3rd wire to motor

[RustlerRacer16]

I thought it was a sensor wire (I made that up after I learned the difference between sensored and sensorless motors). But after learning that the MMM motor is sensorless I'm confused. Evidently, all brushless motors have 3 wires.

What is that for?

Can you tell I'm a newbie to electric power?

[The Oracle]

Yes, we can tell

Read this:

http://www.stefanv.com/rcstuff/qf200212.html

Sensor wires are a seperate bundle that enter the can in a different location- see the novak motors for an example.

[RustlerRacer16]

Hey thanks! I expected the traditional "hey tard, try a search" bit. That's a real informative article.

I wondered what that other thing coming out of the Novak motors was. As you can imagine that only made me worse. "A 4th wire?!"

[brushlessman]

sensorless is really catching up with sensored. plus you can get more power out of a sensorless motor. the mmm is a great esc! i cant get the v3 to fry 10 runs strong! the fan comes on but it wont die! i guess the beat the bugs out of it! good job castle

[RustlerRacer16]

sensorless is really catching up with sensored. plus you can get more power out of a sensorless motor.

Oh really? That's interesting. Do you know why?

[brushlessman]

Because the controller must direct the rotor rotation, the controller needs some means of determining the rotor's orientation/position (relative to the stator coils.) Some designs use Hall effect sensors or a rotary encoder to directly measure the rotor's position. Others measure the back EMF(sensorless) in the undriven coils to infer the rotor position, eliminating the need for separate Hall effect sensors, and therefore are often called sensorless controllers. also the sensorless controlers are better suited for higher voltages.

The controller contains 3 bi-directional drivers to drive high-current DC power, which are controlled by a logic circuit. Simple controllers employ comparators to determine when the output phase should be advanced, while more advanced controllers employ a microcontroller to manage acceleration, control speed and fine-tune efficiency. Controllers that sense rotor position based on back-EMF have extra challenges in initiating motion because no back-EMF is produced when the rotor is stationary. This is usually accomplished by beginning rotation from an arbitrary phase, and then skipping to the correct phase if it is found to be wrong. This can cause the motor to run briefly backwards, adding even more complexity to the startup sequence.

[RustlerRacer16]

Oh wow. This is all fascinating. I'm glad I broadened my horizons beyond nitro. I'm sure all this will make as much sense to me as nitro stuff does shortly.

[asheck]

Because the controller must direct the rotor rotation, the controller needs some means of determining the rotor's orientation/position (relative to the stator coils.) Some designs use Hall effect sensors or a rotary encoder to directly measure the rotor's position. Others measure the back EMF(sensorless) in the undriven coils to infer the rotor position, eliminating the need for separate Hall effect sensors, and therefore are often called sensorless controllers. also the sensorless controlers are better suited for higher voltages.

The controller contains 3 bi-directional drivers to drive high-current DC power, which are controlled by a logic circuit. Simple controllers employ comparators to determine when the output phase should be advanced, while more advanced controllers employ a microcontroller to manage acceleration, control speed and fine-tune efficiency. Controllers that sense rotor position based on back-EMF have extra challenges in initiating motion because no back-EMF is produced when the rotor is stationary. This is usually accomplished by beginning rotation from an arbitrary phase, and then skipping to the correct phase if it is found to be wrong. This can cause the motor to run briefly backwards, adding even more complexity to the startup sequence.
__________________

Nice CC quote

[brushlessman]

its the best i could do in two minutes

[RustlerRacer16]

Hey! I didn't know the difference!

[brushlessman]

lets keep it that way!

[kschauwe]

Sensorless still won't product more power than a Sensored motor. Just two different ways of sensing rotor position.

[Just 4 Fun]

Sensorless still won't product more power than a Sensored motor. Just two different ways of sensing rotor position.

Sensored motors, or systems at that, are more expensive. They also don't give you as much bang for your buck as far as speed goes. Most of the Novak systems (popular for racing because their sensored) can only run up to 7 cells. Unlike a Mamba which can run 11.1 volts. A Mamba runs like a sensored system, almost no cogg. A VXL ESC and a Novak 5.5r motor can get some major Hp.

[HoovHartid]

wait a minute here.
If you are talking about the Novak HV-Pro system that people are putting into their e-revo's, then that system can handle 6-14 Ni-Cd/Ni-MH cells (7.2-16.8 volts) or 2S-4S Li-Po. http://www.teamnovak.com/products/br...ems/index.html


If your refering to the Mamba Monster Max or MMM then it can handle 6s lipo or 25.2 volts http://www.castlecreations.com/produ...a_monster.html

anything under 14.8v on a single motor will not be a very good system for a truck as large as the e-revo.

Sensorless still won't product more power than a Sensored motor. Just two different ways of sensing rotor position.

Just wondering what sensored system will produce more power for an e-revo than a MMM/Neu motor combo. will you please explain this?

[asheck]

Sensored motors, or systems at that, are more expensive.

Well let's see,A havok system is 140 bucks,a Sidewinder is 170 bucks.Both prices from the Manufacturers websight.A Novak HV is 265,MMM combo is 349. I'm not sure where you get more expensive.

Sensorless still won't product more power than a Sensored motor.

