Investigations on Permanent Magnet Synchronous Generator for Different Renewable Energy

ApplicationsSubhrakanti Nanda

(Prime Minister’s Research Fellow)

1

Deptt. of E.E.IIEST, ShibpurGE Motors Pvt. Ltd

Mr. Koushik Pyne(Director)Industry Mentor

Prof. Mainak SenguptaProf. Deptt. Of EEAcademic Guide

PRESENTATION OUTLINE

2

• PART-I (introduction)o Target Applicationo Specification, Main Dimension & Material Selection

• PART-II (PMSG)o Design, Analysis & Fabrication

Surface Mounted PMSG

• PART-III (Converters)o Design, Analysis & Fabrication

Back to Back PWM Converter Vienna Rectifier Cuk Converter

2

• PART-IVo Modeling & Closed-Loop Control

• PART-Vo Experimental Set-Up & Testing

• PART-VIo Conclusion and Future Work

TARGET APPLICATION OF PERMANENT MAGNET SYNCHRONOUS GENERATOR (PMSG): 2kVA-5kVA

3

• 2kVA Permanent Magnet Synchronous Generator (PMSG) –o To provide-

reliable electricity to target group in remote hilly areas with pico-hydel system

o Target Group- Residents of large plantations A group of small planters / agriculturists Populace living in hilly hamlets

o Benefits of target group- Availability of electricity @ 100 W per home (minimum)[2/3 CFL lamps + one television set+ charging of mobile phones] Access to electricity Easy access to information systems

3

SPECIFICATIONS, MAIN DIMENSIONS & MATERIALS

4

o Targeted Specification of 2kVA PMSG

o Main Dimensions of 2kVA PMSG

o Materials usedStator Lamination: M36 (ss)Rotor Lamination: M36 (ss)Copper Wire: first varnish-polyester imide, 2ndvarnish-Polyamide ImideMagnet: NdFeB (grade 38)Rotor Sleeve: PVC Tape (Kevlar Roving for future use)Slot insulation: Nomex paperSlot Wedge: Wooden materialBearing: 6205 and 6206 SKF bearingHousing: Cast IronShaft: EN24

Rated power 2kVARated speed 1000 R.P.MNumber of poles, P 6Terminal line voltage 245V Phase 3 (star)Efficiency 90%Rated line current 5A

o Cross Section View of 2kVA PMSG Stator ID: 95 mm Stator OD: 158 mm Slot No. : 36 Air Gap: 0.8 mm Magnet Thickness:

4mm(At 150C, Br = 1.09T & Hc = 833598.7AT/m)

5

• PART-II (PMSG)o Design, Analysis & Fabrication

Surface Mounted PMSG

5

ELECTRO-MAGNETIC CALCULATIONS

6

o Bav = 0.65Wb/m2o ac = 10000 ac/mo Stack Length = 104.6mmo Efficiency = 0.92o Power Factor = 0.92 (assumed at worst

case)o Magnet Thickness = 4mmo Pole Arc = 44.1 degreeo Turns/Coil = 18o Mechanical Slot Fill Factor = 57%o Winding = staro Phase Resistance = 1.5 ohmo Ld & Lq = 17mHo Weight = 15Kg (considering Al

housing)o Calculations are done as per standard methods– See References 6

ELECTRO-MAGNETIC CALCULATIONS

7

o Permeance Coefficient (PC) value depends on type of permanent magnet using for the designFor sintered magnets 2-5 For Ferrite magnets 7-15Select PC in such a way magnet should not be demagnetized under peak load operating condition with factor of safety.

