The document summarizes the auxiliary converter system used for electric locomotives. It includes two auxiliary converters (Aux 1 and Aux 2) that generate 415V AC power from the 1000V auxiliary winding of the traction transformer. Aux 1 powers variable frequency loads while Aux 2 includes an additional battery charger. The main components are controlled rectifiers, buffer modules, auxiliary inverters, and various electronic control modules. Load is distributed and rearrangement is possible between the three auxiliary converters for redundancy.

1. AUXILIARY
CONVERTER
Vishal M J, Traction Engineering
1

2. Auxiliary System
 Features
 System Overview
 Main Components
 Scheme
 Normal Operation
 Frequency Control
 Voltage Control
 Converter Structure
 Load Distribution & Re-arrangement
 Power Modules
 CREC, Buffer Module, ACPS, LVPS
 Electronic Modules
 ACI, AMC, AGC-T, AGC-I
2

3. Features
 CREC, ACPS, LVPS and Buffer Module –
exchangeable units, have same control board
 All modules contained in a cabinet having IP65
protection
 Sine Wave Filter and Transformer mounted in
IP20 enclosures
 Heat sink at the rear, service access in the
front
 Field replaceable units
 Remote diagnostics possible
3

4. 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
4

5. 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
5

6. System Overview – Aux 1
Buffer-
module
Controlled
rectifier
Inverter
Transformer
25kVAC
AMC AMC
ACI
TCMS
MVB
Sine wave filter
1000VAC
625 VDC
415 VAC
6

7. System Overview – Aux 2
Buffer-
module
Controlled
rectifier
Inverter
Transformer
25kVAC
AMC AMC
ACI
TCMS
MVB
1000VAC 625 VDC
415 VAC
Battery
charger
transformer
415 VAC
AMC AMC
Controlled
rectifier
Buffer-
module
Inverter
ACI
Sine wave filter
Sine wave filter
Circuit breaker
AMC
TCMS
MVB
415V
distribution
415 VAC
140 VAC
110 VDC
625 VDC 415 VAC
1000VAC
Tbat
Ubat
7

8. System Overview… (Contd)
 Supplied from the 1000V auxiliary winding of
the traction transformer
 3 Auxiliary converters installed. On failure of
one of the auxiliary converter, load will be
redistributed
 DC Link Inductor (part of transformer) used
 Thyristor based controlled rectifier and IGBT
based 3 phase inverter
8

9. Main Components - BUR
BUR1, BUR2 and BUR3 are identical. Each
Converter contains:
 Single Phase 1000V/50HZ input terminals
 Input Fuse
 Controlled Rectifier (Fully Controlled Thyristor
bridge)
 DC Link Inductor (part of transformer)
 Discharge Resistor for DC Link
 HV indicator
9

10. Main Components – BUR…
(Contd)
 Buffer Capacitor
 Overvoltage protection – Autonomous crowbar
 Three-Phase IGBT based inverter, 130kVA
 Three phase output filter (for THD<5%)
 Three phase output terminals, 415V/50Hz
10

11. Main Components – Battery
Charger
 The battery charger consists of:
 Three phase insulating transformer
 Three phase circuit breaker
 Chopper Controlled battery Charger 12kW, 111V,
110A
11

12. Main Components
Contactors
Input Fuse
Buffer Module
CTD – Crowbar
Thyristor Driver
12

13. Main Components
Connection
Panel
Sine Wave Filter
Inductor
Ferrite &
Damping
Resistor
13

14. Scheme
14

15. Normal Operation
 Each converter generates a symmetrical 3
phase sine wave voltage with low harmonic
distortion
 Aux1 and Aux2 output frequency can be
controlled to a maximum of 50Hz (while
maintaining V/f constant)
 Aux 3 – Output voltage is 415V and frequency
is 50Hz (fixed frequency loads)
 At low output frequency operation – V/f is
slightly made high to assist speeding of motors
with high startup torque
15

16. Frequency Control
 VCU can change the output frequency in 3
steps – 24Hz, 37Hz and 50Hz (At present only
37Hz & 50Hz available)
 V/f is maintained constant – Motors do operate
normally
 Panto bounce – Frequency will be temporarily
reduced to make use of the stored energy in
running motors. Buffer module capacitors is
the source for extra reserve energy.
16

17. Voltage Control
 DC link is primarily controlled by CREC
 Voltage Feedback is from a sensor which is
connected to the DC Link
 CREC features an onboard synchronization
transformer
 Self supporting unit – in case of an overload,
rectifier will reduce the output voltage
 For better control of heavy motors at low
frequency, voltage boost feature is
incorporated for Auxiliary Inverter
17

18. Converter Structure
 Modular Design
 Power Modules are contained in a well sealed
(IP65) compartment
 Modules have heat sink at the rear, cooled by
forced air
18

