Motor Current Limiting: More Power and Less Heat!!!

[safe]

Maybe this way the bad rider could learn faster but i dont think you looking for solutions for teaching so much lazy riders.

Discipline is always hard.

People are by nature lazy and prefer to have things done for them. But in high performance racing situations it's the rider that is expected to get the MOST out of the motor. If the "goal" is "perfection" then the elimination of areas of obvious "imperfection" can only help to point the rider towards the right behavior.

At first it might make the existing electric bike rider uncomfortable. All of a sudden the motor that had this vague and wide powerband will show a very strong burst of power in one area and very little power elsewhere. The lazy and uneducated rider will say:

"This bike has no power... and is weird..."

...but once they realize that they have to hit the powerband and shift to stay in the powerband then it will all begin to make sense.

THINK how a racing motorcycle sounds when it's screaming through the gears accelerating at full speed:

Brrrrrrraaaaahhhhhh, aaaaahhhhhh, aaaaaahhhhhhh....

(and then the downshifts)

Dot, dot, dot...

You know by sound what they are doing... (have you been to the racetrack before?)

Let's also remember that the top speed on the "Motor Current Limited" bike is about 3 mph faster than the standard version and the "real world" average heat is about the same. Even the acceleration to top speed is very similiar and the edge is really only to the standard bike from 0-10 mph after which the "Motor Current Limited" is better.

 

[eP]

Maybe this way the bad rider could learn faster but i dont think you looking for solutions for teaching so much lazy riders.

Discipline is always hard.

People are by nature lazy and prefer to have things done for them. But in high performance racing situations it's the rider that is expected to get the MOST out of the motor. If the "goal" is "perfection" then the elimination of areas of obvious "imperfection" can only help to point the rider towards the right behavior.


...but once they realize that they have to hit the powerband and shift to stay in the powerband then it will all begin to make sense.

Once they realize when they have change the gears they won't need this type controller.

THINK how a racing motorcycle sounds
...
You know by sound what they are doing... (have you been to the racetrack before?)

You cannot compare 1-2kW crippled motor (by limited current) to multi kW ICE racing machines.

Try to simulate what happend when you cut off the current without any warning.
How much you will have to waste more for the sake of slow acceleration from low speed.

Yours time to speed comparision is useless as you dont know how much time rider will loss for deep gear change and how long time he need accelerate to regain the speed.


How do you think how many people will want controller( for cripling motor's performance ) for one week or two when they will be learning how change the gears ?

For normal riding it is useless in my opinion -the same way as any other forms of unpleasant limits.

 

[safe]

How do you think how many people will want controller( for cripling motor's performance ) for one week or two when they will be learning how change the gears ?

Ah, but you've forgotten the other half of this trick.

First you CUT the amps in the low rpms and then you ADD amps to the peak power rpms.

So from the very beginning you actually are getting MORE peak power than if you were running the standard controller.

It demands DISCIPLINE to get the most out of the motor, but you do get more and WITHOUT creating so much heat that the motor has problems.

So the discipline might seem "weird" at first, but once you get used to the idea of a "peak" in your powerband then you will begin to like it.

Motorcycles have had "constant torque" and "peaky" powerbands in their race bikes for years.

Have you ever ridden a fast "peaky" motorcycle?

If you have no experience with race bikes how would you have the ability to comment about race bikes? (on what experiences are you making your comments?)

 

[eP]

How do you think how many people will want controller( for cripling motor's performance ) for one week or two when they will be learning how change the gears ?

Ah, but you've forgotten the other half of this trick.

First you CUT the amps in the low rpms and then you ADD amps to the peak power rpms.

So from the very beginning you actually are getting MORE peak power than if you were running the standard controller.

NO NO NO !!!

A few more amps cannot help the rider to avoid deep gear change.

Only the early warning could help for smooth gear change. And help to avoid high speed/power (for the time the rider need to get the bottom gear) drop.

Extra amps at most cases only will fooled the rider as the power drop will occur a sligtly later.
This way driver lost more time as he will start to go to right gear more later. He will be more late this way.

The extra amps will be useful only when you use the full power and his needs for extra torque rising slowly for small amount of extra torque.
This way he could avoid the gear change.
It is a rare situation and the driver have a lot of time to switch the gear if he will need.

