Cutout-Proof Wheels

[InfiniteWheelie]

I think cutout-proof wheels are possible, but it would require one piece of technology which isn't available yet. That being cells with extremely high power density (think supercapacitor-like).

The first type of cutout is due to overpowering. Using such cells would allow unlimited acceleration (capped only by traction or lean pressure), and extremely high top speeds (most likely capped by wind pressure).

The second type is due to electronics failure. This could be prevented by making each side of the wheel entirely independent (batteries, controllers, hall sensors etc.) Each side could work in unison until a part failure occurred, at which point the other side instantly and fully takes over. This is another reason extreme power cells are needed, since the battery on each side needs to be capable of solely powering the wheel in any situation. 

An example of this type of cell I'm watching closely is from GMG (Graphene Manufacturing Group). Their current pre-production cells have about 40% less energy density than the best lithium ion, but have up to 70x more power density. If this comes to market it would be a game changer for EUCs, which unlike other PEVs rely on power for safety.

 

I think in the not-too-distant future we could have wheels that are impossible to overpower, with completely independent sides for zero cutouts. I think this needs to be the long term goal to make EUCs into true vehicles, both in terms of safety and performance. What are your thoughts?

Edited August 17, 2023 by InfiniteWheelie

[Heyzeus]

 

I think I read that the v13 is trying to implement some redundancy where the wheel can handle one battery pack failing?

Eventually it will happen and I look forward to a future where my only concerns when riding my wheel are cars and my own stupidity

Then we just need the personal shield from Stargate Atlantis

https://stargate.fandom.com/wiki/Personal_shield_emitter

And then cars and stupidity won't even be a problem

 

 

[mhpr262]

Have fun with your $8.000 wheel

[Murdomeek]

you forgot the 3rd reason: over speeding

your batteries and electronics can be 100%, but they can't physically make the motor turn faster.  That is determined by the motor windings kv.

 

Of course there is beep warnings and tiltback like we do now, but there is nothing stopping an "uneducated" rider to power through those

[VikB]

You can also have an overheat situation that would take out both sides of the EUC even if you could split them into independent circuits that could support the whole wheel at high load.

You could add a 3rd unused set of electronics which would take over if both the working circuits failed, but of course you could have a switching failure or a failure in one of the components of the back up system.

So making a safety EUC less likely to cut out is possible, but there is no way to make one that cannot fail. If that's what you are after get an e-scooter, e-bike or e-skate. You can coast to a stop on all of those if the power system fails.  

[InfiniteWheelie]

 

On 8/30/2022 at 2:36 PM, Murdomeek said:

you forgot the 3rd reason: over speeding

your batteries and electronics can be 100%, but they can't physically make the motor turn faster.  That is determined by the motor windings kv.

 

Of course there is beep warnings and tiltback like we do now, but there is nothing stopping an "uneducated" rider to power through those

If these ultra high power cells become a reality, we'd be using much higher voltages for a couple reasons.

Firstly, these cells would be capable of ultra fast charging (sub 5 minutes). This means we could use electric car chargers. To my knowledge they operate at no less than 200v, so that's the minimum voltage we'd use (perhaps up to around 400v). Imagine being able to charge in a minute or two!

The other reason for higher voltage is of course speed. It's never been tested, but I suspect there's a top speed limit caused by the wind force preventing you from leaning any harder. If that's the case, you could simply design the wheel with extra power beyond that point...

Wind resistance causes an 8x power increase every time you double the speed. So roughly speaking for an EUC: 1kW = 40km/h, 8kW = 80km/h, 64kW = 160km/h. EUC batteries put out roughly 1c sustained, so a 3 kWh battery = 3kW continuous. If these GMG batteries really provide 70x power density, that means a 3kWh battery = 210kW continuous. Even when splitting the the battery into two separate packs (105kW each), that's still well over the 64kW = 160km/h mark, which is probably near the top speed possible due to wind pressure.

 

On 8/30/2022 at 5:24 PM, VikB said:

You can also have an overheat situation that would take out both sides of the EUC even if you could split them into independent circuits that could support the whole wheel at high load.

You could add a 3rd unused set of electronics which would take over if both the working circuits failed, but of course you could have a switching failure or a failure in one of the components of the back up system.

