Discussion How to Convert an Alternator to A Motor

[BobDiode]

[mjsas]

Originally Posted by salty9

I just found this discussion and it is enlightening.

I noticed an earlier post was discussing dynos and am wondering if the altamotor could be used to drive a pump and measure either volume transfered or pressure to determine torque. Perhaps a power steering pump could be used.

I don't know if this is feasible but many dynos use hydralic pumps to measure torque.

A three phase motor when driven with sinusoidal drive has no torque fluctuations. The torque is constant and does not fluctuate like a single phase motor. Also the torque does not change with RPM.

RPM = Kv * voltage
Torque = Kt * current

Therefore you can drive the motor with DC and measure the torque with a torque wrench. Connect phase A to + and phase B and C to -. This would be equivalent to the voltages found at 90 degrees. At 90 degrees phase A is maximum plus and phase B and C are at the same negative voltage.

With a standard 80 amp alternator I got 10 ft lbs of torque which is close to the 75 ft lbs (after a 9 to 1 drive) reported for the PM altermotor.

[BobDiode]

Originally Posted by mjsas

A three phase motor when driven with sinusoidal drive has no torque fluctuations. The torque is constant and does not fluctuate like a single phase motor. Also the torque does not change with RPM.

RPM = Kv * voltage
Torque = Kt * current

Therefore you can drive the motor with DC and measure the torque with a torque wrench. Connect phase A to + and phase B and C to -. This would be equivalent to the voltages found at 90 degrees. At 90 degrees phase A is maximum plus and phase B and C are at the same negative voltage.

With a standard 80 amp alternator I got 10 ft lbs of torque which is close to the 75 ft lbs (after a 9 to 1 drive) reported for the PM altermotor.

I got 75 ft lbs to the wheel from the small 5 lb Ford 12 pole PM rotor alternator/motor posted above on the Huffy Video.
The Delco 10 lb PM 14 pole rotor alternator/motor has about 5 times more N-42 magnet volume with a deeper and larger stator. With a Castle Creations 110 amp controller that you could get 8 HP out of at 50 volts. With only a 2 to 1 reduction I would not doubt that the wheel torque would be over 100 ft lbs.
With the sensorless controller it would be best to measure the wheel torque on a roller tire dyno with at least 100 rpm on the motor. There is not any stock PM three phase Brushless motor made that I know of with this kind of power at any price in a 10 pound package. For under $500. you can have it running in 10 minutes. With the stators available you can pick the torque and RPM that you desire. The efficiency is about 93% including the controller. If you want to run at 36 volts check out the the Phoenix Ice series below.

[ebiker?]

Hi folks

love this . been a shadow for a while and am finally starting on my ebike . LOVE this thread.

would this controller work ? for one of these permenant magnet altermotors )
http://www.tncscooters.com/HK-60.php or
http://www.tncscooters.com/ZY-KK70.php

im more than new at this and im guessing a battery pack with a bms capping it at 100amps or less would be a good thing.

[Hmincr]

Hi guys.
I live in Costa Rica, and have a stream running across my farm. I want to rig up a hydro system.
I bought a 108 Amp Delco Alt, and 2 ring Magnets to convert it to self exciting. It will be 200 feet from the batteries, and, I didn't want to worry about the exciter going bad.

I just found a Mack dump truck, and it has a 270 Amp Leece Neville 12V Alt. and I was wondering if this would be something to make a motor out of ??
Controller might be a problem, but, Amps would be reduced if I upped the voltage to 120 in, correct ??

This is new to me. I'm from old school and motors, not conversions.

ANY thought would be greatly appreciated. Awesome thread y'all hav going here.

[salty9]

I'm not an expert on electronics or electricity but I would suggest a step-up transformer at your generator to avoid I2R losses like they do at large generating stations. I don't know of any but I'm sure there are sites devoted to your situation.

[Hmincr]

OK, what I'm doing is, pulled the regulator and diodes out of the case. I will just let the Alt push out whatever AC voltage it produces, and use the diodes at the battery location. Should be able to just let the batteries control the amperage.

