IGBT based SRs and BURs Locomotives:
The Electrical equipment for loco consists of Two water cooled
Traction Converters with 3 independent Motor Side inverters,(BHEL,
Bombardier, ABB & CGL makes)
Aux. Converter -1 with 1*130 kVA inverter. AUX Aux. Converter -2
with 2*130 kVA inverter and 11 kW battery charger & Two Vehicle
control units.(BHEL, Bombardier, ABB & CGL makes)
Advantages :
The existing GTO based traction converter is a group drive, i.e., all the
traction motors in a bogie are connected in parallel. While, the IGBT
based converter has got single axle drive capability, therefore, in case
of any problem with a particular TM, only that particular TM can be
isolated unlike in the GTO based converter where the whole bogie has
to be isolated.
Due to single axle drive it has got better adhesion performance. Better
slip / slide controls, because of axle control and modern high speed
digital signal processing algorithm
40% reduction in weight and compact in size compared to GTO
equipment will facilitate to install additional equipments like hotel load
converter in the locomotive.
Power loss reduction by approx. 50% in comparison with GTO loco
equipment. Annual energy saving (considering @ Rs 4.62 / unit) will
be approx. Rs. 34 lakhs assuming loco utilization of 85% service per
day.
Water cooled system thus safer vis-à-vis oil cooled system.
Less harmonics because of high switching frequency.
System Description The 25 kV - 50 Hz catenary voltage is fed to the
primary winding of a existing main transformer through pantograph,
main circuit breaker, primary current transformer and a roof cable
bushing.
The two set of secondary windings (four windings) of the main
transformer are connected to 2 nos. of identical IGBT main converters
via line and charging contactors and supply traction power to the
propulsion equipment. The ac power from the secondary windings of
the main transformer is rectified and regulated by a PWM converter
unit consisting of IGBT bridges, and then the regulated DC power is
fed to a VVVF (Variable Voltage Variable Frequency)
IGBT 3-Phase PWM inverter unit. Each inverter shall be feeding three
individual three phase traction motors i.e. axle (Independent) control.
The electric brake is regenerative brake. In the electric brake mode,
the generated power by traction motors in generator mode is fed back
to the catenary by the VVVF inverters and the PWM converters. The
electric braking shall be supplemented with EP brakes by means of
brake blending. The priority shall be for electrical braking and EP
braking will be supplemented when it is required to meet total brake
demand.
An earth fault in each propulsion circuit will be detected by detecting
devices to generate an warning to the driver. With an earth fault
detected driving is still possible.
The Traction Control Unit (TCU) is mainly based on Digital Signal
Processor (DSP), a supervisory microprocessor and IO cards. The
main functions of TCU include control of IGBT main traction
converter/Inverter Control, Braking Control.
The existing Traction motors are modern inverter control shall work
with speed sensors and temperature sensors. Speed and temperature
sensor less vector control will be implemented as well, in case of a
defect speed sensor the sensor less mode will be activated. The
modern slip/slide control shall guarantee that the maximum adhesion
available from the track is utilized. Each traction motor shall have its
own individual slip/slide control. Actual motor temperature and
protections are to be integrated in the modern control system.
IGBT based Traction converter: Each traction converter shall have
two Four Quadrant Converters (FQC) and three inverters, each
feeding a traction motor along with respective control system.
FQC converter (Line Converter-2nos per SR)
The Four Quadrant Converter (FQC) consists of a single phase full
wave converter bridge connected to a transformer winding on the AC-
side and to the DC-link on the other side.
Each FQC-converter comprises of two IGBT-power modules. There
are two FQC -Converter in one Traction converter and there output is
paralleled. Current and voltage transducers are part of the power
modules. The secondary winding of the main transformer is connected
between the two phases of these.
The four FQC power modules are controlled by two DCUs (DCU1 &
DCU 3 ) and they are connected in such a way that in case one DCU
fails then there will be loss of only one FQC-converter and the other
FQC-converter remain operational and there by redundancy of DCU
controller is achieved.
Soft crow-bar chopper (Intermediate Circuit)
The traction converter comprises a step down chopper to limit over
voltages. This soft crow-bar chopper is controlled by the DCU 2 which
is also controlling the inverter of Motor 1.The DC link voltage will be
app. 2800 V for all three versions of the locomotive
Traction Inverter (Drive converter-3 nos per SR)
An inverter generates a three-phase AC-voltage from the DC-link
voltage as well control the power flow to and from the traction motors
during traction and braking respectively.. The fundamental frequency
and the amplitude of the output voltage can be changed continuously
and independently from each other. Independent motor control
requires three inverters .Current- and voltage transducers are part of
the power modules.
