Author Topic: Shorting coil gives back more power (Read 461476 times)

gyulasun · « **Reply #390 on:** March 19, 2011, 06:55:37 PM »

Quote from: Feynman on March 19, 2011, 06:23:34 PM

....
The problem I'm getting is that the output of pin 3 is completely inverted from the output as measured at the MOSFET drain.

For example, if my input is PWM with 1% duty cycle and a specific frequency, on the drain of the MOSFET I see a 99% duty cycle wave at the same frequency.
.....

Hi,

This is normal, a grounded-source stage inverts its input at its output.

Solution is either you input the high duty cycle into the gate of the MOSFET when you wish low duty cycle at the drain as an output and vice versa, OR you use an inverting type MOSFET driver between pin 3 of 555 and MOSFET gate as you intend.

Gyula

Feynman · « **Reply #391 on:** March 19, 2011, 07:24:21 PM »

@gyula

Okay , got it. Does a P-channel MOSFET have the same inverting effect when driving the low side? I know these are probably obvious questions , but I normally deal with microcontrollers and sensors. This is my first time actually doing serious benching with MOSFETs.

I think I'll buy both kinds of drivers... I know I need non-inverting for my Boyce TPU replication. I think I'm going to snag the UCC drivers he used in his HEXFET controller (UCC27322P's) .

gyulasun · « **Reply #392 on:** March 19, 2011, 07:50:51 PM »

Quote from: Feynman on March 19, 2011, 07:24:21 PM

@gyula

Okay , got it. Does a P-channel MOSFET have the same inverting effect when driving the low side?

I think I'll buy both kinds of drivers... I know I need non-inverting for my Boyce TPU replication. I think I'm going to snag the UCC drivers he used in his HEXFET controller (UCC27322P's) .

Yes, a P-channel also has the same inverting effect when you control its gate with an input and use its drain as output.

The UCC27322P is a non-inverting driver indeed and the type UCC27321P is an inverting driver. A similar pair is TC4421/TC4422, there are several others of course.

Gyula

Feynman · « **Reply #393 on:** March 19, 2011, 08:49:51 PM »

@yssuraxu

I read your post carefully, and it reminds me very much of what Rosemary Ainsle is discussing on her blog.

http://newlightondarkenergy.blogspot.com/

Quote

The circuit is designed to allow a secondary current flow that is induced from the collapsing fields of RL1 during the OFF period of the duty cycle as a result of counter electromotive force (CEMF). This reverse current path is enabled by the body diodes in the transistor MOSFETs (Q1). This allows a current flow that returns to the battery supply source to recharge it

yssuraxu_697 · « **Reply #394 on:** March 19, 2011, 10:37:47 PM »

Quote from: Feynman on March 19, 2011, 08:49:51 PM

I read your post carefully, and it reminds me very much of what Rosemary Ainsle is discussing on her blog.

I am not familiar with Rosemary Ainsle work, will look at it. I guess that there are thousands of people over the world arriving at the very same conclusions, only each one from slightly different angle and background.

Tsunami is coming and we are the surfers

Feynman · « **Reply #395 on:** March 19, 2011, 10:57:17 PM »

I just looked into Rosemary's results today, and I'm not sure what to think yet (the screenshots are too low a resolution), but some of the terms make sense...

Current does not necessarily have to be the flow of electrons.

The other idea is that utilization of the back-EMF / counter-EMF may be promising. Thane Heins apparently has a device working on this principle... the magnacoaster patent works by 'pinging' an electromagnet in the presence of Biasing magnets... Naudin's 2SGen works similarly via magnetic coupling, etc.

So it seems to me there are a lot of commonalities.-

---

In terms of future research, I think my plans are to finish winding my electromagnet (I grabbed a ferrite rod inductor from radio shack, around 5cm long and 1cm in diameter, and I will be winding this with 30awg magnet wire . )

I'm going to pulse the electromagnet with HV pwm pulses and see what sort of waveform I can observe.

The one question I'm wrestling with is whether to wind it monofilar or bifilar, but I bought three of the ferrite rods, so perhaps I will make a couple of different types.

I also bought a couple of soft iron nails so I can experiment with electromagnets which have large eddy currents.

i_ron · « **Reply #396 on:** March 21, 2011, 09:30:01 PM »

Quote from: yssuraxu_697 on March 19, 2011, 10:37:47 PM

Tsunami is coming and we are the surfers

You have seen this but for some others who might be interested here is a peak sine event shorted 8 times. The probe was on x10 so 10 volts per square.

Ron

onthecuttingedge2010 · « **Reply #397 on:** March 21, 2011, 11:28:49 PM »

Quote from: romerouk on February 19, 2011, 03:51:45 AM

When the coil is shorted at the right peak time the coil sends back lots of power.

http://www.youtube.com/watch?v=bGbPwXq13GI

Watts in and Watts out please?

ramset · « **Reply #398 on:** March 22, 2011, 01:29:32 AM »

onthecuttingedge2010
Quote:

Watts in and Watts out please?

---------------------
Sniff.............Sniff................
HHMMMmmmmmmmmmmm

You smell familiar??

"Patience Grasshopper"
We'll get to the measuring!

Chet

Thaelin · « **Reply #399 on:** March 22, 2011, 03:18:47 AM »

Since this is about coil shorting, I will throw in my toy. I recently found a F&P style motor for $15 us. I just finished "re-programming" it for single coil access. I will be running 12 mags all N around it on a 36 coil stator. The motor will be triggered by a single coil for each phase. The rest of the coils will be out to connectors for ease of use.
Mounted up the set for a motor run in the next day or so. Then as it progresses, I will start adding the shorting circuits.

