Quote from: listener191 on April 05, 2018, 05:48:56 PM
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

TinselKoala:


http://tinyurl.com/yatk8sgk

hmmmmm....

Quote from: MichelM on April 06, 2018, 04:53:23 AM
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.

Quote from: listener191 on April 05, 2018, 03:50:59 PM
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

Hi MichelM

QuoteAre 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

Quote from: NerzhDishual on April 05, 2018, 10:48:27 PM
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