Yes they’re easy if you have the capability to do reflow soldering. I do but many hobbyists don’t have a reflow station. Just a regular solder iron. Yes a thin film of insulation is placed in between FETs and the heatsink but how are you actually applying mechanical pressure between the directFET and the heatsink? Is the custom(expensive) heatsink that is being used designed to do this somehow?
Yes the though hole packages cause a larger footprint for layout in the power stage but this isn’t anything that can’t be accounted for and managed. TO-220s and TO-247 packages are used in several professional controllers like the SEVCON or Adaptto and have proven themselves to be effective. The downside just tends to be that they’re larger and cause the controller to be larger. Not a big deal for bikes but it is for esk8. The directFETs are small and are good for when small is needed.
The mechanical pressure is added from the PCB mounting holes. The sink doesn’t have to be that complicated, Just enough that a small portion extrudes over the FETs.
Simplest way would be a sandwich of two plates, one as big as the PCB (to mount on) and one ontop of it to make contact with fets, So essensially two squares of metal. One could go wild and make an encasing like the vesc6 tho. But its more expensive
Ah I see. Some BMS boards do this same thing for heatsinking.
To each their own I suppose. Each type of FET has their advantages and disadvantages .Optimize for one thing and you stray from another. It wouldn’t be too hard for one to spin my controller design to accommodate directFETs. Open sourcing this design will allow anyone to do this and create a controller better optimized for esk8. That’s the beauty of open source
@shaman i like your approach, there are enough powerfull small solution available, and yours isnt that much bigger.
I think your design has more advantages than not. This ESC will be epic in Pneumatic (bigger) Builds and other fun application, GoCart ect, that have room to spare.
The changes to Mr. Vedder’s code won’t be too bad. There’s one file that is particular to the DRV being used. That’s the one that needs to be changed. There’s already support for the DRV8323 which is very similar to the DRV8353. Changes will most likely be minimal.
There’s no plan for a dual ESC at the moment. Just run two controllers together through CAN for the dual awesomeness.
works for me. Particular to esk8 and ATB, there are many 80xx motors which reference 15s which fits in with the 12FET version. My knowledge on motor efficiency at Xv is pretty limited.
Wondering what happens theoretically as voltage increases, the current demand should be lower. At some point peak efficiency is reached depending on motor construction and materials used.
Are the advantages worth shooting for? I know we are already stretching the 60v component rating most VESC based clones are geared towards with 13s builds…Trampa VESC 75/300 notwithstanding
motor examples
Leopard LC8072 Voltage up to lipos 16s
APS 8072S MAX VOLT: 15S (63V)
Smaller motors like the ubiquitous 6374 afaik they do not normally get a higher voltage suggestion than about 13s. Perhaps something like the swissboard hub drive with silver windings could utilise.
I’m aware you can run pretty much any of these motors at 20s but things get dangerous and unless it’s a motorbike/kickass MTB/car it does not seem to be a thing
Check for 15-30 kW bldcs on ali f.e, theyre quite pricy but its the “next step”.
What happens with the smaller motors is that they eventually saturate @ magnetic flux. Which is bit mor connected to current then voltage. Sure bigger motor, step up in voltage, but also step up in current if you want the full potential of the motor.
Your looking to change means of transportation your looking for more power. Id be more comfortable with that beast on a motorbike. But towards 20kW on an eskate? If u wanna tow cars I guess?
Sure the 80xx motors are out there, but i think its hard to keep the cogging and drag down the bigger you go. I guess on an mtb or AT setup but freewheeling would get close to minimal
20kW is almost 27HP. That’s motorcycle territory. Would probably rip you or the esk8 apart if you tried something like that on a small piece of wood.
Well I don’t advise licking it. It’s dangerous if you don’t respect it but it can be handled in the proper medium. 16s 160A is about 9kW and roughly 12HP. Probably best applied in ebike or above.
It’s interesting because there are quite a few 80xx builds out there. My understanding is change the ESCs to seriousFOCers, up pack series to 16s and enjoy better efficiency, more linear power delivery and of course higher ERPM, but not necessarily higher top speed/torque?
Speaking of ERPM, is there a limit in mind that you think would be achievable?
While increasing voltage and decreasing current does generally yield higher efficiency, motors still have a sweet spot of rpm vs power that will be the most efficient. There are a lot of variables in that and more than I fully understand. All i know is that the sweet spot can be found by putting the motor on a dyno and conducting tests.
More voltage = higher rpm for motors. More current = more torque at least up to a certain point.
I’m assuming the ERPM limit will be the same as the VESC 6 since my design is the same from a controls standpoint. Only one real way to find out though. Hence beta testing
The applications for the serious FOCer series of controllers are more geared for ebikes or above. I just figured you guys might be interested for shits and giggles. The 6 FET versions would be the most practical for esk8 and could be considered a high voltage version of my Cheap FOCer.
