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

[gotoluc]

That would leave only air coils in the stator and a ferrite in the rotor.
That's only 1:2 inductance ratio between these "ON and OFF moments".

With air coils, that  inductance ratio would be ~100x larger.
Indeed, that would be very good for efficiency.

Really ... Bucking Air Coils would make this more efficient?

That I have a hard time visualizing

Please share an example

Thanks

Luc

[verpies]

Really ... Bucking Air Coils would make this more efficient?

More efficient means more recovered electric energy relative to the electric input energy. 
It does not mean that the motor would have a higher torque. In fact the torque would be quite smaller.

It's all about maximizing that inductance ratio.  If you have an inductance meter, notice how large this ratio becomes for an air coil. 
Just divide the inductance without the rotor nearby and with the rotor nearby.

[verpies]

as promised here is v.2 of the Bucking Field Reluctance Motor. You may be surprised at what happened.
Link to video: https://www.youtube.com/watch?v=5f9TQ8AXglg

That MOSFET is oscillating because that HV inductive spike from the motor winding is turning it ON when it is supposed to turn off.   This effect is known as Miller Turn-on or Miller Oscillation and happens when the voltage on the drain is changing too quickly for the MOSFET to handle.

There are two ways to solve it:
1) The brute force method: Drive the gate of the MOSFET with a strong driver that can sink many amps of current from the gate, such as the UCC27511.
2) The elegant method: Empty the capacitor before each HV spike arrives from the motor winding.

[gotoluc]

More efficient means more recovered electric energy relative to the electric input energy. 
It does not mean that the motor would have a higher torque. In fact the torque would be quite smaller.

It's all about maximizing that inductance ratio.  If you have an inductance meter, notice how large this ratio becomes for an air coil. 
Just divide the inductance without the rotor nearby and with the rotor nearby.

I understand but I didn't know for sure that an Inductance boost during on time will make the flyback have more power. This is what Steorn Orbo was claiming but I never saw any proof to it. Is this what you're sawing?

Luc

[gotoluc]

That MOSFET is oscillating because that HV inductive spike from the motor winding is turning it ON when it is supposed to turn off.   This effect is known as Miller Turn-on or Miller Oscillation and happens when the voltage on the drain is changing too quickly for the MOSFET to handle.

There are two ways to solve it:
1) The brute force method: Drive the gate of the MOSFET with a strong driver that can sink many amps of current from the gate, such as the UCC27511.
2) The elegant method: Empty the capacitor before each HV spike arrives from the motor winding.

I'll test "The elegant method" next time this issue comes up.

Good to know!   thanks for sharing

Luc