Human Powered Electromotive

[Gavilan]

I want to see a Power Averaged, Regenerative Capable, Human Powered Electromotive Power Process applied to small scale freight and human transportation.

I began my study of hybrid power processing as an Individual Studies Project at the University of Northern Iowa in 1978. It was titled - "Flywheel Storage and Regenerative Braking as Applied to Wheeled Vehicle Transportation Processes."

As I continue to study I have scaled the conceptualized power processing technique from a Diesel/Electric Railway Switching Slug, to an automobile, and now to a Human Powered Electromotive using low voltage capacitive storage. The storage technologies studied include mechanical, electro-chemical, and hydraulic.

The simple power processing technique uses circuit reactance as the control for infinitely variable torque demand on the prime mover (human) and the wheel/road interface, within the limits of prime mover power and wheel/road adhesion; in both braking and acceleration.

This process eliminates mechanical linkage, it allows for power averaged input over the entire trip cycle, and enables super high performance by providing peak power assist.

I am now focusing on a Human Powered Electromotive because it is both functional and eloquent; with the potential to improve the human and natural condition.

Having completed the conceptual circuit design I wanted to consider the advantage of moving the mechanical impulse from the axel to the wheel rim. This is for the purpose of optimizing the torque to ampere ratio and therefore keeping the power and braking circuit voltage as low as possible.

Would it be possible to keep close enough tolerance between a frame mounted stator and a wheel rim rotor to produce effective electro-magnetic interaction for both motoring and braking?

If not the process would still be applicable to axel mounted motors.

Would anyone like to discuss how a poor self educated old man might see fruition?

Gavilan

 

[liveforphysics]

Every direct drive ebike hub is also acting as a generator as it turns. The separation between motor/generator is merely if you happen to be feeding it power or drawing power form it's rotors induced changing magnetic fields creating back-electromotive-force in the windings.

Your objective is quite simple to achieve, buy/build essentially any direct drive brushless ebike with regen (a standard controller function), add a battery and you're set.

 

[Punx0r]

Wheel rim as rotor with frame-mounted stator has been suggested many times but is unlikely to be successfully implemented any time soon. Maintaining an appropriate air gap considering the relative flexibility of a bicycle wheel and it's normal run-out would be difficult. The air-gap would also be open to all weather and road debris.

Regarding replacing a mechanical drive-train with pedal-mounted generator and wheel-mounted motor, this is complete non-starter. Overall system efficiency is likely to be around 50% compared to up to 98% for a well-maintained chain. No cyclist will thank you for turning half of their pedal effort into waste heat.

 

[Drunkskunk]

as Punx0r points out, the human power to motor driver is an old idea that doesn't work. any time you convert one form of power to another, you get a loss. human mechanical to electrical at the generator, then transmitted to the drive motor, then electrical back to mechanical in the drive wheel will have a huge loss. with a 50% loss, it would take 2 people to do the work of one with a good chain drive. Also, since you seem to be planning this to optimize torque, your efficacy will be worse. while you would have huge torque available, it comes from a point in the motor's operation where it is least efficient, so your human power to torque conversion would be abysmally inefficient compared to a person driving a chain drive with super low gearing.


The rim motor idea is interesting, but has been discussed before, and has some issues. If you follow the though process far enough, it leads someplace interesting, however. First, a bike rim is made to flex, so you'll never get the air gap right. The air gap needs to be maintained at fractions of a millimeter. You can cure that by making the rim very stiff, but that makes it very heavy and needs massive spokes to keep it rigid. Second, it also leaves the magnets exposed to metallic road debris, that can be picked up and jam against the stator on the frame. the cure for that is to move the stator to the axle, and replace the spokes with hard covers that go around the outside of the stator, and keep the wheel stiff and the magnets inside.

And that leads to the interesting part. once you move the motor's poles out to the wheel, you find that the wheel size is no longer relevant. If you have 2 inches of tire per pole (random example. totaly made up number), as long as you maintain the distance between the pole and the tire tread, that will stay the same even if you shrink the wheel and ditch half the polls. As long as you maintain that 2 inches of tire per poll ratio, the power torque and speed will stay the same regardless of the wheel size. Each poll moves the bike 2 inches.