When the light slope at flat occur the need for torque will rise dramatically, so the extra amps of limit will be useless especially when the driver is riding at low power at the moment.
And at flat extra amps will allow to tolerate the riding at unefficient gear as the higher current limit will not be reached.
So this way controller for long time will tollerate riding at bad gear and when the spike of torque occur will be punish the rider.
It is not good way of teaching the right riders behavior.

 

[safe]

The extra amps will be useful only when you use the full power and his needs for extra torque rising slowly for small amount of extra torque.

But gears allow you to use the full power all the time.

That's the whole point of gears.

Look at the chart... study it carefully... everyone else has already "got it" and you seem to be having some sort of intellectual block where you can't seem to understand.

Remember:

The "Motor Current Limited" bike is using 50 Amps for the maximum.

The "Battery Current Limited" bike is using 40 Amps for the maximum on the battery side, but that varies on the motor side (it's larger at lower rpms which creates lot's of heat)... we've been calling this "current multiplication", but it might go by other names.

The heat "on average" (across the usable powerband) is the same.

 

[eP]

The extra amps will be useful only when you use the full power and his needs for extra torque rising slowly for small amount of extra torque.

But gears allow you to use the full power all the time.

That's the whole point of gears.

I don't deny.
But you should keep in mind the average rider most of the time will use only small fraction of the allowed power.

Look at the chart... study it carefully... everyone else has already "got it" and you seem to be having some sort of intellectual block where you can't seem to understand.

I only show to you what weak sides have yours simple
"blind" motor limited controller.

Remember:
1) Bad riders behaviour will not be punished instantaneous ( until the limit will be reached ), so if the limit is high it is highly probable the bad behaviour will be tolerable most of the time.

2) The lower riders speed the more painful punishment is possible - so riders will be teached racing behaviours (WOT at most of the time and keep speed to the max.)
At public roads it is very bad and dangerous behavior. The public street is not a motodrome.

So if it isn't a general use controller - for novice racers i could admit it could be useful for a moment (maybe few days ).
But for general use it is completely useless and what is worse it is a tool for implementig bad behaviours ( all the time speed and power to max. )

Show me if i'm wrong. But i still see the "blind" controller is at the best case not useful (at flat when you have a high speed and you get the enough power before you reach current limit - and even you reach the current limit yours rpms are close to the limit, so you still have a fair efficiency).

The high torque needs occur if you have low speed (low kinetic energy margin ) and the light or moderate slope occur. At that case if you don't get enough torque instantaneous the painful drop in speed occur.
So the smart controller should early recognize that case and give to the rider early warning and temporary void the motor limit (temporary unlimited or battery limited).
At the other side smart controller should recognize low rpms at high gears and early warning the rider to change the gear down (to boost rpms and efficiency) and the punish the rider at lower current limit if he will ignore the warning signals.

So in my opinion motor current limited is not a bad idea - it is briliant idea but it need a very smart controller to be right implemented.

A "blind" implementation is a bad idea -very narrow usefulness in my opinion (only for novice racers).

Your 50A Motor vs 40A Battery Limited.gif show us only static motor's characteristics.
The point at where you are at the moment (at those characteristic) is moving dynimically. So at "blind" current limited - rider can be punished and move to unefficiency region very quickly (lost of torque until he get the bottom gear)

 

[safe]

The high torque needs occur if you have low speed (low kinetic energy margin ) and the light or moderate slope occur. At that case if you don't get enough torque instantaneous the painful drop in speed occur.
So the smart controller should early recognize that case and give to the rider early warning and temporary void the motor limit (temporary unlimited or battery limited).
At the other side smart controller should recognize low rpms at high gears and early warning the rider to change the gear down (to boost rpms and efficiency) and the punish the rider at lower current limit if he will ignore the warning signals.

But you're not understanding my intentions it seems.

I WANT to have the rider be "forced" to pay attention.
I WANT the rider to be in the "habit" of going fast.
I WANT to "punish" stupid gear choices.

