Brushless motors getting cheaper..will they ever replace the "can"?

I'd still like to understand brushless motors.  I see them in alot of cordless tools and I'm not quite sure how they operate.

my new cordless drills are all brushless. They must be onto something?

Thanks Willygee.  That was most informative.

My thoughts:

With the resistance to change of many in this hobby, and the fact that running brushless motors would require a redesign of motor driver boards, I don't see it any time soon from any of the major manufacturers.  

On the other hand, using BLDC motors would eliminate the need for encoders for speed control, and can be configured easily to know the exact position of the motor, which would allow for perfectly synchronized chuffs if the manufacturer wanted to put the effort into programing for it.  

JGL

If you notice in the video the the energizing of the A, B and C coils that an AC signal is applied. Brushless DC motors are in fact synchronous AC motors. They are called DC motors because the power source is often a battery pack that supplies DC current. The DC is fed into a electronic speed controller (ELC), which is a variable frequency drive. The ELC varies the frequency of the AC signal which controls the speed (RPM's) of the rotor. 

If one drives a brushless DC motor externally and use it as a generator, the current produced is 3-phase AC current, not DC current. 

Brushless DC motors will operate at 60-cycle AC current; however, the motor must be sped up to synchronous speed. It will not self start with 60 cycle AC, it will just sit there and buzz. 

These motors are really important to the RC hobby. This topic has been brought up many times of the forum for the use of these types of motors in our trains:

https://ogrforum.com/t...86#33810031489532186

https://ogrforum.com/t...01#32965472761795801

The main advantage of synchronous or asynchronous motors is that they are 85%+ efficient while DC can motors are only 60% efficient. The more efficient nature of synchronous or asynchronous motors will be very important for battery operation as RC folks have already found out. However, it seems that many in the model railroad hobby are not big fans of a new motor technology. 

The last time I looked, the brand of cordless power tools that I prefer charges considerably more for tools with brushless DC motors. The less expensive, brushed tools meet my needs, so I don't go for the more expensive ones.
Maybe it's all marketing.

If not, how would one justify the increased cost in a toy train?

WBC posted:

The main advantage of synchronous or asynchronous motors is that they are 85%+ efficient while DC can motors are only 60% efficient. The more efficient nature of synchronous or asynchronous motors will be very important for battery operation as RC folks have already found out. However, it seems that many in the model railroad hobby are not big fans of a new motor technology.

Nothing like taking comments out of context.  In truth, the difference in motor efficiency hasn't been an issue until the battery powered discussions, there is always plenty of power available for motors with any of the conventional or command systems.

In truth, it would be the manufacturer's that would have to lead the charge to convert to brushless motors, I doubt the average model train buff is going to invest in the development dollars to design and build the electronics to equip his fleet of locomotives with this technology.  Then there's the issue of the mechanical fit of the new motor into the existing products. 

It's not rocket science to develop a motor driver for brushless motors, I worked with tons of them in the aerospace field before we moved to mostly electronic displays.  There has to be a reason that Lionel, MTH, Atlas, Williams, etc. haven't moved to brushless DC, maybe you should go change their minds?

How many locomotives do you have that use brushless DC motors?  Why don't you have any?

A little negative towards progress John? They are gaining in other fields.

"Why don't you have any?" because they haven't come out...... YET!

If you can save power in battery use, wouldn't that be nice and helpful for miniaturizing boards and other components?

Engineer-Joe posted:

A little negative towards progress John? They are gaining in other fields.

"Why don't you have any?" because they haven't come out...... YET!

If you can save power in battery use, wouldn't that be nice and helpful for miniaturizing boards and other components?

Not negative at all, just pointing out the obvious.  The manufacturers are going to have to be the ones to lead the charge. The end user isn't going to convert to a new motor type without a ton of expense.  Until the manufacturers have a reason to make the change, they're not going to spend the money either.  I don't think any of the manufacturers see this as a priority item right now.  Think of the tooling, both electronic and mechanical, that would be required to bring them to market.  Where's the ROI?  If one maker jumps and bumps the price of his product 20% for no obvious benefit to a vast majority of his customer base, he'll doubtless risk having a smaller customer base.

I have no problem with brushless motors, I dare say I've used them in a lot more applications that most folks here.  However, I never felt the need to make a massive push for them in my model trains, there are a lot of other things I'd rather see before a motor swap.  I do feel they would be more reliable, though other than small motors, motor reliability hasn't been a major source of failure, at least of my locomotives.

