LG Direct drive motors ( similar to F&P )

[gsw999]

I have a few questions about these motors.

I made a quick video with a couple of questions I hoped maybe someone could answer please, I would appreciate any input.

https://youtu.be/Z5t5VdVkWAE

Thanks very much!!

[SparWeb]

There are different ways to connect 2 generators together in one turbine.  There might be a combination that allows these two somewhat different generators to be compatible with each other. 

They seem to have the same number of poles, and same number of turns on each winding.  The magnets seem to be the same, too.  Just to be sure, I would put some masking tape on each of the major parts if you take them apart, so that you can tell which part goes with which when you reassemble them.

You won't really know unless you spin each of them up to the same speed, and measure voltage at that speed, then put a load on, to measure the current.

[OperaHouse]

recently saw a video of one used to propel a boat. One interesting comment was that he cut the coils in series and wired them inparallel for lower voltage.

[MagnetJuice]

I can see your concern, because one motor uses aluminum wire for the coils and the other one uses copper wire.
Aluminum has a higher resistance than copper, so it is natural to think that the motor with the aluminum wire will produce less voltage than the one with copper wire when used as an alternator.

It looks like those motors are made by the same manufacturer. If they are designed to rotate at a certain RPM with a certain voltage, then I suspect that the motor with aluminum wire uses a thicker wire to compensate for the higher resistance.

So it is possible that they will produce the same voltage when rotating at the same speed.

These are screen captures of your video. It looks like the aluminum wire is thicker.




Measure the resistance of the wire and see if there is any difference. You can also measure the thickness of the wire to see if the aluminum is thicker than the copper.

Ed

[Adriaan Kragten]

The generated open voltage depends only on the rotational speed and the number of turns per coil and not on the material if the winding (if the magnets are identical). However, once a current is flowing, the loaded voltage is reduced and how much depends on the internal resistance R of the winding. The resistance R is proportional to the specific resistance of the material which is about a factor 2 higher for aluminium than for copper. R is also proportional to the length of the wire and inversely proportional to the cross sectional area of the wire. If you compare two coils with the same number of turns per coil and the same wire length, an aluminium coil must have a wire thickness which is about a factor square root of 2 larger than a copper coil. But the larger wire thickness will result in a longer wire length for the same number of turns per coil if the inside diameter of both coils is the same and so the wire thickness must be more than a factor square root of 2 larger to get the same resistance. 

[gsw999]

Many Thanks for your replies, I measured the wire with calipers they are saying 0.87mm for the ALI and .61mm for the copper.

I think my plan is to find out which way I want to rewire the copper stator, and then replace the ALI cable with copper, this would be a long process no doubt , hand winding the 36 poles, if I was to do this could I use the same amount of wire in either length , or weight ?? that way I could unwind an ALI coil and see how long it is or how much weight and then duplicate this for each coil , my meter is out of battery so I cannot test the resistance for now.

My plan is to try and run the two off one shaft , with another shaft linked to a set of 1.4m blades, and have simplex platewheels so you can adjust gear ratios etc.

[Adriaan Kragten]

As rewinding is a lot of work, you should first check if rewinding is really necessary if you want to use both generators together. Each generator has a 3-phase winding and I assume that this winding is rectified in star (rectification of a 3-phase current is explained in my public report KD 340). So you should measure the rectified DC voltage for both generators for the same rotational speed. For use as motor, the motors are meant for the same grid voltage, so I expect no big difference. Now expect that you find about the same voltage. If the voltage is about the same, both generators can be used with the DC voltage lines connected in parallel. If the voltages differ, both generators can only be used with the DC voltages lines connected in series.

If the DC voltages differ a lot and if you connect both DC lines in parallel, first only the generator with the highest voltage will produce power. The generator with the lowest voltage will start to produce power only when the open DC voltage becomes equal to the loaded voltage of the other one. So this means that the power generated by one generator will differ a lot from the power generated by the other one. There will be no current flowing from the generator with the highest voltage to the generator with the lowest voltage because this is prevented by the diodes of the rectifier of the generator with the lowest voltage. Even if both DC voltages are equal, the power generated by the one with copper wires may be larger because it has a higher efficiency. The winding temperature of the generator with the aluminium wire will be higher.

[gsw999]

As rewinding is a lot of work, you should first check if rewinding is really necessary if you want to use both generators together. Each generator has a 3-phase winding and I assume that this winding is rectified in star (rectification of a 3-phase current is explained in my public report KD 340). So you should measure the rectified DC voltage for both generators for the same rotational speed. For use as motor, the motors are meant for the same grid voltage, so I expect no big difference. Now expect that you find about the same voltage. If the voltage is about the same, both generators can be used with the DC voltage lines connected in parallel. If the voltages differ, both generators can only be used with the DC voltages lines connected in series.

If the DC voltages differ a lot and if you connect both DC lines in parallel, first only the generator with the highest voltage will produce power. The generator with the lowest voltage will start to produce power only when the open DC voltage becomes equal to the loaded voltage of the other one. So this means that the power generated by one generator will differ a lot from the power generated by the other one. There will be no current flowing from the generator with the highest voltage to the generator with the lowest voltage because this is prevented by the diodes of the rectifier of the generator with the lowest voltage. Even if both DC voltages are equal, the power generated by the one with copper wires may be larger because it has a higher efficiency. The winding temperature of the generator with the aluminium wire will be higher.

Thanks for that information much appreciated, I have them on the wall of my workshop , If I have a spare motor with the 0.8mm I may re-wind it to try and make it as similar as possible to the other one , If you run 2 rectifiers can you join the power output together?

I don't have any kind of controller, the stators would be re-wired to run to a 24 v battery bank.

