Brushless Slot cars

21941 Views 199 Replies 24 Participants Last post by Dr_C, Feb 1, 2020

Damo

Discussion Starter · May 4, 2011

Hi All,

I have been looking into other hobbies recently as I saw an RC plane and thought I'd better give that a go too! Anyhow, these days all the electric motors in RC planes seem to be brushless. Is that something that we'll see with Slot Cars in the future? Are there any already?

Obviously they are more efficient and probably more reliable and have less wear, surely that'd be a good thing?

Cheers,
Damo.

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300SLR

· #21 · Dec 24, 2018

Slot cars have been built with brushless motors.
They did have electronics in the car to switch the dc power from the the normal slot car track between the motor coils.

What advantages were demonstrated?
When track tested using identical chassis etc. brushless powered was substantially slower than normal (brushed) slot car motors (in identical chassis) .
The brushless set up was more expensive than normal (brushed) slot car motors.

Does that mean brushless motors are a waste of time for slot cars?
I don't think so. If a brushless set up more suitable for slot cars were developed who knows how good it would be.

Reactions: 1

UshCha

· #22 · Dec 24, 2018

I have used brushless in RC aircraft and the gains are huge, Higher power in a lighter package and more efficient.

So what about slot cars? Well my current slotcars with standard tyres we use produce more power than can be used so no gain. Brushed are less efficient but that is not a big issue as there is little to be gained by efficency as you are not carrying the power supply and only idiots or stange folk would use absolute power used for fuel based simulations.

Lower vibration possibly yes, but is vibration a problem with brushed, I am aware of no problem that needs to be fixed.

For some models a smaller package may have some advantages but it needs another board for 3 phase motors and they are so far generally not that small so the gain may not be that great.

Lighter weight may not be much of an advantagew as you need weight anyway to get the best, marginal improvement in weight distribution may be an advantage but proably minimal.

Given minimal cost for brushed motors reliability seems not that great a problem.

Given that there seems littlke real gain in going brushless other than for the fun of it. Like 4WD its great fun but not really any great gains to be had.

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Dr_C

· #23 · Dec 24, 2018

Shall we kick this stuff into touch for another 7 years? or press ahead developing a prototype which demonstrates the benefits?

Just to mention... in my opinion there is enough real estate on a DPR module to add two extra half H-drive circuits in addition to the circuit already present for brushed motor control... with these extra components the phasing of signals for brushless can be handled by the already onboard microcontroller. Even when operating under race conditions this microcontroller spends most of its time waiting repeatedly for the interupt service routine to be triggered...

This activity is going to be a lot of fun so will press on (over the next 7 years or less...) and report back on progress from time to time... surely the time will come when we have a race category for brushless GT...?

Enjoy the festive racing...

C

Mr Modifier

· #24 · Dec 24, 2018

If brushless can offer the same characteristics of say a Flat 6 (22k, 220gcm) but in a lower profile package then we could be on to a winner by lowering the centre of gravity. If there are electronics to be incorporated then a conventional motor shape can be disregarded.

How about a 40mm diameter disk about 8mm deep? With the drive shaft coming out radiating from the centre spot. A couple of holes for mounting screws and you have a standard package that could be mounted as in-line, anglewinder or sidewinder. All chassis designers need to do is create a circular tray in their chassis to accept the motor. As sidewinder the motor could be mounted below the axle (provided you used tyres with an outside diameter of 21mm).

But given the economics involved I dont believe the slot car market is big enough to warrant the investment. Its an interesting technical advancement and it would offer the option for full cockpits on any car - but would it improve our enjoyment of racing? We can already generate more power than our cars can handle and if all racers operate similar setups then the racing will be close.

Do we need it? - no. If somebody developed it and offered it at a reasonable price, would we buy it? - probably....

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Reactions: 1

300SLR

· #25 · Dec 24, 2018 (Edited by Moderator)

UshCha said:
Lower vibration possibly yes, but is vibration a problem with brushed, I am aware of no problem that needs to be fixed.

BUT is the vibration any lower?

Indeed balancing isn't significant for the sort of slot car motors used in rug racing. These motors are only reving to maybe 20ish thousand rpm which is way below the speed of the quicker slot car motors. Imbalance forces (and therefore vibration) get much larger as revs increase (the scientists among us will know it is proportional to the square of speed).

A basic unbalanced armature of a 3 pole brush motor are often a good deal further out of balance that a brushless motor BUT higher reving slot car motors all come balanced by the manufacturer. Balancing the armature is crucial for higher reving slot car motors, not just from a vibration point of view but also because an otherwise simlar unbalanced arm won't rev to anywhere nears the same speed as a properly balanced one.

Reactions: 1

Kevan

· #26 · Dec 24, 2018

Brushless motors have left brushed motors waaaaaaaaaaaaaaaaaaaaay behind performance-wise. There's two types used in r/c cars, sensored and sensorless. Cheaper sensorless motors tend to cog at slow speeds and don't have the finesse of the much smoother sensored motors.

Programmable ESC's mean you can go from mild to wild with the same motor just by changing the programmable variables. Typically you use a programming box or a wifi module via a smart phone, can save favourite 'profiles' for different cars or tracks. The range of parameters and descriptions of what these do and how changing them affect the characteristics on the track would fill multiple pages of writing.

