The Anonymous Widower

Thoughts On A Battery/Electric Train With Batteries And Capacitors

I’m going to use a Class 350/2 train as the example.

In Porterbrook Makes Case For Battery/Electric Bi-Mode Conversion, I calculated the kinetic energy of one of these trains at various speeds.

Wikipedia gives this information.

  • Maximum Speed – 100 mph
  • Train Weight – 175.5 tonnes
  • Capacity – Around 380 passengers

If I assume each passenger weighs 90 Kg with baggage, bikes and buggies, the train weight is 209.7 tonnes.

This weight could be a bit high, bnut then the train must perform even when crush-loaded.

Using Omni’s Kinetic Energy Calculator, I get the following kinetic energies at various speeds.

  • 80 mph – 37.2 kWh
  • 90 mph – 47.1 kWh
  • 100 mph – 58.2 kWh
  • 110 mph – 70.4 kWh

In the video shown in A Must-Watch Video About Skeleton Technologies And Ultracapacitors., Taavi Madiberk of Skeleton Technologies likens a capacitor/battery energy store with Usain Bolt paired with a marathon runner. Usain would handle the fast energy transfer of braking and acceleration, with the marathon runner doing the cruising.

This would seem to be a good plan, as the capacitors  could probably quickly store the regenerative braking energy and release it at a high rate to accelerate the train.

Once, up to operating speed, the lithium-ion batteries would take over and keep the train at the required speed.

Obviously, it would be more complicated than that and the sophisticated control system would move electricity about to keep the train running efficiently and to maximum range.

The capacitors should probably be sized to handle all the regenerative braking energy, so for a 100  mph train, which would have a kinetic energy of 58.2 kWh, a 100 kWh capacitor would probably be large enough.

In some ways the lithium-ion batteries can be considered to be a backup to the capacitors.

  • They provide extra power where needed.
  • If during deceleration, the capacitors become full, energy could be transferred to the lithium-ion batteries.
  • If after acceleration, the capacitors have got more energy than they need, it could be transferred to the lithium-ion batteries.
  • The lithium-ion batteries would probably power all the hotel services, like air-con, lights doors etc.  of the train.

Note that the energy transfer between the capacitors and the lithium-ion batteries should be very fast.

A good Control Engineer could have a lot of fun with sorting the trains control system.

 

 

 

November 11, 2018 - Posted by | Transport | , , ,

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