Castle - Make A Special Edition Monster

[TexasSP]

Besides, a lot of what is commonly referred to as cogging is actually not cogging and lack of power or various other things.

[GriffinRU]

I will disagree with you, Patrick, about sensored motors, and there is no "Hype" here. For given application there is a given motor.
Brushed motors can deliver 1000% torque at stand still
Sensored Brushless motors 1/3 of that
Sensoreless not even 20-30% of that sensored systems
You know why and there is no BS here.

Extra wires and sensors are weak links as well as brushes, as long as mentioned them.

Timing with sensors can me more advanced and flexible if you write software accordingly and there is no need to set sensors exactly at "0", you can adjust it anytime as wide as you wish. And back check with motors efficiency, you can even run in dual mode and use sensors for back-check, startup, pulling, holding and braking. If you creative you can even generate brushed mode. Just need to set sensors perfectly spaced to motor poles. If you use encoder instead of hall-sensors, or even IC you can be completely independent of motor type/pole count. I am not going too deep in details, but I think you know the rest.

All the rest about sensored systems in only limited by flaws in software.

I actually was saving this sensored idea from suicideneil for desert, but I guess it would be impossible to convince you otherwise... :(

To BrianG:

The common consensus here seems to shoot for a battery and motor kv setup to get around 30-35k rpm total. This most likely came about because Feigaos tend to heat up at speeds higher than that. However, lower rpm means less EMF pulses at really slow speeds, which increases the chances of cogging.

Brian, I wasn't expecting question like that from you. Efficiency curve defines given motor RPM range. Number of Poles, Motor diameter and rotor length defines torque and speed factors. (Rotor weight, air gap, core material, windings, delta/star...) From motor parameters you can plot it quite easy.
For the same Power motor with
More poles -> Lower RPM Higher Torque
Less poles -> Higher RPM Less Torque.
Smaller diameter -> Higher RPM, Lower Torque
Bigger diameter -> Lower RPM, Higher Torque
Longer rotor -> Lower RPM, Higher Torque
Shorter rotor -> Higher RPM, Lower Torque
I do not even know what to comment on "Less" EMF pulses...
I will call it Monday and I am in bad mood and picky, sorry for harshness.

[Pdelcast]

Originally Posted by GriffinRU

I will disagree with you, Patrick, about sensored motors, and there is no "Hype" here. For given application there is a given motor.

I'm going to disagree with you here. Sensored motors are marketed with a lot of HYPE -- The makes of sensored systems have been BSing the public for a couple years now, telling them that sensorless is inferior, in the hopes that people will buy into their hype. And some people have bought into the hype.

Try this: Take a sensored motor and measure how much phase imbalance the sensors have -- you'll be astonished and shocked at how BAD the sensors are. Typical sensor phase imbalance is around 10 degrees from sensor to sensor, and that's just PHASE imbalance. Even on high-end military motors there is at least 5 degrees of phase imbalance -- just because Hall sensors trigger points aren't precise. And timing itself is completely ambiguous with a sensored system - - and because it is ambiguous, it can't add any meaningful data to the rotor position estimate.
Not only that, but sensors also trigger incorrectly all the time during run (by winding flux) -- and the sensor controllers blindly follow the incorrect sensor outputs...

Granted, sensored systems can produce more torque at stall than sensorless systems. But in RC applications we can generate more torque at startup than is required using only sensorless algorithms.

You state:

Originally Posted by GriffinRU

Timing with sensors can me more advanced and flexible if you write software accordingly

But that really isn't true. Once the sw PLL is locked (within a few commutation cycles) we can control timing to within .1 degrees -- how can an ambiguous sensor system with jitter and phase imbalance add to that? Adding sensors into the equations just makes the position data LESS precise.

Believe me, we build hybrid controllers (that start sensored and run sensorless) for both the military and industrial applications, and have been building those types of controllers for years.

We've done all the math, the simulations, and modeled the systems extensively. Once the sensorless software is locked, sensors add nothing but noise to the system.



Sensors are useful for generating a lot of torque at stall (> 20% PWM duty cycle lengths), but with the motors we use in RC, we can't even PWM at 20% during stall -- they would draw thousands of amps. So even at a 20% max duty at stall we can generate PLENTY of torque at startup -- Seen the videos of people backflipping Monster Trucks with the MMM from a standing start?

So there's my rant about sensors. With respect to timing and control, Sensorless = precision, Sensored = ambiguity.

Ok, so I've kinda got the "Mondays" myself. 'Cause I have to get up at 5:30am to fly to California. And I don't want to go to California.
And it's been raining here a lot, and my backyard is flooding and mulch is pouring into my pool and I keep having to spend hours cleaning it out.
And I got an E-Revo and I haven't even had time to install a Monster in it yet.

And I keep editing this post 'cause I don't want people to think I'm angry or being aggressive about this... I just want to present the facts...

I must be the only person who had a pleasant Monday...