So making a safety EUC less likely to cut out is possible, but there is no way to make one that cannot fail. If that's what you are after get an e-scooter, e-bike or e-skate. You can coast to a stop on all of those if the power system fails.  

If designed properly, parts like the controller shouldn't be overheating. If one does fail due to a manufacturing defect or aging after many years, this wouldn't happen to both at the same time. One side would fail, the other side would take over, and the wheel would notify you that you've lost redundancy. You'd then slow down to make it home and repair it.

The only possibility for catastrophic failure is if the motor windings or magnets overheated. The good thing is, this is basically never the cause of failure because the motor can simply be sized for the job. Sure we'd need bigger motors, but it shouldn't be a problem.

Edited August 17, 2023 by InfiniteWheelie

[VikB]

16 hours ago, InfiniteWheelie said:

If designed properly, parts like the controller shouldn't be overheating. If one does fail due to a manufacturing defect or aging after many years, this wouldn't happen to both at the same time. One side would fail, the other side would take over, and the wheel would notify you that you've lost redundancy. You'd then slow down to make it home and repair it.

 

We see electronic equipment failures around us all the time. You can reduce the likelihood of a failure, but you cannot eliminate it. The more redundancy you want to build in the more expensive it will be and people have to be willing to pay for that.

I worked at an aerospace composite manufacturing company. The cost for quality/reliability was very high. Will people pay that premium for a "safer" wheel? Maybe....maybe not. We'll see what happens.

[RagingGrandpa]

On 8/30/2022 at 12:09 PM, InfiniteWheelie said:

The first type of [crash] is due to overpowering.

Discussed in detail here:    

On 3/2/2022 at 2:06 PM, RagingGrandpa said:

" With today's EUC's, with a full battery, riding at high speeds 
(speeds when maximum possible motor current is limited by motor EMF, and not the controller's self-protection limits),
if a rider leans forward and the controller reaches 100% duty,
motor current (torque) cannot be increased,
because the voltage applied to the motor by the controller reaches the maximum voltage available,
and therefore self-balancing corrections are no longer possible,
and therefore the rider crashes."

To improve this overlean crash problem, there are many options available for consideration:

1. Decrease EMF.
   a. ... by changing the motor construction (It's why we install a C30 motor instead of C38, when maximum speed is desired), or
   b. ... by using field-weakening circuits (changes to the controller; higher heat dissipation and energy-inefficient to sustain; causes additional voltage sag when it activates).
    
2. Increase the input voltage. (It's why 100V EUC's are faster than 84V EUC's using identical motors.)
   a. ... by installing a higher-voltage pack, or
   b. ... by reducing voltage sag of the pack during load 
        1. ... by installing more cells in parallel (a much larger pack), or
        2. ... by using lower-resistance (high-drain) cells, or
   c. ... by installing a reserve energy supply (extra batteries or capacitors, as discussed in the posts above).
    
3. Increase the output voltage. 
   ... by using a boost converter at the input of the controller (large components added to the controller; higher heat dissipation and energy-inefficient to sustain).
    
4. (and perhaps additional ways you can suggest?)

The bold ones are techniques the EUC manufacturers have already used... the rest come with new challenges. 
And 2.b.2. is just now becoming an option, with eWheels, AlienRides, etc offering high-drain cell options in new EUC's. Those should be safer to ride fast (when fully charged, at least) than the standard cells.

These are the same answers to "how to increase the maximum speed of an EUC"... and are missing emphasis on avoiding the crash.
For avoiding crashes, we also need to answer "how best to alert the rider that an overlean crash is imminent?" 
Alarms that activate at the moment that control is lost, don't help. And alarms that attempt to predict a future event (overlean) are often perceived as a nuisance.
Tiltback at the moment of overlean is only possible by using 1.b., 2.c., and 3. (the methods nobody uses yet).

So, room for improvement  

 

On 8/30/2022 at 12:09 PM, InfiniteWheelie said:

The second type [of crash] is due to [component] failure.

It's just not practical to cover all types of failure. 
For example, shorted windings in the motor (e.g.: due to overheating and insulation failure) won't just cause the motor to stop making torque... they'll cause braking. To overcome it, your "second motor" would need to provide torque to sustain self-balancing, plus extra torque to overcome the drag from the failed motor. It is exceptionally severe if motor phase wires are shorted to eachother: a massive amount of braking occurs. 
And of course, broken mechanical components could always result in crashes that no electrical system could prevent (e.g.: jammed tire, broken axle, shattered rim, etc).
 

