(pdf) high output/efficiency alternator white paper

[mobile_bob]

Lloyd:

the CAT link is invaluable to this group on so many levels
would you mind starting another topic in the white paper section,

in the subject line put "pdf, CAT engineering file"

that way it can be located quickly

i have seen various subsections of that pdf, but never seen a comeplete work on the subject
there is tons of useful info in that pdf, some is dated, some is not directly applicable, but most is very useful
in my opinion and will provide answers to many questions that come up from time to time.

thanks for the link

bob g

[mike90045]

I like that large, open heat sink rectifier bridge, looks like it has nice connections.    Got a link ?  8M 300a 600piv 6d


I don't like the 2nd one, with a link, and the cooling fan. Fan will suck in dirt and gunk, along with air, and they eventually fail.

[mobile_bob]

if they can build it to take perhaps as much as 600hz, why not?

however i would include fans even if they say they don't need them, you might sail into the tropics
and be somewhere with very high temperatures?

because the fans will only be running when the alternators are charging, and presumably only when the
temps are high enough to kick them on, even cheap fans likely would outlast you and me together.

its not like they would be on 8 hours a day as with a solar controller, or 24/7 like an inverter

what are we talking a couple hours a day?

yes  i would include fans, and a screen filter such as used in industrial cabinets to keep the crap out
and to provide fire protection,  those metal mesh screen filters do both quite well.

failing that, be sure and mount the heat sinks in such a way that the heat flow is good, and there is nothing
above them that might be overheated by the additional heat, also figuring on extra heat from high ambient temps.

bob g

[mobile_bob]

just be sure the rectifier supplier knows that you might be running upwards of 600hz
which will dictate the use of fast recovery diodes, rather than the standard variety that are good only to a bit
over a hundred hz.

the supplier will understand the need if you tell them what the supply is, if you don't they may assume this is a standard
3phase rectifier bridge for use at line frequency of 50 or 60 hz,, which 99% of there business is centered on.

not all rectifier manufactures make fast recovery diodes or rectifier bridges suitable for use at 400-600hz or so,
that will handle the amount of current you are going to ask of them.

bob g

[mobile_bob]

well you don't have to use the transformers, but
the 3 phase cabling is still going to need to be quite large in order to keep losses down

what size? i don't know for sure, but i suspect it might be as large as 3 x  1/0 cables to get basically 12volts ac
from the alternator stator, some 30 ft? to your rectifier bridge.

the toroids allow the alternator to run at a much higher voltage, higher voltage allows you to transmit the same power
but at proportionally lower amperage.

amperage is what dictates the required cable size

before you order the toroid transformers you will need to know just how high a stator voltage can be at perhaps 50% field
excitation at the speed you want the alternator to turn (4500rpm?)  i mention 50% because it provides some room to wiggle
when it comes to maintaining voltage under load.

if at 4500rpm and 50% excitation current the stator can deliver ~60vac, then we might want to look for a transformer
that can step down the 60vac 3phase and deliver it to the rectifier so that the result is ~14 vdc.

thinking about it, i might want to start out with 25% excitation and work back from there, that way i have lots of room to
increase the field and the output of the system.

that is why i would rather work with cheap surplus transformers and prove out the concept before i picked an expensive set
of toroid transformers.

unless of course you are not locked into a fixed 4500rpm, if you have some flexibility there , then your options increase dramatically.

bob g

[mobile_bob]

Lloyd:

bear in mind that the published curves for the neihoff will be vastly different than the curve of the alternator
as applied here with the transformer pack.

in other words the published curves only give you an indication of what rpm might be needed to get to the output
needed to feed the transformers.

bob g

[mobile_bob]

Lloyd:

after going back and taking another look at things, particularly the power curves

it appears that as built the alternator will not make 60volts at any decent amperage unless it
is turning balls out 8krpm

so, unless the stator can be reconnected as Y instead of delta, there is likely no way to get that
much voltage out of it.

i haven't worked with that alternator so i cannot comment on whether or not the stator can be reconnected
as described.

if you can, then the voltage goes to 1.73 x whatever voltage it can make now at something like 6krpm, which i would suggest
is probably a more realistic goal. 

at 6krpm the alternator should make ~36 volts nominal at maybe 150amps, and reconnected then we would expect
36 x 1.73 =62.8 volts which is about where we need to be in my opinion

at 5:1 we only need about 50amps from the alternator, which is no problem and will require smaller wire to transfer the power.

feeding this into a 5:1 step down transformer returns us to 12volt nominal at 5 x the amperage or 250amps.

so from this it appears that a good starting point for testing might be 6krpm alternator speed, and a reconnection of the stator
from delta to Y (wye, star).

i have no idea whether the neihoff alternator stators can be modified and reconnected as described, and i doubt Todd is going to want
to do the modification.

bottom line?  don't buy an alternator yet, and don't buy any transformers yet
if you are set on the neihoff alternator you might be stuck running triple 1/0 cables from the stator connections to the remote rectifier bridge.

personally i don't like it, but it may be what you end up having to do?

i think it might be easier to accomplish using a leece neville alternator, because of having a single stator that is a bit more agreeable to modification.

remember if it was easy, everyone would be doing it

bob g

[BruceM]

An alternate possibility-  If a schematic for the Neville regulator can be had, it may be practical to modify the regulator for a remote voltage sense.  I can look at it for you if you can get the schematic.