And those wheels already exist. There are plenty of scooter and motorcycle wheels out there which are essentially a rim wrapped around a large diameter hub motor.

 

[Toorbough ULL-Zeveigh]

lmgt 4u

RIM JOB

http://endless-sphere.com/forums/viewtopic.php?f=2&t=9966

http://endless-sphere.com/forums/viewtopic.php?f=3&t=61795&start=50

Wissler also described how a particular engineering challenge with this kind of system is the air gap, between the wheel magnets and inductive coil in the frame. Wissler suggested that if the air gap could be closed to “1mm we could increase the efficiency of the bike to over 1000W, but at the moment it is hard, because of wheel rub.”

http://www.cyclingweekly.co.uk/news/product-news/this-electromagnetic-hidden-motor-bike-can-go-100kph-211660#uDvDRiLKO6Rztw01.99

STATORade (c)

“A motor hidden in the seat tube is old stuff, almost artisan. It’s been overtaken, it’s a poor man’s doping,” Ghisalberti writes. “The new frontier is far more technologically advanced and ten times as expensive. It’s in the rear wheel: it costs 200,000 Euros, and there’s a waiting list of six months.


http://www.cyclingnews.com/news/electromagnetic-wheels-are-the-new-frontier-of-mechanical-doping-claims-gazzetta-dello-sport/

"I sat at a meeting with the UCI last year and drew on the blackboard exactly how this might work," Boardman told the Telegraph. "I showed them some of the sophisticated boosting technology now available, mainly from F1 teams, that can get a kilowatt out of a single AAA battery."

http://www.cyclingnews.com/news/boardman-warned-the-uci-of-risks-of-bike-doping/

wheel motor instead of hub motor - http://endless-sphere.com/forums/viewtopic.php?f=2&t=4902
magnetic wheel - http://endless-sphere.com/forums/viewtopic.php?f=2&t=6001


POWER AVERAGING aka LOAD REGULATOR

eCVT - http://endless-sphere.com/forums/viewtopic.php?f=28&t=10998
cvt from 2 bldc - http://endless-sphere.com/forums/viewtopic.php?f=2&t=15618
field weakening vs gear box vs higher voltage - http://endless-sphere.com/forums/viewtopic.php?f=30&t=63467

Pininfarina ebike - http://endless-sphere.com/forums/viewtopic.php?f=3&t=60945
http://m.youtube.com/results?q=zehus&sm=3
[youtube]VD0dW01-5pw[/youtube]
[youtube]Sx9Dc9ONt_E[/youtube]


GENNYBYKE

With a permanent magnet generator, if you get the voltage constant of the generator matched to the batteries the cadence will be neary constant over a wide range of power.

bicycle powered generator - http://endless-sphere.com/forums/viewtopic.php?f=41&t=26117

Chain driven bike with 100W input to the pedals will deliver around 97W to 99W to the rear wheel and waste around 1% to 3% of the rider power as heat.Pedal generator/motor driven bike with 100W input to the pedals will deliver around 72W to the rear wheel and will waste about 28W as heat.

generating electricity - http://endless-sphere.com/forums/viewtopic.php?f=1&t=22370

[youtube]fA_sZO8QWiE[/youtube]
http://bike2.dk/wp03/specifications/

mmmmMANDO-O-O-O!

http://newatlas.com/mando-footloose-ebike-alternator/24330
http://newatlas.com/mando-footloose-26-inch-wheels/39460
http://endless-sphere.com/forums/viewtopic.php?f=3&t=42538&p=621858
http://endless-sphere.com/forums/viewtopic.php?f=3&t=70424
http://endless-sphere.com/forums/viewtopic.php?f=3&t=81004
http://bicycledesign.net/2015/05/mando-footloose-im-by-mark-sanders/
http://www.mandofootloose.com/en/pages/01about/brandinfo.jsp
http://m.youtube.com/channel/UCH-7xXjNdZBDIyg-gXZ_t7g

 

[Gavilan]

It is a simple Series Hybrid.

