300A VESC in the works, feature suggestions wanted

[TechAUmNu]

Especially when you have 2 of these beasts cable tied to the escs... oops.
https://www.digikey.co.uk/product-de...623-ND/5230581

[TechAUmNu]

I have just about finished the pcb layout for my test power board, which I will just wire into the logic on one of the vescs I have laying around.

2017-07-10 00_57_34-CircuitMaker (1.3) - PCB1.CMPcbDoc - 300A VESC.PrjPcb Euan Mutch is signed i.png2017-07-10 00_58_16-CircuitMaker (1.3) - PCB1.CMPcbDoc - 300A VESC.PrjPcb Euan Mutch is signed i.png2017-07-10 00_58_32-CircuitMaker (1.3) - PCB1.CMPcbDoc - 300A VESC.PrjPcb Euan Mutch is signed i.jpg

I will be getting some copper lasercut to run the high current parts and put a bunch of caps on as well. It is currently 100x100mm so I can get it done at www.seeedstudio.com who have a cheap 4 layer option. So I will have 10 boards for £38.

Will be putting in the order in the next few days so boards should arrive by the end of the month.

[emisnug]

This is all getting extraordinarily interesting... keeping an eye on this one!

[TechAUmNu]

I have been thinking more about heat sinks the last few days.

From what I know, the maximum time that these would be expected to run at for power is under 5 minutes. So since there is going to be very little airflow inside of bot it makes more sense to use the heat sink as thermal energy storage (ie a big block of metal). I have worked out that it would take 200g of Aluminium 5 minutes to go from 50 - 175oC when the heat dissipated is 80W from the driver. If you also factor in some convection it should be even longer. This would make it possible to make each driver board encased in an aluminium shell which would hopefully provide better protection in combat.

You would just need to watch not to burn yourself on it after the fight lol.

[overkill]

Maybe a dumb idea, but have you thought about heat pipes to help distribute the heat across your aluminium shell?

[TechAUmNu]

Maybe a dumb idea, but have you thought about heat pipes to help distribute the heat across your aluminium shell?

I did think about that, the mosfets cover the entire surface area and *should* dissipate the same power each, so there shouldn't be any need for heat pipes. If the aluminium heat sink is very thick then heat transfer should not be a problem.

If it was a bunch of very thin fins like in a graphics card then heat pipes would be a necessity. Currently I have two 150x200mm heat sinks for testing which I will sandwidch the power board between. Link

Also going to get a Flir One http://www.flir.com/flirone/ so I can see what is getting hot.

[TechAUmNu]

I think I got my power dissipation calculations wrong. So I think it should run even better than expected. New numbers are
16s

15W @ 100A Max Power: 6720W
32W @ 200A Max Power: 13440W
65W @ 300A Max Power: 20160W
128W @ 400A Max Power: 26880W
270W @ 500A Max Power: 33600W

[overkill]

What ambient temperature did you allow for in the calculations?

[TechAUmNu]

These are pure heat dissipation so do not include ambient. If you have high ambient then it will be a bit worse, but that depends on the thermal resistance and capacitance of the cooling solution.

Also these are for 100% duty cycle which is worst case scenario.

Should handle 300a with 50oC ambient just fine.

[Maxamuslead]

Maybe a dumb idea, but have you thought about heat pipes to help distribute the heat across your aluminium shell?

not sure how well heat pipes would help in this situation as they help more the moving of heat from A to B also it would add cost and weight

[TechAUmNu]

On the subject of weight, how heavy is too heavy? I am thinking under 800g each would be good. Although for my bot lighter is obviously better. So I maybe could offer them with several different types/weights of heatsink for different power levels?

So for example you would have just a flat plate heatsink on to start with and bolt holes for optional bits to go on. Such as a finned heatsink for use with a fan or for light load with convection cooling while being fairly small and lightweight. Then another which is just a big chunk of aluminium to let you run high power for a length of time at the expense of weight. Or you could even just make your own cooling solution that uses the bolt holes to attach a watercooler or something to let you push it to its limits around 1000A if you can keep it cool enough to not explode.

This would make it more appealing more to different markets without much additional time spent.

[overkill]

Excellent idea!

[typhoon_driver]

I'd make sure there's a sizable safety factor in your heat calculations. Many an esc has had a premature end thanks to too much heat.

[TechAUmNu]

I'd make sure there's a sizable safety factor in your heat calculations. Many an esc has had a premature end thanks to too much heat.

I would think most are not designed to be in an airtight metal box covered in foam with a massive motor breathing fire on it while being shot with 5 sniper rifles. lol

[Maxamuslead]

I would think most are not designed to be in an airtight metal box covered in foam with a massive motor breathing fire on it while being shot with 5 sniper rifles. lol

Sounds like a good test. MAKE IT SO !!!