If your comparing apples to apples,your right,kinda.IMO sensored does not effect power output.But sensorless motors have more powerful options available right now.But I run a Novak 5800ss motor with a sintered rotor on 3s in my Rustler.From what I've seen of specs,it's very comparable to a CC 5700.

[The Oracle]

One very important point has been overlooked in all this- the novak motors are essentially 380 XLs, where as the sensorless motors like neus, feigaos etc we use are 540 XLs (magnet size).

Thats why the hvmaxx systems seem so weak compared to a mere feigao 8XL for example.

If you delve into the past, then you will discover the Aveox line of sensored BL motors and esc; Steve Neu (neu motors) used to work for Aveox, so that should tell you how powerful the Aveox motors are- just a shame they left R/C and now to mainly industrial and military stuff.

Sensorless isnt more powerful or less powerful than sensored, its just a question of how the esc detects the rotor's posistion inside the motor; you can buy sensored feigaos that are identical to the non-sensored ones after all...

*this learning experience was bought to you by the letters S and N*

[asheck]

Thats why the hvmaxx systems seem so weak compared to a mere feigao 8XL for example

The 6.5 might feel weak.But the 4.5 whips the 8xl in every way shape and form.I know it does this with RPM's,but getting it done,is getting it done.

[The Oracle]

True. Speed and power are too different things though- the larger magnet and lower kv of the feigao will generate much more torque than the hvmaxx 4.5- thats why it has to be geared so much lower to get the same top speed; 15/68 vs 22/58 or so. Temps on the other hand will be rather different- buts a question of build quality and efficiency; I've been begging novak to make proper 540XL motors for ages, then they would be compareble to the Aveox motors of yester-year, and sensored smoothness with that much power would be a serious contender to the MMM setups....

[asheck]

Well I guess this is what it boils down to.Since power =torque x rpm's / 1000000 the 60000 rpm's the 4.5 gets away with makes the power higher with less torque,where as the 6.5 turning around 45000 rpms would have a much lower power output even though technically there torque would be the same.The 8xl would have to put out twice the torque of the 4.5 to make up the difference of the rpm's,since the xl's are happiest below 30000 rpm's. Since the overall vehicle torque is regulated by your gearing, the power of either can be used as torque or speed.

[brushlessman]

Well I guess this is what it boils down to.Since power =torque x rpm's / 1000000 the 60000 rpm's the 4.5 gets away with makes the power higher with less torque,where as the 6.5 turning around 45000 rpms would have a much lower power output even though technically there torque would be the same.The 8xl would have to put out twice the torque of the 4.5 to make up the difference of the rpm's,since the xl's are happiest below 30000 rpm's. Since the overall vehicle torque is regulated by your gearing, the power of either can be used as torque or speed.

yes but you will kill a 4.5 (overheat,smoke the esc) before you can touch the reliablity of a hacker.

[asheck]

Only time can tell that,but my 4.5 is about 9 mos old and performs flawlessly,and I have Novak motors that are years old that work just like New.The temp sensors work wonders for keeping things from getting to hot.

[The Oracle]

If the esc is taken out of the equation (use an MMM or MGM for both motors- sensored motors can be ran without the senors on those escs), then it would be a straight forward case of seeing which motor allowed you gear higher before it reached its maximum output power and therefore speed- case in point:

Someone once ran the V-twin setup geared 1:1 (36/36) on 2x 3s lipo, and it still couldnt go faster than ~60mph, because the motors run out of physical strength to go faster (limited by voltage and size).

I doubt you'd get more than 50mph from a hvmaxx motor, and even then it would melt most likely, where as a quality neu etc can reach just over 60mph on its ideal voltage; feigao could too, but it would melt due to being a lump of cheap poop.

Its all good fun discussing this stuff, but comparing a hvmaxx to something more powerful really is apples to oranges pretty much, different leagues.

[asheck]

I doubt you'd get more than 50mph from a hvmaxx motor,

In a 12 lb MT I totally agree with that.But at 45 the HV will be going strong long after the XL has melted itself.But yes once you get into higher quality motors there's really no comparison for higher speeds.My Medusa handles 50 much better then the HV would.

Someone once ran the V-twin setup geared 1:1 (36/36) on 2x 3s lipo, and it still couldnt go faster than ~60mph, because the motors run out of physical strength to go faster (limited by voltage and size).

Right,the total output of watts that the motors can produce had been reached.When I was running my 4.5 in the Pede on nihm I could maxx it out the same way,well kinda I was maxing the batts,but same principal.It didn't matter if it was geared 18/87 or 35/76 it would only go 49. The max wattage available had been used.Once you do that either by the ESc,motor or batteries ,gear it to the moon and it just won't go faster.

Its all good fun discussing this stuff, but comparing a hvmaxx to something more powerful really is apples to oranges pretty much, different leagues.

Different leagues yes,The 4.5 is a dual turbo charged,rev to the moon v6.The Neu/Medusa are the 502 rat motor big blocks.But yet when both are setup correctly they can both produce favorable results,that are very similar on 4s.Now throw a blower on the big block,aka 6s,and the results tip decidely in it's favor.

[brushlessman]

if we could i would! fitting a blower on a bl motor is difficult.
on my 79' ford it would wield much greater results