First I want to thank everyone for their patience and feedback as I develop my understanding.

The picture provided by Toorbough is exactly how I would imagine a wheel rim magnetic rotor!!! Do you have anything else to peruse in that specific regard?

The remarks by Drunkskunk shines the light on primary variables that determine practical application.

"---any time you convert one form of power to another, you get a loss. human mechanical to electrical at the generator, then transmitted to the drive motor, then electrical back to mechanical in the drive wheel will have a huge loss. with a 50% loss, it would take 2 people to do the work of one with a good chain drive." ----

The crank IS the generator. It is agreed that the input efficiency of an electromotive will be somewhat lower than a well maintained chain and sprocket; but not nearly as low as the 50% projected by DS. The net efficiency factor can be estimated by multiplying the efficiency factors of conversion. I believe for mechanical to electrical and vice versa these efficiencies can approach 90 percent. An example would be two conversions at 90 percent would approximate .9 *.9 = .81 or about 81 percent. I do not believe the efficiencies will vary much between motoring and braking.

“Also, since you seem to be planning this to optimize torque, your efficacy will be worse, while you would have huge torque available, it comes from a point in the motor's operation where it is least efficient, so your human power to torque conversion would be abysmally inefficient compared to a person driving a chain drive with super low gearing."

I struggle with the reasoning here, especially that part that states - “it comes from the motor’s operation where it is least efficient.” Is this because of pulse width modulation? Reactive control does not use pulse width modulation and would have a very high and flat efficiency curve compared to pulse width modulation.

The efficiencies to be gained by an electromotive power process are a result of processing the throughput energy. For freight and passenger Pedi-cabs within cities, the transportation power cycle is highly variable with many stop and go cycles in any given trip. In hilly terrain this variability is increased. This puts highly variable demand on the prime mover when that demand is met real time. By averaging the input power over a greater part of the trip and providing peak power assist the maximum power requirements of the prime mover can be greatly reduced, while increasing grade and acceleration performance. This could be very meaningful to both a recreational bicyclist and Pedi-cab driver propelling 100 to 200 kilograms of freight or passengers.

I think it is important to understand the relationship of regenerated energy to prime mover efficiency. This is often very difficult for some people to grasp.

Let us agree that the work to input energy ratio = efficiency factor. Let us assume that the prime mover under consideration has a work to input energy ratio of .25. That is, 25 percent. This level of efficiency means that for each unit of applied work 4 units of input energy is expended. Conversely, in a prime mover powered system with an efficiency factor of .25, each unit of energy regenerated reduces prime mover consumption by 4 units. This is NOT over unity. It is simply the relationship of regenerative braking to prime mover efficiency where Energy Saved would approximate Energy Regenerated / P.M. Efficiency Factor.

“The rim motor idea is interesting, but has been discussed before, and has some issues. If you follow the though process far enough, it leads someplace interesting, however. First, a bike rim is made to flex, so you'll never get the air gap right. The air gap needs to be maintained at fractions of a millimeter. You can cure that by making the rim very stiff, but that makes it very heavy and needs massive spokes to keep it rigid. Second, it also leaves the magnets exposed to metallic road debris, that can be picked up and jam against the stator on the frame. the cure for that is to move the stator to the axle, and replace the spokes with hard covers that go around the outside of the stator, and keep the wheel stiff and the magnets inside.”

Rotor/stator tolerance would indeed be a challenge; but given the rapid development of material science it cannot be considered a forgone conclusion.

The magnetic attraction of ferromagnetic material to the rim was a very enlightening point for me; but considering that ferromagnetic material would first have to be suspended in the air before becoming magnetically attached to the rotor makes me wonder why this is a concern.

 

[liveforphysics]

When you install a direct drive Ebike motor, your feet turning does turn the generator, as well as reducing power that would have been drawn from the battery by a greater amount than would be possible of you were pedaling a second generator which would add it's own mass and losses (~15-20%), then store it in the battery to again have losses when you go to use it of (~15-20%). This series losses spread would mean only (~72-64%) possible conversion, and that assumes no battery impedance sag during charge and discharge that it avoided which realistically may place it as low as ~50-60% useful contribution of your pedaling effort.

