The document discusses the key components of a traction converter used in electric locomotives. It describes the evolution from older GTO and thyristor-based converters to newer IGBT-based converters. The main components of an IGBT converter include the front-end converter, intermediate DC link, inverter modules, electronic control modules like the DCU and VIU, and IGBT power modules. The power modules integrate the IGBT devices, driver circuits, and protection circuits into a single replaceable unit.

1. TRACTION
CONVERTER
Vishal M J, Traction Engineering

2. Topics to be covered
 Introduction
 GTO
 IGBT
 IGBT Locomotive
 Traction System
 Converter
 Power Module
 Electronic Modules

3. Introduction
 Block diagram of a typical locomotive
 Power Semiconductor Devices
 Evolution of Power Semiconductors
 Traction Converter Basic Circuit

4. Block Diagram

5. Power Semiconductor Devices
Device Circuit Symbol Features
Diode Uncontrolled ON & OFF.
Bipolar device. One P-N
Junction
Thyristor (SCR) Controlled Turn ON,
Uncontrolled OFF. Bipolar
Device. 3 P-N Junctions
Power Transistor Controlled Turn ON and
OFF. Current controlled
device. Two P-N
junctions.
Power MOSFET Controlled Turn ON and
OFF. Voltage controlled
device. Low gate power
requirement
GTO Controlled Turn ON and
OFF. Huge gate current

6. Evolution of Power
Semiconductors

7. Basic Scheme

8. Gate Turn OFF Thyristor
 What is a GTO
 Advantages over other devices
 Drawbacks of GTO
 Phasing Out of GTO

9. What is a GTO
 Similar to a Thyristor, but unlike a
Thyristor it can be turned Off by a
negative gate signal
 Faster Turn OFF - Higher switching
frequency than a thyristor
 Improved efficiency
 Elimination of forced commutation
circuitry

10. Advantages of GTO
 Commutation circuit is not needed
 Fast Switching speed
 Larger di/dt at turn ON
 Compact
 Higher efficiency ( due to absence of
commutation elements)

11. Drawbacks of GTO
 Higher latching and
holding current
 Higher ON-state
voltage drop and
power loss
 Higher gate current
 Higher gate circuit
losses
 Lower reverse
blocking capacity
Feature Thyristor GTO
Latching
Current
450mA 14A
Holding
Current
170mA 10A
On state
drop
2.1 V 3.8 V
Gate current 500mA 4 A (ON)
1100 A OFF)
Blocking
capacity
8000V 4500V

12. Phasing out of GTO
 Demand was growing till 2009. Stable now.
The demand is expected to decline by 2014
 No further developments or improvements
expected
 The market is taken over by IGBT technology
 No new designs-in, manufacturer still delivers
only to keep the existing rolling stock running

13. IGBT
 What is an IGBT
 Advantages of IGBT
 Comparison with a GTO & a Thyristor
 Drawbacks of IGBT
 Future Trends

14. What is an IGBT
 Insulated Gate
Bipolar Transistor
 Combines the
advantages of a
Power MOSFET
and a power BJT
 Very high efficiency
and fast switching
speed

15. IGBT = MOSFET + BJT
B
C
E
E
D
S
MOSFET
• High input impedance,
hence very low gate current
•No Secondary breakdown
•Simple driver circuit
•Lower Switching losses
•High frequency operation
BJT
• Low On-State losses
•Large current
handling capacity
G
IGBT – Features
• High input impedance, hence
very low gate current
•No Secondary breakdown
•Simple driver circuit
•Lower Switching losses
•High frequency operation
• Low On-State losses
•Large current handling
capacity
IGBT combines
the advantages
of both Power
MOSFET and
Power
Transistor

16. Advantages of IGBT
 Very high efficiency – Due to lower gate circuit
dissipation and lesser conduction and switching losses
 Higher frequency operation possible – Lowers
harmonics
 Simpler gate circuit design – Complete elimination
of commutation circuitry
 Compact – No snubber circuit
 Simpler cooling circuits – due to lesser losses

17. Performance Comparison
Parameter Thyristor (SCR) GTO IGBT
Efficiency High Low High
Gate Signal Current Current Voltage
Gate Current <2 A 400 – 1000 A < 1A
Gate Control
Component Count
Medium High Low
Voltage Rating High High Medium
Switching losses Medium High Low
Snubber Parts Few Many Few
Switching speed Low Low High