Yep, the battery crowd would doubtless jump on the bandwagon, it's a good match for battery technology.  I haven't been convinced that battery technology is superior to track power yet, so I'm not on that bandwagon.

Another motor type that would be interesting to see developed for model train use are stepper motors.  In aerospace, we actually moved from the brushless motor servo loops to stepper motor technology.  You can get them in all sizes and torque ranges.  Low speed control would be second to none, and with fine enough steps, you wouldn't see any jerkiness.  I'd probably like to see them used before brushless motors, I think they'd work really well.

Here's an example of the application of stepper motors, there are four stepper motor servo loops in this instrument, it was basic on the Boeing 737 for about twenty years, I was the project engineer on the original development.  The pointer movement is smooth as silk, no apparent steps at all when it operates.  I'd love to get this one operating, I just don't have a 737 to plug it into nowadays.

GRJ: "Another motor type that would be interesting to see developed for model train use are stepper motors.  "

Interesting comment John!  The Original Odyssey Motor was a Stepper Motor!  Lionel gave up on it before my time.  I think it deserves another round of R&D!

jon

I always liked the stepper, it has some advantages that other types don't.  I didn't realize the original Odyssey was a stepper, but it makes perfect sense.  Speed control with no feedback required, you know exactly what you're commanding.

So Jon, when can we expect to see the prototype of the new stepper motor drive?  With all the advances in electronics and motors in the fifteen or so years, it should be even easier to make something really nice.

A stepper motor is a form of synchronous motor and the video linked above gives the basics of how they work in the area that it discusses how they smooth out the operation of the rotor. 

Did the Odyssey Motor have a disc rotor? http://solarbotics.net/library...lib/pdf/motorbas.pdf

I guess I read this as more of what the title suggests; Will brushless motors ever end up in model trains, since they are starting to come down in cost these days?  

I don't thing they are competitive with the can motor just yet, but I can see them becoming so in the future.  As I suggested in my last post, the manufacturers can do away with the need for tach strips or slotted disk encoders for speed control by using BLDC motors, as the driver already knows how fast the motor is turning.  In addition, the improvement in efficiency could allow the use of less expensive drivers and/or smaller heat sinks, which can shave some pennies off the total costs.  I think when the prices start to equal out, we could see BLDC motors in out models, but not likely for some time, as there is really little added benefit in this application other than allowing creeping at speeds less than 1 scale mph.  People seem happy with the 2mph or so we have now, so I don't see that being a significant motivation for the manufactures to do a full redesign of the electronics package.  

On the notion of steppers, simplifying things a little, a typical 6 pole BLDC is pretty much just a crappy stepper, having about a quarter of the steps of common stepper motors, but functions in much the same way.  I don't see 24 or more steps providing much in the way of functionality over six... or 12 if you engineered a half step driver, for the purpose of propelling a locomotive.  

In the long run, if BLDC motors become cost competitive with can motors, we may see them, but in the foreseeable future I don't think it's likely we will see them powering our locomotives...They just don't add anything at this point, in my opinion.  

JGL

JohnGaltLine posted:

On the notion of steppers, simplifying things a little, a typical 6 pole BLDC is pretty much just a crappy stepper, having about a quarter of the steps of common stepper motors, but functions in much the same way.  I don't see 24 or more steps providing much in the way of functionality over six... or 12 if you engineered a half step driver, for the purpose of propelling a locomotive.  

Don't get me started on half-step drivers.   Many people misunderstand how that actually works and expect the half-step to be like another full step.  All the half step does is smooth out the rotation of the stepper.

Okay...now l am snowed.  Are or are not either of these types more durable, longer lasting, and trouble free than current motors?   I would think aircraft applications push toward fail-safe technology.

As JGL points out, brushless DC motors are very similar in construction to stepper motors.  Yes, they would clearly be more durable and long lasting than brushed DC motors, that much is sure.  Back in the 1980 when I was doing aerospace cockpit instrumentation, we were looking for a minimum of 10,000 MTBF of the entire instrument.  Clearly, this dictates having all the components be very reliable and the design not to stress anything to the limits.  The instrument I posted the shot of achieved more than 10,000 hour MTBF in actual operation and it is full of steppers, synchro feedback sensors, gears, and electronics.  I don't recall ever seeing an actual stepper motor failure in those, we had more problems with electronics and heat.