Pedaling the direct drive hub gives you ~97-98% of your pedaling effort, has less mass, less moving parts, less complexity, reduced failure modes.

That said, series hybrid can offer a unique flexibility in when you spend your human effort that has appeal for various applications (like a pedal-cab pedaling while stationery waiting for clients to recharge).

 

[major]

A few years ago a fellow posted his human hybrid vehicle on the diy forum. His idea was to sit in/on the vehicle stationary for a while before traveling in/on it and pedal to charge the battery. While in use it would rely on human power, battery and regeneration. I think I finally got thru to him when I showed him the calculation. At my utility cost, he'd have to pedal hard for an hour to put one cent of electricity into his battery. If he was willing to work for those wages, my house needed painted.

Point is: human powered electric generation isn't a sensible proposition. Whether stationary or riding the bike, don't pedal to generate electricity; pedal for propulsion. If you're going to carry a battery and use electric propulsion, charge the battery off the grid or other sensible power source like PV.

I have a difficult time following your regen logic. And efficiency is well defined as power out / power in. Looked as though you were making up your own definition. As for poor efficiency at low speed, zero speed is zero power out so efficiency is always zero when you start from stand still. Can't get around that fact. And at zero + mph (just as motion begins), the low speed will mean low power output and fixed system loss will translate to poor efficiency. However it isn't as bad as it sounds because power is low, so even though efficiency sucks, losses aren't terrible.

Anyway, not sure the case can be made for a human/electric series hybrid. What's wrong with the plug-in parallel hybrid approach?

major

 

[amberwolf]

Just some practical on-road stuff that you might have to ponder ways around:

The magnetic attraction of ferromagnetic material to the rim was a very enlightening point for me; but considering that ferromagnetic material would first have to be suspended in the air before becoming magnetically attached to the rotor makes me wonder why this is a concern.

Stick some magnets to the rim of your bike (on the "brake surface" area if you don't use rim brakes, or on the portion between that area and the spokes if you do), and ride around a while, and see what accumulates.

Around here, there is enough construction debris and other metal stuff that gets ground up in traffic to make metallic dust and particles (and larger bits) that a magnet on the rim would get a fair bit of stuff stuck to it over a few commutes. I've used large harddisk magnets on the bottom bracket of a bike as experiments in activating traffic light sensors, and those also accumulate debris kicked up from the front wheel.

There's also plenty of dust with enough iron/etc in it to build up over time, too.

On the occasions it rains and I end up haivng ot go thru muddy puddles, stuff clumps up from that, too (some magnetic, some not).

Sure, you could wipe the magnets off, even maybe make an automatic system to do it, but it only takes one nail sticking to it that's just large enough to fit in the airgap and jam the wheel, or damage the magnets or coils (or the plastic or whatever is used to cover and protect these from the elements, and then allowing environmental agents in there to damage them over time).

It won't happen to every equipped bike, but it will happen to some, depending on where and how they are ridden.


Another issue with rim-drive (of any type, not just direct magnet) is that rims get bent from various things, and one can just ride on even with some pretty severe damage, even with rim brakes if you unhook them or take off the brakepad if it's really bad. Sometimes it can be retrued enough on the road to work normally again, and sometimes it can't. If it's half an inch to an inch out of true, it might suck to ride it but you could...unless there's something (like a rim drive that's fixed to the bike or part of it) blocking the wheel from getting past it.






As for a serial-hybrid, pedalling a generator to drive a motor, with or without any conversions between them, efficiency is much lower than chain (or shaft, or belt) drive; some of the various numbers on that are pointed out by other posters (and have been worked out in other threads here on ES if you poke around).

Lowracer (Chrisy Luxemberg) here on ES built a serial-hybrid trike, though unfortunately he has taken down all the vids and a lot of pics and stuff, so there's little info about it other than the text descriptions and Q&A, if you look thru his posts. But he wasnt' going for efficiency, and just used the system so he could continue pedalling all the time, whether stopped or in motion.

