Electric Motor Secrets

[lighty]

Yup, you can do that. It would be almost impossible to wind bifilar helical coil with two wires of significantly different diameters.

[Jetijs]

Ok lighty, this sounds good. But in this case can I wind the power coil at first and the recovery coil only after that? Because you know it is hard to wind a good coil if you use two strands of wire with different diameters at the same time

[lighty]

Why do you use same thickness of wire for both the energizing coil and recovery coil? Since you need higher current for energization of actuator coils you definitely need thicker wire (look at the cross-section area) but for recovery you don't need so much current as you're set to drive higher impedance load.

So, use higher number of turns on recovery coils (with thinner wire, of course). There is no miracle in inductive collapse- there is a rapidly varying magnetic flux inducing voltage in wire. So, since normal laws of induction apply you can easily calculate ampere/turns. In other words you don't need thick wire for recovery if you're just going to charge the capacitor and not drive any low impedance load.

BTW- capacitor in recovery circuit is there in order to lengthen very short inductive collapse impulse and thus practically "convert" it into current in order for battery to be able to receive the charge. No miracle there either. The same principles were patented by Tesla and are used in snubber circuits for decades.

[Jetijs]

I used two strands of wire per coil just because this way I can use one wire as a power winding and other as the recovery. I used bifilar coils on both my motors - V2 and V3, it is just that on V2 the wire was thicker and the windings fewer. You can also use only one wire per coil, but then you will not be able to recycle the recovered energy directly to the front end capacitor. Instead you will have to use the recycled energy to charge up a battery or to light a light bulb. This is my latest circuit that I am using right now:



You can see how each pole has its own coil with two windings. The blue ones are the recovery windings.

And this is the circuit of my V1 motor:



See how we need to capture the inductive spike if we do not use bifilar coils?

[uusedman]

jetis,

why would you use 2 strands of .7mm instead of 1 strand of 1.3 mm? Are you hooking the 2 strands to pulse at same time? can you please explain the benefit or the reason.

[Jetijs]

Lighty,
ok I got it. Nevertheless I will perform those tests with both motors. And after that I will see what can I do to wind those coils using thicker wire

[lighty]

My guess is that you used two strands of 0.7mm wire instead of a single 1.3mm in order to give you easier way to wind coil as well as to have same total diameter.

What you should consider is that two added diameters don't count for same resistance. You should look for same total cross-section of those wires in order to be able to estimate wire electrical conductivity.

Example


Diameter:

v2
1.3mm

v3
0.7 + 0.7 = 1.4mm


Cross-section:

v2
(d/2)^2 x pi = total cross-section area of wire

(1.3/2)^2 x pi = 1.327 mm2

v3
((d/2)^2 x pi) x 2 = (total cross-section area of two wires in parallel)

((0.7/2)^2 x pi) x 2 = 0.768 mm2



As for the inductance- as I already said, the higher the inductance the higher the inductive collapse spikes. When you connected those two 0.75 windings in parallel you reduced total inductance.

If I were you I would use single thick wire for windings (instead of two thinner ones) and I would not connect those windings in parallel but rather in series (if resistance permits). If you don't have enough space for thick wire and it's hard to wind it try to get flat enamelled wire of the same cross-section area.

[Jetijs]

Hi lighty
The V3 motor has about two strands, 55-60 turns of 0.7mm thick wire on each stator pole. The V2 has 1.3mm thick wire, also two strands and about 25 turns on each pole. I don't know the exact resistance, because my meter shows 0.6 Ohms even if the meter leads are touching. Anyway, it shows 1.2 Ohms on the V3 motor coil and 0.8 Ohms on the V2 motor coil. Don't know how accurate those results are. I will make more testing tomorrow as soon as my variable power supply becomes available, because now it is being used to defulfate a lead acid battery. Will measure everything and write the results down for each modification. I will try different ON times and voltages. Also I will try the opposite motor coils in series and also in parallel with a MOSFET for each coil. Will see how it performs. I will also make a scope shot on a shunt for each setup so I can see what the current waveform looks like.

Also, if this means something then the coil inductance of my V2 motor is 0.7mH and the inductance of the V3 motor is 0.4mH

[lighty]

Higher inductance of coils means higher inductive collapse spike. The challenge is to balance between opposite requirements. The higher number of turns will reduce current consumption and will recover more energy. On the other side higher number of turns limits your maximum frequency. Also, the resistance in coils with higher number of turns have to be taken into account.

