Electric Motor Secrets

[Mark]

Just use a piece of fuel injection hose and some hose clamps.

[Jetijs]

Steven, I wonder what the air gap of those motors is. Do you know? Anyway, looks good enough and cheap for enthusiasts to play. Also, what are the rotor/stator pole count?

Mark,
still waiting on my shaft coupler.

[Mark]

Its Time For An Update Jetijs

Okay its been 2 weeks now Jetijs I think you owe us an explanation! I dont see any data on your motor, no amp draw, no HP, nothing. Ok enough harping! Whats going on? Is it sweet or what? Please give us an update.

When you figure out a way to check horse power I'd be very interested in what kind of HP you get out of your Tesla Air Turbine also, and at what air pressure.

Keep up the good work and look forward to hearing from you!

Mark

[nali2001]

For all of you who want to experiment with the attraction motor concept. I might have found something interesting. Here they sell for $89.95 commercial reluctance motors of "close to 1hp" it even comes with controller (which you probably won't need.)

Anyway it is a surplus store and they have only 9 sets in stock. So I'd say go for it since I have never seen affordable reluctance motors before.

M132-013A001-16B & Controller-Switched Reluctance Motor & Controller-Electronic Surplus Inc.Offering obsolete IC's, discretes, motors, relays, switches, pots, and much, much more! Always looking for your excess inventory.

-edit-
Oh, they also have 'motor only' sets - 10 of them left:
M132-013A001-16B Motor Only-Switched Reluctance Motor 2-Phase-Electronic Surplus Inc.Offering obsolete IC's, discretes, motors, relays, switches, pots, and much, much more! Always looking for your excess inventory.

Regards,
Steven

[StevanC]

I'm actually not surptised at all - contrary i know that the preferred device are the voltage driven ones.

You are most right that the MOSFETs and IGBTs provide a handfull of advantages ar rough power stages etc. AFAIK

I agree with that.

I only wanted to point out that there might be scenarios where thet 'insignificant additon' of drive current to power handling, might be all what's needed?

Think 'delicate tipover'?

thi topis tends to borderstep this topic, and i had no intention to taint it, just to make a point above?

[lighty]

@StevanC

The truth is that MOSFETs and other voltage driven devices are much easier to set up and it's possible to drive them in floating configuration like with pulse transformers or optocouplers.

Modern MOSFET's easily go into high MHz range although I don't see what that has to do with this particular use in attraction motors.

As for the 1000V/300A devices- they are now commonly replaced by IGBTs (now that the price dropped) especially in switching applications. And guess what IGBTs are also voltage driven.

In case of BJT drive current adds to the power current? Not exactly- some of the bias current will be a portion (a rather small portion I might add) of the total current through coils. Main driving current portion must be provided by driver circuit so no gain there.

However, I suspect this discussion don't have much to do with this thread. If you want we can take it to the greatest EDA forum on the net EDAboard.com although I don't have much time to engage into such discussions I'm sure a number of engineers will have something to say about this topic. However, you might be surprised that preffered switching device (especially heavy duty) are either IGBTs, MOSFETs or (where possible) thyristors.

[theremart]

Looking at the Jetjis design..

I was thinking today about Jetijs setup of two motors. It reminded me of Bob Teals design which resembled a cam shaft in an engine. I was thinking that one could stack stators on the same shaft and stack the coils as Bob teal did...

But Teals design made alot more sense to me today when I looked at Jetijs new version of his setup.

[StevanC]

No TABOO?

You're not correct. MOSFET can be switched On and Off extremely fast as well as the IGBT (the other voltage driven device). Yes, one needs quite fast voltage impulse by source who can also provide short high current impulse. Hence dedicated MOSFET drivers Jetijs is using- check out their datasheet.

I see - it's commonly accepted to think so. Now what do You think, provides the actual switch ON in those driver circuit ? Midget made relays?


It's BJTs that do the MAKE - nothing is faster than a hard driven BJT. AFAIK
)

The MOSFETs only provide a price advantage and size advantage for a given power to handle.


You tell me why they make hFE1000 rated 1000+V 300A BJTs for military?
*Switching 1:1000 ratio with a 0.6V tipover*


And i dint claim it pays better out with BJT, only it's possible to make a more efficient circuit?
the drive current can add to the power current - no loss.


What You think?