There's at least one more but I can't remember who made it here on ES.


The "most efficient" of these serial hybrids (least conversions, anyway) would be to have the pedals directly connected to the shaft of a generator (no gears, chains, etc, each stage of which will have losses of it's own), and have the phase wires of the generator directly connected to the phase wires of the direct-drive hubmotor (again, no gears, chain, etc).

But it would also be the hardest to pedal, and would have no gearing you could shift to adjust for hills, startups, etc., and all speed control would be done via how fast you pedal--like a single-speed bike, it would only be geared for one speed, and you'd have to gear it for the average speed you want on the average terrain you'd encounter, and "suffer" with the rest of the terrain that really needs lower gearing.

I don't know what the actual efficiency would be, or how well such a system would work, but you could try it out and see.



As for the regen efficiency...it doesn't really turn out that way. There's a number of threads discussing it, and at least one by Justin_LE where tests were done to determine efficiency. You're not going to get anything like what you put into it back out of it; there's too many losses in conversion from motion to battery (or other storage).

It can be made more efficient than it is in many systems, but it still won't be anywhere near 100% efficient. Test it with a wattmeter, you'll see.

 

[dogman dan]

I can see some limited applications where it could apply, not the rim magnets, but pedaling away at low effort waiting for the next customer of a pedicab makes sense. There will be big energy losses, but it might still be worth it so the human does not have to sprint and stop, sprint and stop all day.

In my mind, what might make sense is some kind of transmission. This way the cabbie can pedal up 6-7 wh while stopped for 5 min. ( Not full effort, 100w of human power or so) But when he wants to go,, he switches gears and puts his 200w to the wheel. The benefit of this will never be electrical, but the warm up and cool down pedaling vs sprint then stop could be worth a thousand of watt hours over the days shift, in improved human performance when he gets a customer. Eliminating that hard pedaling to get moving certainly worth the motor weight. If the idea is to just get the vehicle to 5 mph then let the motor freewheel, there is a good match between the energy stored up, and the need.

So its not doing it for the few miles worth of energy he stores up during the day, its doing it to improve the human performance during the day.

I's fairly simple math really, if a dumbshit like me can grok it. You can pedal up 200w or so continuously, if you are very fit. Lose even 25% of it, and you can pedal up perhaps 750wh of energy during 5 hours of continuous pedaling. Put two people in a pedicab, and you will get about 50wh per mile, or worse. That gets you 15 miles in 5 hours of pedaling the generator, or less if losses are worse, and wh/mi might be much worse. It won't get you through a 5 hour shift, likely wont get you through one hour.

So you still need a big ass battery to get through the day, still need to plug in, and the most efficient way to put your human power to the wheel is still to pedal the wheel, not a generator. It might be better in the long haul, to just put 150w of solar panel on the roof of the cab. Then add the riders input. Combined,, this could get to a wattage level that would work all day. If you have solar giving you 100w, and a rider giving you 200 when moving, that's now getting somewhere, 300w towards the needed 1000w to move 700 pounds or so more than 10mph. If the cab speed is to remain 5 mph, well then the math does get different. I'm assuming the reason to motorize is to outcompete the competition on trip time.

 

[liveforphysics]

To charge my DSR today, I tap 3x J1772 stations and max out each of them at whatever the threshold of the station tripping off happens to be. At ~5500-8500w for each station, it's around ~17-25KW. The total mass of the equipment to do this charge rate is ~45lbs and ~6-8liters of volume (DigiNow supercharger on bike, and 6 x hacked server supplies in my backpack.).

In 20minutes a pedicab using something similar could take on ~6-8kWh of energy from stopping to charge. I'm not sure it would be possible for any human to deliver 6-8kWh even over an uninterrupted 24hr period of continuous 100% cardio limited pedaling effort.

