The document summarizes information about a traction converter, including: 1. It is composed of a rectifier, middle DC link, and inverter. 2. It provides over-voltage, over-current, and short-circuit protection for the traction motor. 3. Key components include a four-quadrant rectification circuit to convert AC to DC, an intermediate supporting capacitor to buffer voltage, and a PWM inverter circuit to convert DC to variable frequency AC for the traction motors.

1. Traction Converter
Name: Li Zhiping
E-mail: lizhiping704@163.com
Mobile: 18573358213
Name: Li Qing (Lily)
E-mail: 247372278@qq.com
Mobile: 18573358546

2.  The main converter meets standard IEC 61287;
 Integration of main converter and auxiliary
converter;
 The main converter can bear maximum power
caused by traction and electric braking;
 Electromagnetic compatibility meets standards
EN 50121-3-1 and EN 50121-3-2.

3.  Basic parameters of main converter
Please refer to table for basic parameters of main
converter.

4. Item Parameter Remark
Rated capacity 2X379 kVA
Efficiency ≥0.98
Power factor 1
Four quadrant (4QC)
Element type IGBT 3300V-1200A
Switch frequency range 550 – 750Hz
Rated input voltage AC 951V 25 kV catenary voltage
Input current range 0-321A
DC link
Intermediate voltage
DC 1800 V for TractionDC 1850 V for
Braking
Inverter
Element type I GBT 3300 V-800 A
Frequency range 500 Hz-800 Hz
Rated output voltage 1100V
Output voltage range 3AC 0…1500 V
Output current range 0…540A
Output frequency range 0…165 Hz
Cooling system
Cooling mode Water circulation forced air cooling

6. Main Converter Overview
From bottom up
From the front

7. Main Converter Overview

8. Connectors and outputs

9. Rectifier, Inverter

10. Circuit diagram
2 Rectifier(4QC) Each supplies a DC link
2 DC links Each supplies a Traction Inverter
2 Traction inverters Each supplies 2 motors
(SENSOR)
Voltage & Current detector
o protect the 4Q circuit
at 1800 DC
DC Link :
- For SIV supply
- Power accumulator
- Keep stable of voltage
- Absorb the over current / over voltage
- Check the current of short circuit and
cut the main breaker circuit
Connect to
grounding device
1 set of IGBT
Breaking clipper / chopper.
To destroy the regenerative current occurred
Speed more than 20kmh.
To absorb the ove

11.  Main converter
 It is composed of :
rectifier
middle DC link
inverter
 Protection of main converter:
over-voltage protection
over-current protection
short-circuit protection of traction motor
Circuit diagram

12. Circuit diagram

13. Circuit diagram
 a) Four-quadrant rectification circuit
The four-quadrant rectifier has AC-to-DC variation under
traction working condition to provide electric energy for
intermediate DC circuit, while under regenerative
working condition, it has DC-to-AC variation through the
intermediate DC circuit to feedback electric energy to
power grid.

14. Circuit diagram
 a) Four-quadrant rectification circuit
 Each main converter has two four-quadrant rectifiers.
Each four-quadrant rectifier is connected with one
traction winding via a pre-charge resistance and two AC
contactors. Two four-quadrant rectifiers changes AC to
DC and supply power respectively for their own
intermediate return circuit. The four-quadrant
rectification circuit maintains the voltage of the
intermediate DC stable and makes power factor of
transformer secondary side be close to 1.

15. Circuit diagram
 a) Four-quadrant rectification circuit
 When the main converter is put into operation, firstly the
intermediate DC capacitor is charged via pre-charge
resistance, then line contactor closes to avoid large
current impact. Otherwise, if input voltage is fed directly
into uncharged supporting capacitor bank, it will cause
instantaneous peak current. When the intermediate DC
voltage reaches 95% of its theoretical terminal value
(peak voltage of traction winding), the line contactor can
be switched to closing status.

16. Circuit diagram
 b) Intermediate supporting capacitor
Acted as a power accumulator, the intermediate
supporting capacitor can buffer and smooth action of the
intermediate DC loop voltage. The power accumulator is
essential. Because energy input into the intermediate
loop and energy output into it is not equivalent and it
needs supporting capacitor to implement energy
decoupling for traction converter and traction motor.

17. Circuit diagram
 c) PWM inverter circuit
PWM changes the intermediate DC voltage into three-
phase AC voltage with required frequency and
magnitude and supply it to traction motor according to
train operating requirement.
Each main converter has two traction inverters, and each
traction inverter supply power for two traction motors.

18. Circuit diagram
 d) Four-quadrant rectification circuit and PWM
inverter circuit protection
 Over-voltage protection
When value of DC loop voltage is more than setting value, soft short
protection circuit is triggered and main circuit breaker HVB opens.
 Over-current protection
When short circuit and other faults cause over-current, triggering
pulse of relevant module is blocked automatically before branch
current reaches allowable max. value.
 Traction motor short circuit protection
When traction motor terminal or winding has short circuit, triggering
pulse of PWM will be blocked.

19. Traction system-TCU
A110-Traction Control unit
A210-Traction Control unit

20. Traction system-Input

21. Container inside-Rectifier–TBK6L

22. Container inside–Inverter–TBK9L

23. Cooling system
Cooling System
Traction units (4QC, Traction Inverter) Water cooled system with integrated heat exchanger
Internal Heat exchanger Internal closed air loop cooling system
Auxiliary air, Battery Charger cooling system Forced air cooling system

24. Cooling system

25. Container inside–Cooling equipment

26. Container inside–Cooling equipment

27. Container inside–Cooling equipment

28. Container inside–Cooling equipment

29. Container - Maintenance
Time
Component / Activity Once after
1 month
0.5
years
1 year > 1
year
Check for dirt on the container covers and clean outside if required X
Visual check of the container outside:
Check the power connections, grounding connections, signal
connections, and connections outside of the current transducer
Check welding seams and seal welds
X X
Check painted surfaces X
Visual check of the ventilated areas:
Check the ventilated area for dirt and clean if required, especially the
following components:
Cooling fins of the DC/DC transducer, PWM, battery charger, housing of
the MF transformers, booster choke, sine filter choke, and fans
Check the control and power connections
Check gaskets of the container covers for dirt/dust deposits and
damage.
Clean if necessary
X X

30. Container - Maintenance

31. Cooling system - Maintenance

32. Cooling system - Maintenance