Sharing ideas on how to make a more efficent motor using Flyback (MODERATED)

[gyulasun]

Hi Luc,

I also think what Brad wrote on the lack of real magnetic path for the cardboard gap case: the bucking fields must leave the prongs of the facing E cores i.e. leak out of the gap to the outside.   This is why the the inductance of a single MOT coil in the setup is only 13 mH. And the mass of the cores is most probably way too big with respect to the repel force between the facing surfaces, i.e.  resulting repel force is too low be able to influence the core masses.
The repel force can be a low value anyway due to the low 13 mH self inductance and due to the short pulse ON time (about 20 msec).
The low self inductance for the cardboard gap case also manifests in the 9 Amper peak current: the inductive reactance can only be also a low value for the same input pulse frequency.
It would be interesting to learn what the inductance  value for the MOT coils were when the I core was in place instead of the cardboard gap.

These are what I could add to your questions,  certainly there are some unanswered ones left.

Gyula

[verpies]

This would be the closes to what I'm working with.

That probe placement could not have produces an oscillogram like that, because when C2 voltage is increasing there should be current flowing through the CSR ...and there isn't any.
So there is some difference between your circuit and the schematic.

[gotoluc]

Hi Luc,

I also think what Brad wrote on the lack of real magnetic path for the cardboard gap case: the bucking fields must leave the prongs of the facing E cores i.e. leak out of the gap to the outside.   This is why the the inductance of a single MOT coil in the setup is only 13 mH. And the mass of the cores is most probably way too big with respect to the repel force between the facing surfaces, i.e.  resulting repel force is too low be able to influence the core masses.
The repel force can be a low value anyway due to the low 13 mH self inductance and due to the short pulse ON time (about 20 msec).
The low self inductance for the cardboard gap case also manifests in the 9 Amper peak current: the inductive reactance can only be also a low value for the same input pulse frequency.
It would be interesting to learn what the inductance  value for the MOT coils were when the I core was in place instead of the cardboard gap.

These are what I could add to your questions,  certainly there are some unanswered ones left.

Gyula

Thanks for your input Gyula

When the I core is in between to two E cores with the same cardboard spacer but now one on each side (so two) the inductance is 16mH. So only a 3 mH increase as appose to E to E with one spacer.

Luc

[gotoluc]

That probe placement could not have produces an oscillogram like that, because when C2 voltage is increasing there should be current flowing through the CSR ...and there isn't any.
So there is some difference between your circuit and the schematic.

Yes, you're right!... and we went over this before. I always have problems looking at circuits and what I'm making. I guess that's why I don't posts circuits

Let me go back and read what I had done to correct it as it looks to be the same problem.

Thanks for pointing it out once again.

Luc

[gotoluc]

Okay, I've corrected the same thing I did before. I guess I'm not use to the flyback going through the CSR

Below are the new scope shots reflecting this change and I've also included powering one side (one MOT) only in both configurations. Obviously I can only scope one MOT at the time. So when both are powered it would be double the input.

Here are the test device details one again:
Both upper and lower MOT's and circuits are a mirror image. I used a 2 channel  signal generator to trigger each IRF840 (Q1) mosfet's
Each MOT has their own 5Ah 12v battery (C1) which are at 12.98vdc each.
Each CSR (R1) are 0.1 Ohm
Mot primary coils (L1) are 0.35 Ohm, about 13mH (E to E) and 16mH (E-I-E) with a cardboard air gap of 0.023in. (0.6mm) in between (x2 for I test) to simulate a motor rotor to stator coil gap. MOT secondaries are not used.
The capacitors (C2) are 57uf (tested) each and have a load resistor of 4.7k to drain them before the next pulse
The flyback diodes (D1) are RHRG5060

Luc