Bought a hoverboard for 5 dollars .....

[GreenTeam]

I was soooo excited!!! The mats are worth upwards of 80 dollars maybe....
This one came with a really large really nice 18650 battery bank
But the wiring scheme I am really unfamiliar with. Besides being aluminum which is useless as far as I can tell. But , I have no idea how this is wound up. I may just use it as it is for a alternator / wind turbine and rectify them both as they are after cutting out the hall sensors.

It seems as where it would be wired as star , it's connected to every second or third tooth going all around . The three lines going in don't go to one coil, they go to three different coils . I'm afraid this is a useless motor unless it's used as it is for a wind turbine ....

[Mary B]

Spin it and see what voltage you can measure between the phases, my meter came with alligator clips that slide on the probes but some alligator cables will do to clamp on for a good solid measurement. If you an get 6-7 volts AC it would make a good cell phone charger, 16 volts AC a 12 volt battery charger.
Reminds me, I need to order some more alligator cables... they also work as low current fuses when you short something LOL I have melted a LOT of them over the 44 years I have been working on electronics! Those coil connection points are exposed enough to rewire as needed too.

[GreenTeam]

I bolted the lid back on, attached my rectifier and multimeter. And I found it hard to spin , but i got upwards of 12 and 13 v on spikes when hand spun. I am totally lost on how it's wired up. Plus aluminum wires bleh!!! Was considering scrapping it for magnets , bearings and led and batteries. But, i think I may just get a coleman charge controller and cheap rectifier and do a bang up vertical turbine with the motors and sell it in the tent cities here in vancouver. People living outside with no heat lights or anything. In a unheated tent.

[Mary B]

Disconnect the control board and measure at the 3 twisted together wire phases.

[Adriaan Kragten]

I have tried to determine the winding of this motor. In the third photo one can count the number of magnets and the number of coils for 1/3 of the armature and stator.  I counted that there are 10 magnets opposed to 9 coils. So for the whole motor there must be 30 magnets and 27 coils. This difference in magnet number and coil number is made to minimize the peak on the clogging torque.

Now lets focus on 1/3 of the armature so on the 120° part where you have 10 magnets opposed to 9 coils. I assume that three of the coils are of phase U, three are of phase V and three are of phase W and that the sequence of the coils is U1, U2, U3, V1, V2, V3, W1, W2 and W3. The magnets of the north poles are called N1 - N15. The magnets of the south poles are called S1 - S15. The sequence is N1, S1, N2, S2 and so on. Now suppose that the armature has a position such that N1 is just opposite coil U2. This means that S15 and S1 are about opposite to coils U1 and U3. So if coil U2 is wound right hand, coils U1 and U3 must be wound left hand! Only then the voltage generated in these three coils will strengthen each other if the three adjacent coils of one phase are connected in series. It must be possible to confirm this by following the incoming and outgoing wires of three adjacent coils of the same phase.

The armature pole angle is 120° / 10 = 12°, The stator pole angle is 120° / 9 = 13,333°. So there is a difference of 1,333° in between the heart of magnet S15 and the heart of coil U1 and also a difference of 1,333° in between the heart of magnet S1 and coil U3. This difference makes that the voltage generated in the coils U1 and U3 is not exactly in phase to the voltage generated in coil U2. But this isn't a problem as the sum of three identical sinusoidal voltages which are out of phase is again a sinusoidal voltage. 

You have the same situation if the armature has rotated that much that now magnet N15 is opposed to coil U2. This means that the armature has rotated over 360° / 15 = 24°. So 24° rotation of the armature corresponds to a phase angle of 360°. So 1,333° rotation of the armature corresponds to a phase angle of 20°. This means that if the phase angle for the coil U2 is zero, there will be a positive phase angle of 20° in between coil U1 and U2 and a negative phase angle of 20° in between coil U2 and U3.

It is easy to prove that there is a phase angle of 120° in between the voltage generated in coil V2 and U2 and also a phase angle of 120° in between the voltage generated in coil W2 and U2. So a 3-phase voltage is generated in between the three bundles of three coils.

For the total winding it must be such that the coils of the other two 120° segments are connected such that similar bundles of the three coils of the same phase are connected in series or in parallel. As I see many wires at the soldering points, I assume that the three bundles of three coils are connected in parallel.

The fact that one has used aluminium in stead of copper means that an aluminium coil with a certain wire length and wire thickness will have a larger resistance than a copper coil with the same wire length and thickness but this doesn't mean that the given motor can't be used as a generator. You only should not expect a high efficiency at high currents.

[MattM]

Isn't it 28 coils connected to four separate circuits of 7 coils apiece?