[BrianG]

Originally Posted by Pdelcast

...Ok, so I've kinda got the "Mondays" myself. 'Cause I have to get up at 5:30am to fly to California. And I don't want to go to California.
And it's been raining here a lot, and my backyard is flooding and mulch is pouring into my pool and I keep having to spend hours cleaning it out.
And I got an E-Revo and I haven't even had time to install a Monster in it yet....

Don't feel bad, I think I have a pool in my basement! The water is coming up through the floor almost faster than I can pump it out. And just when I make decent headway, the stupid weather decides to drop another 1-2" of rain in 5 minutes!

And since my workshop is in my basement, it's not fun. I only have standing water is the low spots, but still tough to work on things hopping from high spot to high spot. Grrr.

I guess when it rains, it really does pour...

[GriffinRU]

Originally Posted by Pdelcast

I'm going to disagree with you here. Sensored motors are marketed with a lot of HYPE -- The makes of sensored systems have been BSing the public for a couple years now, telling them that sensorless is inferior, in the hopes that people will buy into their hype. And some people have bought into the hype.

Try this: Take a sensored motor and measure how much phase imbalance the sensors have -- you'll be astonished and shocked at how BAD the sensors are. Typical sensor phase imbalance is around 10 degrees from sensor to sensor, and that's just PHASE imbalance. Even on high-end military motors there is at least 5 degrees of phase imbalance -- just because Hall sensors trigger points aren't precise. And timing itself is completely ambiguous with a sensored system - - and because it is ambiguous, it can't add any meaningful data to the rotor position estimate.
Not only that, but sensors also trigger incorrectly all the time during run (by winding flux) -- and the sensor controllers blindly follow the incorrect sensor outputs...

Granted, sensored systems can produce more torque at stall than sensorless systems. But in RC applications we can generate more torque at startup than is required using only sensorless algorithms.

You state:

But that really isn't true. Once the sw PLL is locked (within a few commutation cycles) we can control timing to within .1 degrees -- how can an ambiguous sensor system with jitter and phase imbalance add to that? Adding sensors into the equations just makes the position data LESS precise.

Believe me, we build hybrid controllers (that start sensored and run sensorless) for both the military and industrial applications, and have been building those types of controllers for years.

We've done all the math, the simulations, and modeled the systems extensively. Once the sensorless software is locked, sensors add nothing but noise to the system.



Sensors are useful for generating a lot of torque at stall (> 20% PWM duty cycle lengths), but with the motors we use in RC, we can't even PWM at 20% during stall -- they would draw thousands of amps. So even at a 20% max duty at stall we can generate PLENTY of torque at startup -- Seen the videos of people backflipping Monster Trucks with the MMM from a standing start?

So there's my rant about sensors. With respect to timing and control, Sensorless = precision, Sensored = ambiguity.

Ok, so I've kinda got the "Mondays" myself. 'Cause I have to get up at 5:30am to fly to California. And I don't want to go to California.
And it's been raining here a lot, and my backyard is flooding and mulch is pouring into my pool and I keep having to spend hours cleaning it out.
And I got an E-Revo and I haven't even had time to install a Monster in it yet.

And I keep editing this post 'cause I don't want people to think I'm angry or being aggressive about this... I just want to present the facts...

Monday-Monday - it is Friday :)

Patrick you are:

• talking about spindle motors...
• miss the fact that we would like to have hybrid system (or based your opinion)
• sensors imbalance is fixed (constant for given motor) and can be offset (I am not even going into phase shift with RPM business)
• optical sensors are rock-solid
• motor windings are even worse in terms of matching, not even considering that load on the motor shaft is not constant in car-applications
• once motor spinning use sensoreless feedback, it is free no hardware to add
• braking, pulling and holding that is what you can do great with precise rotor position feedback
• for $$$ you can add encoder and it can be single wire, or even wireless

Couple thoughts, sensoreless ESC starts at stand sill only if you have backslash or you being in motion before or at least kept memory of position (Or very clever software :) ). 20% PWM at stall is not high current if you matched with magnet pole and motor is rated for the load.

Hall sensors are cheap and sensitive to all kind of things, including magnets or screwdrivers in their proximity, but can be shielded or replaced with opto...

All the rest is irrelevant, because there is no good sensored controller on the RC market to do the comparison.

____
MGM hardware with CC software - I am hearing that allot. Patrick have you checked what is different between your creation and theirs?

[Pdelcast]

Originally Posted by GriffinRU

Monday-Monday - it is Friday :)

Patrick you are:

• talking about spindle motors...

• No, I'm not... talking about motors in general - - applicable whether using spindle motors, linear motors, axial or radial flux, etc.
  

  Originally Posted by GriffinRU

  miss the fact that we would like to have hybrid system (or based your opinion)

  Nope, didn't miss that either. Didn't say I wouldn't make a hybrid system either... just that the halls are useless in most situations.
  

  Originally Posted by GriffinRU

  sensors imbalance is fixed (constant for given motor) and can be offset (I am not even going into phase shift with RPM business)

  So -- Why would I want to take my high accuracy sensorless position and use it to correct an inaccurate sensor? Why? To what end? To lower my position accuracy? To lower efficiency?
  
