170 watts in - 1600 watts out - looped - Very impressive build and video

[Belfior]

The question of why two relays. Why?

72 relays 36 transistors ??

Maybe he is using them as a charge pump? Charge coil (relay), stop current, spike over a diode to a cap, repeat

[listener191]

As previously posted.

I think he is using the two relays in the same configuration as a two transistor switch (like a you get in a forward converter).

As the relay coils are isolated you only need one transistor to switch them both.

L192

[seaad]

Oh Yes!  , "As the relay coils are isolated you only need one transistor to switch them both."
But what is the benefit of that? Two diodes with loss. (small)
The return wire (red) is relatively thick. Just a coincidence.

[listener191]

Hi Seaad,

With a single ground-referenced relay switch to drive the coil, the drawback to this approach is that the voltage stress on the switch is the sum of the bus voltage, the reflected coil voltage, and the turn-off leakage-inductance spike.
If you add a second high-side relay switch, the voltage stress reduces to the bus voltage only.

The two MOSFET switch is the only one I use when switching coils now, as the circuit is very robust however, a high side driver is required so component count goes up.

Regards

L192

[pmgr]

Hi PmgR,

All good perhaps a little slow now.

you are still simulating coils in adjacent slots rather than coils with a larger pitch. Whereas I agree that we dont know his exact detail, you only have to look closely at the stator to see that the coils are pitched between 6 to 8 slots. This would cause a large increase in  inductance and induced flux.

L192

Hi L192,


I will make the frame rate 0.1sec for the next animation.


Regarding the windings, I understand what you are saying, but let's say a winding covers slots 1-10-19-28 (9 slots in between), second winding covers slows 2-11-20-29, etc. last winding 9-18-27-36, then you would only need 9 transistors as it become as 4 pole stator with only 9 sets of windings to drive. Then why is Pierre using 36 transistors?


PmgR