Electric Motor Secrets

[Peter Lindemann]

Totally on the Right Track

Ok, here is a little update.
At first I was getting some random results because the primary battery was depleted and lost voltage very fast while motor was running. So instead I used a variac vith a bridge rectifier and 20 000uF smoothing capacitor. This way I could get a steady DC. At first I tried how much energy I could get back if I increased the voltage and thus the speed of the motor. Here are my results:


Test1
IN____19.0V___1.37A___26,03W___100%____2241RPM
OUT__24.0V___0.13A___3,12W____11,98%___2241RPM

Test2
IN____23.1V___1.57A___36,26W___100%____2516RPM
OUT__24.0V___0.20A___4,80W____13,23%___2516RPM

Test3
IN____25.1V___1.67A___41,91W___100%____2632RPM
OUT__24.1V___0.232A___5,583W____13,34%___2632RPM

Test4
IN____27.2V___1.76A___47,87W___100%____2750RPM
OUT__24.2V___0.27A___6,53W____13,64%___2750RPM

From these tests i figured that increasing voltage/speed is one way to get better IN/OUT ratio in percentage. But if I would like to get something like 80% back, I would have to increase the speed to maybe 6000-8000RPM. I doubt that my motor could handle that speed, even now when the motor is running at about 2500 RPM, it is very loud and it is hard to speak to someone in the same room. So increasing the voltage and thus the RPM's is not the way to go.
I also tested what the difference between two circuits is (isolated output and non isolated output). Here are the results:

Test 1 Isolated output
IN____23.4V___1.59A___37,2W___100%____2537RPM
OUT__24.1V___0.20A___4,82W___12,96%___2537RPM

Test 2 NON isolated output
IN____23.4V___1.58A___36,97W___100%____2531RPM
OUT__24.1V___0.20A___4,82W___13,03%____2531RPM

From these tests we see that ihe non isolated output works just a tiny little bit better. The amp draw is a little bit less and so are the RPMs at the same voltage.

So next I looked at the input current waveform and the top line. I figured that in order to get the perfect wave (only a straight line) I have to decrease the ON time two times, but when doing that I have another 15 degree left on my 30 degree operation window, also only one such perfect impulse would not deliver enough power to get the motor to high speeds, so I figured I will make a comutator wheel that gives two impulses per rotor leg (30 degrees), not just one. That way I could deliver about the same ammount of power to the startor coil and get two pulses with better waveform and thus IN/OUT ratio. Here is what I mean:


So I made the timing wheel this way:


Each gap is 7,5 degree of an arc, total ON time is the same (15%) and there is plenty of time left for the BEMF fall time. Here is the waveform I got now:


And here are the test results:

Test 1
IN____25.4V___1.27A___32,25W___100%____1815RPM
OUT__24.2V___0.24A___5,80W___17,98%____1815RPM

Test 2
IN____30.0V___1.38A___41,40W___100%____2237RPM
OUT__24.5V___0.34A___8,33W____20,12%____2237RPM

So here we see, that with these two pulses instead of only one, we get more back with less speed and current draw
Any comments?
Also, Peter I think you missed my post with a question about motor loading in the previos page

Thanks,
Jetijs

Jetijs,

You have entered the zone of self-learning where you can see what the motor's behavior is teaching you!!! You can begin to see that by properly limiting the input pulse to just what you can get back, the motor can run 55% of the time on your applied currents and 45% on the recovered currents. The recovered currents increased when you chopped the ON-TIME window into two parts. But you are still ON for too long for the magnetic behavior of your stator.

The LAST TRICK to fine tune this arrangement is to open up the ON-TIME window on your commutator wheel to about 25 degrees, and flash the LED at the inductive rise-time rate. This keeps the motor in the maximum energy recovery mode regardless of speed or loading. From the looks of your recovery wave-form, it looks like the optimum ON-TIME is between one and two time divisions on your scope.

Make a little 555 timer circuit and chop the LED front end of your optical commutator with a 50% duty-cycle and an ON-TIME equal to about 1.5 time divisions on your scope.

Now, it is just about maximizing torque with small air-gap, maximizing energy return with proper input chopping and recycling the recovered energy back to the front with an isolated output winding.

