High speed Diesel/gasonline electric

[StianM]

I gues moust here know I'm sceptical to using diesel electric in annything fast like a planing hull, but over the last few days I have changed my mind alot.

I think the sulution is permanent magnet motors running on frequensy converters.

Problems with traditional AC drives is that you will not get max torque befour closing 50-60Hz and after this the magnets will get problems changing polarety fast enough so at 110Hz the engine will have no torque or close to zero.

Permanent motors will have max torque allready at 0Hz and the torque will be the same all the way so the powercurve will be paralell to the rpm of the motor and continuing up in rpm will not be a problem befour you pas 300Hz and then you will be producing alot more hp than a convencial engine ever would and a diesel electric instalation in a powerboat now might not weight more than a longer proppeler shaft with gearbox.
There efficensy is closer to 1 and produce almoust no heat.

Permanent motors is not perfect there is two big disadvantages.
1: They cost 3 times more, but increased use of them could get the price down to 2 times.

2: You can't just drop in in and expect it to runn, if you do it will just stand there shaking. You will nead to install a decoder on the engine that can tell a frequensy converter the exsact position of the motor at anny time so it can time the frequensy to match the magnets and you nead to runn the motor on the frquensyconverter with a motor identification program with no load the first time so the frequensy converter can learn the magnets posistions and this has to be done every time you chenge converter, change motor or change decoder so if you have to change the converter or decoder you have to disconect the motor from the shaft.

I hope someone find my thoughts interesting

[c-cat]

I've persued the topic on rc forums with regard to a brushless generator powering two brushless motors.Seems as motors get larger rpm goes down.Seems the deisel-elec. has been done.I'd like to see turbine-elec. possibly with on-demand hydrogen as fuel.

[ted655]

What type of motors are used in locomotives? AND do they work for boats?

[masalai]

If you have a big enough boat ted, seems many go that way... for recreational needs the story is a little different and covered in several places herein...

[mario_maggi]

ted,
on new locomotives there are three-phase AC motors, asynchron type.
Locomotives need a very high starting torque, boats don't need so high torque at zero speed. Therefore electrical characteristics are differents.
Bye
Mario

[apex1]

For my fellow members interested in a deeper insight into marine propulsion efficiency I´ll provide some links. Start here:
http://www.proboat-digital.com/proboat/20070607/
goto "content" then page 82 "Hybrid Marine Power" read the article in the following issues too.
And do´nt forget to dl this (achieving the impossible), it may save you several thousands of $ or €...:
http://www.victronenergy.com/support.../white-papers/
Regards
Richard