Saved all the parts, just in case it doesn't work out with regulation.

I'd like to move on the 270 Amp Alt, if I can get answers to my question on it ??

[mjsas]

I Was looking at the generator specs at http://www.hydrogenappliances.com/pmacurves.html and they have the following note:

PLEASE NOTE:
VOLTAGES - ARE RATED WITH CIRCUIT OPEN -
AMPERAGES - ARE RATED WITH CIRCUIT CLOSED-
ACTUAL CHARGING VOLTAGES MAY VARY DEPENDING ON YOUR SPECIFIC LOAD.
These curves shows the maximum Voltage OR Amperage
POTENTIAL but is NOT showing both SIMULTANEOUSLY!!!
Only YOUR specific LOAD can determine the final Wattage.

One of their charts show 325 amps and 100 volts at 16,000 RPM. As a generator it cannot do both simultaneously. However as a motor it would require as least 100 volts to reach 16,000 RPM (RPM = Kv * V) and it has the cooling capacity to run with 325 amps so as a motor it can do both simultaneously. It appears as a motor it is 32,500 watts and as a generator it is less. How much less?

They also have the following statement:

Simply dividing the peaks by 2 (in half or by 50%) if not enough especially if the driver is weak and prone to lag under loads. Figuring this out is not for amateurs or beginners!

If the peaks are divided by half the best the generator could do would be 160 amps at 50 volts or 8,000 watts. Ok, I am a beginner in this case, can some one figure out the most power the generator can produce.

[Hmincr]

Mjsas, If you are replying to my post, is it possible you are mixing up the 2 different alternators, as one ???

I can follow some of what you are saying, however, the 108 Amp Alternator will not have the diodes or regulator IN the Alternator. The waterwheel will drive the Alternator at whatever it will produce in AC. It will be rectified AT the batteries, to whatever I decide to put the voltage of the bank at.

Ohm's law is V X A = W, so, whatever I get I will work with.

The 275 Amp Alt, I would like to see if I can make it a motor. 746 watts + 1 HP, so, I was figuring IF I put 120 volts into the rotor, would that drop the amps as torque FROM the motor???

I THINK, I read, that, it only takes a little voltage on the rotor to control the RPM's ??? This is where I need help.

I have read this thread 4 times, and, it still eludes me as to just what makes these things work as a motor, without a multi-segmented commutator ???

Thanks for taking the time to reply, and, it CERTAINLY could just be me, that's not getting it. I'm NOT looking for absolute numbers, just need to be guided into the right frame of mind, to understand this stuff.

Also, (I KNOW I'm not going to get this right), I THINK I read that the Voltage sets the RPM's and the current rises to try to maintain the RPM's OR amps out, or power available ???

There, see how lost I am

[mxspode]

Originally Posted by ebiker?

Hi folks

love this . been a shadow for a while and am finally starting on my ebike . LOVE this thread.

would this controller work ? for one of these permenant magnet altermotors )
http://www.tncscooters.com/HK-60.php or
http://www.tncscooters.com/ZY-KK70.php

im more than new at this and im guessing a battery pack with a bms capping it at 100amps or less would be a good thing.

I am a lurking fan of this thread as well. I am just learning all of this PMA stuff but I can tell you that the two options you listed will not work. They are designed for Brushed DC motors. You need an ESC that works with Brushless DC motors.

Rob...

[carlsoti]

Originally Posted by BobDiode

I got 75 ft lbs to the wheel from the small 5 lb Ford 12 pole PM rotor alternator/motor posted above on the Huffy Video.
The Delco 10 lb PM 14 pole rotor alternator/motor has about 5 times more N-42 magnet volume with a deeper and larger stator. With a Castle Creations 110 amp controller that you could get 8 HP out of at 50 volts. With only a 2 to 1 reduction I would not doubt that the wheel torque would be over 100 ft lbs.

Holy Crap! My old XR650R didn't even put out that much torque at the motor, and they're known for being torque monsters!

[BobDiode]

Originally Posted by ebiker?