If by having more energy available, your pedicab could effectively run longer routes at reasonable paces, it could replace what otherwise would likely involve moving multiple ton metal cages around at higher destructive kinetic energy levels and perhaps needlessly spraying toxins that directly cause millions of deaths yearly and yet-unknown magnitudes if genetic defects from mutagen vapor inhalation.

That said, if the drivers objective was to reduce BMI, then continuous pedaling even if it only offers the gesture of charging from a practical perspective would still be a welcome alternative to pedaling a stationary bike in a gym just heating the atmosphere and releasing CO2 for your efforts.

It's interesting how if a few people were

 

[Gavilan]

The efficiencies realized in hybrid automobiles can be realized in human powered conveyance. It is simply a matter of scale.

The energy regenerated in hilly urban terrain would significantly reduce required energy input; far in excess of additional process losses.

 

[Punx0r]

IIRC Justin at Grin Technologies made a good study of regenerative braking on ebikes and found in hilly terrain up to 10% regeneration was possible. More significantly, regenerated energy in these circumstances approximately equalled the parasitic drag of an average direct-drive hubmotor, thus making the system energy neutral, not "far in excess" of the losses.

The efficiencies realized in hybrid automobiles can be realized in human powered conveyance. It is simply a matter of scale.

Can you explain this?

The lighter and less aerodynamic a vehicle the less effective regenerative braking tends to be. A bicycle is about the least suitable vehicle for it.

 

[dogman dan]

Might still be well worth harvesting whatever regen you can though. Add that to some solar on the roof of the cab,, and yeah, fast charge if there is a reliable plug.

As for overall energy efficiency, nothing seems to be worse than converting human food into motion. Almost as bad as animal food into motion, which we sure couldn't wait to get rid of depending on.

 

[Drunkskunk]

The efficiencies realized in hybrid automobiles can be realized in human powered conveyance. It is simply a matter of scale.

The energy regenerated in hilly urban terrain would significantly reduce required energy input; far in excess of additional process losses.

Unfortunately, this isn't true the way you have layed this out. What you are purposing is a series hybrid. Series hybrids work best when the power source is most efficient in a way that would be otherwise difficult to extract variable power from, and their efficiency significantly exceeds the loss of efficiency from the electric transmission. Gas turbines and Atkinson cycle motors, for example, run most efficient at a small RPM range. They are more efficient than a conventional 4 stroke motor, but with their limited RPM range, they aren't useful with a direct drive transmission for a passenger car. When used in a series hybrid drivetrain, they can overcome the loss of efficiencies in the electric system and get more MPG than a conventional ICE coupled to a mechanical transmission.

If a conventional 4 stroke motor is used in a passenger car, it's still more efficient to use a parallel hybrid, where the gas motor is connected to the wheels directly, and the electric motor runs in parallel to the gas motor.

What you propose is more like trying to make the 4 stroke motor into a series hybrid. Human power is as efficient over a wide range of RPM, and the efficiency of a bicycle transmission is extremely high. it's extremely efficient to get human power to a back wheel at any RPM you need. On a bicycle, cutting that mechanical link is throwing away efficiency.

You also proposed an 80% efficiency on your series hybrid format. IF you could design a special crank generator, and IF you could design a special hub motor that both peaked at 90% efficiency each (they don't exist, but it's not impossible), and IF they were both DC and had no other controllers, batteries, throttles, or devices between them, then perhaps you could peak at 80% efficiency. However that would only apply when being run at full speed under light load conditions, not trying to start out from a dead stop. electric motor's efficiency goes down as the RPM go down under load. And on a setup like that, regen would be impossible.

If you want to be a blke to do regen, then we're back down to 50 to 60% efficiency we talked abut before. Human > generator > charger > battery > motor controller > motor. And each step has loss.

As for your ability to significantly regen power in hilly terrain, this has been shown to run at around 5% to 10%. with a light weight bike setup, it can be significantly less. Bicycles lose most of their energy to overcoming wind resistance and don't have much mass to store kinetic energy as potential.

 

[Gregory]

Lowracer (Chrisy Luxemberg) here on ES built a serial-hybrid trike.......

There's at least one more but I can't remember who made it here on ES.

Fitek built one here.