The brushless induction motor that's down in my well has been there since 1998, and I know people that have had them for twice that time.  Motors can be made very reliable, the brushed DC motor is probably one of the least reliable of any type.

Brushless motors were a game changer in the R/C world because they are more efficient for BATTERY operation. 

They tend to cog at low speeds.

As JGL points out, brushless DC motors are very similar in construction to stepper motors.  Yes, they would clearly be more durable and long lasting than brushed DC motors, that much is sure.  Back in the 1980 when I was doing aerospace cockpit instrumentation, we were looking for a minimum of 10,000 MTBF of the entire instrument.

Given the quality of the electronics used in trains, it that likely to be true in that application?
Wouldn't the motor manufacturers cheapen the motors used for toys to get the price down?
What do the motors  / electronic driver components cost in cockpit instruments?

I ask because I think it all comes down to money.

The train companies don't seem to want to do something as simple as putting fuses or surge suppressors inside their locomotives. Why would they want to put a more expensive motor system in their trains unless it brought them more sales and increased profit?

SPSF posted:

Brushless motors were a game changer in the R/C world because they are more efficient for BATTERY operation. 

They tend to cog at low speeds.

Probably  more efficient no matter what is powering them.

Another benefit of BLDC would be the reduction of EMI or Electromagnetic interference due to no arcing brushes. Might be helpful with signal data over rail power.

Brushless motors are big in the automotive industry as well.   Side door window regulators, latch, mirror, wiper motors are just to name a few. As far as durability, electrical feed back, and lower amp draw, they are a real winners. Of course with their larger sizes (We call them pancake motors) I did not realize they could make a good candidate for O gauge trains.

Brushless DC motors come in all sizes, and they're not all pancake shaped.

sinotech brushless DC Motors

C W Burfle posted:

Given the quality of the electronics used in trains, it that likely to be true in that application?
Wouldn't the motor manufacturers cheapen the motors used for toys to get the price down?
What do the motors  / electronic driver components cost in cockpit instruments?

Like I stated previously, the cost will be the primary driver, after all we're just talking expensive toys, right?

The ones we used long ago in the cockpit instrumentation were not cheap, in quantity they were around $30-50.  With an instrument that sells for $8,000, you can afford more expensive components.  However, the commutator and brushes are the most troublesome aspect of standard brushed motors, so just eliminating those would certainly improve reliability, all other things being equal.

Size comparison between a synchronous (BLDC) motor and the Pullmor Universal Motor. 

Unless we match specifications like torque, size comparisons don't mean much.

How about this wrinkle? Use a conventional can motor to drive a "distributor" to route the voltage to the stators in truck-mounted brushless motors. You have wires rather than rods and chains going from the superstructure to the trucks. In the superstructure, you have more space for an interior and strategic placement of weights. In theory, the "prime mover" can motor wouldn't need to be that powerful as the main operating current for the truck motors can come from a set of bridge rectifiers running of track power. Just a thought that popped into my head and didn't die from loneliness.

Come on Matt.  

Where's the diesel (ethanol?) gen set powering the traction motors? 

We add ethanol to the tanks thru the new diesel service pit stop stations.

We still need rods and chains! Just add real wires.

What, are you running from catenary now?

AGHRMatt posted:

How about this wrinkle? Use a conventional can motor to drive a "distributor" to route the voltage to the stators in truck-mounted brushless motors. You have wires rather than rods and chains going from the superstructure to the trucks.

You should have let that thought die!

It's much less expensive and more to the point to simply build the fairly simple electronics to run the brushless motors.  After all, what's controlling the can motor?  Why did we add an unreliable can motor and multiple brushless motors?  How do you precisely control the speed of the can motor since it's determining the speed of the truck mounted motors?

What do you gain by adding all this complexity?

Wow and we can reduce the carbon footprint of our trains while increasing the cost of the product.

gunrunnerjohn posted:

AGHRMatt posted:

How about this wrinkle? Use a conventional can motor to drive a "distributor" to route the voltage to the stators in truck-mounted brushless motors. You have wires rather than rods and chains going from the superstructure to the trucks.

You should have let that thought die!

It's much less expensive and more to the point to simply build the fairly simple electronics to run the brushless motors.  After all, what's controlling the can motor?  Why did we add an unreliable can motor and multiple brushless motors?  How do you precisely control the speed of the can motor since it's determining the speed of the truck mounted motors?

