The Anonymous Widower

Is Bombardier’s 125 mph Bi-Mode Aventra With Batteries, A 125 mph Battery-Electric Aventra With Added Diesel Power To Extend The Range?

The LEVC TX taxi is described in Wikipedia as a plug-in hybrid range-extender electric vehicle.

Could Bombardier’s 125 mph Bi-mode Aventra with batteries, be an equivalent rail vehicle?

I will start with the Class 720 train for Greater Anglia, which is probably the nearest train to a 125 mph Aventra in production.

  • It is formed of ten-cars.
  • It is 243 metres long.
  • It can accommodate 1,100 seated and 290 standing passengers.
  • It has a 100 mph operating speed, although this article on the East Anglian Daily Times, says it will be tested at up to 110 mph.

I will use this information to make some assumptions about Bombardier’s proposed 125 mph bi-mode Aventra with batteries.

Weight Of A Ten-Car Class 720 Train

In The Formation Of A Class 710 Train, I give the weight and length of a four-car Class 710 train as the following.

  • Weight – 157.8 tonnes
  • Length – 82.88 metres

Adjusting this weight to the 243 metres length of a ten-car Class 720 train, gives a weight of 462.7 tonnes.

This is the best I can do for the moment.

Kinetic Energy Of A Train At 125 mph

This is my calculation.

  • The empty weight of the train is 462.7 tonnes
  • To that must be added 1390 passengers, who average out at 90 Kg each with baggage, bikes and buggies. This is 125.1 tonnes.
  • This gives a total train weight of 587.8 tonnes.
  • Using Omni’s Kinetic Energy Calculator, gives a kinetic energy of 255 kWh at 125 mph.

For those of you, who feel I am a bit cavalier over the use of mass and weight, I agree with you, but many reading this won’t know the difference.

Handling Regenerative Braking

Imagine a train stopping from 125 mph at a station.

  • Looking at the roof of a Class 345 train, they don’t have any resistor banks, so energy must be stored on the train or returned through the electrification. Are all Aventras the same? See Class 710 Train Rooves At Blackhorse Road Station.
  • The batteries must be able to handle all the energy generated by the traction motors in their braking mode.
  • So they must be able to handle the 255 kWh of a train running at 125 mph.

It would probably mean energy storage over 300 kWh.

Some Aventras Are Two Half Trains

In A Detailed Layout Drawing For A Class 345 Train, I give the formation of a nine-car Class 345 train as.

DMS+PMS+MS1+MS3+TS(W)+MS3+MS2+PMS+DMS

Note.

  1. Eight cars have motors and only one doesn’t.
  2. The train is composed of two identical half-trains, which are separated by the TS(W) car.
  3. There are four wheelchair spaces in the TS(W) car.

In this article in Global Rail News from 2011, which is entitled Bombardier’s AVENTRA – A new era in train performance, gives some details of the Aventra’s electrical systems. This is said.

AVENTRA can run on both 25kV AC and 750V DC power – the high-efficiency transformers being another area where a heavier component was chosen because, in the long term, it’s cheaper to run. Pairs of cars will run off a common power bus with a converter on one car powering both. The other car can be fitted with power storage devices such as super-capacitors or Lithium-ion batteries if required. The intention is that every car will be powered although trailer cars will be available.

Unlike today’s commuter trains, AVENTRA will also shut down fully at night. It will be ‘woken up’ by remote control before the driver arrives for the first shift

This was published over seven years ago, so I suspect Bombardier have refined the concept.

The extract talks about pairs of cars, which share the main electrical components.

So in the Class 345 train and possibly the ten-car Class 720 trains, are the DMS and PMS cars at the ends of the train, these pairs of cars?

I like the half-train concept, as I suspect a clever computer system on the train can reconfigure the train, if say a pantograph or other major component fails.

Distributing The Energy Storage

I feel that the best philosophy would be to distribute the batteries and/or supercapacitors through the train.

Energy storage of somewhere between thirty and sixty kWh in each car would probably be more than sufficient to handle the braking energy by a wide margin.

As typically, hybrid buses like London’s New Routemaster have batteries of about 60 kWh, I’m fairly certain a big enough battery could be placed under each car.

My Electrical and Control Engineering experience also suggests that if most axles are powered on the train, distributing the energy storage could mean shorter and more efficient cabling and electricity flows.

Could the train be a formation of more independent cars each with their own computer systems, connected by the common power bus mentioned in the earlier extract and a high-capacity computer network.

How Much Power Would A Train Need In The 125 mph Cruise?

I investigated this question in How Much Power Is Needed To Run A Train At 125 mph? and came to the conclusion, that 3 kWh per vehicle mile is a sensible figure.