The bike you describe is "nice" and typical of how things are done right now but it's not a race machine. I'm seeking "behavior modication" from "pleasant and easy going" riding into the type of "adrenaline fueled frenzy" that racing is about. Electric bikes have been "boring" for too long, it's time to give them some sex appeal and speed.

We are talking about "race track" style performance here!

Now...

Since you now understand the "goals" do you agree that if you are in line with the "goals" set forth that this system is a very good idea?

 

[xyster]

I WANT to have the rider be "forced" to pay attention.
I WANT the rider to be in the "habit" of going fast.
I WANT to "punish" stupid gear choices.

Then rig electrodes to the seat or handlebars to jolt the rider whenever he or she nods-off, goes too slow, or chooses a less-than-optimal gear. :?

 

[safe]

Then rig electrodes to the seat or handlebars to jolt the rider whenever he or she nods-off, goes too slow, or chooses a less-than-optimal gear. :?

Lights, ammeters, electrodes... those will all work.

The good "old fashioned" approach tested and proven on racetracks around the world for decades is the good old "peaky powerband". It's been a mainstay of gasoline motors forever, so why would there be any objection to transferring that wisdom to the electric bike world?

It "seems" like a match made in heaven... gears and a peaky powerband on an electric bike...

Can you imagine a customer talking about a road racer motorcycle purchase:

Customer: "I like how this bike looks, but the powerband is so peaky, could you fix that?"

Salesperson: "Fix it, what do you mean?"

Customer: "Well I want to cruise on the freeways and don't want to have to think about what rpm I'm in all the time."

Salesperson: "I think you need to buy our 'Electroglide Special' with cruise control instead..."

 

[eP]

But you're not understanding my intentions it seems.

I WANT to have the rider be "forced" to pay attention.
I WANT the rider to be in the "habit" of going fast.
I WANT to "punish" stupid gear choices.

Pay attention for what ?
Yours "blind" controller will not give any signal at right moment which could be received by the rider.

The only "signal" it will give is a late cut off the power. So it is not a desirable signal by the rider.
He/she will be forced this way to WOT and not pay attention at all, as this way the power cut off (and fast speed drop ) will not occur (at high speed).

You want BAD habit to implement.
We dont talk about solar car controller (very low air drag), we are talking about bike controller (high air drag), so the habit of going fast is very unefficient riding habit (a lot of enery is wasted for the air drag).

You will not punish the stupid gear choices as the rider will be forced to use the top gear (afer he reach a high speed ).
In fact he will be forced to stupid deep gear reductions (by your "blind" controller) if the power cut occur.
After that he/she get the slow acceleration.

The bike you describe is "nice" and typical of how things are done right now but it's not a race machine. I'm seeking "behavior modication" from "pleasant and easy going" riding into the type of "adrenaline fueled frenzy" that racing is about. Electric bikes have been "boring" for too long, it's time to give them some sex appeal and speed.

I dont think so the slow acceleration is so sexy.
Yes -the adrenaline limit could rise to highest level when rider start to think what at f**ed idiot designed such cripled bike which is unable to accelerate at the right moment.

We are talking about "race track" style performance here!

Now...

Since you now understand the "goals" do you agree that if you are in line with the "goals" set forth that this system is a very good idea?

A "blind" controller is definitely a not good idea even for the racing purposes.( It could be useable as it force the rider to keep as high speed as possible to avoid the - lack of torque / slow acceleration - punishment )

 

[Lowell]

Whiskey Tango Foxtrot.

Motor current limiting is not a difficult concept, and combined with gears it will work very nicely to maximise the performance envelope. It may not be for everyone, but the theory is sound.

 

[eP]

Whiskey Tango Foxtrot.

Motor current limiting is not a difficult concept, and combined with gears it will work very nicely to maximise the performance envelope. It may not be for everyone, but the theory is sound.

In which way "blind" controller can maximise your performance if it is able only to punish you ? (No early warnning signals)

And what is also very bad it is able to tolerate unefficient riding until you dont reach high current limit - so at flat you are permised to riding unefficient, but still you have cripled torque/acceleration ability.

