Electric buses

Cars, buses, bicycles, electric airplanes: all electric transportation that exist. Conversion, engines and electric drives for transport ...
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chatelot16
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Re: Electric buses




by chatelot16 » 29/04/18, 16:37

a low autonomy battery is theoretically possible if we count the kWh but impossible because we exceed their maximum power, and we cycle too much, and the lifespan is ridiculously short ... so we need batteries big enough not to exceed their maximum power

if we want to put catenary on a part of the course to be satisfied with a very weak autonomy between the catenary, the batteries are not suitable ... we need means supporting more cycle like flywheel, or compressed air, or supercapacitor ... but currently I find the flywheel better than the supercapacitors

but we accumulate the disadvantages: you need both an expensive new bus, and an infrastructure to recharge often

the bus solution with enough large batteries avoids the need for a special infrastructure: it simply replaces diesel buses

we could also think of interchangeable batteries with an autonomy of 1/2 day ... that divides by 2 the weight of battery compared to a whole day

but we cannot think of too small interchangeable batteries that we change at each terminus, because it will not do the power

it would not be stupid to put the batteries in a trailer, to reuse the old diesel buses or there is no place to mount the batteries because of the lowered floors to facilitate access ... to change the battery on change trailer
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Re: Electric buses




by Bardal » 29/04/18, 19:01

I think there is more simple than that:

- suppose an agglo with an approximate diameter of 10 km, with a central station, or approximately.

- imagine a star network of catenary lines 2,5 km long, on average, around this center, and buses equipped with batteries giving them autonomy on batteries of around 20 km. This network is in theory capable of running a fleet of buses, without any stop linked to a recharge, serving the entire agglomeration (and even a little more).

The advantages are obvious:

- vehicles only have to transport a minimal battery bank (7 or 8 times less than a "pure battery"), without downtime for recharging, while benefiting from sufficient storage for recovery functions of energy. Their unit price should approach that of a diesel vehicle.

- the system is extremely flexible, making it possible to serve all the service points entering the perimeter; it can be upgraded at the cost of extending certain lines, or increasing the capacity of the batteries, or any intermediate solution ...

- for a little extra dollar, we can imagine long distance connections (with short lines in each major town crossed)

- with a slight effort of standardization, the network can be used for other uses than that of city buses, even opening up to the private sector. And at other times of the day, further increasing profitability.

Etc., etc...

I hardly believe, at least in the short term, in supercapacitors (this is not currently suitable for this kind of use), nor in flywheels (too low autonomy except ultra-sharp technology); compressed air would be more suitable, but at the cost of complexification which I consider unacceptable. On the other hand, I think that in current battery technologies, we must be able to find an interesting compromise given the constraints that you list (frequent discharges, instantaneous power, no other infrastructure than the catenary line ...).
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Re: Electric buses




by chatelot16 » 29/04/18, 21:15

The Oerlikon gyrobus nevertheless operated for a certain time despite a catastrophic defect! use of three-phase without electronic converter, therefore poor efficiency, poor use of the variable speed of the steering wheel, both when loading and unloading poor adaptation to bus speed ... with modern electronic drives we would do at least 4 times better easily and maybe even more

the advantage of the flywheel is an almost unlimited number of cycles, much better than the batteries

it remains to invent the right way for a bus to transform into a troley bus without having to place the troley with precision on the 2 cables ... I have for a long time a solution that deserves to be patented ... but I renounce to the patent and puts it in public on econology!

my solution is to make an overhead line where there is only one conductor, but with a phase change every 20 meters: the bus has 2 poles, one in front and one behind with a distance between the 2 point of contact of exactly 20m ... so it receives power almost permanently with just a small interuption where there are phase changes ... which would be bad for a traction entirely by the catenary, which has no matter if it is mainly used to recharge something ... and I do not say a battery because I think that for a very frequent recharge the flywheel is better than the battery ... which does not prevent also have a backup battery to be able to advance at low speed to the next catenary if the flywheel is completely exhausted

with my phase change every 20 m the bus pole can have a wide sensor without the need for precision, without the risk of making short circuits between the 2 lines close to the troley buses

