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3 phase testing.
By Jerry, Section Homebrewed Electricity Posted on Mon Mar 28th, 2005 at 04:46:34 AM MST
Did a compairison test today.

I finaly got time to do a preliminary test of the normal 3 phase star wireing and using a fullwave bridge rectifier per phase.
This first test was done on a GE ECM motor. This is a smart motor. That is it comes with a brain. I discard the brain. After that it has 18 coils and a rotor with ceramic magnets.
In the stock form each phase consists of 6 coils wired in sires. In this mode it makes prety high voltage at low rpm when conected normal star. Its ok that way for 48 volt use.
I've been expirimenting and I think I've found the best arangement for 12 volt use.
To reduce the voltage and increase the current I wired all 6 coils per phase in perelell. Then wired these 3 groups of 6 coils in normal star.
Here are some voltage finding both loaded and unloaded. I chucked the ECM into my lathe and set the rpm to 500. This is the lowest setting on my lathe.
For a load I used a 50 watt 12 volt incandesent bulb.
Each coil measure 6.62 volts ac. I'm using a Fluke true rms metter. I wired star to a GM alternater 3 phase bridge. DC output no load measure 15.30v. With the bulb as a load the dc droped to 12.65 volts.
Next test is with each phase rectified seperatly. When wired normal star each coil is basicly in sires with the other coils. This gives about 11.5 volts when measuring accross any 2 coils.
To duplicate this sires arangement for this next test I took each phase and made it 3 coils in perelell in sires with the other 3 coils of that phase also in perelell. This was an atempt to mimic the sires affect of the star wireing. This gave 13.0 volts per phase. Not the 11.5 volts of the star wireing.
I did this with all 3 phases. Then a fullwave bridge rectifier for each phase. Then perelell all 3 bridge dc outputs. The voltage reading are no load 17.674v and with load 14.094v
SO.
Star no load 15.30 load 12.65v
3-BRDG no load 17.674 load 14.094v
The star connection should have higher current. But with the coils out of phase with each other I don't think that lower resistance will ever make it to the plate.
This is not all the testing that should be done with these 2 formates. A full bore high power load test should be done. I may try that tomorrow.
I plan on doing a simular test with my dual rotor disc alt.
These are my findings so far. Here are a couple pix. I connect 2 wires per coil. I used white ph 1, orange phase 2 and yellow for phase 3.

<
JK TAS Jerry

3 phase testing. | 10 comments (10 topical, 0 editorial)

Re: 3 phase testing. (3.00 / 0) (#1)
by Nando (nando37-at-tx-dot-rr-dot-com Correct theanti-spam) on Mon Mar 28th, 2005 at 06:12:18 PM MST
(User Info)

JK TAS Jerry:

Well I see all the extra work you have been doing just to determine the output capabilities of the ECM motor.

What is the Amp capabilities and the voltage of the motor ( model number ?. )

It would have been much easier to keep the coils all in series and take the measurements in a more accurate way.

Also, knowing the number of coils and the number of mag poles then quite easy to calculate the output frequency.
The motor seems to be 6 coils/phase and 6 pair magnets, therefore 6 Hertz per turn/second.

Using 3 transformers or 3 Variable (Variac) transformers -to-adjust-the-output voltage that would be a more practical setup allowing a lot of variations in testing.

Connection from Neutral to phase for each transformer. OUTPUT from Neutral to Variac's Brush terminal, or with transformers the output can be isolated in STAR or DELTA outputs.

And a lot of less mechanical work, like those wire rat-nests the photos shows.

I am basing this on the many decades I have done electrical and electronic work.

Regards

Nando

Re: 3 phase testing. (3.00 / 0) (#2)
by Jerry on Mon Mar 28th, 2005 at 10:07:21 PM MST
(User Info) http://www.dplusv.com/Photo-03.html

Hi Nando.

Actully the above test was not so much to determin the power output capabilities of the GE ECM motor but to compair the diferance between the normal 3 phase star conection of doides to the use of a fullwave bridge on each phase.

This motor is much like the Fisher Paykill washing machine motor of New Zealand.

It normaly has an electronics for drive, tourque, rpm and such atached to its back half.

These motor are used in high end furnaces and are not normal ac induction motors.

Heres the GE model number and specs.

GE ECM Programmable Motor

GE Model No. 5SME39SL011
HP 1 RPM 1050 VOLTS 120/240
PH 1 FREQ 60 AMPS 12.5/9.0
Although this DC motor runs on sigle phase ac it is a 3 phase motor. It brain creats the nessesary frequency to conltrol rpm.

Keeping the coils in sires would not have facillitated my evaluation of the 2 very diferant doide configurations.

There are 18 coils. Very easy to visually count. The number of coils and magnet count were not the purpus of my test.

