Using a motor or alternator to generate electricity

In summary, the author is looking for a way to generate 24vDC with a 100-150A max output. He is struggling to get his head round how to generate such a voltage/current and then be able to control it's output. He is considering using a motor as a generator, but is unsure of its limitations. He is also looking for a way to power his locomotive. He has found an automobile alternator that has outputs of 12/28 volts. He is also looking for a way to power his locomotive from scrap yards in his vicinity.
  • #1
Nelson 47845
2
0
I'm looking into building a 7 1/4 gauge Diesel Electric Locomotive

I will be using 4x 1hp (or 1 1/3hp) 24vDC permanent magnet motors for the traction motors. What I am looking for is someway of generating 24vDC with a 100-150A max output. (Im using a 3cyl 16hp Diesel engine to drive a motor/generator/alternator). I am struggling to get my head round how to generate such a voltage/current and then be able to control it's output. Can anyone point me in the right direction please?
 
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  • #2
Are you absolutely set on the 24VDC motors? The motors that are used in the new cloths washers and dish washers are 3 phase motors driven with a VFD that is powered by 120 or 208 or 240VAC single phase depending on country of origin and size. Finding a generator that gives normal mains voltage will be easier than trying to get 24VDC. The VFD will allow more precise control as well. You might be able to find some used appliances and salvage the motors and drives you need.

BoB
 
  • #3
Alas, it has to be low voltage DC because of the track circuits, and the smaller motors fit nicely in the back to back of the wheelsets. I know some have used car or lorry alternators without the rectifier, but you have to get them with external rectifiers which are like hens teeth to get hold of, I'd like something that can be easily replaced. I wondered if using a motor as a generator would be better/easier, but I'm unsure of its limitations...
 
  • #4
Hmm. That's a lot of current.

The obvious first thought would be to build a big liner supply, big step-down transformer with huge rectifier diodes and a enormous cap. You don't need much filtering for a DC train motor. But these components wouldn't be easy to come by. And efficiency would be questionable. 150A across a 0.6V diode would dissipate 60 watts. A switching supply would too complicated. I think low-tech is the way to go.

The other option would be a motor-generator set like what you are already describing. But if you are here then your current setup in inadequate and you would need bigger components than you already have. That sounds like more sourcing trouble.

What kind of duty cycle do you need? Just a high current burst, to get the train moving, and then lower power? Does it have to run all day, or only for a short periods of time? You make be able to get away with using a bunch of deep-cycle lead-acid batteries (aka "boat batteries"). Wire them in series-parallel to get what you need. Then recharge them a night using a 24V charger. You would easily be able to find all of the lugs, heave gauge wire, and miscellaneous bits at local automotive and marine stores. And please, REMEMBER FUSES! A short in that system would be all kinds of bad news.

Golf cart batteries would also work. Their normal use more closely resembles you're purposes than something that was built for a trolling motor.
 
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  • #5
I often see alternators from large trucks at my metal salvage yard.

Would something like this help ?
http://delcoremy.com/Alternator-Models/55SI-High-Output-Brushless-Heavy-Duty-Alternator.aspx


Specifications
  • Performance Output: 250 & 275 Amps – 24 Volt, 430 Amps - 12 Volt
  • Efficiency: 80%
  • Temperature Limits: 250 Amp - 125°C/257°F, 275 Amp - 110°C/230°F, 430 Amp - 93°C/200°F
  • Weight: 43.2 lbs (19.6 kg)
  • Overall Length: 11.3 in (285.9 mm)
  • Length w/o B+ Terminal: 10.5 in (265.8 mm)
  • Stator Diameter: 6.9 in (175 mm)
  • Mounting Style: Pad Mount

http://delcoremy.com/Images/55SI/55SI-pad-mount.aspx http://delcoremy.com/Images/55SI/PerformanceCurve-55SI-24V-250Amp.aspx
 
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  • #6
You might experiment with an automobile alternator.
You need one without a voltage regulator but with brushes.

The rectifiers in 12V alternators are plenty hefty to make 24 volts
you'll just need to spin it somewhat faster to get that 24 volts.

With constant current to the field it'll make voltage in proportion to RPM
and its inherent current limiting will give you somewhat of a soft start

old Chryslers used external regulator
one might remove the internal regulator from a newer one and bring wires out from the brush-holders.

i find these dual voltage military alternators at my metal salvage yard
but I'm afraid they're brushlesshttp://www.govliquidation.com/auction/view?auctionId=9966344
C.E. Niehoff & Co, Alternators,
p/n: 3043161,

200 amp dual voltage, 12/28 volt outputs

any good scrap yards in your vicinity ?
 
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1. How does a motor or alternator generate electricity?

A motor or alternator works by converting mechanical energy into electrical energy. This is achieved through the use of magnets and wire coils. When the motor or alternator is spinning, the magnets create a changing magnetic field which induces a current in the wire coils, resulting in the generation of electricity.

2. What are the differences between a motor and an alternator?

A motor is designed to convert electrical energy into mechanical energy, while an alternator is designed to convert mechanical energy into electrical energy. Additionally, a motor typically uses direct current (DC) power, while an alternator uses alternating current (AC) power.

3. Can a motor or alternator generate enough electricity to power a household?

Yes, with the right size and type of motor or alternator, it is possible to generate enough electricity to power a household. However, it may require multiple motors or alternators and other components such as batteries and inverters to store and convert the electricity for household use.

4. What are some applications for using a motor or alternator to generate electricity?

Motors and alternators are commonly used in power plants to generate electricity on a large scale. They are also used in renewable energy systems such as wind turbines and hydroelectric dams. Additionally, small motors and alternators can be used in DIY projects to generate electricity for personal use.

5. How efficient is the process of using a motor or alternator to generate electricity?

The efficiency of a motor or alternator in generating electricity depends on various factors such as the type and size of the motor/alternator, the speed at which it is spinning, and the load it is powering. Generally, modern motors and alternators have high efficiency rates, with some reaching over 90% efficiency.

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