That's it! You now know how to make the machine work.

Peter

[Jetijs]

Ok, here is a little update.
At first I was getting some random results because the primary battery was depleted and lost voltage very fast while motor was running. So instead I used a variac vith a bridge rectifier and 20 000uF smoothing capacitor. This way I could get a steady DC. At first I tried how much energy I could get back if I increased the voltage and thus the speed of the motor. Here are my results:


Test1
IN____19.0V___1.37A___26,03W___100%____2241RPM
OUT__24.0V___0.13A___3,12W____11,98%___2241RPM

Test2
IN____23.1V___1.57A___36,26W___100%____2516RPM
OUT__24.0V___0.20A___4,80W____13,23%___2516RPM

Test3
IN____25.1V___1.67A___41,91W___100%____2632RPM
OUT__24.1V___0.232A___5,583W____13,34%___2632RPM

Test4
IN____27.2V___1.76A___47,87W___100%____2750RPM
OUT__24.2V___0.27A___6,53W____13,64%___2750RPM

From these tests i figured that increasing voltage/speed is one way to get better IN/OUT ratio in percentage. But if I would like to get something like 80% back, I would have to increase the speed to maybe 6000-8000RPM. I doubt that my motor could handle that speed, even now when the motor is running at about 2500 RPM, it is very loud and it is hard to speak to someone in the same room. So increasing the voltage and thus the RPM's is not the way to go.
I also tested what the difference between two circuits is (isolated output and non isolated output). Here are the results:

Test 1 Isolated output
IN____23.4V___1.59A___37,2W___100%____2537RPM
OUT__24.1V___0.20A___4,82W___12,96%___2537RPM

Test 2 NON isolated output
IN____23.4V___1.58A___36,97W___100%____2531RPM
OUT__24.1V___0.20A___4,82W___13,03%____2531RPM

From these tests we see that ihe non isolated output works just a tiny little bit better. The amp draw is a little bit less and so are the RPMs at the same voltage.

So next I looked at the input current waveform and the top line. I figured that in order to get the perfect wave (only a straight line) I have to decrease the ON time two times, but when doing that I have another 15 degree left on my 30 degree operation window, also only one such perfect impulse would not deliver enough power to get the motor to high speeds, so I figured I will make a commutator wheel that gives two impulses per rotor leg (30 degrees), not just one. That way I could deliver about the same amount of power to the stator coil and get two pulses with better waveform and thus IN/OUT ratio. Here is what I mean:


So I made the timing wheel this way:


Each gap is 7,5 degree of an arc, total ON time is the same (15%) and there is plenty of time left for the BEMF fall time. Here is the waveform I got now:


And here are the test results:

Test 1
IN____25.4V___1.27A___32,25W___100%____1815RPM
OUT__24.2V___0.24A___5,80W___17,98%____1815RPM

Test 2
IN____30.0V___1.38A___41,40W___100%____2237RPM
OUT__24.5V___0.34A___8,33W____20,12%____2237RPM

So here we see, that with these two pulses instead of only one, we get more back with less speed and current draw
The best achievment yet is 20.12% recovered energy.
Any comments?
Also, Peter I think you missed my post with a question about motor loading in the previos page

Edit: I made another timing wheel with three gaps (5degree of an arc).



Here's how the waveform looks:


I tried several timing adjustments and voltages. The best result I got so far is 24,25% recovered energy.


Thanks,
Jetijs

[Aaron]

start new thread

Hi Sykavy,

You're welcome to start a new thread on iron casting as it relates to building rotors, cores, etc... so that it ties into a renewable-energy topic. I don't know anything about it but I'm sure there are others that can kick around some ideas with you on this. If you don't mind doing that, I'll clean this thread up a bit.

[sykavy]

Sykavy,

CAST IRON is an industrially available metal. Whether or not it is readily available near you is beside the point. That you do not know this, or even know how to find out, is a reflection on your general lack of scientific knowledge. Even the assumption on your part that you could some how make your own "cast iron" by melting down "old drain pipes or car radiators" shows a complete lack of understanding.

Just to clarify, I am not suggesting that you cast your own iron.