18. IGBT Locomotive
 Electrics of Loco
 Equipment Overview
 IGBT v/s GTO Loco
 Advantages of IGBT Loco

19. Electrics for E-Loco
The Electrical equipment for loco consists of:
 Two Water cooled Traction Converters with 3 independent Motor Side
inverters
 AUX. Converter - 1 with 1*130 kVA inverter
 AUX. Converter - 2 with 2*130 kVA inverter and 11 kW battery charger
 2 Vehicle Control Units

20. 6000 HP Loco’s equipment
overview
VCU VCU
TRC 1
DDU DDU
AUX 2-1 AUX 2-2
Non-redundant
MVB (OGF)
Redundant MVB
(EMD)
Redundant
MVB
(OGF)
Gateway
WTB line A
WTB line B
RIOM
RIOM
RIOM RIOM
RIOM
RIOM
Non-redundant
MVB (OGF)
EMD/OGF EMD/OGF
Redundant MVB
(EMD)
VCU1 VCU2
AUX1 TRC 2

21. IGBT Loco Vs GTO Loco
GTO Propulsion System IGBT propulsion System
Bogie control , One inverter for 3
motors
Axle Control, One inverter for each
motor
Weight of converter is 3.3 Ton Weight of converter is 1.8 Ton
Oil Cooling Water Cooling
-- Better Slip Slide Control
-- Possible to operate without Speed
Sensors
Rack & Card based control unit Stand alone computer cards
No of Cards- 16 No of Cards – 5 + power supply (2)
Electro pneumatic Main contactor Electro magnetic Main contactor

22. Advantages of IGBT based
System
Major Semi Conductor industries have introduced high power IGBTs
• No snubber circuits
• Smaller gate circuits
• Higher switching frequency
• Lighter (20%) and smaller
• Reliability (30% longer MTBF)
• Lower noise
• Better slip/slide control (vector control)
Water Cooled System
Individual Axle Control Configuration

23. Traction System
 Salient Features
 System Overview
 Main Components
 Scheme

24. Salient Features
 Axle Control
 Existing Transformer and Traction motor
retained
 Vector Control
 Earth Fault detection
 Better Slip/Slide control

25. System Overview

26. System Overview… (Contd)
 25kV, 50HZ OH catenary is fed to Transformer
through a VCB and a Current Transformer
 Four numbers of secondary winding, two per
converter, 1 per FEC (Front End Converter)
 Front End Converter
 Rectifier while motoring
 Inverter while braking
 DC Link
 VVVF PWM inverter
 Overvoltage protection system (Soft Crowbar
Resistor)

27. Main Components
 Main Transformer
 A 100 Hz filter inductor Existing (integrated in
main transformer)
 Charging contactor
 Line contactor (double pole) & Charge resistor
 Earthing switch & Earthing / Discharge resistor
 Earth fault transducer
 100 Hz series resonant circuit capacitor
 Output filter 4 Quadrant Controller

28. Main Components… (Contd)
 IGBT water cooled power module
 DC-link capacitor
 FQC Common mode EMI filter
 Inverter Common mode filter
 Soft crow-bar resistor
 Traction motor
 Drive Control Unit (DCU)
 Vehicle Interface Unit (VIU)
 Power supply
 Line Voltage Transformer
 Cooling pump for IGBT Power Modules

29. Main Components… (Contd)
• Earth fault transducer • Pre-charge contactor
• Line Contactor
• DC-link capacitor
• 100Hz resonant capacitor • Internal fan

30. Main Components… (Contd)
• Earth resistor
• Pre-charge resistor
• Soft crowbar resistor
• Earthing switch
• Pump
• Electronics power supply
assembly

31. Scheme
PMI Interface board
PMI Interface board
2F45_600
15A2
15C1
2x Internal
Axial Fan
Traction converter main components
PMI Interface board
PMI Interface board
15A4
15A3
PMI Interface board
PMI Interface board PMI Interface board PMI Interface board
PMI Interface board
2F45_600 2F45_600 2F45_600 2F45_600 2F45_600 2F45_600 2F45_600 2F45_600
Vehicle Network
15A5 15A6 15A7 15A8 15A9
DC
DC
Vehicle Interface Unit (15A20)
Drive Control Unit #1 (15A21)
Power Supply
110VDC
DC
DC
+24VDC
Traction link
Drive Control Unit #2 (15A22) Drive Control Unit #3 (15A23)
-24VDC
Traction link Traction link
+24VDC
Splitter
15K1
15K2 15R2
15L12
15R3
15C11/C14
15Q1
15R4
15U1
15L13 15L14 15L15
15L10 15L11 15L16 15L17 15L18
15R1
15A10 / 15A11
15M10/11
MFI (15A24)
15C2
15C3
15C4
15C5
15C6
15C7
15C8
15C9
15A1