On the multi short scope shot, what is the unloaded ac out voltage? Mine is about 10v per coil or 120 per phase. Looking to have 2 coils in each circuit with the left over 3 supplying operating voltage for the shorting power.

thay

joefr · « **Reply #400 on:** March 22, 2011, 10:05:02 AM »

Hi i_ron

Very nice scope shoots

Can I ask you which circuit you used to make shorting peak sine event 8 times ?

i_ron · « **Reply #401 on:** March 22, 2011, 04:24:27 PM »

Quote from: Thaelin on March 22, 2011, 03:18:47 AM

On the multi short scope shot, what is the unloaded ac out voltage?

thay

6 volts AC

Ron

Feynman · « **Reply #402 on:** March 22, 2011, 04:27:14 PM »

Okay guys, I haven't gotten to coil shorting yet, but I'm about halfway through winding my electromagnet. This takes FOREVER.

I have to superglue the damn magnet wire every 8 turns or so, then wait for it to set, then continue another 8 turns, etc, so it's really tedious! But it's worth it to be able to control the effect I'm looking for (direction of B-field, amperage capacity of wire, number of coil layers, etc)

I'm using (I think) 26/28awg enameled magnet wire on a 5cm x 0.5cm diameter ferrite rod. I pulled the ferrite rod from an RF choke I bought at radio shack.

Over the weekend, I also finished the PWM circuit (the 555 timer thing I posted) , which uses a 555 timer modulating a MOSFET as a low-side driver. I can control the pulse width (aka duty cycle, from 0-100%) and I can control the frequency from about 200hz up to 100khz (depending on the timing capacitor , 0.01uF gives 200hz - 2khz, 0.001uF gives 2khz - 200khz).

My plan at the moment is to finish winding the electromagnet, then do some experiments with magnetic flux saturation (biasing the rod with permanent magnets), sort of like a magnacoaster replication. I want to figure out how to know exactly when I've hit magnetic flux saturation in the ferrite, so I'll probably get some pins, nails , or iron filings of some kind so I can do a crude test of magnetic field strength at fixed distances from the ferrite.

I'm going hit the electromagnet with about seven 9V batteries in series connected to the MOSFET source/drain, for a total of 63V DC input pulses, of about 1% duty cycle from the 555, somewhere in the frequency of 200hz to 100khz.

Once I get that working, I'll try to set up some sort of astable trigger to short the 'ringing' in the rod so this is relevant to coil shorting, but that's about 1-2 weeks out.

This week I'll have flux saturation results hopefully, as well as some raw data on the behavior of a pulsed DC electromagnet in ferrite vs soft iron. (pulsed electromagnet information is surprisingly scarce).

i_ron · « **Reply #403 on:** March 22, 2011, 04:43:27 PM »

Quote from: joefr on March 22, 2011, 10:05:02 AM

Hi i_ron

Very nice scope shoots

Can I ask you which circuit you used to make shorting peak sine event 8 times ?

Thank you!

It was posted some pages back, the zero crossing from:

http://www.8051projects.info/blogs.asp?view=plink&id=198

But here are the two parts...(first part again)

I am using the Si8410 as the replacement for an opto isolator. It takes 5 volts from the first circuit and a separate 5 volt regulator from the second circuit, so that the second circuit is completely isolated... and could be used in the highside of an H bridge. I like it

http://www.silabs.com/Support%20Documents/TechnicalDocs/si8410.pdf

J2 and J3 go across the generator coil.

Q1 and Q2 are setup as in Gyula's AC switch, posted here and on EV Gray.

Ron

joefr · « **Reply #404 on:** March 22, 2011, 08:20:30 PM »

Hi i_ron

Thanks for circuit I will try it I just need to buy missing components

I am using this circuit from Gyulasun:
http://i920.photobucket.com/albums/ad43/JoeFR/Coil%20Shorting/GyulasunCoilShorting-1.jpg

Without shorting I get this:
http://i920.photobucket.com/albums/ad43/JoeFR/Coil%20Shorting/WithoutShorting.jpg

With coil shorting I get much better results:
http://i920.photobucket.com/albums/ad43/JoeFR/Coil%20Shorting/CoilShorting.jpg

With coil shorting it charges 680uF cap to 150V quite fast

I will change two hall sensors to just one hall omnipolar sensor for more easy adjustment

Does anybody have good and reliable circuit to dump cap at preset voltage to battery (at 100v dump cap to 36v battery bank) ?

News:

User Menu

Author Topic: Shorting coil gives back more power (Read 461476 times)

gyulasun

Re: Shorting coil gives back more power

Feynman

Re: Shorting coil gives back more power

gyulasun

Re: Shorting coil gives back more power

Feynman

Re: Shorting coil gives back more power

yssuraxu_697

Re: Shorting coil gives back more power

Feynman

Re: Shorting coil gives back more power

i_ron

Re: Shorting coil gives back more power

onthecuttingedge2010

Re: Shorting coil gives back more power

ramset

Re: Shorting coil gives back more power

Thaelin

Re: Shorting coil gives back more power

joefr

Re: Shorting coil gives back more power

i_ron

Re: Shorting coil gives back more power

Feynman

Re: Shorting coil gives back more power

i_ron

Re: Shorting coil gives back more power

joefr

Re: Shorting coil gives back more power