[Adriaan Kragten]

As rewinding is a lot of work, you should first check if rewinding is really necessary if you want to use both generators together. Each generator has a 3-phase winding and I assume that this winding is rectified in star (rectification of a 3-phase current is explained in my public report KD 340). So you should measure the rectified DC voltage for both generators for the same rotational speed. For use as motor, the motors are meant for the same grid voltage, so I expect no big difference. Now expect that you find about the same voltage. If the voltage is about the same, both generators can be used with the DC voltage lines connected in parallel. If the voltages differ, both generators can only be used with the DC voltages lines connected in series.

If the DC voltages differ a lot and if you connect both DC lines in parallel, first only the generator with the highest voltage will produce power. The generator with the lowest voltage will start to produce power only when the open DC voltage becomes equal to the loaded voltage of the other one. So this means that the power generated by one generator will differ a lot from the power generated by the other one. There will be no current flowing from the generator with the highest voltage to the generator with the lowest voltage because this is prevented by the diodes of the rectifier of the generator with the lowest voltage. Even if both DC voltages are equal, the power generated by the one with copper wires may be larger because it has a higher efficiency. The winding temperature of the generator with the aluminium wire will be higher.

Thanks for that information much appreciated, I have them on the wall of my workshop , If I have a spare motor with the 0.8mm I may re-wind it to try and make it as similar as possible to the other one , If you run 2 rectifiers can you join the power output together?

I don't have any kind of controller, the stators would be re-wired to run to a 24 v battery bank.

If each generator has its own 3-phase rectifier (so a rectifier with 6 inside diodes and five outside terminals) you can connect the positive terminal of one rectifier to the positive terminal of the other and the negative terminal of one rectifier to the negative terminal of the other. However, you should only do this if both generators give about the same open DC voltage at the same rotational speed.

If you have two identical generators, theoretically it is also possible to use only one 3-phase rectifier and to connect the three phases of the two generators. However, in this case you must be sure that the alternating voltage generated in a certain phase of one generator is in phase to the voltage of the same phase of the other generator. If you make a mistake and if the voltages are 180° out of phase, the resulting voltage is zero. Even if all coils of both generators are connected correctly, problems will also arise if the magnets of the armatures of both generators are not orientated in the same way. So as there is a good chance that this goes wrong, it is better to use two separate 3-phase rectifiers and to connect the DC lines.

[gsw999]

As rewinding is a lot of work, you should first check if rewinding is really necessary if you want to use both generators together. Each generator has a 3-phase winding and I assume that this winding is rectified in star (rectification of a 3-phase current is explained in my public report KD 340). So you should measure the rectified DC voltage for both generators for the same rotational speed. For use as motor, the motors are meant for the same grid voltage, so I expect no big difference. Now expect that you find about the same voltage. If the voltage is about the same, both generators can be used with the DC voltage lines connected in parallel. If the voltages differ, both generators can only be used with the DC voltages lines connected in series.

If the DC voltages differ a lot and if you connect both DC lines in parallel, first only the generator with the highest voltage will produce power. The generator with the lowest voltage will start to produce power only when the open DC voltage becomes equal to the loaded voltage of the other one. So this means that the power generated by one generator will differ a lot from the power generated by the other one. There will be no current flowing from the generator with the highest voltage to the generator with the lowest voltage because this is prevented by the diodes of the rectifier of the generator with the lowest voltage. Even if both DC voltages are equal, the power generated by the one with copper wires may be larger because it has a higher efficiency. The winding temperature of the generator with the aluminium wire will be higher.

Thanks for that information much appreciated, I have them on the wall of my workshop , If I have a spare motor with the 0.8mm I may re-wind it to try and make it as similar as possible to the other one , If you run 2 rectifiers can you join the power output together?

I don't have any kind of controller, the stators would be re-wired to run to a 24 v battery bank.

If each generator has its own 3-phase rectifier (so a rectifier with 6 inside diodes and five outside terminals) you can connect the positive terminal of one rectifier to the positive terminal of the other and the negative terminal of one rectifier to the negative terminal of the other. However, you should only do this if both generators give about the same open DC voltage at the same rotational speed.

If you have two identical generators, theoretically it is also possible to use only one 3-phase rectifier and to connect the three phases of the two generators. However, in this case you must be sure that the alternating voltage generated in a certain phase of one generator is in phase to the voltage of the same phase of the other generator. If you make a mistake and if the voltages are 180° out of phase, the resulting voltage is zero. Even if all coils of both generators are connected correctly, problems will also arise if the magnets of the armatures of both generators are not orientated in the same way. So as there is a good chance that this goes wrong, it is better to use two separate 3-phase rectifiers and to connect the DC lines.

Thanks for that, I will be using 2 generators and they will be re-wired the same way ( haven't decided which setup to use yet )

[makenzie71]

You can get two of them working together on the same rectifier but you need to have the coil configuration really, really close in orientation.  It took probably an hour of fiddling to get them to work together...

https://youtu.be/81DhgWsiluQ

...I really need to finish that project!

[gsw999]

You can get two of them working together on the same rectifier but you need to have the coil configuration really, really close in orientation.  It took probably an hour of fiddling to get them to work together...

https://youtu.be/81DhgWsiluQ

...I really need to finish that project!

Yes you do mate for sure !!

[XeonPony]

Rather than starting whole new thread I thought better to recycle this one, I have at last started the wind turbine build now that I have got the solar tracker 100% opperational.

I'm using an LG Smart drive P# 10CA05751

Rating DC310V 0.92HP 2.5A 1400RPM 3ph
Year: 2011

My Question to our resident LG Expert is what will the Wild AC be at 1800rpm?

I am doing a 1 to 3 gear up via chain drive, intend to use GOE222 blade profile at 10 foot total diameter 3 blade.