Fancy New Brushless Motor Tech

[speedy_w_beans 4272]

I wonder if we'll see this tech eventually trickle down to RC...  The video suggests full 1:1 EVs can operate without gearboxes, so I would think we could see the same thing with 1/10 scale vehicles.  No more picking pinions and spur gears, maybe.  Is this the next tech improvement in RC?

 

[Mad Ax 9312]

Interesting.  TBH I don't really understand it but I have often wondered if clever electronics and moving internals would make the motors more efficient.  Like for example could the endbell be adjusted in motion to adapt motor timing to the conditions?  I don't know if any current tech does this.  I guess that's part of what the above gets at, among other things.

The proponents of electric power in automotive applications always bang on about how the electric motor produces peak torque form 0 RPM and has a much higher rev ceiling.  OK, it does produce torque from 0 RPM and it does have a high rev ceiling, but anyone who had raced EP RC knows the motor still needs to be tuned to its performance range or it will overheat.  Overheating a brushed motor requires a skim of the comm and some new brushes, which is way less work than rebuilding an overheated IC engine, overheating a brushless motor could destroy that expensive magnet, which is made from a finite resource.  I don't know what tech goes on underneath a Tesla to keep it operating within its acceptable range during urban running (where it's mostly designed to be) and the drag strip (where it can embarrass some very expensive IC hardware).

IIRC the rules for Formula E allowed cars to run a 1- or 2-speed transmission, and there was a split across the grid, so some were obviously happy using the full rev range and I guess some felt the extra weight and drag of a transmission was worth it to keep the motor in its sweet spot.  AFAIK they're all going / gone to a single platform soon so that level of experimentation and variety will disappear, which I think is a shame.

[moffman 5752]

Good as new technology! But I still like good old brushed and easy use of HiMH batteries (and receiving my rc magazine through the post) that's what the hobby is to me brushless and (if it does trickle down) this technology as brilliant as it looks kinda limits wrenching time which is a good 70% of what I do! I'm afraid it would make everything a bit boring (as a hobby)

[speedy_w_beans 4272]

I can certainly see where brushed motors will still be an option for a long time, but maybe current brushless tech will be superseded by this newer motor construction and electronic control scheme.  I have to believe racers would be the first to adopt it through sponsorship and paying the expected higher cost, with it trickling down to mainstream hobbyists over time.  What did it take for current brushless to become mainstream?  5 years?  10 years?  Given this new tech is in demonstration phase, it will take quite awhile to convince manufacturers, get licenses in place, build out the supply chain, prove it in applications, etc.  I bet it's an easy 5 to 10 years away from hitting the RC scene.

Quite a few of my cars have brushless systems in them, but I still like brushed motors for monster trucks and pan cars.  There's something about the soft startup and somewhat spongy dynamic that I like for these vehicles vs. the harsher startups and direct response of brushless in my buggies and touring cars.  Plus, brushed is pretty inexpensive now with Mabuchi motors available for $4 and brushed ESCs available for $11.

[nowinaminute 2815]

I'll have to read up on it because it takes a while for stuff this advanced to sink into my thick skull but it certainly looks promising. It almost looks like and inrunner and outrunner combined with very smart adaptive timing. 

I'm no expert on the subject but there's certainly a lot you can do just with the control algorithms to increase performance/reduce cogging/increase efficiency etc so combining that with a physically new design certainly has the potential for big improvements.

I wonder if it would sound anything like those AC electric trains that almost " shift gear" where the frequency output by the motor controllers is changed according to speed and loading
 

Imagine that noise coming from an RC!

[nbTMM 433]

 

On 8/13/2019 at 6:42 PM, Mad Ax said:

Like for example could the endbell be adjusted in motion to adapt motor timing to the conditions?  I don't know if any current tech does this.  I guess that's part of what the above gets at, among other things.

That's what ESCs with boost/turbo currently do. The endbell on a brushless DC motor (what RC cars have) just houses 3 hall effect sensors which are used to tell the ESC what the position of the rotor is, hence it knows when to switch the 3 electrical phases to the motor. Physically rotating the end bell makes the ESC think that the rotor is in a different position and hence retards or advances the timing of the electrical control. Physically rotating the end bell or simply adding or subtracting an angle in software achieves the same thing. So if you have 20 degrees boost starting at 5k rpm and ending at 20k rpm it's like someone is sitting there monitoring the rpms and seamlessly rotating the end bell up to +20 degrees as the rpms increase from 5k to 20k. On a 540 size BLDC motor you can widen the power band slightly and increase efficiency over that range by perhaps 10-20%. Not a huge difference but better than nothing.

I think the point of the OP's video was more that they increased the efficiency above 85% for 20-100% of the motors usable rpm range, versus existing motors that are only >65% efficient over that range. Existing motors are already quite efficient once the motor is up to speed. Hence for stop start traffic the efficiency would be increased 20% or so by the proposed motor design. Of course, you could also just introduce a gear reduction so the motor gets up into it's efficient range at a lower speed, and sacrifice top speed, or add an automatic gearbox with more than 1 ratio. Reducing size, weight and cost of manufacturing is a big deal for 1:1 cars, so if something can be eliminated that's a very good thing, hence why most EVs run fixed gear ratios as the added weight, complexity and efficiency loss of an automatic gearbox isn't justified when you could just install more batteries instead. At the moment range is given more consideration than the actual efficiency of an EV.
Tesla's Model S already operates with decent efficiency over a wide rpm range, and key to this is the use of an induction motor. It still has a fixed gear reduction however as the induction motor is built for much higher rpm than typical wheel rpms. Unfortunately, induction motors don't scale down in size very well, hence why no RC cars use induction motors (and I don't think many if any popular small 1:1 EVs). The motor in the smaller Tesla model 3 is a BLDC motor somewhat more like a really big RC car motor.

The same problem as the Tesla Model S is true for RC cars, a little 540 size BLDC motor wants to spin at say 15,000rpm to make peak power when we only want a few thousand rpm at the wheels, hence a gear reduction is used. Making a small motor that turns at low rpm and produces a great deal of power on a low voltage isn't practical/possible. Similarly, efficiency at very low rpms (<20% of max rpm) is rarely a major consideration for RC. 

The tech in the video looks interesting but I doubt it will make it to RCs as it's too complicated for negligible gain in a racing context where you don't care if the power/efficiency band of the motor is somewhat limited. RCs are largely driven by controlled racing series, simplification, light weight and low cost. It's hard to beat what we already are running for that.

[Wooders28 4723]

As above, the current brushless motors in RC cars is generally more than enough, running boost/timing etc, and with lipos, battery dumping just isn't even a consideration these days. It may play more in the controlled motor racing. Modern RC racers seem to be adding more gears!, 5 gear stand up etc, and without a gearbox, I'm not sure we're you'd put the slipper clutch? 

For a 1:1 to be gearbox free, you'd need a hub mounted motor? But I'm thinking the braking regeneration part may a part in the design?

Be interested in a classic elec car....🤔