It also looks like magnets equal the coils which makes sense.   There is input driven by the two position switches/pressure pads, one up front and one in the back. These switches detect weight distribution.  The person provides the inputs by shifting their body center of mass in very small increments.  When the pressure pad detects movement it knows to cycle the direction of the electromagnetic fields at a maximum safe rate.  The person again shifts weight on the pedals to initiate speed control or force a full stop.  The equal number of coils to magnets would give it the ability to brake with maximum effectiveness, which would be handy for helping a person maintain balance.  If it oscillated to regulate balance you'd get crazy results as our kinematic sense lags behind conscious inputs.

[Adriaan Kragten]

Isn't it 28 coils connected to four separate circuits of 7 coils apiece?

It also looks like magnets equal the coils which makes sense.   

No, I don't agree with that lay out. I have counted the magnets and the coils accurately in the third photo and you can see that there is a slight shift of the magnets with respect to the coils. There is a position about at the top where a magnet is just opposed to a coil and this happens again after turning 120° to the right. So when you count the magnets and the coils you see that 120° is taken by ten magnets and by nine coils. If the number of magnets would be the same as the number of coils, you would have very strong preference positions. It would be good if Green Team could confirm my perception.

[tanner0441]

Hi

The give away is only 3 wires connected to the coils so 120 Deg makes sense, standard 3 phase so a basic 3 phase rectifyer would give DC to at least test the output.

At only $5 if the cotroller is dead you have the basis for a couple of turbines and hours of fun and possibly a working project.

As for the 18650 Li batteries buy an Opus charger. It charges discharges measures the capacity in mAh and the internal resistance of the cells. You have to seperate the cells and test them 4 at a time and you don't need a BMS to worry about.

Brian

[Adriaan Kragten]

What is still unclear to me is if the winding is connected in star or in delta. Star connection is the most general as higher harmonic currents can circulate in the winding for delta connection and this reduces the efficiency. But delta connection gives a higher maximum torque level and one may have chosen this to give the hover board the maximum possible acceleration.

If the winding is connected in star there must be four soldering points, one for the star point and three for the star ends. If the winding is connected in delta there are only three soldering points. On the third photo you see three soldering points to which the three coloured wires green, yellow and blue are soldered. But it might be that there is a fourth point just behind the shaft.

Correction. When I looked again to the second photo, I saw the star point at the left side with no coloured wire connected to it. So the winding is connected in star. If you want to use this motor as a generator for a wind turbine and if you want to stop the rotor by using the generator as a brake, I advise to connect a fourth wire to the star point and to connect all four wires together during braking because this gives the highest peak braking torque.

[GreenTeam]

Interesting is it it?!? I can open it back up and take some better pics if any of you wanna tackle the challenge for me.

[GreenTeam]

SO, I just finished taking the plate off again, and taking pics
It is 30 magnets, and 27 slots. Alum windings, its all I can telll about it

[Adriaan Kragten]

So my perception that it has 30 magnets and 27 coils is right. This also means that the winding must be laid like I have explained in my first post. As you have four coil ends, the winding is connected in star. The soldering point without a coloured wire is the star point. You should count the number of wires which come together at one of the phase ends. If you have three aluminium wires and one coloured wire, the three coil bundles with three coils are connected in parallel. If you have one aluminium wires and one coloured wire, the three coil bundles with three coils are connected in series. If there are no soldering points in between the coil bundles, it means that all nine coils of one phase are wound with one wire in a row. I think that one has used a programmed winding machine which winds the coils directly one the stator cores. This is different from an asynchronous motor for which the coils are wound outside the motor. However, this is only possible with thin wire.

If you have three aluminium wires and one couloured wire, you can modify the winding by connecting all nine coils of one phase in series. This results in increase of the voltage by a factor three and decrease of the current by a factor three.

To test if the motor can be used as a PM-generator for battery charging, you have the connect a 3-phase rectifier in between the three phases and measure the rectified DC open voltage for a certain rotational speed. The open U-n curve will be almost a straight line through the origin. The DC-side of the rectifier can be loaded with a range of low Ohmic resistors to find out for which resistance you get the maximum power at a certain rotational speed. If you have found the optimal resistor, you should measure the loaded voltage for a range of rotational speeds with this resistor. The rotational speed for which the loaded voltage is 13 V DC, is the rotational speed for which the generator should match with the chosen windmill rotor for 12 V battery charging. More about matching is given in chapter 8 of my report KD 35.

The resistance for which the power is maximal isn't the resistance for which the efficiency is maximal. The highest efficiency is reached for a much higher resistance. So if the generator becomes too hot at the resistance for which the power is maximal, you have to take a higher resistance. You can only determine the efficiency if you can measure the torque and the rotational speed.

January 16. I have looked more in detail to the last set of photos and saw that at every soldering point with a coloured wire, there are three aluminium wires. So the three coil bundles with each three coils are connected in parallel. As three coil bundles are connected in parallel, you have three wires per phase at the star point. So at the star point you have 3 * 3 = 9 wires. This is in accordance with the photo of the star point where you see nine wires soldered together.