aesthetic question it clogs the sky less than the 2 troley lines ... it will be like a high line in the form of a chain for one phase, and a low horizontal line for the other phase ... and every 20m an isolator and an inversion of the 2 phases
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Re: Electric buses




by gildas » 29/04/18, 22:34

Unsightly electrical wires would be the disadvantage of trolleybuses, which have a lot of advantages.
Saint Etienne (...) The transformation of part of the trolley network into a bus started in 1999, with line 1. Persistent works on its route (Ondaine valley) as well as the aesthetic will of the mayors of the municipalities crossed ( Chambon-Feugerolles in particular) were right about trolleys. Line 6 was interrupted with the arrival of the Agora L, more modern than the old articulated trolleys which have become dilapidated. Throughout the course, the LACs are still in place. This strong line cannot receive a tram because of the slope of its route, without however that the return to trolley-buses is not included in the agglomeration's projects.

https://fr.wikipedia.org/wiki/Trolleybus
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Re: Electric buses




by Bardal » 30/04/18, 06:29

However, this did not prevent trams from being acclaimed; in an urban environment, the disadvantage seems minor, we can even notice that it is more common to see a municipality claiming the extension of a tram network on its territory than to refuse it ...

Chatelot, I don't see the point of this phase change every twenty meters; can you develop a little Is DC power not suitable?

And the technology of current batteries (without forgetting the "flux" batteries) cannot cover all the needs, without appealing to the flywheels, heavy and expensive, except possibly for the braking-starting phases (but the supercapacitors are suitable? also for this)? Needlessly complicating vehicles (I know, this is the general trend ...) hardly seems desirable to me.
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Re: Electric buses




by Eric DUPONT » 30/04/18, 08:22

there is the range extender with liquid nitrogen which is possible.
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Re: Electric buses




by chatelot16 » 30/04/18, 08:59

a bus has no rail to return the current ... so you need 2 contact in the air ... and to avoid the 2 parallel line of the troley bus I prefer a contact at the front of the bus and a contact in the back ... 20m is a possible distance with a pole in front and a pole in back

it could also be direct current with 20meter at most and 20m at least but currently direct current has no more interest ... it was useful before electronics because DC motors were the best way to have a good efficiency over a wide speed range, and it made more sense to do continuous AC conversion in fixed power stations

now with current electronics it is easier to supply the catenary with 50Hz

the Parisian metro is always in direct current for historical reason, because to change the type of current it would be necessary to change all at the same time ... but I would not be surprised if new lines are in alternative ... rer are in alternative their beginning

for the sncf it was direct current in the mountainous region because it made it possible to recover energy in the descents without electronics ... and in alternative in the other region because the alternative allows higher voltage therefore less loss of energy in the catenary

now the question does not arise anymore we know how to recover the energy of braking and descent in alternative too
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Re: Electric buses




by Bardal » 30/04/18, 11:55

But,

- most trams are supplied with DC

- It is simple, and inexpensive, to place a conductive strip on the ground, at zero potential, with a wiper linked to the vehicle; it is also possible as an alternative.

That said, whatever the technical solution chosen, we know how to do it and the material is produced and used ... Let the engineers do their job ...

What is essentially lacking is a coherent political will, making it possible to achieve an energy transition plan in the shortest possible time; with a minimum of national standardization and coordination ...

For the moment, we're not going anywhere, leaving local decision-makers subject to local lobbies and fashion effects, which seems the royal road to waste and ineffectiveness ...
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Re: Electric buses




by Ahmed » 30/04/18, 12:13

"Waste and inefficiency ..." being also and above all a form of maximization of consumption and financial flows, this is therefore not surprising.
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Re: Electric buses




by Antoine SanMarty » 30/04/18, 17:26

I find it really good that more and more transport is electric, even at the level of energy suppliers we can see a real transition, just by seeing Total who bought direct energy recently https://www.fournisseur-energie.fr/four ... ectricite/ it shows an awareness ... Good after there is the business aspect anyway to take into account since there will be no more oil in a few decades they anticipate ....
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