Electric Motor Secrets

[Jetijs]

I live in Latvia, that is not too far away
Got any links form mu-metal manufacturers in Germany?

[lighty]

I'm from Croatia. The transformer silicone steel is cheap but I'm not sure how much would shipping cost since the steel is heavy as hell.

As for the Mu-Metal we get it from Germany.

[Jetijs]

Lighty, where are you from, if you can get this silicon steel so easy? Where are you getting this steel? Maybe someday you could ship some of these steel plates to me, for a reasonable price of course

[lighty]

@Jetijs
@nali2001

I didn't know it's so hard to get the transformer silicone steel. It's extremely cheap here and easily obtainable and I used it many times for various purposes. Some of the forms I made were quite complex but as you know it can easily be cut by water and laser (depending on the required precision and the thickness of silicone steel plate). These days I prefer to use the Mu-Metal cores but I rarely do because the material is rather expensive.


@Peter Lindemann

Reed switches are a great little component but they do suffer from slow turn-on times and slow turn-off times (a few orders of magnitude longer periods in comparison to semiconductor devices). Fast turn-on and turn-off periods are useful in more than one way and especially if you're into energy recycling. As for the bias currents, they're extremely low- for example an optical switch with three stages of level adjustment and logic control consumes about 30mA at 12V -> 0.36W. In comparison to the overall consumption of any motor it's negligible.

That being said- I do recognize that reed switches are much simpler to work with and probably the best choice for fast and simple experiments.

[Jetijs]

Thank's Peter
I did not know, that a reedswitch can operate that fast. This is great
As for the coil wire. What about those cables with insulation? Can I use these? Because it is hard to get the magnet wire of that thickness here, but I can get a cable with insulation at every store.
Of course the insulation would reduce the total count of the windings, but that is what is available here. I could order some magnet wire form ebay, but that would take weeks to deliver and would be more expensive. I don't see why i could not use such a cable instead of a magnet wire. What do you think?
Thank's
Jetijs.

[Peter Lindemann]

Magnetic Reed Switch... Much Better Than You Think

Nice Peter
I am sure that this is only the beginning
I am almost done all the mechanical stuff, there are some some minor things I have to take care of. I will post pictures tomorrow. Meanwhile I have some questions for you.
1. I was wondering about your reedswitch and its construction. I mean a reedswitch is a physical switch and I am surprised that you could get 3600 RPM using reedswitch. That means the switch fired 7200 times per minute or 120 times per second. Can a reedswitch operate that fast? Or did you use some special kind of reedswitch? I have some of these:

Will they work properly? Have you considered using hall switches?
2. When I look at your coils, I see those thick wires, but I have only gauge 21 wire, I think that this is a little too thin. Also the winding will be a pain in the ass Maybe I could use a simple standard 1mm thick cable with plastic insulation? That way It would be easier to wind the coil and I could probably get some 300 to 400 turns on my startor. Also the resistance would be less and stronger magnetic field. Of course also the amp draw would increase.
Thanks

Jetijs,

I have used the exact type of Reed Switch you show in this picture in a motor I built 5 years ago. It had two of these reed switches firing two different circuits through the same coils in opposite directions, alternately, twice per revolution. The motor was capable of 11,000 RPM and was run at that speed often. Each of the two reeds were switching cleanly and discretely (with no over-lap) 400 times a second. These devices outperformed my wildest expectations!

They must be operated in a section of the circuit that has no inductive characteristics to prevent arching at the contactor. My current demonstrator uses the magnetic reed in just such a configuration (operating a voltage divider bridge) and has never malfunctioned.

The reason I chose these devices is that they do not require any power to operate. Both Hall-Effect circuits and Opto-Interrupter circuits require continuous "stand-by" current. While I agree that more complex circuits may benefit from optical commutation, your single coil with an X rotor will run very well on the magnetic reed as the control device. The "trick" is to set up the physical spacing between the magnets and the reed to get the proper On/Off timing. Don't be surprised if it takes an hour or more to tweek this into perfect operation.