19. Converter Structure – Front
View
19

20. Converter Structure – Rear
View
20

21. Auxiliary Converter 1
21

22. Auxiliary Converter 2
22

23. Auxiliary Converter 1
 Auxiliary Converter 1 comprises of
 Controlled Rectifier (1)
 Buffer Module (1)
 Auxiliary Inverter (1)
 Sine Wave Filter
 Electronic Modules
 Auxiliary Control Interface (1)
 Auxiliary Module Control (2)
 MVB to Fibre Interface (1)
 Thyristor and IGBT drivers
23

24. Auxiliary Converter 2
 Auxiliary Converter 2 comprises of
 Controlled Rectifier (2)
 Buffer Module (2)
 Auxiliary Inverter (2)
 Sine Wave Filter
 Battery Charger
 Switchgear
 Electronic Modules
 Auxiliary Control Interface (2)
 Auxiliary Module Control (5)
 MVB to Fibre Interface (2)
 Thyristor and IGBT drivers
24

25. Load Distribution
 Redundancy is achieved by switching load from one BUR to
the other two.
 BUR1 and BUR2 feeds variable frequency loads – Blowers
and Pumps
 BUR3 feeds fixed frequency loads – Compressor, Scavenge
Blower
25

26. Load Rearrangement
26

27. Load Rearrangement… (Contd)
27

28. Controlled Rectifier - CREC
 Converts 1Ph 1000Vac into
controlled DC voltage of 700V
 CREC comprises of
 MOV for over voltage
protection
 Synchronization voltage
sensor
 Thyristors and Snubber
 Thyristor driver (AGC-T)
 AMC Control Board
 Temperature sensor (Heat
28

29. Controlled Rectifier - CREC
 Completely
independent unit,
requires only a power
supply
 External
communication with a
vehicle network via ACI
 Robust Design
 Protected against over
load, over voltage (i/p &
o/p), DC Link short
circuit and over
29

30. Buffer Module
 Stores electric energy – line
interruption ride through
 Capacitive buffer
 Contains autonomous
crowbar – protection against
over-voltages
 CTD operates when DC
voltage exceeds 1000V
 Main Parts are
 Buffer capacitor
 Crowbar + Associated trigger
ckt
30

31. Buffer Module… (Contd)
31

32. Auxiliary Inverter - ACPS
 Converts DC Link
voltage into 3Ph PWM
sine wave voltage
 Voltage & Frequency
can be independently
controlled
 Localized protections,
implemented in AMC
32

33. Auxiliary Inverter – ACPS.. (Contd)
 Main components of the
ACPS are
 Three phase-leg IGBT
modules
 AMC Board
 Three AGC-I control boards
 DC Link capacitors
 Discharge Resistor
 Heat sink temperature
sensor
 Three Output current
33

34. ACPS – Normal Operation
 Inverter will start as soon as the DC voltage
exceeds minimum start value
 Voltage and Frequency will rise with constant
rate (while maintaining V/f constant)
 Output voltage is controlled by modulation
index
 Output frequency is controlled by frequency
modulation
34

35. Battery Charger - LVPS
 Input voltage supply is an isolated 3Ph
140Vrms/50Hz voltage
 Forced air cooled module
 Includes 3Ph Diode bridge rectifier and a down
chopper
 Has one AMC board for control
35

36. Main Component List
 Controlled Rectifier
 Buffer Module
36

37. Main Component List… (Contd)
 Auxiliary Inverter
 Battery Charger
37

38. Auxiliary Control Interface (ACI)
 Interface between Auxiliary
Modules (AMC) and the
vehicle (VCU)
 Has three processing units:
 DSP – runs control and
regulation tasks
 Microcontroller – runs
communication and support
tasks
 FPGA – several interfaces
and timing tasks
38

39. Auxiliary Module Control (AMC)
 Used for control of Auxiliary
converter modules
 Three processor boards
 DSP – control and regulation tasks
 Microcontroller – runs communication
and support tasks
 FPGA – interfaces, timing tasks and
phase leg protection
 Control functions configurable by
software
 Main functions are
 Protection of auxiliary converter
modules
 Pulse generation
 Control of Auxiliary modules
39

40. Auxiliary Module Control (AMC)
 Protection Functions
 Phase leg protection
 Overlap protection
 Minimum pulse detection and protection
 Dead time generator
 Current measurement and detection
 Di/dt detection
 Temperature measurement and detection
 Max voltage protection
 Voltage monitoring
40

41. 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
41

42. Auxiliary Gate Controller (AGC-
T)
 Driver stages for controlling
the two thyristor modules
 Control electronics through
10 pin flat cable connector
 Power supply and control
signals galvanically isolated
 Compact and rugged –
Maintenance free and easily
replaceable unit
42

43. Auxiliary Gate Controller (AGC-
I)
 Used to control a
Semikron Semix IGBT
module
 Driver stages for
controlling two IGBTs of
an IGBT module
 Mounted directly on IGBT
 di/dt control
 High speed short-circuit
detection
 Control electronics
43