ISRO Satellite Centre, Bangalore, India
To obtain a challenging position that will enable me to use my organizational skills, educational background and ability to work well as a team member. I will work my best to contribute to the growth of the organization and to the growth of my career. I have more than 5 years of experience in development of various kind of power supply like dc-dc converter, power processing unit for various ion thrusters for space application. I also have sound knowledge of various kind of Military standard required for qualify develop products.
Company : ISRO Satellite Centre, Indian Space Research Organization
Location : Bangalore
Country : India
Job Title : Scientist/Engineer
Job Role : Research and development of Power units for ion thrusters and dc-dc converters
Duration : Aug 2011 to till date
As a member of Power Conditioning and Distribution Section, Power Electronics Division, my major responsibilities are to develop various kind of power supplies required for ongoing projects.
My contributions are
POWER PROCESSING UNIT FOR 18mN ,75mN and 300mN ELECTRIC ION THRUSTER (PPU)
Realization of proto and flight model of PPU for ongoing GSAT-9 18mN ion thruster and involved during interface between ion thruster, NCT package and PPU and debug the problems during interface test. Also involved in design and development of PPU for 75mN and 300mN ion thruster for future projects.
Anode Supply :
Anode Supply for Gsat-9 18mN ion thruster:
Realized buck cascade push pull topology based 300V/1.5A constant voltage power supply. Ignition circuit also designed from Anode Supply to ignite thruster with high surge current and also 0.6A constant keeper supply Ored with ignition.
Development of 550V/1.5A constant voltage module supply to get 550V/3A anode supply (2 modules in parallel) for 75mN thruster and 550V/9A anode supply (6 modules in parallel). Ignition circuit is also designed from Anode supply (requirement of ignition circuit: 300V, 60A surge current). Ignition circuit and anode module are developed and successfully interfaced with 75mN ion thruster.
Heater Supply for Gsat-9 18mN thruster : Realized isolated 12A constant current power supply for load range of 0.2 ohm to 1.5 ohm for GSAT-9
Heater Supply for 75mN thruster: Developed isolated constant current power supply with DAC interface to get initialization current of 1A, 3A, 5A, 7A and 8.3A constant current for resistance range of 0.2 ohm to 2 ohm. Heater supply is developed and interfaced with 75mN thruster successfully.
Magnet Supply :
Magnet Supply for Gsat-9 18mN thruster: Realized magnet power supply of 1.8A for inner magnet and 1.4A for outer magnet with two outputs single power supply.
Magnet supply for 75mN: Constant current power supply with step change from 1.4A to 1.8A similar to heater supply made for 75mN and successfully interfaced with 75mN thruster.
Realization of bias supply , Output Filter , switching circuit for 18mN thruster:
Realization of 3 numbers of 10W fly back topology based converter to provide isolated bias supply to various power module in PPU.
Realization of filter box between anode supply of PPU and thruster anode
Switching circuit is also realized to power on and off various power module of PPU
Interface between proto model of PPU, 18mN ion thruster and NCT package
Involved during interface between proto model and flight model of GSAT-9 PPU, thruster and NCT control package and troubleshoot problems when encountered.
BATTERY CHARGE REGULATOR:
BCR For 70V bus :
Development of 750W BCR (buck converter) Engineering model for autonomous charging of battery in satellite from Bus.
3D control loop implementation to take care of bus priority over battery charging and taper the current as battery gets fully charge.
Qualification model of BCR is under progress
Flight model Is planned for NISAR and RISAT projects
DESIGN AND DEVELOPMENT OF ISOLATED DC-DC CONVERTER
10 W fly back topology based dc-dc converter with multiple output
Design and develop 10W three outputs dc-dc converter for 42V and 70V bus.