This forum is about experimental electric motor building. Casting your own metal alloys is an experiment in metallurgy. That you would even suggest this is shocking to me. Your lack of knowledge about electric motors and electronics in general is profound, but the idea that you would attempt to begin a project like this by casting your own iron core is beyond my comprehension.

Over the last 6 months, I have been extremely patient and polite with you, but I am going to draw the line right here. I will not offer you any help with such a project. If you attempt any of this, you are totally on your own. I will not be drawn into a discussion about casting techniques, raw materials stocks, fluxes, slag, molds, or the like. Any posts on these subjects in this forum will be deleted.

The scientific knowledge base and engineering skill set required for success in the project of building your own experimental electric motor is considerably beyond your current abilities. A reciprocating solenoid engine like Teal's is a complex electro-mechanical machine. Building one from scratch is very difficult. Building one by modifying an existing internal combustion engine is no less difficult. Please don't waste any money by starting a project you are unlikely to be able to finish successfully.

Peter

I understand that I may seem foolish in wanting to cast and that point is well taken. My friend, who is experienced in casting, will be handling the iron part. I had no intention of drawing the tread away from its purpose or asking you metallurgy questions.

I know my knowledge is limited but I have to start somewhere. You have been patient with me and I thank you for that.

Ok if you say that I'm on my own.

I'm still going to try and make it from what I understand from this thread and your DVD. I never intended to be a problem. I know I may be naive but I am sincere in my interest in your project and I'm willing to learn. So for now adieu

[Peter Lindemann]

Right

Um, if one puts a diode cathode on battery negative and diode anode on the negative side of the capacitor, wouldn't that block current from capacitor to battery?




I suppose one should connect recovery coil to capacitor with appropriate diode in between? Otherwise it wouldn't make sense (at least to me it wouldn't).

Lighty,

Yes, the idea is to block the energy from going back to the battery. Why? Putting the energy back on to the RUN battery is the same as throwing the energy away, because the battery cannot be charged and discharged at the same time. In the arrangement I am suggesting, the capacitor acts as a buffer stage. Its voltage will never drop below the battery voltage, but it may rise above the battery voltage whenever the return energy pulse arrives.

The isolated output coils already have their respective diodes associated with them to block any current flows during the input phase, so they only allow current to flow during the magnetic field collapse phase. When you collect the output energy from the same winding as the input, the output current is reversed and cannot be applied back to the front of the circuit without producing a short circuit in the system. By collecting the output on an isolated winding, the problems associated with this current being in the opposite direction are negated, so the energy may be applied directly back to the front of the circuit with no other complications.

This frees the system from needing a second battery to receive the recovered energy.

The idea is to optimize the circuit conditions for this recovery mode, so the motor can be run by simply replacing that fraction of the energy that is NOT recovered. When this circuitry is coupled with a mechanical section with a very small air-gap, so that the mechanical torque production is high, the probability of running the COP>1 is also very high.

Peter

[lighty]

Place your 10,000uf capacitor in parallel with the input battery and isolate it from the battery with one diode on the negative line with the cathode toward the battery.

Um, if one puts a diode cathode on battery negative and diode anode on the negative side of the capacitor, wouldn't that block current from capacitor to battery?

Then just connect the plus and minus from the isolated output directly to the capacitor plus and minus.

I suppose one should connect recovery coil to capacitor with appropriate diode in between? Otherwise it wouldn't make sense (at least to me it wouldn't).

[Jetijs]

Peter,
while I am experimenting, I was wondering about one thing. In your videos I see, that when you slow your motor down, it consumes more current, but also the charging battery voltage increases more. That means if we are drawing more current, we also can get more back. But for example:


Here you see two current waveforms, the first one is the waveform of the motor running at full speed, second waveform shows what happens to current when the motor is loaded. So in both cases we can only get back the yellow part, right? no mater how long the pulse is. But why is it then, that we are getting more back, if we are drawing more prom the primary? I mean the rise times are the same in both cases, so must be also the recoverable energy ammount per pulse. Why is the battery charging more when the motor is loaded? I should look at the current waveform on the output when the motor is loaded
Thanks,
Jetijs

[Peter Lindemann]

Do NOT cast your own Iron!!!

Thanks Peter!