...one thing though, the motor would have to be cylindrical.

A brushless motor doesn't need balancing, the rotor is basically a trued magnet so much smoother than a brushed motor. I don't think revs are a problem, even some of the 1/8th scale brushless motors are rated at 60k rpm.

scuderia_turini

· #27 · Dec 24, 2018

With the usual lowering in manufacturing cost as technology advances, will we get to the stage where brushed motors are more expensive than brushless, so manufacturers will switch?

Dr_C

· #28 · Dec 24, 2018 (Edited by Moderator)

cylindrical brushless motors heading to my test track... 16mm diamter (similar to vertical dimension of a mabuchi 130-type motors), and same length and same 2mm shaft diameter i.e. ready for some slot.it pinion gears... and balanced for 50k rpm... and currents up to 8A... but we really wont need more than about 5% of that... (but that is guessing at this stage...)

C

Ade

· #29 · Dec 24, 2018

Hi

the days of rms based throttle curves and the need for throttles to be programmed with curves could be coming to and end,everything done on the motor board

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300SLR

· #30 · Dec 24, 2018 (Edited by Moderator)

A supplier who makes very fast slot car motors and very fast brushless motors for RC would be well placed to develop brushless motors for the fastest slot cars. They haven't chosen to make brushless motor for slot cars, whatever their reasons for not doing so - the reasons won't be lack of knowledge of brushless technology nor a lack of knowledge about what's need to make a really fast slot car nor a lack of interest in making motors so slot cars can lap even faster.

Spin anything to high enough rpm and something and it will fail. With high end brushed slot car motor what fails first is generally the commutator. On high end slot car motors that happens at somewhere over 200k, but of course it's not a limit anybody chooses to explore. The quickest slot cars don't run at much over half that on track. Would a motor that could go beyond that be a practical advantage in a slot car?

Dr_C

· #31 · Dec 24, 2018 (Edited by Moderator)

interesting....

C

BigC

· #32 · Dec 24, 2018

Having just started a new thread about standardized motors, I wonder if I've found the answer immediately in this discussion about brushless motors.

Bearing in mind brushless motors have performance to spare for slot car implementations, could we create standardized motors using software rather than hardware ? It would certainly be easier to enforce !

Ade

· #33 · Dec 24, 2018

Hi

interesting to read that most seem to be thinking of speed, well for digital use only I'm thinking increased reliability is the key reason to look at this topic, would you rather be installing without the need for the pesky little ferrite men everytime....

Maybe there still needed though, anyone now

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Dr_C

· #34 · Dec 24, 2018 (Edited by Moderator)

on the motor side of the SSD decoder...

no sparks = no need for ferrite men.

... except perhaps three tiny little smd ferrite beads on the decoder pcb itself... i.e. one more than current brushed motor designs.

... and while we are redesigning the pcb for brushless lets add high speed optocouplers on the track reader side... that should take care of track transients that can confuse decoders...

Meanwhile ferrite men will still have a use in this brave new world... we will still need to suppress rf noise generated where the small sparks fly... i.e. at the track-pickup interface...

C

300SLR

· #35 · Dec 24, 2018

Ade said:
Hi

interesting to read that most seem to be thinking of speed, well for digital use only I'm thinking increased reliability is the key reason to look at this topic,

Are you talking about reliability of the whole digital car or just the motor? At the sort of power level appropriate to digital, ordinary brushed motors normally last a long time.

Brushed motors with suppression discs on the armature need less external suppression components. (Come to think of it, wouldn't it be niece to have a comprehensive list of which motors have that feature, afraid I don't have such a list - any offer?)

injectorman

· #36 · Dec 24, 2018

We have non brushless motors doing 165 in 1.5 seconds. Im not sure we need brushless.

Dr_C

· #37 · Dec 24, 2018 (Edited by Moderator)

What about more cars per amp and smaller voltage drops along the track (i.e. more cars and more consistent power)?

Anyway... it feels like time to write some new decoder firmware to control brushless motors - both power and braking... lets see where it takes us... so with motors en route... next a driver circuit... three pwm inputs for brushless motor poles and one for pwm brake function...

C

Ade

· #38 · Dec 24, 2018

Hi

all looks like win win from my point,no arcing or sparking,linear power and how good this could be for events where cars are set up to controlled regulations with tight tolerances but use old fashioned brushed motors that vary greatly in performance.

looking forward to seeing how things develop

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injectorman

· #39 · Dec 24, 2018 (Edited by Moderator)

Ade, Ive already held events where motors are evened out using the controller. Then there is the added cost. And are there even any on the market?
More cars and less voltage drop. If the track is set up properly in the first place this wont make any difference.
Im all for new technology but im just balancing the topic here. Cleaner power is a good point but even that can be addressed using normal motors.
Will i be able to corner faster? No.
If i want deadly speed using normal motors i can always turn the voltage up too. I really dont need more speed. Truly. I can achieve traction control also not using a brushless motor........So im not convinced just yet 😊

Rick

Dr_C

· #40 · Dec 24, 2018

Hi injectorman... let me try this one... lighter motors means we can add extra weight with very low centre of gravity i.e. lower centre of gravity for equally powered brushless motored cars as compared with brushed motored cars (for the same vehicle total weight). Result... like-for-like brushless will give better cornering...

C

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