Qualify this converter to meet all Military standard like EMI, vibration, thermovac etc
First flight model Flown in IRNSS-1G
40 W Single output Forward topology based low voltage high current converter
Development of 3.3V/8A and 5V/8A single output converter for space application
Qualification of this converter for both 42V bus and 70V bus
Planned for future spacecraft like Risat-2, Cartosat-3
Supervisees the vendors for Production of 4.5W and 20W converter dc-dc converter
Supervises the vendors and troubleshoot all problems when encountered during production of fly back topology based 4.5W converter and forward topology based 20W dc-dc converter.
Involved in modification of 20W converter to work as 60W converter.
LINEAR REGULATOR LDO
Requirement: Subsystem are facing problem with imported LDO like OM7764 is whenever 1553 transient is there, they observe change in output voltage that degrade the performance of their package. For improvement they are forced to use high value of capacitors which results in oscillation for some users. This is the driving factor for us to develop current control based indigenous LDO which support 1553 transition of no load to 3A also without any overshoot and with less capacitor of 22 uF instead of 680 uF.
Two versions of LDO were designed. One with Mosfet as a pass element and the other was Transistor as a pass element.
Both the circuits were simulated using PSPICE.
The MOSFET based circuit is used in 10W DC-DC converter for output voltage of +5V.
The transistor based LDO is hybridized and realized as an off the shelf product.
The pin configuration and the size of the hybridized LDO package is maintained similar to existing imported package OM7764 (IR LDO)
The HMC was tested for various specifications at ambient temperature and -40 to +65 at thermovac.
Interacted with SRG for carrying out the derating analysis.
MODELING AND SIMULATION:
Simulation of Power processing unit for ion thruster various power supply like Heater, Magnet and Anode in PSIM
Simulation of Battery charge regulator in PSIM with 3D control system
Simulation of EMI filter and studied the effect for the same on input impedance of various power supply in PSIM and PSPICE
Modeling and simulation of 40W (5V/8A) forward converter and 10W fly back converter and 20W forward converter in Simulink/Mat lab and used this model for feedback controller design for converters.
Modeling of saturable core and simulation of magnetic current sensor (unidirectional and bidirectional) for sensing dc current up to 1000A in PSIM software without fold back
Simulation and analysis of effect of multi-junction Solar Array capacitance, inductance and resistance of harness on Switching String for 42V Bus application in ORCAD as well as in MATLAB.
Simulation of various analog circuit used during design of power supply in Orcad /Pspice.
Software Used : PSIM, Orcad/Pspice, Simulink/Mat lab
Sound knowledge of various MIL Standard used for space application products like Derating analysis, Thermovac condition, vibration limit, EMI requirement etc.
Good knowledge of EMI filter design for power supply to meet MIL STD
Experience in end to end design and development of various topology of dc-dc converter and qualify the design for space application.
Experience in design and development of low dropout regulator for satellite application
Experience in Hybridization of dc-dc converter and LDO to reduce the size from SMT version
Sound knowledge of various software like Pspice, PSIM, Matlab etc
Experience in working on ADC, DAC and Microcontroller for mixed signal operation.
Bachelor in Avionics from Indian Institute of space science and technology with CGPA of 8.73./10 (www.iist.ac.in)
Pre – University course, Bihar intermediate science with Percentage: 75.4% (3rd topper in state board)
Matriculation (Class X), C.B.S.E, with Percentage: 89.4%
“Simulation And Verification of Discontinuous Mode Fly back Dc-dc Converter Using Simulink” in Mat lab Expo 2014, Bangalore.
“Effect Of Solar Cell Capacitance And Interface Cable Inductance On The Shunt Switch Current Transients In Spacecraft Power Conditioning Unit” in IEEE international conference ICRAIE-2014, Jaipur.
“Modeling of Solar array and Analyze the Current Transient Response of Shunt Switch Voltage Regulator in Spacecraft Power Conditioning Unit” in Journal of Advanced Computing and Communication Technologies (ISSN: 2347 - 2804) Volume No.3 Issue No. 2, April 2015 pp 33-39
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