[crazynoto]

Hello I am new to this forum and I have a few questions for my build.
What I have is a 1995 Cushman truckster that will be a hybrid that will be powered by a military generator MEP362a Turbine GPU that outputs a continuous underrated 10kw at 28VDC (should be good for 30% more with a unknown peek output). I would like it to be capable of 45-50mph, the total finished weight with driver should be between 1600-1800lbs. I should be able to get used fork lift motors for free or near free.I also have a few smaller Curtis pmc motor controllers.
My questions are: should I use the 28v output or is their a way to convert it to a different output? should I use the clutch and 3 speed trans? what batteries should I use? can I run Curtis motor controllers in parallel to run a bigger motor? let me know what you guys think. Thanks

 

[brian_]

... a hybrid that will be powered by a military generator MEP362a Turbine GPU that outputs a continuous underrated 10kw at 28VDC

Just two small heads-up from a discussion of what to do with one of these:

• The genset burns 56 lbs of fuel per hour, thtt's 8.2 gph. Thirsty little buggers.

• The output might be 28 volts AC at 400 Hz (because that's what some aircraft need from a ground power unit), rather than 28 volts DC; check the placard.

This page confirms the output and fuel consumption values.

While the 10 kW rating may be below the engine's capability, this comment in the above-linked discussion is probably incorrect:

It's a nice little MEP-362A GPU powered by a Tiernay TT10-1 gas turbine that produces about 130 horsepower and weights (the turbine engine) about 65 lbs.

Another discussion suggests that this engine is only good for 25 to 30 hp (so perhaps 15 to 20 kW of electrical output)... still fine for this purpose.

 

[crazynoto]

Thanks for the links! same info I have found I belong to the JATO forum already.

I am aware and ok with the fuel consumption, pretty much the main reason for the build is to use the turbine to power something and so I can drive it down the road, I know what I am trying to do is the opposite of what most on forum try to achieve, but I know this is where the knowledge is to figure out how to best utilize and apply the power output I have available for the build.

 

[Duncan]

Hi Crazy
Fork lift motors are usually 48 volt - but you can run them at higher voltage

If you take your 28v AC and rectify it you get about 44v - sounds like that could be the way to go! - you could use the Forklift controllers

That would probably be the easiest way

 

[brian_]

I am aware and ok with the fuel consumption, pretty much the main reason for the build is to use the turbine to power something and so I can drive it down the road, I know what I am trying to do is the opposite of what most on forum try to achieve, but I know this is where the knowledge is to figure out how to best utilize and apply the power output I have available for the build.

Okay, then build on!

The shaft output to the generator apparently runs at about 13,000 rpm, which is a bit fast for most EV motor/generators, but within the range of some (e.g. Tesla). It might make sense to change to a different generator which is designed for a higher voltage, if you can find one of a suitable size (efficient at 10 to 15 kW) and suitable for the speed.

Turbines put out a high volume of hot exhaust, and are certainly unusual, so there's a lot to be said for an installation which exposes the turbine unit as much as possible, with minimal exhaust plumbing. I believe that a Cushman Truckster engine is usually under the driver, but that could give new meaning to the term "hot seat"... so, at the very back, under the cargo box?

 

[brian_]

Fork lift motors are usually 48 volt - but you can run them at higher voltage

Higher voltage is usually used to get higher power (by running faster while maintaining torque). In this case, with only 10 to 15 kW of generation capacity, a significantly higher voltage wouldn't be needed for continuous operation... but would likely be desirable for acceleration.

 

[crazynoto]

The output is 28v DC, the shaft output of the turbine rpm is 12k but I want to use the unit as is. The entire generator enclosure will be removed from the trailer and transplanted where the bed is on the Cushman ( it is the exact same size).
The controls from the Gen will be moved to inside the cab. What I need help with is what motor and drive components will be needed to utilize the the output I have available.

 

[Kevin Sharpe]

The output is 28v DC, the shaft output of the turbine rpm is 12k but I want to use the unit as is.

Are you sure this unit can run continuously at this power level? Arn't GPU's designed for intermittent use?

FYI 10kW is 360A at 28V...I'd look at having the GPU generator rewound/rewired... if you could get it to 48V you'd have a lot more motor choices and a lot less current.

 

[brian_]

Are you sure this unit can run continuously at this power level? Arn't GPU's designed for intermittent use?

Sure, but possibly for hours at a time. That's quite a low power output, even for a turbine this small.

 

[brian_]

The entire generator enclosure will be removed from the trailer and transplanted where the bed is on the Cushman ( it is the exact same size).

That will certainly work.

 

[crazynoto]

So I was able to find a GE 2CM77 starter / generator
It is a compound wound motor, what is the best way to speed control this type of motor? Suggestions?

 

[Geoff2012]

I was the project engineer that developed the TT10. The power rating for the army contract was 10KW to be delivered and maintained under variable loads at THE DISTANT END OF A FORTY FOOT CABLE. To do this the engine's Teledyne Brown generator produced 17.6 KW. So this is the power available at the generator.
The engine's controller, manufactured by Tiernay, was required to allow only one and a half sinewave variations during load change before it was again holding perfect output.