The traction inverter is controlled by Three DCUs ( DCU1, DCU2 &
DCU3). and they are connected in such a way that in case any one
DCU fails then the traction converter still in operational and there by
redundancy of DCU controller is achieved .
BHEL make SR Connections between cooling system & existing heat
exchanger (Radiator) 1- Hot Water inlet to Heat exchanger, 2- Cold
Water outlet from Heat Exchanger, 3 -Air Vent
Technical Data Of Traction Converter
Main transformer voltage (nominal) 1269 VAC
DC-link voltage (nominal) 2800 VDC
Power factor 1,Maximum r.m.s. output current 450 Arms
Nominal voltage 2180 V, Frequency 65 Hz
Coolant: water /glycol mixture
Cooling system
The water cooling system is a closed loop system with water /glycol
mixture as a cooling medium BHEL and ABB makes . In Bombardier
make the coolant mixture of water and Antifrogen N .The cooling
system comprises a pump, heat-exchanger and a expansion tank.
As shown in Figure, the pump circulates the coolant. The Cooling
pump is located inside the SR in ABB and Bombardier makes.
The coolant enters to the water cooled heat sinks of individual power
modules through common inlet manifold and absorbs the heat
dissipated by IGBT modules. This heated water collected from the
common outlet manifold will flow to the Radiator .Radiator is cooled by
forced air and the cooled water re-enters the traction converter. This
process is continuous. The function of expansion tank is to give
provision to accommodate change in the cooling water volume due to
temperature variation and acts as a reservoir for compensating losses
due to evaporation and also minor leakages. The level of the water
can be viewed from sight glasses on the side wall of the expansion
tank between Min-max mark.
SR1 and SR2 cut out cocks are in closed condition since converter
contactors are Electromagnetic/ Motorized Contactors. Though the
individual inverters are supplying power to Traction motors, it is
possible to isolate one traction motor by Loco Pilot. Loco pilot can
isolate one SR by using 154 as like in GTO based SR provided Locos.
However if fault in any one inverter module / Traction motor circuit in
SR, Control electronics will isolate the same and causes to reduce
th
1/6 of Traction/Braking. If fault in any one Line Converter out of two
Line converters in SR, Control electronics will isolate the same and
th
causes to reduce 1/4 of Traction/Braking.
BHEL make IGBT Based SR Cooling system and 3way cock positions
IGBT Based General Description of Auxiliary Converter:
Auxiliary winding on the main transformer is for feeding the Auxiliary
converters 1 & 2. The input voltage is 1000VAC .Auxiliary converter 1
is also called as Bur 1 but Auxiliary Converter will have Bur2, Bur 3
and Battery Charger. (Three-phase IGBT-based inverter, 130kVA,
cos(j)=0.8,415V/50Hz) The control Electronics supply is taken from
the 110VDC battery.
The energy conservation feature through multi level ventilation/cooling
is adopted. The frequency steps for multiple frequency operation are
24Hz, 37Hz, 47Hz and 50Hz. The speed is controlled in three steps
(17Hz, 33Hz and 50Hz) for the traction motor blowers, oil cooler
blowers depending on the temperature of the traction motors / cooling
oil sensed by the temperature sensors in traction motor stator winding
and oil cooling circuit. Aux 3, operates at a fixed frequency of 50Hz. It
enables soft starting of the compressor motors by varying the voltage
and frequency from zero at start to full value.
Control Electronics: Controlled by TCN based network. The
advancement in the processor speed which has paved the way for
less number of PCB cards (only 3 major cards compared to 17 in
MICAS) with better performance at the higher temperatures. Isolation
of cab due to card failure will not take place. The card names and
comparison between MICAS-S2 and TCN based network is given
below. ICP –inter face control and processing Board, DDU –Driver
Display unit and RBU-RIOM Base Unit
SL.no MICAS TCN(BHEL) SL.no MICAS TCN(BHEL)
1. FLG1 ICP1 7. SLG1/2 VIU1/2
2. FLG2 ICP2 8. NSC1/2 DCU1/4
3. STB1 RBU1 9. ASC1 DCU2 & DCU3
4. STB2 RBU3 10. ASC2 DCU5 & DCU6
5. HBB1 RBU2 11. BUR1/2/3 ACI1/2/3
6. HBB2 RBU4 12. DDA1/2 DDU1/2