As to efficiency:

watt hours per mile on an electric bike is like gallons per mile in a car. The smaller the number, the more efficient your bike is. Also like a car, your efficiency is affected by speed. The faster you go, the less efficient you are. I'm getting around 24 watt hrs/mile at around 20+ miles per hour.

http://endless-sphere.com/forums/viewtopic.php?p=15900#15900
so forcing to higher speed is first of all energy inefficient.

 

[Lowell]

This thread is about 'more power and less heat' which motor current limiting does both of. Any more questions?

 

[eP]

This thread is about 'more power and less heat' which motor current limiting does both of. Any more questions?

So when the "blind" controller allow for less heat ?

The ansewr is: only when is punish you.
So you never get more power and less heat at the same moment.

Exactly the same you can say about battery limited controller: more power and torque and less heat ( as it has lower battery current limit).
But at this case it is true as you get more power when you really need it (for smooth acceleration), and less heat at higher rpms as current limit is set lower.

So the rider is not punished at all. If he/she has good habits than she/he can riding more efficiently as will be not punished at extereme load conditions.

You cannot to say the same for the "blind" controller.

Have you any reasonable to say ?

 

[safe]

Motor current limiting is not a difficult concept, and combined with gears it will work very nicely to maximise the performance envelope. It may not be for everyone, but the theory is sound.

eP is a strange fellow that's for sure. He's never actually ridden or built anything "real" and yet he posts here as if he was an expert. Thanks for the comment.

 

[safe]

Study, study, study until it makes sense eP... everyone else "gets it" but you...

 

[TylerDurden]

eP is a strange fellow that's for sure. He's never actually ridden or built anything "real" and yet he posts here as if he was an expert.

The only thing safe has built is illegal in 49 states and useless for everything but burning up unite motors.

 

[eP]

Study, study, study until it makes sense eP... everyone else "gets it" but you...

I have one idea

Give us an example when the bad/novice rider will be punished by your "blind" controller.

Lets assume the slope (could be 0% if you need ), lets assume the speed (at begin), rpm, gear (could be the top gear as the worst case ), acceleration, total mass and we see the needed current.

If you set up high limit the punishment occur at rider's great gear miss so it occur very rare and will be almost quite useless.
If you set up limit to low motor will be totally cripled.

So show us the case (for the limit) when the punishment will be useful/needed before motor will be highly cripled.

For fixed "blind" controller it is hard or impossible to find nice setup.
For smart flexible controller it is quite easy as you can set up different limits for different cases which the smart controller is able to recognize.

"Blind" controller is able to recognize only the motor current - nothing else i see - this way at most cases will be cripling the performance instead helping i suppose.

Show us (me) the case that i'm wrong.

The synthetic chart is not a real case.

Regards

 

[safe]

The End

Okay, let's end this thread with the idea that if you don't want to do this idea then don't do it.

The idea is presented as an "option" for those with gears and is the same idea that racers use.

Thanks all...

 

[eP]

The End

Okay, let's end this thread with the idea that if you don't want to do this idea then don't do it.

The idea is presented as an "option" for those with gears and is the same idea that racers use.

Thanks all...

If You are feel like an expert, so why you don't want show us one case.
So then we could see how good/needed option you offer to us.

Don't give up Mate.

TD

Nice commented picture. :wink:
I see i'm not alone in my doubts.

 

[TylerDurden]

Okay, let's end this thread with the idea that if you don't want to do this idea then don't do it.

Not the End

Isn't it funny how some people leave the room when the questions get too difficult?

(Tooo bad they can't make a genius-proof forum.)

Motor-side current limiting is a fine idea, if it employs feedback to regulate the limits. Just like battery-side current limiting, blind control comes with risks & sacrifices.

 

[safe]

Motor-side current limiting is a fine idea, if it employs feedback to regulate the limits. Just like battery-side current limiting, blind control comes with risks & sacrifices.

Wow, you guys simply don't want to let it rest do you?

Okay, let's try this again...

Let's get back to what is really being presented here:

1. This is ONLY for a geared bike - I can't stress this enough. For a hub motor user this idea would make things WORSE and you should never do this. If for some reason you are fixated on hub motors as the "best solution" in all cases then this will ruffle your feathers and get you all upset. If you are "obsessed" with hub motors then simply ignore this thread.

2. More power - The "more power" part is easy. The standard solution uses one current limit and the new idea uses a higher limit. More current gives more torque. Case closed.