I'm not sure what you are sugjesting about the 3 transformers and 3 varyacs?
I'm not itrested in using this motor as a motor and I don't think this motor would operate on a normal 3 phase power source.

The rats nest of wires in the photo gave me accsess to each coil.

This motor is designed to opperate at much higher voltage then I wish to use it as a wind generator.

When all 6 coils are wired in sires the out put voltage is high.

Lets say for discusion sake that the voltage accross each coil is 7.5 volts at 5 amps
Thats 45 volts at 5 amps. Thats just 1 phase this voltage will be higher when all 3 phase are used.

If I wire 2 of the six coils of 1 phase in sires that gives me 15 volts for the 2 coils at 5 amps. If I do the same with the other 4 coils of the 6 coil group this and perelell all 3 of the 2 coils sets I get 15 volts at 15 amps. Now if I do the same with the other 2 phases I have a potential for 15 volts at 45 amps.

However the amperage woun't be that good because the phase diferances between the 3 phases. 120%,120%,120%. These phases are never in phase with each other.

The reason I did all the RATES nest was to operate this alt at the voltage I will be using it at. Not at 45 volt were the amperage will be much less and the alt will be under a sirius miss match and load.

I also wanted to see if there was any improvement operating this unit with a full wave bridge per phase and there is.

If you can explain to me how 45 volts at 15 amps is better for 12 volt charging then 15 volts at 45 amps I'll be forever thankfull?

Your vast years of expirience will be a plus for both of us and I can stop doing rats nests.

So Ok Nando dig into those many decades of electronics and electrical work and lay it on me budy? LOL

JK TAS Jerry

Airheads Page

[ Parent ]

Re: 3 phase testing. (3.00 / 0) (#3)
by hiker (hiker.wild[at]yahoo[dot]com) on Tue Mar 29th, 2005 at 06:21:11 PM MST
(User Info)

how many mags are you using on that motor jerry?
looks like your getting some good power out of ceramics...
it would most likly cog real bad with neos[unless of course you offset them somewhat]..
i have a little six pole motor [somthing like your 18 coil motor]they dont need very many rpms to get started thats for sure...................later.
WILD IN ALASKA
[ Parent ]

Re: 3 phase testing. (3.00 / 0) (#4)
by Jerry on Tue Mar 29th, 2005 at 09:14:01 PM MST
(User Info) http://www.dplusv.com/Photo-03.html

Hi Hiker

This motor comes from the factory with 3 ceramic magnets. I'm not sure how many poles per magnet. I suspect 3, 9, or maybe 12 per magnet?

They are curved of cource with a very thin gap. I've seen 380 watts from this thing at 30 mph.

No bad for a through away motor just add diodes a blade and a yaw and your done.

JK TAS Jerry

Airheads Page

[ Parent ]

Re: 3 phase testing. (3.00 / 0) (#5)
by Gary D on Wed Mar 30th, 2005 at 04:57:31 AM MST
(User Info)

Jerry, I was wondering since you have all the starts and finishes separated.... don't you have many options? As you said, you could wire coil 1 and 10(?) together rectify 9 sets that way. Or you could Star coil 1 7 and 13, 2 8 and 14 etc. giving you 6 (3 phase sets) depending on battery voltage? You could do 3 (3 phase sets) using 2 coils together (1 and 10?for example) for lower startup or higher voltage? Might rectifing these ways save rewiring with heavier wire by being like wiring with 2 wires in hand?
Your work promotes thought... biggest drawback would be the rectifires up on the tower subject to nature's fury... I enjoy your postings... wish I had the equipment to experiment with- will come in time... Gary D.

[ Parent ]

Re: 3 phase testing. (3.00 / 0) (#6)
by Nando (nando37-at-tx-dot-rr-dot-com Correct theanti-spam) on Fri Apr 1st, 2005 at 10:49:56 PM MST
(User Info)

JK TAS Jerry:

This is 1 HP ECM motor. By the way, what can I do to get one of those 1 HP motor and how much do they cost to you ?>

The evaluation that you are doing is un-necessary, from Star connection with full 3 phase rectifier circuit to full way rectification of each independent phase will give you the EQUIVALENT DELTA configuration and in reality DELTA configuration will give you 2 less diodes drops.

Why don't you ask to the group what would be the results if you do something like what you are doing -- I do not mind if I am asked directly. -- then wait for the replies from those that are knowledgeable in the matter in question.

If you supply 180-240 Volts DC you can run the motor as well.

The brains inside is a rectified circuit ( full bridge) single phase, either 120 or 240 Volts AC. with a 3 phase 6 IGBT driving circuit and a microprocessor to run the motor at different speeds that can be controlled externally.

Unhappily I do not have the data of the input pins behavior and voltage levels.

If you remove the controller you will have a 12 pair poles rotor( 3 large magnets) and the 3 sets of 6 coils in series for the 3 phases in STAR connection.