7

FINITE ELEMENT ELECTRO-MAGNETIC ANALYSIS

8

o 2-D Flux Plot o 2-D Flux Density Plot @ Rated Load

o No-Load BEMF @ 1000 rpm o Torque Current Characteristics8

9

Total weight 31 kg. Shell weight 19kg. Core and Copper weight 12 kg. Electrical Power Density = 154W/Kg Overall Power Density = 64W/Kg Electrical Torque Density= 1.47 N-m/Kg Overall Torque Density= 0.613N-m/Kg

Performance Prediction

o Predicted Performance of Designed PMSG -- Maximum continuous power 1840W Efficiency at rated load & speed 89% Temperature rise 0.613 deg C/W Maximum winding temperature 155 deg C Load current 5.7A No load AC voltage 245V(l-l) Loaded AC voltage 238V(l-l)

Figure: Phasor Diagram

Figure: Power Vs. Efficiency9

10

RMS 82V, 50Hz

Fabrication

Figure:2kVA PMSG Rotor withStainless Steel material

Figure:2kVA PMSG Rotorwith Silicon Steel material

Figure:2kVA PMSG Stator with Silicon Steel material

Figure:2kVA PMSG Stator with Silicon Steel material

Figure: Assembled 2kVAPMSG

Figure: Line Voltage, 50 Hz

Figure: Assembled 2kVAPMSG

Figure: Phase Voltage, 40 Hz

RMS 196V, 40Hz

10

11

Fabrication

2kVA PM-Rotor damaged during load test

2kVA PM-Rotor during repair at work-shop

12

Comparison between 2KVA PMSG (in motor mode) Induction Motor (IM) and Synchronous Motor (SM)

items Designed PMSG(D=95mm & L=101.4mm)

Available induction machine

Designed SM(D=95mm & L= 128.5mm)

Electrical weight 12 kg 23 kg. 22 kgTotal weight 31kg 42 kg 40kgPower density 64 W/kg 47.6 W/kg 50W/kgTorque density 0.613N-m/kg 0.45 N-m/kg 0.475 N-m/kg

12

1313

• PART-III & IV (Converters)o Design, Analysis & Fabrication

Back to Back PWM Converter Vienna Rectifier Cuk Converter

o Modeling & Closed-Loop Control

CONVERTER SPECIFICATIONS

14

Representative Diagram of Grid Interactive/ Isolated 2kVA PMSG

Protection Scheme- Over Current: Protection by

true current sensing on Input / Output AC side.

Over Voltage: Protection by voltage sensing on Input / Output AC side as well as DC side.

Short Circuit: Protection by Vce de-saturation detection

Cooling System- Forced air cooling with Fan

Environment- Ambient Temperature: 0-45oC Humidity: 95% RH max. Non-

Condensing Protection- IP 41 Control Platform- ALTERA

Cyclone-II FPGA (Ver.3.0)

Converter Topology-Two no. of 2-level 3–phase Inverters connected with common DC Cap Bank and Pre-charge Section.Rated Input Voltage- 440V, +5% / -10%, 3-Phase, 50Hz.Rated Input / Output Current- 30ASwitching Frequency- 10kHz

Active Front End

15

Representative Diagram of Active Front End

IGBT- BSM75GB120DN2- 75A, 1200V (Infineon)Electro Lytic Capacitor- 4700μF/450V, 6 Nos. (Kendeil)Snubber Capacitor - 0.47uF, 1.5 kV (Advance Comp. & Instr.)Gate Driver (Concept)Voltage Sensor– LV 20-P (LEM) Current Sensor - LA 55-P (LEM) Heatsink - 30F126 (Bhoomi)Pre-Charge Resistor- 100Ω±5%/60W (Kiyosh)Bleeder Resistor- 47kΩ±3%/10W (Raatronics)

Developed Back-Back PWM Converter

16

Module Level Test- Back to Back PWM Converter

17

Fig.1: Output voltage and load current with resistive load of 15 ohms

Fig.2: Output voltage and load current with inductive load of 4mH

Fig.3: VC-E of one group of IGBTs on load side

Load Test Result- Input Voltage: 3-Ph, 415V,50 Hz Output Voltage: 430V (measured at no load

condition) Load Current: 25 A Ambient Temperature: 28.9oC Final Temperature: 52.3oC Test duration: 30 min.