3. Less heat - The new idea is to be more strict with current at low rpms compared to the standard controller. Since low rpms can have very high current you get a lot of heat from those rpms. It's central to be able to comprehend the difference between torque and power. If you can't understand that it's power that is the "true output" and not torque alone then you will forever be lost. Low rpm torque in a standard controller doesn't actually produce that much power... but it does produce heat. So the "big idea" is to restrict the low rpms so that the rider doesn't get caught in the mistake of using it. The "real world" average of heat over the usable powerband will be about the same with either system.

All the "smart guys" like Lowell and Fechter have approved the idea and agree that what I've proposed is 100% correct.

I know it's going to be hard for you guys to admit you are wrong, but well... you guys are wrong.

"Motor Current Limiting" is a "perfect match" for a geared bike...

 

[safe]

Understanding Torque and Power

Being able to comprehend the difference between torque and power is so central to understanding how a motor works that I feel it's necessary to review this again with a new chart for clarity.

Power is what actually gets to the rear wheel.
The gearing determines WHICH part of the powerband is APPLIED as power.

Repeat:

YOU CAN ALWAYS BE NEAR THE PEAK POWER IF YOU USE GEARS!!!

Until that thought gets through your mind you will never understand power as it relates to a geared bike.

Okay... now hopefully that "stuck" in your mind. Let's look at the chart. We see on the left that the "Battery Current Limited" seems to have lot's of torque in the lower parts of the powerband but it does NOT have all that much POWER.

See that?

On the right side the "Motor Current Limited" bike doesn't have that much torque at low rpms, but it clearly produces more top end power. As long as you shift to "stay in the powerband" you will always get more power with "Motor Current Limiting".

Anyone who has ridden a race motorcycle with a peaky powerband knows this as a fact...

"Hopefully" this will put the thread to rest (I have my doubts) and we can simply accept that for gears "Motor Current Limiting" is the preferred option...

"Motor Current Limiting" - 50 Amps

"Battery Current Limiting" - 40 Amps (more due to "current multiplication" at low rpms)

Power is in Watts.

Torque is in Newton/Meters and is times 100.

 

[eP]

Motor-side current limiting is a fine idea, if it employs feedback to regulate the limits. Just like battery-side current limiting, blind control comes with risks & sacrifices.

Wow, you guys simply don't want to let it rest do you?

Okay, let's try this again...

Let's get back to what is really being presented here:

1. This is ONLY for a geared bike - I can't stress this enough. For a hub motor user this idea would make things WORSE and you should never do this. If for some reason you are fixated on hub motors as the "best solution" in all cases then this will ruffle your feathers and get you all upset. If you are "obsessed" with hub motors then simply ignore this thread.

ad 1. OK. I'm not obsessed - i like both in fact.

ad 2&3. We want a REAL case not a synthethic demagogy.

So give us a one REAL case. Lets assume a power to ground, total mass, etc.
And we will see how frequently we will be punished or how much we could gain at this specific case.
So we will see it is option for us or maybe for someone else.

One case please !!

 

[safe]

One case please !!

I posted this a short time ago.

This is a case of a simulation of "Motor Current Limiting" vs "Battery Current Limiting" for two otherwise identical bikes accelerating from zero to top speed.

The "Motor Current Limiting" bike is slower for the first 10 mph, but reaches it's top speed faster and has a higher top speed by about 3 mph. So in a "race" situation the "Motor Current Limiting" is definitely faster.

At speeds below 10 mph the "Battery Current Limiting" bike is faster.

At speeds from 10 mph to 50 mph the "Motor Current Limiting" bike is faster.

My "average" speed on my rides right now are around 22 mph (38 mph on flat, 50 mph down a hill) on my present bike, so most of the time this idea would prove to be faster than a regular controller in "real life" conditions.

If you are looking for some "product" you might find one somewhere (Fechter claims he knew of one) but I don't know of anyone currently manufacturing this idea yet. It's so closely tied to geared bikes that it's a vary specific market and not likely something you could buy right now. (assuming that was what you were asking about)

However, Lowell claims that the newest DrainBrain product may incorporate this into their new release.