Motor braking. - Page 7 - RC-Monster Forums

GriffinRU · 05:33 PM

Quote:

Originally Posted by Serum

the lower the KV, the less resistance it has, and the less energy it produces when turning. The higher the KV, the less resistance it has, and the more energy it produces when it's turning.

Rene, this is very wrong. The same motor (independent of Kv) produce the same amount of power at given RPM, Efficiency is different...

I will be back later, need to go.

zeropointbug · 05.20.2007, 05:33 PM

Quote:

Originally Posted by GriffinRU

Rene, this is very wrong. The same motor (independent of Kv) produce the same amount of power at given RPM, Efficiency is different...

Yes, i agree

zeropointbug · 05.20.2007, 05:32 PM

Well, I don't want to seem superstitious or anything... but I think, I THINK there is a new thing out on the street, it's called inductance? :005:

Serum · 05.20.2007, 05:39 PM

then what makes the different KV? it's not efficiency. internal resistance varies with different KV's and since some producers of motors give the KV value with the motor as a generator, i don't think your theory is right?

GriffinRU · 05:53 PM

Quote:

Originally Posted by Serum

then what makes the different KV? it's not efficiency. internal resistance varies with different KV's and since some producers of motors give the KV value with the motor as a generator, i don't think your theory is right?

Kv have nothing to do with resistance, it just happen that with more turns R goes up...
If you have motor 10 meters of copper wire goes through the magnetic flux but in one configuration you have single wire and in another double, the amount of power would be the same. One will have higher voltage another higher current...

Kv is complex number based on Magnet strength, gap, core properties, windings and much more, there are complicated programs dealing with how to calculate or estimate its value and most of them still black magic, in reality it is much easier to measure...

Now, definitely need to run :)
On braking part, there plenty BL motor control algorithms published on line, fined them check them. There is no other magic then shorting phases to stop the vehicle. And none of real R&D engineers will publish here unless he want to loose his job :)

zeropointbug · 05.20.2007, 05:57 PM

higher numbers of turns, higher inductance, along with the core which it's wound on, and some other factors which may be out of control as far as manufacturer techniques that will probably effect efficiency as well as Kv.

Serum · 05.20.2007, 05:45 PM

Sorry Artur; i meant internal resistance; not mechanical resistance..

Serum · 05:56 PM

Yeah, but i was talking about braking; this whole topic is about braking; so when i said that the motor of a lower kv produces less energy when turning; i meant that with the motor as a generator, and the energy it produces when the motor is turning, due to the inertia of the vehicle/moving mass. I guess i told it with too few words..

A lot of misunderstandings are going around here...

zeropointbug · 05.20.2007, 06:01 PM

Quote:

Originally Posted by Serum

A lot of misunderstandings are going around here...

I agree, you're not the only one. :005: :019:

supralover72 · 05.20.2007, 06:08 PM

Would it be safe to use motor braking on a MM with 12 NiMh cells in a Jammin buggy with a fegiao 8xl and 14/46 gearing?

Thanks.

BrianG · 05.20.2007, 10:59 PM

Sounds like it would take about as much time as a normal disc brake setup since you are basically doing the same thing.

zeropointbug · 05.20.2007, 11:28 PM

actually probably longer, because it has to get aways away from it in order to stop resistance. (does anyone know of a magnetic transistor? :005: )

BTW, this setup cannot be explained by regular Faraday laws of induction. There have been many 'over-unity' claims by such setups.

silentbob343 · 04:06 PM

Saw this posted in the tekin forum:

Quote:

Originally Posted by teamtekin

Pretty much everyone is using 30v fets. 6s is getting pretty close and does not leave much headroom for voltage spikes. Some fets handle over voltage better than others. The manufacturers do not address areas beyond the specs so you just have to test them and see. So far these fets are incredible. The better the circuit the lower the spikes and the better the chances, but braking battery regen can still be an issue. If the battery is full and will not accept the regen charge, the voltage can go really high, really fast. Just like motor flyback current that needs a diode or a rectification circuit like our G11, if you do not give the current somewhere to go then voltage spikes can be off the map.

We will know shortly. I am pretty excited about this market and with everything else finishing up we have time now to look at some new challenges.

IF you really need 6s or more and this will not handle it, we will build one that does. That is why we are here learning.

http://www.rc-monster.com/forum/show...?t=6361&page=4
I guess that confirms regen on braking.