  That's like saying -- "Lets measure this distance with a tape measure, and then I'll count how many steps the distance is. Then we'll correct the number of steps using the measured distance, because we know the number of steps in inaccurate." -- Doesn't make any sense to correct an inaccurate measurement using an accurate measurement in the first place. There is no additional information that the hall sensors add to the system. Only noise -- which I don't want to add to the system.
  

  Originally Posted by GriffinRU

  optical sensors are rock-solid

  SLOW, same imbalance problems as halls...
  

  Originally Posted by GriffinRU

  motor windings are even worse in terms of matching, not even considering that load on the motor shaft is not constant in car-applications

  Phase imbalance is compensated for in sensorless -- so it doesn't matter. Not compensated for with sensors... another sensor drawback...
  

  Originally Posted by GriffinRU

  once motor spinning use sensoreless feedback, it is free no hardware to add

  That doesn't even make any sense. Sensorless isn't free -- it requires a lot of hardware... Adding sensor support on top of that adds cost.
  

  Originally Posted by GriffinRU

  braking, pulling and holding that is what you can do great with precise rotor position feedback

  Holding torque is better sensored. But not really important in this hobby except MAYBE for rock crawling. I don't understand where braking would be different - - same positioning algorithm as running the motor, just different FETs being turned on.
  

  Originally Posted by GriffinRU

  for $$$ you can add encoder and it can be single wire, or even wireless

Throw more money at something that doesn't work well in the first place? No thanks... :)

Originally Posted by GriffinRU

20% PWM at stall is not high current if you matched with magnet pole and motor is rated for the load.

Incorrect -- remember there is no back-EMF at stall, and most (hobby type and high performance) motors don't have enough inductance to enter that into the equation -- So the only thing sure to limit current at stall is phase resistance. There is a non-linear (1/x) relationship to current draw vrs RPM at a given PWM level.

Originally Posted by GriffinRU

Hall sensors are cheap and sensitive to all kind of things, including magnets or screwdrivers in their proximity, but can be shielded or replaced with opto...

Exactly -- so why spend money trying to fix something that doesn't work well to start with?

Don't think I don't hear you -- I'm being purposefully obtuse to make my point... -- there are situations where a hybrid would be nice to have. I just don't think that 95% of people need (or would benefit from) a hybrid system, and the reliability and efficiency issues outweigh the usefulness.

[GriffinRU]

Patrick, as I said earlier for given application.

If optics are slow than you are really fast my friend!!!!!!

Quote:
Originally Posted by GriffinRU
20% PWM at stall is not high current if you matched with magnet pole and motor is rated for the load.

Incorrect -- think about it. (Hint -- it has to do with back-emf)

No comments, Maybe I am not clear, but how you get the motor moving if you cannot draw the current...

P.S. It is pointless discussion, you like what you have, I am trying to let you know how it can be done right for given application.
You current sensoreless ESC is great for RC but I am looking for rock-crawlers as application for brushless as well.
And out-runners are great motors and with sensors can be direct coupled to wheels...

[Pdelcast]

Originally Posted by GriffinRU

Patrick, as I said earlier for given application.

If optics are slow than you are really fast my friend!!!!!!

Quote:
Originally Posted by GriffinRU
20% PWM at stall is not high current if you matched with magnet pole and motor is rated for the load.

Incorrect -- think about it. (Hint -- it has to do with back-emf)

No comments, Maybe I am not clear, but how you get the motor moving if you cannot draw the current...

P.S. It is pointless discussion, you like what you have, I am trying to let you know how it can be done right for given application.
You current sensoreless ESC is great for RC but I am looking for rock-crawlers as application for brushless as well.
And out-runners are great motors and with sensors can be direct coupled to wheels...

Sorry griffinru -- my post was put up while I was still editing it. So you didn't see the final version.

The stall current thing is a 1/X relationship current vrs RPM -- non linear with RPM. So at stall, current is infinite (limited by motor phase resistance -- not much of a limitation.)

[bdebde]

Originally Posted by GriffinRU

...MGM hardware with CC software - I am hearing that allot. Patrick have you checked what is different between your creation and theirs?

I would guess by the layout of the MGM, they have more (or larger package) fets. If my third try on the MMM fails, I would be willing to Frankenstein together my MGM power boards with the MMM brains for a totally bulletproof ESC (sorry Patrick).

GriffinRU: can it be done? (brain transplant)

[GriffinRU]

Originally Posted by bdebde

GriffinRU: can it be done? (brain transplant)

Not really,
The trick is at fet's drivers not in fets. While they do have nice layout, CC's board is also nice. But there is a small difference which is clear on the board and inside firmware as well. I think if Patrick will do the same, he might get similar performance with current firmware.
But, Frankenstein, in this case would be very complicated.

New MGM's I think have the same fet as CC, if you check old 160Amps ESC had 4 boards now 160Amps has 3 while 224Amps has 4...