I also feel that as the three kWh per vehicle mile relates mainly to an InterCity 125, that Bombardier could do better with a modern train.

Consider.

  • Derby and Leicester are thirty miles apart.
  • A journey takes twenty minutes.
  • A train is running non-stop between the two stations at 125 mph.

Using the train consumption figure of three kWh per vehicle mile, means that a ten-car train would need 900 kWh.

The required power would need to be supplied at a rate of 2,700 kW.

This means one of the following.

  1. The train has an enormous on-board power-unit.
  2. The train has an enormous battery.
  3. The train has a very high aerodynamic and electrical efficiency.

Or it could be a figment of Bombardier’s imagination.

Only the Option 3 is feasible.

Consider.

  • Bombardier also build aircraft and must have some aerodynamicists, wind tunnels and other facilities of the highest class.
  • Aventras seem to have very clean lines.
  • Aventras are very quiet trains inside and outside.
  • Bombardier claim that the trains have intelligent air-conditioning and lighting.
  • Class 710 trains have an average car weight, which is seven percent lighter than Class 378 trains.

It is also known that Bombardier have had a lot of trouble programming the advanced Train Control and Management System (TCMS). I believe that this could be because it is very sophisticated and getting it right took longer than expected.

I say this because the specification for the first version of Artemis was challenging to program as so much was first-of-its-type software. It was late, but once correct, it became an amazing world-wide success.

Is the Aventra another game-changing project?

There are all sorts of ways, that a sophisticated TCMS, can save electricity on a train.

  • Ultra smooth acceleration and braking.
  • Intelligent power management.
  • Precise control of all train systems, like heating, air-conditioning and lighting, according to ambient conditions and passenger loading.
  • GPS or ERTMS-controlled Driver Assistance Systems.

Couple this with lightweight structures, innovative design and world-class aerodynamics and could the train have an electrical usage as low as one kWh per vehicle mile?

This would mean a train between Derby and Leicester would consume 300 kWh, at a rate of 900 kW for twenty minutes.

Have Bombardier read about the design of the Douglas Skyhawk?

Wikipedia says this about the design and development of the aircraft.

The Skyhawk was designed by Douglas Aircraft’s Ed Heinemann in response to a U.S. Navy call for a jet-powered attack aircraft to replace the older Douglas AD Skyraider (later redesignated A-1 Skyraider). Heinemann opted for a design that would minimize its size, weight, and complexity. The result was an aircraft that weighed only half of the Navy’s weight specification. It had a wing so compact that it did not need to be folded for carrier stowage. The first 500 production examples cost an average of $860,000 each, less than the Navy’s one million dollar maximum.

I remember reading how Heinemann was ruthless on saving weight and complexity to get a more capable aircraft.

Every improvement in efficiency means you need less power to power the train, which in a multi-mode train, means one or more of the following.

  • Physically-smaller diesel engines and fuel tanks.
  • Smaller hydrogen fuel cells and hydrogen tanks.
  • Smaller onboard energy storage.

I wouldn’t be surprised to see some radical weight-saving developments in the traction system. Lightweight diesel engines, energy storage and other large electrical components are all possibilities.

This all may seem pie-in-the-sky thinking, but a similar control revolution happened at Rollls-Royce with the RB 211 engine, when around 1990, full authority digital engine control or FADEC was developed

Is another company, with its designers and researchers in Derby going down the same route? Or do they all drink in the same pub?

Rolls-Royce certainly appear to have been successful, with their large aero engines.

I stated earlier that an energy use of one kWh per vehicle mile, would mean a train between Derby and Leicester would consume 300 kWh, at a rate of 900 kW.

Here’s a complete set of figures for a ten-car train.

  • 4 – 1200 kWh – 3,600 kW
  • 3 – 900 kWh – 2,700 kW
  • 2 – 600 kWh – 1800 kW
  • 1 – 300 kWh – 900 kW
  • 0.5 – 150 kWh – 450 kW

The second figure is the energy needed by the train between Derby and Leicester and the third is the rate, it would need to be supplied for a twenty-minute schedule.

Note how, that as the train gets more efficient and needs less power per vehicle mile, the rate of supplying energy to the train gets dramatically less.

Supplying 3,600 kW from electrification would be easy and trains like the Class 390 train are designed to take 5,000 kW to maintain 125 mph. But supplying that energy from on-board diesels or batteries would durely require enormous, heavy components.

Could 125 mph Be Sustained By Diesel Engines?

Bombardier have said, that their proposed High-Speed Bi-Mode Acentra with batteries will have the following characteristics.

  • Ability to run at 125 mph on both electricity and diesel.
  • A flat floor
  • A class-leading passenger environment.

The last two points are the difficult ones, as it means that engines must be smaller.

