Traction motor commutation
Traction motor commutation
(OP)
I am looking at a possible conversion of a diesel-electric locomotive so that it can be run off the catenaria instead of from the usual DC generator.
The railway grid in question is a 16.7 Hz grid and the ripple in the rectified voltage will cause a lot more armature current ripple (33.3 Hz) than the existing DC motors were built for. At least, that is what I think.
I haven't been very successful in searching for information on this problem. Anyone out there with first-hand knowledge? Especially practical data on allowed ripple percentage, allowed current A/s, needed inductance and other such things for DC traction motors at around 1000 kW.
Thanks a lot for your inputs.
The railway grid in question is a 16.7 Hz grid and the ripple in the rectified voltage will cause a lot more armature current ripple (33.3 Hz) than the existing DC motors were built for. At least, that is what I think.
I haven't been very successful in searching for information on this problem. Anyone out there with first-hand knowledge? Especially practical data on allowed ripple percentage, allowed current A/s, needed inductance and other such things for DC traction motors at around 1000 kW.
Thanks a lot for your inputs.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.





RE: Traction motor commutation
A friend lives in a small city where freight trains are often stopped.
These are very long trains and the location is at the eastern edge of the Rocky mountains. The majority of the freight is Canadian grain destined for the seaport of Vancouver. There is an issue of residential foundations cracking in the city. It is attributed to the cogging of the locomotive drives as the trains start.
These are AC motors supplied by PWM drives.
Yes, I know you are working with DC motors, but it may be well to consider whether a ripple on the DC will cause cogging.
My thought is that 16.7 Hz is fast enough that any cogging will be negligible.
Bill
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"Why not the best?"
Jimmy Carter
RE: Traction motor commutation
My concerns are not about the community, though. It is enough to have the commutator to think about...
*Full block switching is used because the switched voltage is usually in the 1500 - 2000 V region in those drives and switching losses are quite high.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.