On 8/30/2022 at 12:09 PM, InfiniteWheelie said:

I think cutout-proof wheels are possible

I don't 
#ATGATT

 

Edited September 1, 2022 by RagingGrandpa

[yoos]

No vehicle is absolutely safe, bicycles, cars, planes also fail from time to time. If you go max speed in a car you are also guaranteed to crash albeit for different reasons than the EUC. Part of the EUC problem is educating riders about how self-balancing works and how it can always be overpowered at high enough speed. Of course eventually the fastest EUCs will be so fast that you will crash the traditional before you get a chance to overpower it: by losing traction, hitting something, wobbling, or being blown off by the turbulent airflow. However such powerful EUCs would be too heavy, expensive, impractical for 99% people. 

A healthy demand is that cutouts due to electronic failures should become much less frequent than cutouts/overpowers caused by rider error (ignoring speed beeps, power safety margin beeps, overheat beeps, error beeps etc). Professional riders participating in races and other challenges should have the option to turn off tiltback (and thus perhaps waive their warranty rights) but generally EUCs should have alarms and tilltback annoying enough to fully inform the general rider about nearing cutout danger zone. 

[GothamMike]

Begode Boiz want to go faster than the others, they will hack software, replace boards, sensors, and chips.

Even if manufacturers get better at BMS and severely tilt-back a battery on the very razor's edge of cut-out, word will spread it is a "lame wheel"

[yoos]

7 hours ago, GothamMike said:

Begode Boiz want to go faster than the others, they will hack software, replace boards, sensors, and chips.

Even if manufacturers get better at BMS and severely tilt-back a battery on the very razor's edge of cut-out, word will spread it is a "lame wheel"

Well, let them do their thing  while manufacturers should do theirs and fix the sadly abundant low-speed cutoff scenarios. Once this is done, we just have to make the casual ridership, general public and legislators that cutout events are not an incontrollable omnipresent danger but rather rider error in 99+% cases (and not somewhere between 60% and 90% like it might seem today ) 

Edited September 2, 2022 by yoos

[InfiniteWheelie]

It's just annoying having to constantly monitor your acceleration and speed to avoid cutouts. If extreme power density cells become a reality, this could become a thing of the past. Where no matter how hard you lean or how fast you attempt to go, you won't overpower the wheel. You could just focus on actually riding instead.

Anyway I don't see why we can't have total redundancy in the electronics. Sure the motor could short but that's extremely unlikely unless the motor melts from extreme overheating or something. The redundancy part could basically be done now, even with current battery tech. Tesla's self driving cars have totally redundant chips, and you're in a metal cage with airbags. I think it's just as important for us riding unprotected on a self balancing single wheel.

Edited August 17, 2023 by InfiniteWheelie

[Eucner]

52 minutes ago, InfiniteWheelie said:

Where not matter how hard you lean or how fast you attempt to go, you won't overpower the wheel.

That would be possible with practical, moderate lean angles. At the extreme lean angles power need approaches infinite.

52 minutes ago, InfiniteWheelie said:

Sure the motor could short but that's extremely unlikely unless the motor melts from extreme overheating or something.

Stuck bearings, shorted MOSFET's and ripped off phase wires seems to be a current trend. It is very hard to build redundancy for those. EUC manufacturer's should use more experienced engineers and better QC.

[MetricUSA]

Pretty much any wheel if you ride below class 3 Ebike speeds w/proper battery charge level...and avoid stupid acceleration movements... 

Edited September 4, 2022 by MetricUSA

[InfiniteWheelie]

I think even the motors could made electrically redundant by using 6 phases (dual 3 phase).

Edited August 17, 2023 by InfiniteWheelie

[Roadpower]

This seems like a non issue if people just abide by the safety margins. We already know by famous Youtuber examples that constantly pushing a wheel near the ceiling limits is begging to get stung. On my V11 there is a option to unlock the wheel for three extra MPH, did I do that? No, no I didn't. Why? Because I adore a beefy overhead margin, that's why.

[InfiniteWheelie]

That doesn't stop equipment failure though.