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Author Topic: Pierre's 170W in 1600W out Looped Very impressive Build continued & moderated  (Read 429876 times)

seaad

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Hi Seead,
At such a low clock frequency DC resistance dominates so..
L192
Hi L192
Your coil: About 1.2mH (free)  assuming 2.5 mH (tight to secondary core)
1.2mH => XL 60Hz ==> about 0.5 Ohm
2.5mH => XL 60Hz ==> about 1 Ohm
Roughly;  DC flows half the time of the outgoing frequency (60Hz; 8.3ms) then DC in the opposite direction next half, if looking at one single coil.

Pic : one single coil Z (Roughly)

Regards Arne

listener191

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IRF3205 / IRF4905

Max values
55V, 200W, continuous Id=52A/80A, Pulsed I=260A/390,  Rds(on)  8mOhm/20mOm

An interesting mosfet matching and cheap. With a capable heatsink it will run fine

http://www.irf.com/product-info/datasheets/data/irf3205.pdf
https://www.infineon.com/dgdl/irf4905.pdf?fileId=5546d462533600a4015355e32165197c

As for clamping diodes i was thinking about UF5408. 1000V/3A. Any other idea here?

Hi Jeg,

Whats wrong with using the body diodes, or are you concerned about heat?

Regards

L192

listener191

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Hi L192
Your coil: About 1.2mH (free)  assuming 2.5 mH (tight to secondary core)
1.2mH => XL 60Hz ==> about 0.5 Ohm
2.5mH => XL 60Hz ==> about 1 Ohm
Roughly;  DC flows half the time of the outgoing frequency (60Hz; 8.3ms) then DC in the opposite direction next half, if looking at one single coil.

Pic : one single coil Z (Roughly)

Regards Arne
Hi Seaad

Except if I clock at 60Hz then current reduces. Clocking at 20 to 25Hz produces the largest output.

Also even if I take your impedance example for a single coil, I have 6 in series (under test), =8.4 ohms.

I have been operating at 35V so 35/8.4= 4.1A.

4.1A is achievable at 20Hz clock rate, not 60Hz.

Regards

L192 

seaad

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Hi Seaad
 A) Clocking at 20 to 25Hz produces the largets output.

Also even if I take your impedance example for a single coil, I have 6 in series (under test), =8.4 ohms.
I have been operating at 35V so 35/8.4= 4.1A.
B) 4.1A is achievable at 20Hz clock rate, not 60Hz.
L192

A) Pierres freq. 13-15 Hz  8)

B) You have a multiplicative effect with the (total 6 coils) m-Henry value due to overlapping coils and some weird half and full transformer function depending of the proximity to to the output core. Due to that the Z goes up steeper than just adding coils. A higher total Henry value favorably even at 20 Hz.

Which inductance value do you get to a 6 coil overlapped "section"? Away or close to the output core.

Regards Arne

listener191

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A) Pierres freq. 13-15 Hz  8)

B) You have a multiplicative effect with the (total 6 coils) m-Henry value due to overlapping coils and some weird half and full transformer function depending of the proximity to to the output core. Due to that the Z goes up steeper than just adding coils. A higher total Henry value favorably even at 20 Hz.

Which inductance value do you get to a 6 coil overlapped "section"? Away or close to the output core.

Regards Arne

Hi Seaad,

With the rotor open circuit and rotated through 360 degs, the minimum inductance of 6 coils in series is 9.7mH  and the maximum inductance is 98mH.

There is nothing particularly strange about the windings, apart from the linear distribution that produces a triangular wave.
The individual coils flux add, with the peak half way between the start of the first coil and the end of the 6th coil.

For a distributed winding to produce a sine wave, a gap is needed between the coils so the flux rise rate reduces towards the peak.

Regards
L192
« Last Edit: April 06, 2018, 02:37:33 AM by listener191 »

NerzhDishual

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    • FreeNRG.info

 Hi People,

These bloody  H-Bridges...
Used to excite coil(s) with  tricky arrangement(s) thereof might be one key for OU. No?

My question is (for low freq) :
How many relay(s) do you need to build such an H-Bridge?
My answer is : just one 4 poles relay.

Now, you, perhaps,  might consider  Duncan Pickthallp's more simple ideas.

Le bonsoir vous sied,
Jean


NerzhDishual

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    • FreeNRG.info
Here is the circuit:


NerzhDishual

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OK. Here is the Duncan Pickthall'pdf


TinselKoala

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The Secret of DPDT:

MichelM

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Here is my analysis of P.C. circuit with flyback diodes. Who is, or is not, of my opinion?
Are the diodes well positioned and in the right direction?

FR
Voici mon analyse du circuit de P.C. avec les diodes flyback. Qui est, ou pas, de mon avis ?
Les diodes sont-elles bien positionnées et dans le bon sens ?

seaad

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Hi Seaad,
With the rotor open circuit and rotated through 360 degs, the minimum inductance of 6 coils in series is 9.7mH  and the maximum inductance is 98mH.
L192
Hi L
Some compared values (rough):

6 "free"   (single coils) just mH added = 7.2 mH ,            6 coils group overlapped "free" = 10 mH   ( your min. value) "transformer effect"  + 2.8mH extra
6 "close" (single coils) just mH added = 15 mH  ,            6 coils group overlapped "close"= 100 mH ( your max. value) "transformer effect" + 85mH  extra

6 coils group overlapped impedanse values are :

 20 Hz  "free"  Z= 6.5 Ohm , "close" Z= 12.1 Ohm

 60 Hz  "free"  Z= 15.4 Ohm , "close" Z= 40.5 Ohm

To improve the loss values it is important to have some "semicore sections" at the free parts of the stator see my pic. Or make two output cores separated from each other.
Another suggestion is to remove / disconnect (not use) all coils nearby the semi core sections??

Regards Arne

r2fpl

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TinselKoala:


http://tinyurl.com/yatk8sgk

hmmmmm....

Jeg

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Here is my analysis of P.C. circuit with flyback diodes. Who is, or is not, of my opinion?
Are the diodes well positioned and in the right direction?

The below diodes are for grounding the negative peak. In your drawing they don't.

Hi Jeg,

Whats wrong with using the body diodes, or are you concerned about heat?


It is always a better practice to share body's diode strain with an external fast diode.
It prolongs mosfet's life.

Regards

onielsen

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Hi MichelM

Quote
Are the diodes well positioned and in the right direction?

The diodes are placed in parallel. D1+//D-, D2+//D2- etc. Half of the diodes can be omitted or else put the D- diodes in parallel to the bottom switches just like the D+ diodes are in parallel to the top switches. The D- diodes are then to be placed reverse biased like the top diodes. E.g. put the anode to the negative supply voltage and the cathode to the coil junctions.

Placed as described here is the way the parasitic diode points in power MOSFETs or the protective diode points in bipolar transistors if having a protective diode.

Regards
Ole

listener191

  • Sr. Member
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  • Posts: 253
Hi People,

These bloody  H-Bridges...
Used to excite coil(s) with  tricky arrangement(s) thereof might be one key for OU. No?

My question is (for low freq) :
How many relay(s) do you need to build such an H-Bridge?
My answer is : just one 4 poles relay.

Now, you, perhaps,  might consider  Duncan Pickthallp's more simple ideas.

Le bonsoir vous sied,
Jean

Hi NerzhDishual,

Yes it may be the best replication would be to first use relays.

The opto isolated boards available on Ebay seem to be single pole only and are cheap enough to just use two relays for each half bridge.

If you find such boards with double pole single throw relays, please let us know.


Regards


L192