  • Smaller engines make a flat floor, which is so good for less-mobile passengers, buggy pushers or case-pullers, much easier to design.
  • Smaller engines make much less noise and vibration.

But surely, small engines wouldn’t provide enough power to drive the train at 125 mph.

CAF’s new Class 195 train has a Rolls-Royce MTU 6H1800R85L engine, which is rated at 390 kW in each car. These engines aren’t that noisy and fit neatly under the train floor. But disappointingly, they drive the train, through a noisy ZF Ecolife mechanical transmission.

Dimensions and weight of this engine are as follows.

  • Length – : 2.6-4 metres
  • Width – 2.1- 2.8 metres
  • Height – 0.8 metres
  • Dry Weight – 2.9-4.0 tonnes
  • Wet Weight – 3.0-4.2 tonnes

If engines like this were packaged properly with an alternator to generate electricity, I believe it would be possible to put enough power under the floor of a ten-car train.

  • The train is 240 metres long.
  • It will probably be two half trains, so it could be easy to fit two engines in each half train.
  • One engine could be under the driving cab and the other in the best place for balance.

I’m sure Rolls-Royce MTU could oblige.

They have a 12V1600R80LP PowerPack, described in this datasheet on the MTU web site.

  • It has a 700 kW output.
  • It is built for diesel-electric operation.
  • It is slightly larger than the engine in the Class 195 train.

Could one of these engines be put under each driving car?

Calculating backwards would mean that the train would need an energy use of 1.55 kWh per vehicle mile.

I believe that by good design, this is a very attainable figure.

As in London’s New Routemaster bus, the engines would top up the batteries on the train, which would then power the traction motors and the other train systems.

The TCMS would control everything.

  • Use an appropriate number of engines in every phase of the trip.
  • Raise and lower the pantograph without driver action.
  • Use battery power if required to boost diesel power.
  • Even out engine use, so that wear was equalised.

I’m led to the conclusion, that with power of about 1,400 kW from two modern underfloor diesel engines, a high-speed bi-mode Aventra with batteries can cruise at 125 mph.

Kinetic Energy Implications

If I modify the kinetic energy calculation to add ten tonnes for the diesel engines, the kinetic energy goes up to 259 kWh.

This may seem surprising, but the kinetic energy calculation is dominated by the square of the speed of the train.

If the engines at ten tonnes each, that only increases the train’s kinetic energy to 264 kWh.

One of the arguments against bi-mode trains, is that they are carrying heavy diesel engines around, that are doing nothing most of the time.

Whe  the train is accelerating to operating speed, some extra kWhs will be expended, but once in the cruise, they enjoy a free ride.

Stopping At A Station

As I said earlier, when the train is running at 125 mph, it has an energy of 255 kWh.

With the two added diesel engines, this could be a bit higher and perhaps up to 264 kWh.

This energy would be used to recharge the onboard storage at a station stop.

The TCMS would probably ensure that, when the train came to a full stop, the onboard storage was as full as possible.

In a five-minute stop, running the two diesel engines could add 116 kWh to the batteries, but I suspect an automatic charging system could be better.

Accelerating From A Station

Diesel power would probably not be enough working alone, but the energy in the onboard storage would also be used to accelerate the train to the 125 mph cruise.

Optimal Station Stops

The Class 720 trains on Greater Anglia will be sharing tracks and platforms on the Great Eastern Main Line with Class 745 and Class 755 trains from Stadler.  It has been stated by Greater Anglia, that the Stadler trains will provide level access between platform and train and will use gap fillers to improve the operation.

I wouldn’t be surprised to see the Class 720 trains providing level access on Greater Anglia, where most of the platforms seem to be fairly straight.

Level access is important, as it speeds up station calls by easing entry to and exit from the train.

Most of the stations on the Midland Main Line appear to be fairly straight. The exception was Market Harborough station, which has now been rebuilt with step-free access and straighter platforms.

I would think it extremely likely, that whatever bi-mode trains run the Midland Main Line in the future, they will save time on the current service, by executing very fast station stops.

I would expect that maximum stop time at the stations will be of the order of two minutes.

This time may not be long enough for a train to connect to a charger and take on more power for the batteries.

Conclusion

The TCMS and the way it manages all the energy on the train, is key to creating a successful 125 mph bi-mode Aventra with batteries.

It would appear that the diesel engines can be used as required to charge the batteries.

So it perhaps might be best to consider the train to be a battery one, with diesel engines.

As a Control Engineer, I’m proud of what Bombardier are doing.

But the aviation industry was doing this thirty years ago, so it has probably been a long time coming.

 

 

 

 

 

 

 

 

 

 

July 9, 2019 - Posted by | Transport | , , , ,

No comments yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.