The output stage will be build according to the principles outlined in this thread:
https://endless-sphere.com/forums/viewto ... 30&t=55641
To mount the FETs choose some sort of platform attachable to a heatsink. I use a 4mm thick L-piece of aluminium which I can later
(with the short leg of the L) mount to the wall of my controller box, with the heatsink on the outside of the box.
The L-piece has 6 small holes where the FETs will be screwed down and 3 big holes though which the 3 motor phases exit.
The FETs need to be isolated from the aluminium to prevent shorts (as the tabs are also connected to the drain of the FETs)
Take 2 FETs (I use 4115's for this design, part nr. same as the 4115 in the PCB's power supply) for each motor phase. Cut the
gate tab short, for one FET bend the drain up, for the other the source. Attach opposite of each other as shown in the picture below.
(Note: the mica isolation plates will be added later, I did not want to risk damaging them during soldering)
Place the FETs for all three phases, solder the legs together that meet in the middle over the hole for the phase wire. Make sure the
legs that are sticking up are exactly opposite each other (this is the reason the 2 times 3 holes for attaching the FETs are not alligned
exactly opposite each other, but have an offset such that the legs sticking up are exactly opposite)
Attach the phase wires
take a copper sheet and some scissorts and cut two rectangles (I used 6 cm x 2 cm x 0.6 mm), these will be the power supply 'wires' from the
battery. Solder the copper pieces on each side to the legs sticking up. Add a 470nF and a 220uF capacitor as shown in the picture, keep connections
as short as possible !
view from the top
to connect the output stage to the PCB wires should be attached to each FETs gate and source. It is very important that the wires are
tightly twisted as shown in the picture ! (else you'll have too much inductance in the gate path and will get ringing)
while you're at it, solder the phase wires from the FETs to the 'FETs' side of the current sensors. Later on, make 100% sure the gate drives and current
sensors are matched up, the FETs driven by gate drivers 'A' must have their phase wire soldered to current sensor 'A' !!!!