What do you gain by adding all this complexity?

Like I said. Popped in my head. I was thinking controlling can motor voltage would be simpler than a variable square-wave generator since you could utilize existing motor control hardware designs. You definitely have a point, though.

Simply controlling a can motor open loop, as long as you don't need speed control, is indeed pretty simple.  However, since most of us want cruise for constant speed up and down grades and with variable loading, adding the constant speed control to the motor ups the electronic cost significantly, and it's probably the same as direct drive of the brushless motors anyway.  Then there's the contacts in the brushed motor, and we've added the distributor contacts, all contacts to arc, create electrical noise, and sap reliability.  Suddenly this got very complicated to solve a pretty simple problem.

My two cents is how much do we run our trains per day/month/year?  Unless its department store or museum displays. I don't think you would wear out the brushed motor, barring poor batch of motors that got into the engines.  So you would pay much more for having state of the art motor that would give a personal low ROI.  But would be your money.   

Same argument I suppose the conventional train runners argued the same when electronics first came on market, especially Lionel command and MTH DCS systems.  Big deal, you control your train speed and whistle bells by remote rather than hands on transformer handles/buttons.

Interesting topic!

rrman posted:

My two cents is how much do we run our trains per day/month/year?  Unless its department store or museum displays. I don't think you would wear out the brushed motor, barring poor batch of motors that got into the engines.  So you would pay much more for having state of the art motor that would give a personal low ROI.  But would be your money.   

Same argument I suppose the conventional train runners argued the same when electronics first came on market, especially Lionel command and MTH DCS systems.  Big deal, you control your train speed and whistle bells by remote rather than hands on transformer handles/buttons.

Interesting topic!

I doubt you can run 4/5/6 multi engine units as i do with transformer handles and buttons.

Hi Willygee,

I was referencing those conventional runners of single engines who just can't see the reason to run multiple trains at once.  Ya know old fogies, stick in mud, head in sand etc.  (not that I was ever one when these systems first appeared )

I have complete respect for buttons and handles...but honestly i would be completely lost without command with my style of running trains.

PLCProf posted:

rrman posted:

My two cents is how much do we run our trains per day/month/year?  Unless its department store or museum displays. I don't think you would wear out the brushed motor, barring poor batch of motors that got into the engines.  So you would pay much more for having state of the art motor that would give a personal low ROI.  But would be your money.   

 

Well. maybe today, but not for long. I am 100% certain that the train manufacturers use the can motors today because, all things considered, they are less expensive than the open universal (Pull-Mor) style. I am also 100% sure that eventually, brushless will be the lowest cost option, and at that point, the train manufacturers will be forced into using it. Electronics have become so inexpensive that it is hard to justify anything involving switches or contacts or mechanical parts any more, at least in the tiny sizes we deal with.

I'm guessing you will see brushless DC in trains in 5 years, and it will all be brushless DC in ten. Even the starter sets!

 

I didn't think anybody used open frame motors anymore...mostly dc permanent magnet aka the "can"

PLCProf posted:

I'm guessing you will see brushless DC in trains in 5 years, and it will all be brushless DC in ten. Even the starter sets!

Well, it really depends on whether they want to redesign all the electronics.  I don't have an issue with the fact that sooner or later they'll appear in model trains, but I suspect that the brushed motors will hang in there for a long time in certain models.  Think about all the places and accessories that have motors and no electronics.  Hard to believe they're going to add electronics to all these items.  I see them appearing in high end stuff and being advertised as more reliable.

Well, when they fit the electronics into this motor, I'll be impressed.

Well, the bulb circuit needs to handle a few milliamps, the motor drive circuit will need a bit more capacity.   Of course, for that little motor it wouldn't take much more.

Just as SFPF stated, most brushless motors do not like slow RPM operation.  They ideal for RC cars, planes and drones that need 100,000 RPM to go fast.  If you follow RC cars, you see racing and guys doing actual 120mph speed runs is dominated by brushless.  However, Rock Crawling RC is all brushed motors as they have higher low end torque and smoother operation at low RPMs.    

I doubt, due to the lack of slow speed smoothness, that brushless can easily be put in our trains.  I would assume that the gearing would have to be rather extremely low to enable much higher RPMs to smooth out a 3 scale MPH pull.

BB