by rowan bell graduate electrical engineer, interfleet technology ltd an overview of the electrical...
TRANSCRIPT
By Rowan BellGraduate Electrical Engineer,
Interfleet Technology Ltd
An Overview of the Electrical Design Process of Interfleet
Technology’s IMechE Railway Challenge 2012 Winning
Locomotive
Railway Engineers Forum Scotland, Young Railway Professionals’
Presentation Competition
Glasgow, 21st November 2012
The Challenge comprised of three tests for the
locos:
Traction
A time trial between two points, limited to
10km/h, with penalties for speeding!
• Acceleration• Deceleration• Speed control
10km/h
T
ω
Energy Recovery& Reuse
A test of regenerative braking efficiency
regen
regen fwd
rev
The IMechE Railway Challenge
• A competition to design, build and trial a 10¼’’ gauge locomotive
• Open to universities and companies of the railway industry
• Loco to be refuelled within 90s, and meet emergency braking and gauging
specs
Ride Comfort
A test to quantify the movement and
vibration of a loco’s bodyshell during
motion
ITL’s Design Process: My Contribution
• Boundaries of the specifications, mechanical requirements and our timescales
were tight!
• An ICE prime mover and an electrical traction system were both required..
Electrical Traction System
The regenerative
braking function?
EnergyStorage
2Q or 4Q, BLDC, inductionmotor or PMSM drive?
Li+ batteries
Brushed DCmotors with 1Q
controller
Regenerative Braking and
Traction Facility...
Supercapacitors
compact economical proven!
feasible challenging!
high power lightweight safe eco?
Options:
Aux.
Generator
ElectricalTraction System
Rail
Energy Storage
?
RegenerativeBraking and
Traction Facility
Power Scheme:
The Topology
Traction power
Regenerative braking power
Regen. energy traction power
Auxiliaries’ power
Armature Voltage Feedback signal
User interface signals
AC-DC convert
er24V, 8A o/p
4 Electromagnetic
Disc Brakes
Control Relays, Interlock Relays
&Safety Features
Petrol Generator 110V / 230V,
50Hz, 13A o/ps
1Q DC Motor
Controller 90V, 32A
o/p
4 Brushed
DC Motors
in series24V, 28A
Regenerative Braking and
Traction Facility with supercapacitor
bank..
• The loco employs the following electrical topology:
Regenerative Braking and Traction Facility (1)
• Falling generated voltage + supercapacitors’ charging curve + ? = practical
deceleration..
• Supercapacitors’ discharge curve + rising Back EMF + ? = practical
acceleration..
• Two variable-output DC-DC converters in anti-parallel?
• The driver would control braking and traction by changing the Output Voltage
demand..
Traction converter(Flyback)
Braking converter(Flyback)4
Brushed DC
Motors in series
24V, 28A
Supercapacitor bank(with series inductance)
Output Voltage
Output Voltage
Regenerative braking power Regen. energy traction
power
User interface
signals
Regenerative Braking and Traction Facility (2)
• For braking, the solution was to employ PWM of the generated voltage..
• The motors may be configured in series or parallel
• For traction, the supercapacitors are simply switched onto the motors, configured
in parallel
• The PWM time period was to be calibrated during testing
Generated
voltage
Added series
inductance
4 x supercapacito
rs, 30,443J
PWM
58F, 16.2V supercapacitor
ITL’s Performance and Success
• ITL’s loco came first in all three tests!
• Ride Comfort was excellent!
• Traction was good!
• Energy Recover & Reuse wasn’t great..
The braking effort was huge, and the starting torque was really small..
That 4Q motor controller is looking pretty good!
BO O M !