DC Link Discharge Test-The DC link capacitor bank 4700μF/450 V with sharing resistor 47kΩ is charged to rated DC link voltage of 700 V without triggering IGBTs. The total time required for discharge is found to be 14 minutes approximately.

18

Three level three switch Vienna rectifier.

18

Vienna Rectifier

Circuit Operation Control Block Diagram

1919

Developed Vienna Rectifier

2020

Module Level Test- Vienna Rectifier with Hysteresis Controller

Hysteresis Reference Phase V & I without switching

Input Voltage & Current Unit Vectors from Encoder

Prototype Cuk Converter

Fabricated Cuk Converter in Laboratory

A Cuk Converter in Continuous Conduction Mode

21

Close-Loop Control of Cuk Converter

Linear State Variable Feedback Control with Reference Tracking

• LSVF for Non-Minimum Phase System (Cuk Converter): Conventional Control Principles not applicable• A full state feedback regulator plus integral controller (to reduce steady state tracking error) is given by

u = -Kx + KI*e(t)• Which uses the matrix K to place the poles of the system at desired locations.

22

Real Time Simulation Results

23

Output Voltage (Vo) and Input Current (I1)

Voltage across C1 (Vc) and Output Current (I2)

23

Output Voltage (Vo) and Input Current (I1)

Voltage across C1 (Vc) and Output Current (I2)

Module Level Test- CuK Converter

24

2525

• PART-V o Experimental Set-Up & Testing

2626

Prototype PMSG & Converters

PMSG set-up: 2kVA , 1000 rpm PMSG coupled with 3.5kW, 220 V DC motor load

PMSG, Converter & Load

Parameter Estimated value Experimental value

Ra(ohm)/phase 1.6 1.82Ld(mH) 17 18.86Lq(mH) 17 18.86Ke (VL-L(rms) /1000rpm) 245 247

PMSG

LOAD

CONVERTER

27

2kVA PMSG Full Load Test Result (Gen. alone)

Sl. No.

V(L-L)(V)

I (L) (A)

Speed (rpm)

Generated power(W)

I/P shaft power(W)

% Load Generator eff (%)

1 236 1.3 1008 540.4 659 33 82

2 232 2 1001 803.6 924 40 87

3 230.5 4.2 1001 1676.7 1895 84 88.5

4 226 5.5 1005 2153 2360 104 90

27

28

Test Results & WaveformsSpeed (rpm) No-load Line

Voltage (Vrms)1000 247.5900 223.4800 198.5700 172.9600 147.5500 123400 99300 73200 49

Experimental BEMF (line) at Different SpeedExperimental BEMF (line) Vs. Speed

Experimental Waveform BEMF(ph) at 1000 rpm (gain:50)

bemf vs. speed

050

100150200250300

0 500 1000 1500rpm

Vrms bemf vs. speed

28Sim. &Exp. BEMF (line) Vs. Speed

29

Test Results & Waveforms

Unit Vectors Generated from Encoder Input Voltage & Current Waveformsof AFE

Output Voltage & Current Waveforms of Inverter (R Load)

Output Voltage & Current Waveforms of Inverter (R-L Load)29

30

Experimental Results withHysteresis Band based ControlSl. No.

Speed(rpm)

DC Link(V)

GeneratorCurrent(rpm)

Generated power(W)

DC link

current (A)

% Load

DC link power (W)

1 1000 419 1.4 540.4 1.1 27 460

2 1000 418 2 803.6 1.67 40 700

3 1000 418 4 1590 3.23 80 1350

4 1000 418 5.5 2100 4.6 105 1920

30

Test Results & Waveforms

Power Vs. Efficiency (Simulation) Power Vs. Efficiency (Test)

0102030405060708090100

0

500

1000

1500

2000

2500

0 200 400 600 800 1000 1200

Effice

ncy in

%

Powe

r (W)

rpm

outputpowerinput power

efficiency

3131

Simulation & Experimental WaveformsWith Hysteresis Band based Control

Dc Link Voltage (yellow)Generated Phase Voltage (magenta)Current drawn from the generator (sky blue) Scale- 1:140

