EVolution EV "EVO" - The "Made in USA" EUC!

[meepmeepmayer]

2 hours ago, EUC Addict said:

He's doing this for cooling purposes.

Can you elaborate? What has this to do with cooling?

[EUC Addict]

11 minutes ago, meepmeepmayer said:

What has this to do with cooling?

I don't see how it cools anything, but his rationale is use a higher voltage controller to prevent mosfets from burning up. I don't know enough how that works to know if that's true.

[Chriull]

18 minutes ago, EUC Addict said:

I don't see how it cools anything, but his rationale is use a higher voltage controller to prevent mosfets from burning up. I don't know enough how that works to know if that's true.

I hope i'm not jumping in just on a single phrase which i got wrong ;), but a higher voltage controller alone does not change anything.

A higher battery voltage allows a motor with more windings per coil giving the same torque with less current.

Less current means less losses (power dissipation) for the mosfets. So cooling is easier.

So this whole design has to match for less cooling measures beeing sufficient.

Together with the firmware to cope with all possible borderline cases.

[EUC Addict]

I have to correct myself because I miscommunicated what he said, which was "I chose to go with a 84v system with a programmable 100v VESC because I felt it was important to create a higher ceiling with the vital electronics instead of expecting a daily function that borderlines on max performance of the major current handlers (ESC,BMS, and connections)."

[Chriull]

13 minutes ago, EUC Addict said:

I have to correct myself because I miscommunicated what he said, which was "I chose to go with a 84v system with a programmable 100v VESC because I felt it was important to create a higher ceiling with the vital electronics instead of expecting a daily function that borderlines on max performance of the major current handlers (ESC,BMS, and connections)."

Which could be a mishap again:

The specified voltage of the VESC does not specify the current ceiling of the system. In contrary a 100V VESC could have a lower current ceiling as an 84V VESC system for the same mechanical power output with the appropriate motor.

But i have no idea or expirience of available VESC systems - there could be side implications by chosing 100V vs 84V which are not mentioned explicitly.

This exact phrase (without as written above knowing all side implications of these VESC systems) to use a "100V VESC for a 84V system to increase performance" is nonsense - mayve even counterproductive.

So without further specification of the exact _whole_ system it's not possible to draw any further conclusions.

Could easily be that the choosen 100V VESC system is designed for (much) higher power output and by this the ceiling is increased...

 

[WI_Hedgehog]

23 hours ago, meepmeepmayer said:

So it's 84V because the parts he wants to use are 100V (less than 100.8V) and he wants a margin. Aren't there equivalent ~120V parts or something?

I believe the highest voltage well-tested board is 100V.

There is a 150V board under development, but high voltage brings design issues along for the ride.

With power usage being constant, current generates heat due to losses, voltage does not. However, as Bryan states, pushing components to their limits invites risk of failure, and he wants a larger safety factor.

Edited April 16, 2021 by WI_Hedgehog
added definition of Safety Factor

[Patrick Robert]

3 hours ago, EUC Addict said:

I don't see how it cools anything, but his rationale is use a higher voltage controller to prevent mosfets from burning up. I don't know enough how that works to know if that's true.

Just like it's safer to ride at 30 mph on the Sherman vs the 16X, because you're so far from the maximum threshold, and your ultrabook computer also runs cooler at slower CPU speeds... 

Running a wheel with higher grade components, which have a much higher performance threshold, will run cooler at the same given speed than with cheaper, lower performance components. 

An example is the first version of the Nikola, whose controller blew during Marty's Overheat Hill test. Gotway upgraded the assembly method but also the mosfets so they could handle higher currents without overheating. The upgraded mosfets run cooler with the same current passing through than the older ones. 

[mrelwood]

4 hours ago, Patrick Robert said:

An example is the first version of the Nikola, whose controller blew during Marty's Overheat Hill test.

Maybe not the best example, since the first gen Nikola had glue between the mosfets and the cooling plate, which very effectively ruined the intended cooling properties. First gen Nikolas with the glue removed worked just fine, even with the smaller TO-220 mosfets.

 The EVO design might very well work fine as an over-engineered design, as long as appropriate cooling is not being replaced by over spec’d board. Insufficient cooling is insufficient, even with a bit of power headroom.