BTW you mentioned that there maybe a possible to short out by having the steel inside the coil?
you said: "But the cylinder wall will act like a big shorted turn, so the magnetic structure will have to be mounted some distance from the block."

What does this mean?

Before my friend casts it, I 'd like to know if there needs to be a distance around the coil and the iron keeper around the coil.

BTW I also have access to a lathe but no pure iron to lathe. I'll have to melt-down some old drain pipes or car radiators that is why i plan on casting it.

Will the drawing on your DVD about the Teal Motor due? Also I assume a small air gap on the botom part of the iron/magnetic enclosing the coil as to complete the magnetic circuit.

Sykavy,

CAST IRON is an industrially available metal. Whether or not it is readily available near you is beside the point. That you do not know this, or even know how to find out, is a reflection on your general lack of scientific knowledge. Even the assumption on your part that you could some how make your own "cast iron" by melting down "old drain pipes or car radiators" shows a complete lack of understanding.

Just to clarify, I am not suggesting that you cast your own iron.

This forum is about experimental electric motor building. Casting your own metal alloys is an experiment in metallurgy. That you would even suggest this is shocking to me. Your lack of knowledge about electric motors and electronics in general is profound, but the idea that you would attempt to begin a project like this by casting your own iron core is beyond my comprehension.

Over the last 6 months, I have been extremely patient and polite with you, but I am going to draw the line right here. I will not offer you any help with such a project. If you attempt any of this, you are totally on your own. I will not be drawn into a discussion about casting techniques, raw materials stocks, fluxes, slag, molds, or the like. Any posts on these subjects in this forum will be deleted.

The scientific knowledge base and engineering skill set required for success in the project of building your own experimental electric motor is considerably beyond your current abilities. A reciprocating solenoid engine like Teal's is a complex electro-mechanical machine. Building one from scratch is very difficult. Building one by modifying an existing internal combustion engine is no less difficult. Please don't waste any money by starting a project you are unlikely to be able to finish successfully.

Peter

[sykavy]

Sykavy,

Look for Cast Iron. If it's pure, it releases its magnetism completely, and can be machined to any shape. But like Lighty says, stay away from Italian Cast Iron, because it is all "re-cast" material and does retain its magnetism slightly. I also have some direct experience with Italian Cast Iron and don't recommend it. Here in the USA, Cast Iron works fine.

Black Sand only magnetizes to levels equivalent to about 35% of iron, so does not magnetize to sufficient levels for making attraction motors.

Peter

Thanks Peter!

BTW you mentioned that there maybe a possible to short out by having the steel inside the coil?
you said: "But the cylinder wall will act like a big shorted turn, so the magnetic structure will have to be mounted some distance from the block."

What does this mean?

Before my friend casts it, I 'd like to know if there needs to be a distance around the coil and the iron keeper around the coil.

BTW I also have access to a lathe but no pure iron to lathe. I'll have to melt-down some old drain pipes or car radiators that is why i plan on casting it.

Will the drawing on your DVD about the Teal Motor due? Also I assume a small air gap on the botom part of the iron/magnetic enclosing the coil as to complete the magnetic circuit.

[sykavy]

Peter, what do you mean with that? Why would it be impossible to charge the batteries with the recoverable energy if we use a more powerful motor?

Speaking about core material, I experimented a little with some black sand material after I saw Peter talking about that in one of the videos. We actually do not have access to the real black sand here in Latvia, because there is no gold mining business here. But I searched around the web for the content of black sand. I found that it basically consists of two main materials - magnetite and hematite. Both are iron oxydes. I could get them from a local chemist shop as powder. I tried various ratios and resin types. I found that magnetite is attracted by a magnet more than hematite, almost like iron fillings. Also the best resin type I found is that type they use in fiberglass molding, making car bumpers, small boats and so on. With this resin I could add more magnetite/hematite powder and the mix would not turn out so britle. Also that stuff is easy to machine afterwards. But I must agree to Peter, taht althought there is a little drag if I use this core material for a generator coil, there is also a little voltage generated. The same goes if I use that kind of coil for a electromagnet. This stuff may have a high magnetizing/demagnetizing rate, but it can not magnetize to the level of an ordinary iron. Still, that was an interesting experience



sykavy, I dont really know what grade of steel am I using, but ir works well. I will clarify this when I meet my laser cutting guy

Jetijs

Diekujeme!
I have just met a friend that may be able to help me. He told me that if I just make what I need in foam rubber he may be able to cast it in 100% iron or close to it maybe 70%.

