Pierre's 170W in 1600W out Looped Very impressive Build continued & moderated

[onielsen]

Hi T-1000,

Pierre did not show his circuit and how he connects positive and negative switching so I created my version of module - https://i.imgur.com/muSF3CN.png
This module allow full control with MOSFETs of positive and negative switching for 4 coils in series.

The top MOSFETs should be bootstrapped as else they will work in the linear region instead of working as switches. When the gate voltage of a top MOSFET is at its drain voltage its source voltage will be the drain voltage minus its gate-source voltage. This leaves a voltage between the drain and source which generates heat if a current is passed at the same time.

For generating least amount of heat the MOSFETs must be fully turned on (saturated) or fully turned off (open). This leaves the heat generated to switching transitions and some on state loss.

Regards
Ole

[pmgr]

Hi T-1000,
The top MOSFETs should be bootstrapped as else they will work in the linear region instead of working as switches. When the gate voltage of a top MOSFET is at its drain voltage its source voltage will be the drain voltage minus its gate-source voltage. This leaves a voltage between the drain and source which generates heat if a current is passed at the same time.

For generating least amount of heat the MOSFETs must be fully turned on (saturated) or fully turned off (open). This leaves the heat generated to switching transitions and some on state loss.

Regards
Ole

Alternatively, you can use a P-type MOSFET at the positive supply side (although it will have a bit more resisitance than an N-FET).
For more info on bootstrapping, see this Wiki https://en.wikipedia.org/wiki/Bootstrapping_(electronics) under "Driving MOS transistors". Easiest solution is to use P-FET.
PmgR

[seaad]

https://vimeo.com/178144785

[T-1000]

https://vimeo.com/178144785

The coils arrangement are pretty much in similar fashion due series connection for all coils. Unless there is opposite polarity starting on each 1/6th from the 36 coils the weak opposite polarity is going all way around ring from coil X-7 due 3rd set setting negative polarity on X(3rd)+4.

[T-1000]

Alternatively, you can use a P-type MOSFET at the positive supply side (although it will have a bit more resisitance than an N-FET).
For more info on bootstrapping, see this Wiki https://en.wikipedia.org/wiki/Bootstrapping_(electronics) under "Driving MOS transistors". Easiest solution is to use P-FET.
PmgR

Yes, the positive side N-Channel MOSFET may be unstable when its voltage is higher than VS side of the driver. However, according to datasheed the voltage difference will be enough to turn MOSFET ON due coil side going to negative and voltage drop. And IRFP460 can handle up to +/-20V on the gate. I will look on possible replacement with P channel MOSFET in mean time but that mean additional logic inversion in signal just to drive it.

Cheers!