32. Converter Structure
Compartment 1 – This
Compartment contains total 9
number of power modules
and their Driver control unit
Compartment 2 – This
compartment contains the,
ferrite cores used for current
sharing and cabling
Compartment 3 – This
compartment encloses all the
switch-gear
Compartment 4 – This
compartment encloses the
Control electronics
compartment

33. Converter Structure
Front View Rear View
Overall dimensions: 3000x1100x2085
Weight: 1810kg

36. Traction Converter
 Front End Converter (FEC)
 Soft Crow-bar
 Inverter
 Power Module
 Features
 Components
 Scheme
 Electronic Boards – PMI, VMD & SID
 Electronic Modules
 VIU
 DCU
 MFI

37. Traction Converter
 Each Traction Converter comprises of
 Front End Converter (2)
 Intermediate DC Link (1)
 Resonant Filter (1)
 Soft Crowbar Resistor (1)
 Three Phase PWM Inverter (3)
 Electronic Modules
 Drive Control Unit (3)
 Vehicle Interface Unit (1)
 MVB to Fibre Interface (1)
 Electronic Power Supply

38. Front End Converter
 Also known as FQC (Four Quadrant Controller)
 Single Phase Full Wave Converter Bridge
 Connected to Transformer secondary on AC side and DC link
on the other side
 Uses 4 Power Modules ( Two power modules per FQC)

39. Front End Converter… (Contd)
 Redundancy ensured (Two DCUs
independently control each FQC)
 Current sharing by paralleling ferrites

40. Current Sharing Ferrite

41. Soft Crow-bar
 Step down chopper to
limit over-voltages in
DC link
 Only 1 IGBT of the
phase leg is used
 Resistor used is air
cooled and is rated
for 1MW-s

42. Inverter
 Generates 3 Ph AC voltage from DC Link
 Controls the power flow to and from the motors
 Independent axle control – One inverter per motor
 9 phase legs (or 4.5 power module) used

43. Vehicle Interface Unit (VIU)
 Forms an interface
between 3 DCU and a
vehicle
 Two processing units
 Microcontroller – runs the
communicatio and support
tasks
 FPGA – programmed with
logic for several interfaces
 Powered by a stabilized
24V supply
 Has an ethernet port for
maintenance

44. Drive Control Unit (DCU)
 Capable of controlling upto 4
power modules
 Upto 14 voltage and current
measurements and 4 optional
speed probes can be connected
 Three processing units
 DSP – runs control and regulation
tasks
 Microcontroller – runs
communication and support tasks
 FPGA – programmed with logic for
several interfaces and timing

45. MVB to Fiber Interface (MFI)
 Interfaces electrical signals
of the MVB bus with optic
signals
 One electrical MVB
connection and max 5 optical
MVB connections

46. Power Module 2W45_600

47. 2W45_600 – Salient Features
 All active components on standalone module
 Simple & Robust design
 Less maintenance – Line replaceable unit
 Self protecting
 Controlled IGBT switching
 Simple paralleling of modules
 Standard components used

48. Components of Power Module
 IGBT (4)
 PMI – Power Module Interface
 Interfaces the power module with DCU
 Local protections of devices are incorporated in PMI
 VMD – Voltage Monitoring Device
 SID – Strukton IGBT Driver
 IGBT driver
 Current transducer (2)
 For measuring the phase currents
 Temperature Transducer
 Measures the heat sink temperature

49. Power Module - Scheme

50. Power Module

51. Power Module Interface (PMI)
 Interface between DCU
and the power module
 Contains all local
protections – makes the
PM fully self protecting
 Max Current
 Max Voltage
 Max Temperature
 Short Circuit Detection
 Protection against wrong
timing

52. Voltage Monitoring Device
(VMD)
 Measures the DC
voltage of the
power module
 Transmits the
measured value
digitally over a
optic fibre

53. Strukton IGBT Driver (SID)
 Used to Turn ON
and OFF an IGBT
 Mounted directly
on an IGBT
 dV/dt and di/dt
sensing
 High speed short
circuit detection

54. Location of Electronic Boards
on PM