[Jetijs]

Peter, that is what I was thinkink, but I thought that maybe there is something else. It makes sense. For example, if we have a bigger motor and are recovering say 10 amps, that means the charging battery bank should be at least 200 amphours large to charge them safe at this current (C20 rate). That is a BIG battery.

[Peter Lindemann]

Bigger Motors...

Peter, what do you mean with that? Why would it be impossible to charge the batteries with the recoverable energy if we use a more powerful motor?

Jetijs

Jetijs,

For little motors, charging and discharging batteries is fine. But what happens when the motors are 100kw or 1000kw? Charging batteries with the recovered energy becomes extremely challenging, not to mention the size and weight of the batteries. If the recovered energy can be put right back into the supply and seamlessly reused, it is a more practical solution, even if the total amount of energy recovered is 20% lower.

Every design has an economy of scale. What works in larger scale systems is quite often very different than what works in the desk top.

Peter

[Jan H]

about iron

I wonder what metal characteristic makes for a good rotor, it has to lose all its magnetism right? The biggest diffrence i see between steel and pure iron is the carbon content.
But cast iron holds even more carbon, so it would perform even worse? Since peter says that cast iron works great I'm confused.

Could it have something to do with the crystalline structure? If it does than heat treatment could change the properties.

All i know is that pure iron is VERY rare, because it does not have a lot of purposes. The next best thing would then be S235JR (Fe-360) wich is just plain old construction steel.

[Jetijs]

As the power of these systems goes up, it becomes impossible to charge batteries with the recovered energy, so it must be recycled immediately.
Peter

Peter, what do you mean with that? Why would it be impossible to charge the batteries with the recoverable energy if we use a more powerful motor?

Speaking about core material, I experimented a little with some black sand material after I saw Peter talking about that in one of the videos. We actually do not have access to the real black sand here in Latvia, because there is no gold mining business here. But I searched around the web for the content of black sand. I found that it basically consists of two main materials - magnetite and hematite. Both are iron oxydes. I could get them from a local chemist shop as powder. I tried various ratios and resin types. I found that magnetite is attracted by a magnet more than hematite, almost like iron fillings. Also the best resin type I found is that type they use in fiberglass molding, making car bumpers, small boats and so on. With this resin I could add more magnetite/hematite powder and the mix would not turn out so britle. Also that stuff is easy to machine afterwards. But I must agree to Peter, taht althought there is a little drag if I use this core material for a generator coil, there is also a little voltage generated. The same goes if I use that kind of coil for a electromagnet. This stuff may have a high magnetizing/demagnetizing rate, but it can not magnetize to the level of an ordinary iron. Still, that was an interesting experience



sykavy, I dont really know what grade of steel am I using, but ir works well. I will clarify this when I meet my laser cutting guy

Jetijs

[Peter Lindemann]

Don't Use Black Sand

congrads on your great work! What material did you use for your rotor?

Ive been looking for 100% iron for my project but can't find it anywhere!! I did some reading and iron doesn't hold the magnatism while steel does. In the SG motor, John Bedini uses welding rods, are they close to iron. I think they are soft steel. Do they hold magnatism? I'm really shocked to find it soooo hard to find some pure iron. It just seems so weird.

Ps Peter,
In one of your videos you spoke about black sand that can be molded in plastic and it magnatizes and releases magnatism very quickly with no retention of magnatism. Would this material be good for iron parts of my motor? At least to enclose the coil?

Sykavy,

Look for Cast Iron. If it's pure, it releases its magnetism completely, and can be machined to any shape. But like Lighty says, stay away from Italian Cast Iron, because it is all "re-cast" material and does retain its magnetism slightly. I also have some direct experience with Italian Cast Iron and don't recommend it. Here in the USA, Cast Iron works fine.

Black Sand only magnetizes to levels equivalent to about 35% of iron, so does not magnetize to sufficient levels for making attraction motors.

Peter