Dc Link Voltage (green)Generated Phase Voltage-180Vpk (magenta)Current drawn from the generator-7.8Apk (yellow)

Corresponds to DC Link Voltage 418V and Generator is 100% Loaded with rated speed of 1000 rpm3232

33

• PART-VIo Conclusion & Future Work

33

Conclusions

Future Work

34

Fabrication & Testing of IPMSG Sensor-less closed-loop control of Vienna Rectifier Integration of the total system and testing

Fault Tolerant PMSG- insulation / vector control Simulation shows +/- 40% speed variation of the generator is able to

maintain 700V DC-Link Voltage It’s expected that the proposed scheme (with Cuk converter included)

can handle further speed variation while maintaining the same DC Link Voltage.

Conventional Synchronous Alternator is inferior in performance

Publications Nanda S, Ganguly D, Sengupta M, ‘Weight Optimised Design, Performance

Comparison and Finite Element Analysis of a Brushless DC Motor Using Two Different Materials’, Proc. of the 1st National Power Electronics Conference, NPEC-2005, Dec. 2005, IIT Kharagpur, INDIA.

Nanda S, Sengupta M and Sengupta A, ‘Modeling, Real-Time Simulation, Fabrication of and Experiments on a Boost-Buck (Cuk) Converter’, Proc. of the 6th National Power Electronics Conference, NPEC-2013, Dec. 2013, IIT Kanpur, INDIA.

Nanda S, Sengupta M and Sengupta A, ‘Modeling, Simulation, Fabrication, Experiments and Real-Time Linear State Variable Feedback Control of CukConverter using Pole Placement Technique’ Trans. of The Institution of Engineers (India): Series B , Volume 95, issue1, Jan-Mar 2014.

Nanda S, Sengupta M ‘Design, Analysis, Fabrication and Investigations of a Permanent Magnet Synchronous Generator for different renewable energy applications’, proc of PEDES - 2014. IEEE Conference, Dec. 2014, IIT Bombay, INDIA

Nanda S, Sengupta M, ‘Fabrication, Parameter Evaluation and Testing of a Permanent Magnet Synchronous Generator’ , Proc. of the 7th National Power Electronics Conference, NPEC-2015, Dec. 2015, IIT Bombay, INDIA.

35

References

36

[1] S.Paitandi And M.Sengupta, Design, analysis of a PMSM and its Comparative study With a Induction Machine of Same Nominal Rating, NPEC, December 2013, IIT Kanpur[2] D.O’Kelly And S.Simmons, Generalized Electrical Machine Theory, McGRAW HILL, 1968.[3] M. Sengupta, Construction, Analysis and Performance of Switched Reluctance and Brushless D.C Motors, M.E Thesis, IIT Kharagpur, December 1993.[4] R.Krishnan, Permanent Magnet Synchronous And Dc Motor Drives,Crc Press,2005[5] S.K. Nanda, 1kW, 48V, 2000rpm, 4pole BLDC Motor for Electric Vehicle Application, M.E. Thesis, Department of EE, BESU, Shibpur, 2006.[6] Nanda, S.; Sengupta, M. Design, fabrication and analytical investigations on a permanent magnet synchronous generator, Power Electronics, Drives and Energy Systems (PEDES), 2014 IEEE International Conference[7] www.ansys.com[8] en.wikipedia.org/wiki/Picohydro[9] D. Hanselman. Brushless permanent magnet motor design. US: The Writers Collective, 2 edition, 2003.

ACKNWOLEDGEMENTSo CII, DST for the Prime Minister’s Research Fellowship o M/s G E Motors Pvt. Ltdo Director IIEST, Shibpur, Prof. Ajoy K. Ray o My research guide – Prof. Mainak Senguptao Fund Support for POC -- funded by the Department of Electronics and Information Technology (DeitY), GOI under NaMPET – II Programo Advanced Power Electronics lab, Research Scholars and colleagues in the lab, particularly Mr. N. Datta, TAo Veeral Controls, Gandhinagar

37

38