What is the difference in turns and resistance between v2 and v3?

[Jetijs]

Thanks Elias
I will check the current waveforms. My V2.0 motor performs better for now, it gives about 40% recoovery without any optoswitch LED pusling, but the V3.0 motor gives me only about 17-19% recovery. I checked the old motor with the new circuit and vice versa, the recovery stays the same, that means that the problem is not in the circuit. The stator and rotor cores are made of the same material, the air gap is about the same on V2.0 and V3.0 motors. So the only difference really are the coils

[elias]

Hi, for my V2.0 motor I used about 1.3mm thick copper wire. The coils were wound with two strands of wire at the same time for a bifilar coil. Each coil had only 25 turns. My latest motors use 0.7mm thick wire, the coils are also bifilary wound and have about 55-60 turns.

Congratulations for your new motor dear Jetijs,
It is so lovely, and fast!

It seems that your coils saturate too soon, and you are driving at least 50% of your coils on the saturated level, which you can check by the scope.
Perhaps you need more windings.

I think that you can increase your recovery by either using higher voltage (which seems scary! ) or decrease your on time by more that 50-60 percent.

I admire the work you have done and I am eagerly waiting for better results!

Thank You!
Elias

[uusedman]

I have 100 and 150 turns on my stator that is why it is slow.

On vacation, should be back to work in a week.

thanks for the info.

[Jetijs]

Jetis,
I will try 16 gauge wire of 200 turns. How many turns and what gauge is your motor using? Can you list the different gauges and turns you used, I would like to work off some of your experiments.

Hi, for my V2.0 motor I used about 1.3mm thick copper wire. The coils were wound with two strands of wire at the same time for a bifilar coil. Each coil had only 25 turns. My latest motors use 0.7mm thick wire, the coils are also bifilary wound and have about 55-60 turns.

[uusedman]

Jetis,
I will try 16 gauge wire of 200 turns. How many turns and what gauge is your motor using? Can you list the different gauges and turns you used, I would like to work off some of your experiments.

Dr. Lindemann,

Thank you, trying to make this work. I have four magnets on the commutator wheel, and yes, it did make it faster. Got it to do over 900 RPM.

My current setup is capturing the inductive collapse with 3 4007 diodes to a 16 VDC Capacitor. How do I know how much electricity am I recycling? Should I add more? How do I determine which kind of diodes to use and how many to use?

I will purchase Radio shack alarm batter and put it in series with a car battery.

This motor already had optic sensor which I removed to put the magnet reed switch scheme. Should I put it back on the motor and work to make motor work on the optic sensor switch?

Thanks

Abbas

Uusedman,

Great little experiment. The easiest way to make your motor go faster right now is to add one more magnet to the opposite side of your commutator wheel. The rotor structure looks symmetrical, so it should work just fine to fire your coil more often per revolution. If that works, you might be able to add two more, so you fire every 90 degrees. Just start with one more and see how it goes.

The second thing that will speed up your motor is if you put the recovery circuit in, to capture the inductive collapse. This will also stop any arcing in the reed switch, and give you some of the energy back.

The third thing you could do is use some larger batteries. The little 9 volt batteries are (probably) current limiting the situation because of their limited capacity, so you are not seeing the full speed that is possible for that voltage.

Just take it step by step. You are doing GREAT!

Peter

[Peter Lindemann]

More Magnets on Commutator Wheel

If I want to increase the RPM of my Motor, what steps should I take?

Uusedman,

Great little experiment. The easiest way to make your motor go faster right now is to add one more magnet to the opposite side of your commutator wheel. The rotor structure looks symmetrical, so it should work just fine to fire your coil more often per revolution. If that works, you might be able to add two more, so you fire every 90 degrees. Just start with one more and see how it goes.

The second thing that will speed up your motor is if you put the recovery circuit in, to capture the inductive collapse. This will also stop any arcing in the reed switch, and give you some of the energy back.

The third thing you could do is use some larger batteries. The little 9 volt batteries are (probably) current limiting the situation because of their limited capacity, so you are not seeing the full speed that is possible for that voltage.

Just take it step by step. You are doing GREAT!

Peter