Alternately, see if Neville engineering will make this modification. This is not as good a solution as the transformer setup Bob suggests, but it would allow for as much voltage drop in the wire to the battery bank as you can stand, efficiency wise, which in turn allows for a smaller pair of wires.  


It drives me nuts to see alternators of such low voltage and high currents without a remote voltage sense capability!

[mobile_bob]

Bruce:

he has the balmar mc612 controllers now, they have the remote sense wire which would
be very good at adjusting to overcome cable drops as you mention.

some of the delco and leece neville regulators also have remove sense capability, altering those
that don't would pretty much require destroying the units, as they are impregnated or potted
pretty tightly.

its just really difficult to armchair design around and unfamiliar alternator like the neihoff
nothing wrong with the alternator, i just don't know for sure how it reacts to different operating parameters.

at least not enough so to feel comfortable in spec'ing expensive transformers.

having said all that, i am very interested in Lloyd's project, it would be a serious application of the principle
and addresses most if not all of the concerns related to 12volt systems and long distance transfer of large amounts
of power. (relatively speaking of course)

he gets this sorted out and working well, i suspect there will be much interest from a certain sector of offgrid folks that
are using 12volt systems.

it wasn't long ago that i too was planning a 12volt system, the difference would have been the transmission distance
would have been under 6ft, i figured 2/0 cable was sufficient for my needs at that distance and ~150amps.

once you get invested in a certain voltage it is hard to make the jump to another, thats for sure.

bob g

[BruceM]

Bob, now I understand why you like the Balmer controllers.  For 12V systems, remote voltage sense is a near necessity.

 

[BruceM]

Are the Zena alternators crappy?  The seem to have some higher voltage options, and claim to be continuous duty types.

http://www.zena.net/htdocs/alternators/alt_inf.shtml

[mobile_bob]

Lloyd:

no worries here, you aren't wearing me out at all.

the 12volt and 30 ft situation is just something i haven't given any thought to, actually like i said
even when i was seriously considering 12volts it was with the idea of keeping the distances down to inches if i could.

i wanna do some testing on my end, collect some data, and crunch some numbers.







Bruce:

i haven't looked into the zena alternators for a few years, it looks like they have expanded their offerings.

i don't have a clue how good they are, or aren't

bob g

[mobile_bob]

i have been following perraults work for many years, and figure to make a trek to meet the gent at some point in
the future.

while i agree on most of his assessments i part company with him on the predominate loss factors of the lundell design
at least as it applies to the 110-555jho and the 4400 series leece neville where it is clearly the I2R losses that are the prevalent
limiting factor.

there is a ton of reading out there if one digs around a bit, some of it very good.

it amazes me how few people that work with automotive alternators are unaware of the work that has been done recently, or rather
the last decade or so.

bob g

[mobile_bob]

all of the 24volt machines i know of also use 24volt fields and excitation

there are only a couple or so 48 volt machines i am aware of that have 12volt excitation, and i only verified this after i wrote the
white paper at the head of this topic.

i am in hope of getting in to see my dr this week, and get him to adjust my pain meds so that i am feeling able to get back into the shop
and do some testing and maybe get some useful info to you that might help you with your system.

the last 7 months with my current dr. has been horrible, and i thought it was due to my declining condition, i found out yesterday after meeting
with my pharmacist that this dr has me on 50-60% of the daily load than that of my prior doctor that had my pain under control for the 2 plus years prior. (even at the higher load, i was under 50% of max doseage).

that was a huge eye opener for me, i had come to believe that i was going down hill fast, and might never be able to work on completing my projects or even do more testing.

fingers crossed here, hope to know later this week whether he is willing to increase the doseage to the prior amount.

i am beginning to understand why there is a black market for drugs! 

you know things are getting bad when you can't even work two half days a week, and have tears well up in  your eyes just to get up
to go the the bathroom.

bob g

[V5CVBB]

Bob, thanks for all the work and effort and even more so for sharing.

I hate to hear about your health and the effect it has on your work.  I do hope that your Dr. can find something that works well for you.

Look forward to hearing more from you on a very interesting topic.

Kevin