As for your wire size, the motor will run if you wind the coil with #21 wire, but it won't run very fast, or have very much power. The reason is.......too much inductance. The current "rise time" will take up the whole window as the Rotor is attracted to the Stator, and even be turned OFF before rising to its maximum. Consider trying to find different wire for your your coil. I would recommend at least #16, or as large as #14. Currently, my coils are 250 turns of #12, but my unit has four of these coils and an optical commutator. (I'd have it running by now, but I have been diverted by another project for the last few weeks.)

As for winding the coils, I built a special jig that holds the core by one of the bolt holes and chucks up into my variable speed Mill. At about 30 RPM, winding becomes manageable. It will take more time to make the tool for winding than it will to wind the coil. But after that, unwinding and rewinding with different wire is simple.

I hope this helps.

Peter

[nali2001]

Answers

To Jetijs:
A reedswitch would be a workable solution for some testing and such. And not everybody is going to do 3600rpm. Keep in mind that you should only used the reedswitch for triggering transistors and such and not use it as the actual switching mechanism for the coil since the current and the Back Spike will burn it out. You see them used here: YouTube - OverUnity Pulse Motor - Doug Konzen

And about the coil winding. In theory there is no difference in field strength using 1wrap at 100amp compared to 100wraps at 1amp. But it is a balance, it depends... like do you for instance actually have a 100amp source, transistor or diodes, if not don't bother building a coil that requires it. And if one is not happy with the first coil just wind another one. (keeps you from the street)

To Lighty:
The reason why most people don't use silicon steel laminations is because there is no 'real' way to obtain them. That is one of main underlying reasons why I choose my design and use regular induction motor stator cores (which are of course made of precision cut silicon steel laminations) In my experience the only other 'kinda' available source of laminations is indeed microwave oven transformer cores (MOT) but even that is not practical since you most of the time need more than one transformer and that also means the same size/type. Ant if you salvage them from dead microwaves you can spend a few months hoping for two identical sized transformers(that is if you only need two). That is why next to nobody is building. The needed material is just not realistically available. (I'm not even talking about machining) Sure you can have a custom motor core made for you but how are we going to pay that... These are the main problems that plague this project (and field)

Regards,
Steven

[Jetijs]

Thank's lighty
I want to make this first prototype model as easy as possible. I will consider advanced switching methods on the next model if this one will be successful (And I am sure it will). About not using silicon steel, I cant find this stuff in my country in a form of big sheets that I could cut in a way I need. So in order to get some custom shapes, we need to use other materials. Of course, the silicon steel is the best material for these purposes, it's just hard to get.

[lighty]

@Jetijs

I was just passing by and saw your post.
Why use reed switch at all? Why not using the optical switch? It's a more complicated solution but it's extremely fast, doesn't wear off and you'll avoid any possible arcing losses and/or problems. All you need is an optical switch, a proper reflective target, a couple of small bipolar transistor to get your levels and logic correct, a MOSFET driver and a MOSFET or IGBT. It may sound complicated but once it's done it's performance is by far better in comparison to reed switch and it's much more versatile so you can easily adjust your optical reflection target. At least that's my experience when it comes to advanced switching and high versatility.

BTW- you and nali2001 did a great job but I was wondering why nobody used silicon steel material used for transformers? It has high permeability, narrow hysteresis loop and it's made in such a way to conduct magnetic flux better in 2D so the 3D losses are reduced. Oh, and it's not expensive at all and is mechanically tough.

I'm just wondering, that's all.

[Jetijs]

Nice Peter
I am sure that this is only the beginning
I am almost done all the mechanical stuff, there are some some minor things I have to take care of. I will post pictures tomorrow. Meanwhile I have some questions for you.
1. I was wondering about your reedswitch and its construction. I mean a reedswitch is a physical switch and I am surprised that you could get 3600 RPM using reedswitch. That means the switch fired 7200 times per minute or 120 times per second. Can a reedswitch operate that fast? Or did you use some special kind of reedswitch? I have some of these:

Will they work properly? Have you considered using hall switches?
2. When I look at your coils, I see those thick wires, but I have only gauge 21 wire, I think that this is a little too thin. Also the winding will be a pain in the ass Maybe I could use a simple standard 1mm thick cable with plastic insulation? That way It would be easier to wind the coil and I could probably get some 300 to 400 turns on my startor. Also the resistance would be less and stronger magnetic field. Of course also the amp draw would increase.
Thanks

[Peter Lindemann]

WOW! 20,000 views!