The way to test it is to drive the shaft of the motor at known RPM and read the voltage which is AC and like I said 6 pulses per rev/sec.( one phase data is sufficient).

Read the voltage then load the phase until 10 % of the read voltage is reduced -- there is the best voltage point, measure the resistor to get the Current, or measure the AC current directly.

To test the 3 phases.

Also you can add a 3 phase full wave rectifier, capable or 600 volts reverse breakdown as a minimum. do a resistive load until 10 % of the voltage is reduced.

Do the same for each incremented RPM until not greater than 2400 RPM, The rotor may not have the capability to last at much higher RPM.

With the data, then you can do all the calculations for voltage output with different winding settings and RPM

Regards

Nando

[ Parent ]

Re: 3 phase testing. (3.00 / 0) (#7)
by Nando (nando37-at-tx-dot-rr-dot-com Correct theanti-spam) on Fri Apr 1st, 2005 at 11:00:28 PM MST
(User Info)

Regarding what is better 15 volts at 45 Amps or 45 volts at 15 Amps.

All depends how the need is.
For charging a battery using a wind mill generating the above power, I would prefer to use the 45 V- 15 A with a good charge controller that has MPPT -- charging a 12, or a 24 battery bank.

With the 12 V, 45 Amps you are limited to battery charging directly since the battery may need 14.4 volts and that would happens just a lower % of the time the wind is flowing.

I prefer even higher generator voltage to allow charging at lower wind conditions. like one set up I did many years ago, 10 KW charging a battery bank that started charging with 50 watts wind generated power and the generator voltage could go as high as 4 times the battery bank voltage -- also with MPPt

Regards

Nando

[ Parent ]

Re: 3 phase testing. (3.00 / 0) (#8)
by commanda (alwynne at unwired dot com dot au) on Sat Apr 2nd, 2005 at 12:24:18 AM MST
(User Info)

We're all waiting to see your circuit for this MPPT. At least I am.

By the way, I agree totally with your philosophy. I'm working on one myself (High voltage DC-DC down converter that is).

Seems to me, because of the cubic relationaship between wind speed and available power to turn the alternator, any alternator/blade combination is a serious compromise.
If the alternator can make some current at low rpm's, it will never make enough current at higher rpm's to really use the power available from the blades.
And if the alternator makes lots of current at higher rpm's, it will make nothing down low.

Star-delta switches can partially alleviate the situation, but still not "elegant" from an engineering perspective.

Amanda

[ Parent ]

Re: 3 phase testing. (3.00 / 0) (#9)
by TomW on Sat Apr 2nd, 2005 at 03:47:24 AM MST
(User Info)

Amanda;

Seems to be a common need to go from one DC voltage to another. Ibedonc and I have been collaborating on just such a circuit. Don has designed the W-S booster that can take any input voltage from around 3 volts DC up to 100 volts DC and put out any voltage up to 300 volts DC. It has the ability to set the low "on" voltage and high input "bypass" voltage where it passes the input voltage directly to the output as well as adjustable, regulated output voltage. It will be offered as a kit when testing is completed to our satisfaction. If you are the brave sort who doesn't mind the bleeding edge of things you could probably get one any time, however.

I have been testing one lately and it is showing good numbers. It has an efficiency of consistently over 70% and I have seen 80% boosting from a 3 volt source to 14.4 VDC to charge batteries. Other tests to date have been 3 or 12 volts DC to 90 volts DC to drive standard CFL lights. Obviously a complex circuit for just driving a CFL but it is just a test of the circuit and it works well. It is not an MPPT but has a similar function in that it can take basically any input voltage and give you any output voltage at fair efficiency. On my TDM mill that sees very little charging voltage I can get something from those 8 volt winds and while the "efficiency" is in the 75% range I do see charging from as little as 10 watts of low wind power using the W-S booster. In a way it is something for nothing since at, say, 8 volts I would get no charging but with the W-S booster I do get something even if its only a few watts. With a high current, low voltage source you could turn that unusable low voltage into charge voltage.

I plan to do a diary entry on my results this weekend with a little more detail if I get the time.

Cheers.

TomW

"Education consists mainly of what we have unlearned."--Mark Twain
[ Parent ]

Re: 3 phase testing. (3.00 / 0) (#10)
by commanda (alwynne at unwired dot com dot au) on Sat Apr 2nd, 2005 at 04:01:26 AM MST
(User Info)

I'm actually going in the opposite direction. 70-700 volts DC down to 12 volts at 35-50 amps. I've actually got my prototype switchmode built, and am just starting to test it. The pwm is set by a control voltage. This will be derived either from a micro running an mppt algorithm, or a straight mathematical function of rpm.

Gizmo probably needs what you're working on for his 24 volt Oatley Electronics motor project.

Amanda

[ Parent ]

3 phase testing. | 10 comments (10 topical, 0 editorial)

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