanced studies on rotor dynamics and vibrations of high speed rotors have been initiated which need to be taken forward. The project team has been actively interacting with a number of industries to explore field deployment and transfer of a variety of technologies developed in this project.

Publications and reports

1. Chetan Urabinahatti, Syed Shahjahan Ahmad and G. Narayanan, Magnetic Characterization of Ferromagnetic Alloys for High Speed Electric Machines, accepted for publication at IEEE PEDES 2018
2. S S Ahmad, Eshan Dhar, Pramod Kumar and G Narayanan, Electromagnetic Design of a 5 kW, 10,000 rpm Switched Reluctance Machine, IICPE 2016
3. Abhishek Kar, Syed Shahjahan Ahmad, G. Narayanan and Mainak Sengupta, Design, Performance Evaluation, Fabrication and Testing of a SiC MOSFET Gate Driver, IEEE SPICES, Kollam, Kerala, Aug 2017.
4. Syed Shahjahan Ahmad and G. Narayanan, Double Pulse Test Based Switching Characterization of SiC MOSFET, National Power Electronics Conference, Pune, Dec 2017.
5. Chetan Urabinahatti, Syed Shahjahan Ahmad and G. Narayanan, Device Loss Estimation and Heat-Sink Design for SiC based Power Converter Feeding a Switched Reluctance Machine, IEEE SPICES, Kollam, Kerala, Aug 2017
6. Chetan Urabinahatti, Roja Peri, Syed Shahjahan Ahmad and G. Narayanan, SiC MOSFET based asymmetric H-bridge power converter for switched reluctance machine, manuscript under preparation
7. S. S. Ahmad and G. Narayanan, Predictive Control Based Constant Current Injection Scheme for Characterization of Switched Reluctance Machine, IEEE Trans. Ind. Applicat., vol. 54, no. 4, pp. 3383-3392, July-Aug. 2018.
8. S. S. Ahmad and G. Narayanan, Analysis of Voltage Build-up in a Switched Reluctance Generator, submitted to ECCE Asia, Korea
9. S. S. Ahmad and G. Narayanan, Flux Linkage Characteristics of Solid Rotor Switched Reluctance Machine, manuscript under preparation
10. Sakshi, Chetan Urabinahatti, Ashutosh Patel, Shreyas Srivatsa, Pramod Kumar and G. Narayanan Experimental Investigations on a High Speed Rotor for a Switched Reluctance Machine, IICPE 2018


Invention disclosures The following 8 invention disclosures have been submitted to IPTeL, IISc, out of this project:
1. Switched Reluctance Device, Provisional Indian patent application filed in December 2017
2. Apparatus for Fast Fault Detection in Power Electronic Devices
3. System and Method for Current Control of Switched Reluctance Motor
4. System and Method for Direct Power Control of Switched Reluctance Generator Operating in Single Pulse Mode
5. Apparatus for Characterization of Magnetic Materials for High Speed Electrical Machinery
6. Single-wafer large-area multifunctional device array
7. System and method for static and dynamic characteristics of rotors
8. System and method for liquid cooling of electrical machine

Scholars and Project Staff

1. Syed Shahjahan Ahmad, PhD student
2. Eshan Dhar, PhD student
3. Ashutosh Patel, PhD student
4. Kamisetti N V Prasad, PhD student
5. Mouli Thirumalsetty, PhD student
6. Sudheer Patlegar, MTech student
7. Sakshi, MTech student
8. Sagnik Kumar, MTech (Res) student
9. Chetan Urabinahatti, Project Associate,
10. D.M. Channegowda, Consultant
11. B. Pavithra, Project Assistant
12. Nithin, Project Assistant
13. Prabha N, Project Associate
14. Shreyas Srivatsa, Project Associate
15. Vijai Biradar, Project Assistant
16. Linet Thomas, Project Associate

Challenges faced


Other information

The project has led to an excellent interdisciplinary team with strengths ranging from electromagnetism, power electronics, control, heat transfer, manufacturing, noise and vibrations, structural dynamics, bearings, MEMS sensors for bearings etc.

Financial Information

  • Total sanction: Rs. 395.04 lakhs

  • Amount received: Rs. 261 lakhs/p>

  • Amount utilised for Equipment: Rs. 88.08 lakhs

  • Amount utilised for Manpower: Rs. 31.61 lakhs

  • Amount utilised for Consumables: Rs. 68.95 lakhs

  • Amount utilised for Contingency: Rs. 7.5 lakhs

  • Amount utilised for Travel: Rs. 2.41 lakhs

  • Amount utilised for Other Expenses: 22.47 lakhs

  • Amount utilised for Overheads: Rs. 43.44 lakhs0

Equipment and facilities


1. Electronic load - 800V, 6kW, 120A ;
2. 200 MHz oscilloscope
3. 30A current probes - 2 nos.
4. Desktop PC
5. UPS for the desktop PC
6. Modal hammer
7. Inductive Displacement Sensor/Controller
8. Vibrational Frequency Spectrum Analyser
9. Torque Transducer & Coupler with standard accessories
10. Uni-axial Accelerometers
11. Hydraulic Torque Wrench
12. Dell Precision Workstations
13. Dell workstation laptops
14. OROS Multiple Balancing Module
15. SCO2 Test Loop Pressure Testing Unit
16. Simulia Academic Software