Hi folks

love this . been a shadow for a while and am finally starting on my ebike . LOVE this thread.

would this controller work ? for one of these permenant magnet altermotors )
http://www.tncscooters.com/HK-60.php or
http://www.tncscooters.com/ZY-KK70.php

im more than new at this and im guessing a battery pack with a bms capping it at 100amps or less would be a good thing.

You can complicate things by making a guess.
first of all if you don't have a SENSORLESS BLDC controller you will need to make a hall sensor board to get commutation from the magnets for a a good 3 phase controller. I have done that but the Castle Creation controllers are perfect at a great price.

[ebiker?]

Originally Posted by BobDiode

You can complicate things by making a guess.
first of all if you don't have a SENSORLESS BLDC controller you will need to make a hall sensor board to get commutation from the magnets for a a good 3 phase controller. I have done that but the Castle Creation controllers are perfect at a great price.

thanks bobD

im gonna start with precisely what youve mentioned . But at 70-90 bucks ill get the scooter one and try it afterwards and report back. Im hoping it will be interesting , not concerned with wich one will work better just excited to "play".

ill be disappointed if all i get is the "magic" smoke out of the scooter model

for those wondering the magic smoke is the smoke that makes electronics work. once its out that device no longer worky to good.

[BobDiode]

Originally Posted by ebiker?

thanks bobD

im gonna start with precisely what youve mentioned . But at 70-90 bucks ill get the scooter one and try it afterwards and report back. Im hoping it will be interesting , not concerned with wich one will work better just excited to "play".

ill be disappointed if all i get is the "magic" smoke out of the scooter model

for those wondering the magic smoke is the smoke that makes electronics work. once its out that device no longer worky to good.

To save you some trouble. What you are attempting WILL NOT WORK.
You need percice commutation. Either by a sensorless ESC that uses back emf sensing to know exactly where the rotor is so the controller or ESC will know when to switch phases. If you have a hall sensor BLDC controller you will have to know exactly where to place 3 hall sensors and wire them up properly with 9 stator controller phase wire combinations after you hook up each of the hall sensors properly with 5 wires from the controller to hook up to each of the three leads from each of the three hall sensors. then there three more controller phase wires to hook up to the 3 phase wires from the stator in the proper order with 9 combinations. If you miss 1 hall sensor placement or have 1 wire out of place your controller will fry. And the controller still may not work if the electronics are matched for the motor you are using. They only way you may have sucess is with the controller I told you about and with the peticular alternator and rotor and stator on the link. Your voltage, speed and torque will then depend on your stator selection. Just giving you fair warning.! Be careful if you have no idea what you are doing. The best advise is to play games you know about and save yourself from hurting yourself or someone else and save your money for beer.

[mjsas]

Originally Posted by Hmincr

Mjsas, If you are replying to my post, is it possible you are mixing up the 2 different alternators, as one ???

I have read this thread 4 times, and, it still eludes me as to just what makes these things work as a motor, without a multi-segmented commutator ???

Actually my post was a stand alone post, it seems to me that the same unit has 4x the power as a motor than as a generator. On another totally unrelated forum I was flamed big time for saying such a thing.

It may help to look at the animation shown here:

http://en.wikipedia.org/wiki/Three-phase_electric_power

It is about 3 pages down. In the simple motor shown the fields generated by the three coils add to a rotating field that rotates with a constant velocity and constant magnitude. Note that for this example it has sinusoidal drive. The rotating field is the same as that generated by a rotating bar magnet. The end of the blue vector would be the N pole and the S pole would be at the center. You could think of it as a simple coupler with a rotating bar magnet on the drive side and a bar magnet on the output side.

The torque transmitted by such the simple coupler depends on how much the output lags the input which is the torque angle. With a torque angle of 0 no torque is transmitted. As the torque angle is increased the torque transmitted increase to the maximum and then it falls out of sync.


BLDC motors are usually run at a constant torque angle and the RPM is controlled so the load matches the motor torque. The ESC is set to some timing advance and the ESC varies the RPM to maintain that advance.