Thanks everybody for staying interested and making this the most viewed thread in the forum. In the near future, stay tuned for more exciting developments as Steven and Jetijs get their prototype motors up and running.

Peter

[sykavy]

Sykavy,

No, I did not say anything of the sort. My comments were addressing Steven's misunderstanding about the timing issues. The motors CAN be configured to produce both torque and electrical recovery, as I have said all along.

Peter

OK sorry about that, my mistake. I thought that it seemed strange.

[Peter Lindemann]

Misunderstanding the Last Misunderstanding

Hi Peter
Great videos!! Congrads! to Aaron too.

I understand the demonstration is for illustration only but now I'm a little confused, please forgive me if I'm not understanding well, are you saying if we scaled up bigger this motor with stronger torque ( say for a scooter) we wouldn't be able to recover the energy to the second battery?

Sykavy,

No, I did not say anything of the sort. My comments were addressing Steven's misunderstanding about the timing issues. The motors CAN be configured to produce both torque and electrical recovery, as I have said all along.

Peter

[sykavy]

Steven,

The magnetic reed does NOT just produce a fixed pulse. It stays on as long as the magnet on the wheel is in range. This means the "ON TIME" to "OFF TIME" ratio is the same regardless of speed! So, that does not cause the motor to draw more current at slower speeds, since the "Duty-Cycle" or percentage of "ON TIME" is always the same.

The point of these motors is NOT to make them as powerful (mechanically) as possible! The point is to make them operate in a special window, to make them as EFFICIENT as possible, which means to harvest as much FREE MECHANICAL ENERGY as you can while still recovering the maximum electrical energy.

The machine is a "balancing act" between the two outputs, as can be seen in the new videos. Tweeking the machine into this window will NOT make it produce its maximum possible mechanical energy. It will make it produce its maximum COP.

If you just maximize your motor for torque, you will recover very little electrical energy, if any, and it will run like an off-the-shelf Switched Reluctance Motor. If that is what you want, then Great, but this is NOT what this project is about.

Peter

Hi Peter
Great videos!! Congrads! to Aaron too.

I understand the demonstration is for illistration only but now I'm a little confused, please forgive me if im not understanding well, are you saying if we scaled up bigger this motor with stronger torque ( say for a scooter) we wouldn't be able to recover the energy to the second battery?

[Jetijs]

Steven,
I was wondering about the same thing today. But I figured, that the "on" period of the coils would be for about 30 degree from 360 degree (15 degree per pulse) each revolution. That means that we have a certain percentage of "on" time in every period. This percentage will be the same regardless of the RPM. So for example, if we have only 1 RPM rotor speed, that means the complete transistor ON time would be 5 seconds. 360/60=6 degree per second, 30/6=5 seconds ON time. So at 1 RPM the total ON time would be 5 seconds and the OFF time - 55 seconds. Now lets say that now we have 60 RPM rotor speed, that is one revolution per second. This time each ON time will be 1/12 second, since we have the speed of 60 RPM we need to multiply this time by 60. 1/12*60=5 seconds. So you see that the total ON time will be about the same regardless of RPM, because at faster speeds the ON pulse will be shorter, bur there will be more pulses per minute. Also at slow speeds the ON pulse will be longer, but there will be less pulses per minute. In the video that circuit Peter used was a simply transistor switch that opens when a magnet passes a reedswitch and stays open till the magnet is so far away, that the reedswitch closes. There is no fancy pulse circuits
This is how I understand how Peters motor works
Thanks.

Edit: Peter was quicker