[lighty]

I learned the other day that to switch a IRFP260N really fast, one has to supply 10V minimum - the closer to 20V the better. And to saturate it to 10V during less than 100nsec one can easily require 10A to flow - now to supply as much current for similar time again a BJT is needed - the FETs need simply too much energy to be switched hard ("who's older chick or egg") so in the end we need a really hefty 40V 20A SOA BJT thats FAST.

You're not correct. MOSFET can be switched On and Off extremely fast as well as the IGBT (the other voltage driven device). Yes, one needs quite fast voltage impulse by source who can also provide short high current impulse. Hence dedicated MOSFET drivers Jetijs is using- check out their datasheet.

[StevanC]

Jetijs, i saw the vid...

i had a talk to a friend of mine who's a EE from semiconductor background (riz of ex YU) and when i asked regarding diodes (1N vs UF) he expressed the following:

A diode in this configuration (the back-shunt on SSG) is by far more fast than a BJT - it's regarded that a 1N4007 is lots faster than a 2N3055 emitter to base - and the times You presented:
95 nsec is by far (twice) faster than 150nsec (0.15usec) the BJT operates at HARD SPEED.

Normally, there seem to be very little devices capable to switch as much current as a 2n3055 that fast and not require a lot more tension:

I learned the other day that to switch a IRFP260N really fast, one has to supply 10V minimum - the closer to 20V the better. And to saturate it to 10V during less than 100nsec one can easily require 10A to flow - now to supply as much current for similar time again a BJT is needed - the FETs need simply too much energy to be switched hard ("who's older chick or egg") so in the end we need a really hefty 40V 20A SOA BJT thats FAST.

Now I ask:
Why not drive it with a such one already @12V?

and IMHO that's EXACTLY what Bedini figured: It CAN be driven FASTER but the most efficient way is trough a single BJT rough ENOUGH and fast ENOUGH.

Please, do all tests with the FETs ans especially pay attention to efficiency, recovery and performance, for i 'have a feeling' that the most sweet lies in the garden of "BJT" and i mean above 60hFE while over 32A SOA...

I look forward to news from You

commercials:


-in case of abduction call our hotline-
RENT-A-RUG limited.

[Jetijs]

Thanks Peter
I love "e-beers"
Thanks also to gyula and erfinder for the diode suggestions

[Peter Lindemann]

As Usual....

Jetijs,

Excellent, as usual. Watching you, methodically, go through the process of solving each problem and moving on the the next, has been an inspiration. You have not only built a beautiful motor, but you have produced a grand tutorial on how much work, skill, time, money, and PERSISTENCE it takes to advance this work.

Congratulations!

I have every confidence that your model, when fully operational, will demonstrate all of the characteristics this motor is capable of. I definitely owe you a beer. To bad all I can afford is an "e-beer".

Peter

[erfinder]

I like this one.....

30A 1200V 40ns

http://ixdev.ixys.com/DataSheet/L189.pdf

[gyula]

Mark, I could not find any data about the 1n5408 diode speeds and I looked in data sheets of several manufacturers. I don't think that they are good for fast switching. Sure, they will work, but for this purpose we need the fastest diodes we can find. I need something that can handle up to 1000v and is very fast. Unfortunately the fastest diodes can handle lower voltages. I was thinking of using something like MUR4100 (SI-D 1000V 4A/70Ap 75ns), UF4007 (SI-D 1000V 1A/50Ap 75ns) or UF5408 (SI-D 1000V 3A/150Ap 75ns). These are the fastest 1000V diodes I can get in my electronic shop. Any suggestions are welcomed here.

Hi

The 1N5408 is a general purpose rectifier, if it were a fast diode its switching speed would have been included in its data sheet.
Better to use fast or ultrafast diodes for catching the flyback pulse. Here are some further types as an addition to your types mentioned above:
STTH5R06 600V 5A 40ns
RHRP860 600V 8A 35ns
STTH1210 1000V 12A 90ns
STTH1212 1200V 12A 90ns
STTH512 1200V 5A 48ns
STTH812 1200V 8A 50ns

rgds, Gyula

[StevanC]

pursuit for excellence

"The jedi council must know of this one..."



I can only say one thing, and that's two words:

"I congratulate You"

now back to work and do some benchmarks,
and make that on the double ("all in sixteen" would we say around here )

:threatening 'hands on hips' position: