Building a Regenerative Capable Bicycle

Maybe a wheel rim generator, along with a battery, and some kind of charge controller.

Another possibility would be a flywheel coupled via a CVT (continuously variable transmission).

A very special and elegantly simple pancake motor/generator, a temporary electrical storage device, and a controller. ----- That's kind of what I had planned.

"Maybe a wheel rim generator." - good idea !!!

I've never used this manufacturer and this is NOT an endorsement.

http://www.goldenmotor.com/

I only suggest you review the site for ideas to get your project started.

Good Luck!

Thanks !! Great link. Regen capable motors already available!!! Now I just need to solve the slow acceptance problem in order to increase regen efficiency!!!

Gav

I see this application also involves a motor driven bicycle (I was only thinking of generation of electric current using kinetic energy from the moving cycle) As someone who bought his wife an "e-bike" I must say to please be sure that the drive wheel is on the rear. My wife has had several nasty wrecks (much road rash) from small amounts of gravel using a front wheel driver. A front wheel with torque input creates very erratic handling when the tire breaks loose on a curve.

Yes Phys; that is indeed the goal. In an electrical version you would be recovering the kinetic energy and re-launching using a motor/generator. In a nut shell what you would have is a human/electric hybrid. The key is keeping it at safe voltage, simple, and efficient.

Another possible approach is a human/hydraulic hybrid.

When you look at the physics, once the system is charged to its operating energy, mass becomes less of a factor if the regenerative braking is at high efficiency.

As in all self-contained regenerative capable transportation systems the key to efficient regenerative braking is storage acceptance rates; perhaps more conventionally called - power density in acceptance. Common re-chargeable electric storage devices have relatively high power density in discharge but very low power density in acceptance; in a nut shell they can't accept the power that is generated in fast braking from high speed.

An efficient storage device would have to accept power at .5m(v^2) /t = fs/t where m is system mass, v is maximum recoverable velocity, t is braking time, f is the maximum friction force between the wheel and road, and s is braking distance.

Because the energies are relatively low in a human powered bicycle it becomes a bit less problematic but still challenging; especially the power density in acceptance issue.

I have some ideas in motor/generator design, storage, and control. Perhaps I will take the time to put them out into the public domain; but for a guy like me who doesn't know how to use CAD everything has to be done with pencil and paper.

There is a very high probability that there is nothing new here in terms of component design; just a matter of finding the right off the shelf technologies.

I think you may be overestimating the importance of regen braking.

Energy recovered from braking is not a large percentage of the energy used during travel. Most of the energy expended goes into overcoming mechanical and air drag. Neither of these can be recovered. I've run many calculations/simulations and cannot recover more than ~15% energy using "ideal" regen braking. It is important to note that this % only occurred during heavy stop & go travel. Continuous point A to point B travel basically gets "0%" energy recovery from regen braking.

Assuming it is done correctly and with reasonable cost, regen braking is just one small step towards improving overall efficiency. Reduction of rolling resistance and air drag losses are usually more important. Motors and controllers are already very efficient, but may still have some room for improvement. Battery technology is where we could use some significant advances.

Ideally we want batteries that have the following characteristics:

small
light (low mass)
capable of fast charge/discharge
safe (non-toxic, non-explosive, non-combustible)
long life
low cost

The ideal battery doesn't exist... yet. For now, lithium technology seems best. Cost is coming down and performance is incrementally increasing.

I suggest you work out some calculations using realistic losses for mechanical drag and air drag so you don't overestimate the significance of regen braking. Learn where all the energy goes and you have a better chance of increasing efficiency and improving the whole EV as a system.

Best wishes :-)

MJB;

Thank you for that very comprehensive reply.

Since you have done many calculations regarding kinetic energy recovery I have some questions.

If a car has a combustion energy to work efficiency of 25 percent how many units of joule combustion energy must be used to generate 1 joule unit of kinetic energy?

If I am able to recover 1 unit of kinetic energy and reuse it to relaunch the vehicle how many units of combustion energy have I saved?

Is it possible that Prime Mover to work efficiency is a very significant variable when considering regenerative capable systems?

Was that factored into your calculations?

Gav

Chemical to mechanical energy conversion of 25% is a reasonable working value for an Internal Combustion engine.

>Assuming 25%, you need 4 joules of fuel energy for every joule of mechanical energy.

>Theoretically, 1 unit of recovered kinetic energy saves 4 units of fuel energy.

>If you start with an initial primer mover efficiency of 25%, then (regen_braking_energy/total_system_energy) is far less than the 15% I'm calculating.

>Your post is titled "Building a Regenerative Capable Bicycle" and my simulations are for "electrified bicycles" so IC efficiency isn't a factor. For E-bike sim I use theoretical battery capacity and motor+controller efficiency of 90%. I further assume that the motor_controller_battery system can recover 90% of the kinetic (braking) energy. I'm also using classic air drag force calculations with a small additional loss for rolling resistance. This is intentionally optimistic.

I'm NOT claiming regen braking is useless. As previously stated, it is just one factor we can implement to increase overall system efficiency. I AM claiming that I see too many people, who have not thoroughly reviewed all the system losses, overestimating the importance/significance of regen braking from an Engineering/Physics perspective. Of course regen can be a superb marketing ploy if sales/profit is the primary goal.

I've reviewed other literature and empirical data regarding recovered braking energy and see values ranging from "0%" to "~17%". My sim numbers are in line with published research.

Please try to calculate the energy needed to overcome rolling resistance and air drag over a given distance and then compare it to the kinetic energy recovered during braking.

MJB;

Thank you again for your comprehensive and thoughtful replies.

It was a breath of fresh air to see someone who understands how prime mover efficiency is a primary factor in the economics of regenerative braking.

In your E-bike sim; can you describe how many stop and go cycles you used for the given displacement?

For the bicycle commuter this would be the most significant variable; more significant than the road drag or even the aerodynamic drag given the low velocities and small aerodynamic cross-section.

The work done in any transportation cycle would approximate the (aerodynamic drag X displacement) + (road drag X displacement) + (∑ KE dumps) + (mgΔh).

What was your value for the coefficient of dynamic drag? What was your aerodynamic cross-section, operating velocity, and total system mass?

The ratio of KE recovery to total energy consumption may define the fraction of energy recovered; but without factoring the system efficiency into the equation it really is a meaningless ratio.

If you are attempting to calculate energy savings then the ratio should be Kinetic and gravitational energy recovered /(applied energy/input energy) = energy savings; where applied energy (work) / input energy (energy used) is the efficiency fraction of your process.

I AM claiming that too many people who analyse Kinetic Recovery systems fail to factor prime mover efficiency and underestimate the number of stop and go cycles.

Did you write your own algorithms? I don't suppose I could get you to share your formula for road drag with us could I?

Gav

For any practical round-trip bicycle travel I'm going to claim mgh recovery is pointless. The extra energy used up-hill is saved during a coast down-hill without any regen capture losses. I'll consider mgh important if your travel destination is another planet.

For my e-bike sim I use a rolling loss of 2 Watts/meter/second. This is my estimate with no reference for confirmation.

Other calculation refs:

http://en.wikipedia.org/wiki/Drag_coefficient

http://en.wikipedia.org/wiki/Density_of_air

http://en.wikipedia.org/wiki/Work_(physics)

For a human adult on a typical street bicycle, I use a drag coefficient of 1 with a frontal area of 0.75 square meter. Average travel speed is 15 miles/hour (~6.7 meters/second) and bike+rider mass is 125kg. I just ran a quick sim for a 1 hour trip at 15 miles/hour with 20 stops. This would be a realistic ride cross city for my location. Best case energy recovery from regen braking is just under 10%. Significant, but not a large factor.

I suggest anyone interested should attempt to setup and run all the calculations themselves so they understand all the variables and constants. I strongly suggest that anyone attempting this should understand the proper use of "units". They should carry units fully through ALL calculations to verify their results.

I disagree on a couple points. If regen energy is a small portion of an ideal system, it is an even smaller part of a lossy system. I'd claim that improvements are needed to make the system less lossy first. Regen brake energy takes a lower priority until the other more important factors are addressed. As an example, the focus on improving the energy efficiency of an IC vehicle system should start with the engine conversion efficiency, then drag reduction, rolling resistance reduction, and lastly braking energy recovery.

Thanks for the further information.

Let's take one part at a time.

You stated - "For any practical round-trip bicycle travel I'm going to claim mgh recovery is pointless. The extra energy used up-hill is saved during a coast down-hill without any regen capture losses."

The above would only apply if there were no braking required to control speed on the downhill side. Gravitational potential is a very significant factor; especially when you are the power source.

You stated - "If regen energy is a small portion of an ideal system, it is an even smaller part of a lossy system."

Yes the ratio of kinetic recovery to energy use is smaller in a lossy system; but again, are you factoring applied power efficiencies into the whole energy savings equation?

Regenerative payback increases as the ratio of applied energy to consumed energy decreases not the other way around. In a single stop the energy savings approximates the energy recovered/ efficiency fraction of the power process. No --- this is not over unity; it is simply factoring the power process losses.

You stated - "For my e-bike sim I use a rolling loss of 2 Watts/meter/second. This is my estimate with no reference for confirmation."

It might be valuable to revisit this. Although road drag is somewhat dependent of velocity, it is not an increasing linear relationship as your calculation infers. If I am reading this right you are estimating road drag to be consuming about 13.4 watts at 15 mph; and half that at 7.5 mph.

Based on the sim found here - http://www.exploratorium.edu/cycling/aerodynamics1.html your road drag equation consumes nearly half of total power at 15mph. Is it possible that this is significantly overstated?

What is the total displacement in the 1 hour period? Since average speed in constant acceleration is only ½ that of the final velocity is it possible that the air pressure drag may be significantly overstated in your calculations? Is one stop every 5 minutes a realistic scenerio for an urban commuter in busy traffic?

Having said all of this; even a 15% increase in process efficiency is HUGE!!!

You stated - "For any practical round-trip bicycle travel I'm going to claim mgh recovery is pointless. The extra energy used up-hill is saved during a coast down-hill without any regen capture losses."
The above would only apply if there were no braking required to control speed on the downhill side. Gravitational potential is a very significant factor; especially when you are the power source.

I agree that energy to maintain velocity on positive grades IS significant. However, mgh energy recovery is dependent on geography. On a typical bicycle commute I would not benefit from the process. My one small grade change does take more effort uphill, but the free 25mph coast (no braking necessary) on the way down is a nice respite.

You stated - "If regen energy is a small portion of an ideal system, it is an even smaller part of a lossy system."
Yes the ratio of kinetic recovery to energy use is smaller in a lossy system; but again, are you factoring applied power efficiencies into the whole energy savings equation?
Regenerative payback increases as the ratio of applied energy to consumed energy decreases not the other way around. In a single stop the energy savings approximates the energy recovered/ efficiency fraction of the power process. No --- this is not over unity; it is simply factoring the power process losses.

We have different priorities here. Since drag accounts for most of the energy consumed, aerodynamics would be my first target for improvement. If the cost, complexity, and reliability are acceptable, I'd also implement regen braking to recover some energy.

You stated - "For my e-bike sim I use a rolling loss of 2 Watts/meter/second. This is my estimate with no reference for confirmation."
It might be valuable to revisit this. Although road drag is somewhat dependent of velocity, it is not an increasing linear relationship as your calculation infers. If I am reading this right you are estimating road drag to be consuming about 13.4 watts at 15 mph; and half that at 7.5 mph.
Based on the sim found here - http://www.exploratorium.edu/cycling/aerodynamics1.html your road drag equation consumes nearly half of total power at 15mph. Is it possible that this is significantly overstated?

My results indicate power to maintain 15 miles/hour is about 160W or 4x what their calculator indicates. I couldn't find their values for the drag coefficient or the frontal area. As stated on the linked site, a racing cyclist will modify body position (head-down-crouch) to reduce the drag coefficient and frontal area. Each one of these could be halved (Cd=0.5 and A=0.375), resulting in the 4x difference in their calculator. I'm intentionally NOT using racing class cyclist numbers for city commuter applications.

A premium racing bike with thin high pressure tires will have lower rolling resistance. On my pot-hole ridden city streets, these beautiful bikes wouldn't last long. My calculations are based on the knobby fat lower pressure tires similar to those found on mountain bikes. While the rolling resistance is higher, these tires are better suited for the simple commuter application I'm investigating.

Rolling resistance is a complex process since the coefficient actually varies with velocity and several other factors. My approximation is reasonable for my current use. When I can gather some empirical data, I will attempt to refine my approximation.
http://en.wikipedia.org/wiki/Rolling_resistance#Rolling_resistance_coefficient

This calculator appears to generate some interesting values:
http://www.mne.psu.edu/lamancusa/proddiss/bicycle/bikecalc1.htm

Is one stop every 5 minutes a realistic scenario for an urban commuter in busy traffic?

My conditions were:
1 hour = 60 minutes
60 minutes/20 stops = 1 stop every 3 minutes
This would be realistic in my area.

Since average speed in constant acceleration is only 1/2 that of the final velocity is it possible that the air pressure drag may be significantly overstated in your calculations?

From velocity errors, no. I get up to speed in 10-12 seconds. Short quick stops (5-8 seconds) are realistic for city traffic. The 180 seconds between stops is at the stated velocity of 15 miles per hour. My simplified calculation is optimistic in that it assumes no drag or rolling resistance during the acceleration/braking periods.

What is the total displacement in the 1 hour period?

Using 15 [miles/hour] and 20x 20[s] acceleration+brake periods, ΔX~14.2 [miles].

Having said all of this; even a 15% increase in process efficiency is HUGE!!!

It seems we don't share the same frame of reference, especially for the definition of huge. I don't consider 15% here "huge".
Good luck with the huge energy savings and I hope your project is hugely successful.

Thanks for the great Bicycle Power Calculator link!

I ask you to consider the variable power required to do your ride.

Now imagine a system where the sum energy of the system remains nearly constant over the entire cycle if the Prime Mover puts in "Average Power." Perhaps now that hill doesn't't look so long on the uphill side.

I like your analysis of your commute; probably not much different for millions of folks on this planet who commute by bike.

When I have refined my description of the process to the extent it would support a ruling of "public disclosure" I will get it out.

Gav

You are going to take all the fun out of cycling. I ride around 4000 miles/year, so I know a bit about cycling. I, and others I ride with, look forwards to long fast scary descents. Other than the occasional very busy highway intersection (a bit of a rarity in my remote location) on many road rides I never touch the brake levers except for the mid ride break or final stop. The whole premise of the other side of cycling, mountain biking, is to climb as high as possible so you can fly back down the mountain trails. Now you are going to have the cycle try to use up a portion of that energy to generate electricity? Won't go over with the typical cyclist. When we point the bike downhill we want to go too fast.

The goal is not electrical generation - it is Kinetic Energy Recovery.

Renerative braking is of no advantage in a transportation cycle where there is no stopping.

But to a commuter in Amsterdam or any other major city where the transportation cycle includes stop and go driving, a regenerative capable system would significantly reduce the energy input required to get from home to work. I recently visited Amsterdam and when I asked a rider there what she thought of the idea of being able to recover the the kinetic energy for relaunching the bike she thought it was a great idea.

I guess desirability is a matter of application and taste.

Such a system would also have the benifit of encouraging more people to ride.

Also, the American experiance with bicycles is not what the rest of the worlds is.

Improve someone else's efforts?

A regenerative capable Bicycle that uses:

A low voltage single sprocket gear Pan Cake motor/generator rear axle.

A single gear crank set.

Four modes of mg operation.

1. Coasting

2. Infinitely variable transmitted power from the rider.

3. Infinitely variable electric/human transmitted power from storage and rider.

4. Regenerative Braking at high efficiency

Electrical Storage - Low Voltage Super-caps by Maxwell

I still believe that the best approach in designing a Power Averaged Regenerative Capable transportation power process, regardless of scale (a bicycle, auto, bus, or train) would be more efficiently achieved in a series process.

In order to reserve energy storage capacity in the storage device for regenerated brake energy the total energy state of the system must be monitored. That is - the approximate Instantaneous Kinetic Energy + Instantaneous Stored Energy (+ in an advanced system the gravitational potential energy relative to original position or destination). The KE+SE(+GP) is the approximate total energy of the system.

To simplify we will ignore the gravitation component and focus only on the KE and SE where Total Energy = KE + SE. We will also use a "reserve energy" to allow us to "average" or "balance" power input throughout the entire transportation cycle.

Let us look at a "Transportation Cycle". In this case the "Transportation Cycle" will be a trip to work.

The "average" power required in this specific Transportation Cycle is equal to the total energy expended during the trip divided by the trip time. P = E/t.

If the storage device only stores enough power to equal the kinetic energy of the system at maximum sustained speed then the power could not be "averaged" or "balanced." Why? Because the trip cycle power varies greatly from one moment to the next. To deal with that variability and maintain a charge state that would allow for regeneration, the stored energy is allowed to fluctuate somewhat above and below the value required to maintain a constant system energy. This is achieved by adding a arbitrary value to the Operating Energy Constant.

In a human hybrid bicycle the control could be achieved simply by an indicating gauge showing power input relative to the average input required for the specific transportation cycle, or more simply, just a generic value.

In an automobile the prime mover demand would be controlled by an algorithm that has recorded some number of times that specific transportation cycle has been performed, computed the average power required, and using generator field and fuel control, and puts power into the series storage device at that rate. The same type of algorithm could be used for a bicycle only instead of controlling fuel and generator field control would simply gauge indicate whether more or less power is require by the human.

If using a Maxwell Boostcap for a storage device the Instantaneous Total Energy would approximate TE = 1/2mv^2 + 1/2CE^2 where m is system mass - v is velocity, C is storage capacitance - and E is the voltage across the terminals of the storage device. For operations through significant variable altitude a gravitational energy component could be added to the equation.

In operation the energy stored would be at maximum when the system is not moving. As the system accelerated the available energy in the storage device would begin to decrease maintaining an acceptance capacity approximately equal to the kinetic energy of the system.

In this type of process the system energy would translate between stored energy and kinetic energy with the prime mover (Human or Engine) putting power in to make up for losses.

BUT if only this is used to determine demand then the system reverts simply to a delayed variable demand system; that is why the algorithm must calculate and compare additional variables throughout the transportation cycle or use a generic program to determine the approximate average power required.

Power Averaging presents a VERY significant advantage by reducing the required maximum power of the prime mover to that just a bit above the Average Power required for the trip cycle as well as reducing the required storage capacity. This allows for significantly smaller mass and volume fractions required for those purposes.

It also has advantage in All Electric Vehicles because if the primary storage device is applying average power to a load leveling device it reduces peak power density requirements and simplifies thermal energy management.

The design engineers seem to miss this opportunity; but as shown in the letter from GM below; sometimes it takes a little time for the message to sink in.

They STILL haven't got it right - but at least now they are trying.

<The goal is not electrical generation - it is Kinetic Energy Recovery.>

Even under ideal conditions, energy recovered will be less than 20% of the total "trip" energy. MOST of the trip energy will be lost to mechanical friction and air drag. These losses can NOT be recovered, however they can be minimized with careful system design.

<Renerative braking is of no advantage in a transportation cycle where there is no stopping.>

That is correct.

<But to a commuter in Amsterdam or any other major city where the transportation cycle includes stop and go driving, a regenerative capable system would significantly reduce the energy input required to get from home to work. I recently visited Amsterdam and when I asked a rider there what she thought of the idea of being able to recover the the kinetic energy for relaunching the bike she thought it was a great idea.>

Anecdotal stories and public opinion are not suitable substitutes for a proper analysis using math, physics, and current engineering technology.

<I guess desirability is a matter of application and taste.>

Partially true. More important considerations are cost, complexity, reliability, weight, AND actual measured performance benefit.

<Such a system would also have the benefit of encouraging more people to ride.>

Also partially true. However, many will never ride a bicycle until you add 2 more wheels, a 3000 lb metal shell, heated reclining seats, blue-tooth, stereo, gps, dvd, beverage holder...

<Also, the American experience with bicycles is not what the rest of the worlds is.>

Yes, the transportation infrastructure in the USA is MUCH less bicycle friendly than many places around the globe. Cycling is also seasonal/regional. Here in the "lake effect" North-East, only a rare hardy (or desperate?) few will ride a bicycle in the winter.

As previously stated, I think regen-braking (or any practical energy recovery/scavenging) CAN be useful under the RIGHT conditions.

<The design engineers seem to miss this opportunity; but as shown in the letter from GM below; sometimes it takes a little time for the message to sink in.>

Really? An almost 30 year old (1984) rejection letter? As evidence of what? Technology has dramatically improved over the last 30 years. What was prohibitively complex and expensive to design and implement 30 years ago can now be found in commodity consumer goods.

<They STILL haven't got it right - but at least now they are trying.>

You are obviously not a design engineer. Home tinkerer, hobbyist, dreamer maybe? All fine and I applaud your effort, but I take offense to your criticism of design engineers when you seem to have little knowledge of the actual design complexity.

If I'm reading your posts correctly, you seem to be looking for a power assisted pedal bicycle design. This is just one source found with a quick Google search.

http://www.yukontrailinc.com/home/electric-bicycles.html

If not already used, an IDEAL regen-braking system could THEORETICALLY increase a 30 mile range to ~36 miles (maybe). We still seem to disagree on the importance of this incremental improvement.

MJB: Thanks for taking the time to comment.

>Even under ideal conditions, energy recovered will be less than 20% of the total "trip" energy. MOST of the trip energy will be lost to mechanical friction and air drag. These losses can NOT be recovered, however they can be minimized with careful system design. <

The "return" on regenerated energy is a function of prime mover efficiency and depends on how much braking is done. For a process that uses an internal combustion engine as the prime mover, with an overall efficiency of 25 percent, the "return" is 4 to 1. That is, you conserve four units of combustion energy for each unit of kinetic or gravitational energy recovered. This IS NOT over unity, it is a simple reflection of poor power production efficiencies.

>Anecdotal stories and public opinion are not suitable substitutes for a proper analysis using math, physics, and current engineering technology.

Anyone who has ever ridden a bicycle in compliance with traffic laws in an urban area knows what the benefits would be if high efficiency regenerative braking could be utilized.

>Also partially true. However, many will never ride a bicycle until you add 2 more wheels, a 3000 lb metal shell, heated reclining seats, blue-tooth, stereo, gps, dvd, beverage holder..<

I agree - that is most definitely true!!! But the reality is there are many millions of riders in any number of Chinese Cities alone, who have the technology and engineering capability to realize significant benefit.

>Really? An almost 30 year old (1984) rejection letter? As evidence of what? Technology has dramatically improved over the last 30 years. What was prohibitively complex and expensive to design and implement 30 years ago can now be found in commodity consumer goods. <

The technology was available in 1984. Can you imagine where GM would be today had they begun an earnest investigating of that technology then? Perhaps not marketing it; but at least exploring it. What would the hybrid share look like today?

>but I take offense to your criticism of design engineers when you seem to have little knowledge of the actual design complexity<

So be offended if you choose - yes I expect complex engineering in small packages,- we had it available in 1984, and its even better today.

>If I'm reading your posts correctly, you seem to be looking for a power assisted pedal bicycle design. This is just one source found with a quick Google search.<

You do seem to understand how power processing has a major impact on overall efficiency; but you don't appear to be looking for it in currently available technology. Why is that?

Yes there are MANY electric pedal bicycles on the market and there have been for some number of years.

>If not already used, an IDEAL regen-braking system could THEORETICALLY increase a 30 mile range to ~36 miles (maybe). <

I think it might be beneficial if you would compare the 2.0 liter Fusion Hybrid City mileage rating to the 2.0 liter Ford Fusion Conventional. This is NOT the plug in hybrid model.

For the city mileage rating the Hybrid it is 47 mpg vs. 22 mpg for the conventional. I will suggest that regenerative braking accounts for most of that difference.

Do you understand why power averaging and regenerative braking would reduce mass and volume fractions dedicated to prime mover and storage?

You have made some incorrect assumptions as to my understanding of physical and technological challenges that existed in 1984 as well as today. I also noted that you fail to understand that the mass component becomes less of an issue when high efficiency regeneration is available given the same aerodynamic cross-section. That, for an engineer, is a very fundamental oversight. In anticipation of your conventional thinking, I state that I know road drag and bearing drag is affected by system mass; but those fractions are not large enough to offset the advantage of regeneration, especially when mass committed to regeneration can be offset by reduced prime mover mass, which is inherent to power averaged processes.

Yes, I may be all those things you say that I am; and in addition I understand the "math, physics, and current engineering technology" quite well, which I have been following for quite some time.

If you are an engineer interested in hybrid transportation technology and were offended by my remarks that the technology still isn't where it should be given available control and processing technologies; then I guess all I can say is - "suck it up cupcake, and get back to work before the other guy eats our lunch ----- again."

We are still focused on first generation technology developed by the Japanese; but I believe the second generation will be developed by the Chinese because they have the largest domestic market and the most to gain by the incremental efficiencies achieved.

Now MJB; do you wish to discuss the enabling motor/generation control technologies, or do you want to continue mulling over the proven, apparent, and applied advantages of regeneration technologies as they apply to transportation power processes?

A good study of those control technologies would the application to a human/electric hybrid bicycle - an elegant application that could probably be scaled all the way up to a switching locomotive; which was my first study in 1978, that included the use of off the self traction motors and included an algorithm that calculated minimum mass for a storage flywheel based on material constants, physical design, and energy storage requirements.

I've been aware of and following regen-braking (kinetic energy recovery) technology since 1982. At that time the control, switching electronics, and energy storage technology to perform regen-braking was too complex and expensive for practical small scale use. The big players understood that and were waiting for the technology to make regen viable for smaller applications.

Progress occurred with the development of better batteries, advanced control ICs, more powerful microprocessors, improved magnetics, and very efficient high current MOSFET switches. NONE of these were cheap or readily available back in the 1980s.

While it may not be included in the products in my last link, regen-braking is included in most of the products in my first link (post #2 http://www.goldenmotor.com/ ).

< "Regen capable motors already available!!! Now I just need to solve the slow acceptance problem in order to increase regen efficiency!" >

You acknowledge regen is available but still feel acceptance is slow and efficiency is too low? Available products indicate the technology is used as soon as the cost/benefit ratio makes sense.

I am interested in human/electric hybrid bicycle technology for my own personal use and understand why leading technology is not always implemented in small scale applications like e-bicycles. Manufacturers know their price points and understand how their products work. For some the cost/benefit ratio is just not acceptable.

< "I also noted that you fail to understand that the mass component becomes less of an issue when high efficiency regeneration is available given the same aerodynamic cross-section. That, for an engineer, is a very fundamental oversight." >

I seem to more clearly understand this than you do. Mass becomes irrelevant if IDEAL regen can be implemented. Then air drag and rolling resistance become the only significant system losses. I've been trying to show that air drag is THE most important loss factor since post #9. Rolling resistance is next. Third is kinetic energy loss, which is only significant during frequent stop & go travel.

I don't understand many things, but try to learn when necessary.

I don't understand why:

-internal combustion engine efficiency is mentioned in a discussion about "Building a Regenerative Capable Bicycle".
-the main focus for system improvement is on regen-braking when other factors are more important.
-air drag, the largest system loss, is not given more attention.
-I'm still here trying to provide realistic information (and craving a cupcake ;-P).

That's all OK because this is your thread and my understanding of your intent is not necessary.

Using your words, I choose "conventional thinking" and will "continue mulling over the proven, apparent, and applied advantages of regeneration technologies as they apply to transportation power processes" for my own projects. Sorry that I don't have the time or the energy "to discuss the enabling motor/generation control technologies" with you.

Good luck with your quest.

For those interested in real-world applications, the person/company below seems to understand the cost/benefit ratio of adding regen AND where the real energy loses occur in electrified bicycles.
http://www.ecospeed.com/resources/what-about-regenerative-braking/

MJB;

Again - thank you for your comprehensive reply.

I think what we have here is a "failure to communicate. "

Your referenced link may be quite relevant to an "electrified bicycle" but is highly irrelevant to a Human Powered Electric Hybrid Bicycle.

You stated - "I don't understand why:

-internal combustion engine efficiency is mentioned in a discussion about "Building a Regenerative Capable Bicycle".

Because the Three Fundamental Efficiencies of Hybrid Technology applies to both processes.

-"the main focus for system improvement is on regen-braking when other factors are more important."

It is not the main focus, it is one component of applying the three fundamental efficiencies of hybrid technology.

"-air drag, the largest system loss, is not given more attention."

Because you can only do so much with the aerodynamic cross-section and Coefficient of Drag for a fat guy like me.

From your link -

http://www.ecospeed.com/wp-content/uploads/2012/10/regenbraking.pdf

"So, what does it take to get 10% more range? Well, it takes 10% more battery power. In other words your regenerative braking system has to be able to recover 10% of whatever the capacity of your battery is, over the time it normally takes you to discharge the battery completely."

This is one of the leading premises of the paper showing that regenerative braking in an electric bicycle is not worth the effort;.

This tells me that the bicycle is primarily a plug in electric bicycle with pedals; not a human/electric hybrid where human energy is the prime mover.

Again - the power is not being properly processed.

In addition - the total usable capacity of a very high efficiency regenerative capable Human/electric hybrid would only be about 2 to 4 times the amount of KE at cruising speed on level ground.

Using a very liberal 100 kg at 7 meters/sec the total KE is 2450 Js, 2450 watt seconds. or about .68 watt hours per stop. The total storage requirements for a very high performance Human/electric hybrid is at 1.36 to 2.72 watt hour. Which, using that higher figure, means that the battery being used in the referred to electric bicycle s sized about 217 TIMES more than is required for a human powered /electric hybrid bicycle.

"Batteries are always designed to be charged at a certain maximum rate. Charge them above the designed rate, and they will suffer from a shortened service life. In the case of our 16Ah lithium ionpolymer battery, we recommend charging at no more than 3 Amps to maximize life. Three Amps at 37Volts, is 111 Joules per second. If we have 1800 Joules to put in the battery, it will take 1800 divided by 111 or 16.2 seconds to do so. Taking 16 seconds to stop from 16 miles per hour, is a very slow stop.A more typical, but still relaxed stop, would be 3 or 4 seconds. If we've got four seconds at 111 Joules per second charge rate, we can only put 444 Joules or .12 Watt-hours into the battery per stop."

Chemical batteries alone are a very poor choice for energy recovery and temporary storage in regenerative capable system. They have low charging rates which limits regen efficiency, high thermal losses, and low total cycle lifespan.

The energy storage component for a high efficiency - high performance - human electric hybrid would be a about 9 Maxwell Boostcaps having a total mass of .54 KG (1.19 lbs), a continuous current rating of 25 amp in both acceptance and discharge, a 500,000 cycle life span, would fit a 12 volt system quite nicely, and supply or accept about 300 watts of power.

300 watts of power would allow for acceleration and deceleration to and from 7 m/s (without ANY human power input) in about 8 seconds. Increase storage mass to a whopping 2.38 pounds and that time drops to 4 seconds.

However relevant your paper may be to a an electric powered bicycle of simple design using chemical battery storage; it is nearly irrelevant to topic of this thread.

The analysis of grading was quite interesting - but again - irrelevant to a human powered electric hybrid bicycle designed for a typical urban environment.

Did you look at the author's company, mission statement, and product offerings?

http://www.ecospeed.com

Disclaimer: I am in no way affiliated with this company and am not endorsing any of their products. The link is supplied only to provide information related to the post "Building a Regenerative Capable Bicycle".

Regarding our "failure to communicate", you have found at least one point we can completely agree on

Good luck in your quest.

I believe a bicycle would be the most elegant application of "The Three Fundamental Efficiencies of Hybrid Technology."

Initial design would focus on urban use.

It integrates these capabilities:

Power Averaging - Allowing power input at very low variability if desired. This allows the operator to pedal input power at near the AVERAGE POWER of the trip displacement; eliminating the need for hard effort during acceleration or climbing small hills. (the word displacement was put in there to avoid one of you really astute fellars from pointing out it would be near impossible to do without automated stabilization when stopped.)

Regenerative Braking - Recovering braking energy at high efficiency.

Peaking Power - Accessing stored energy for the purpose of meeting peak demand - acceleration and climbing hills.

Although the first bicycle would be very expensive to build; China has a very large population, and a very large hip consumer market. There is a HUGE potential market there - in scaled production the cost of making a really cool Human Powered Electric Hybrid Bicycle would make it affordable to some number of millions of consumers and would see very favorable economy of scale.

This is what I envision in the first generation -

The bicycle will be a Human Powered Electric Hybrid Bicycle that uses a generator that is directly couple to the crank as the source of power.

The regenerative capable drive motor would be mounted at the rear axle

OR

The regenerative capable drive motor would consist of numerous very strong magnets inlaid in the rim of the rear wheel, in optimal configuration. The rim would be the rotor of the motor/regenerator.

The stator would be mounted across the rear fork or on the seat post. The stator coils would envelop the magnets on the rim much like a caliper brake envelopes the rim.

It is claimed that because the permanent magnets are mounted on the rim it would optimize the amount of torque per ampere flowing in the stator. It is envisioned that the rim would be designed so that it would also make it possible to easily change out the magnets.

Human control input would be integral with the brake levers in the handlebars with initial compression of the brake levers initiating circuit switching, with further compression incrementally manipulating the control signal, until the mechanical linkage would begin to initiate conventional friction braking.

Power capability of the prime mover generator:

300 watts.

Power and storage requirements of the drive motor/regenerator:

300 to 600 watts depending on storage capacity.

Storage medium - Maxwell Boostcaps - modules operating in 12 or 24 volt configuration. Total energy storage approximately .7 to 1.4Whr.

Storage Mass - .5 to 1.25 KG

Control methodology - Frequency modulation of fixed resonant power circuits.

Control methodology allows for infinite variability of circuit acceptance in source, power, and braking circuits. This translates to infinitly variable power in prime mover input, drive motor output, and regeneration within the limits of generator and motor/regenerator ratings.

Now if somebody were to run out and beat the Chinese Engineers (who will have this in about 5 minutes) to the patent office, could the Chinese Engineers be prevented under international IP agreements from applying it in the Chinese cities without paying a tribute to patent trolls?

If five years down the road I decide to build these things for myself could it not be considered a "Free Speech" issue instead of an IP issue?

Perhaps something like this -------

The prime mover is a human that is powering a generator mounted at the bicycle pedal crank.

This power is fed to a Maxwell Boostcap assembly that also serves as the regenerated energy storage unit.

The motor power is pulled from this storage unit. The regenerated kinetic and gravitational energy is stored in this same unit.

In the picture the RIM of the rear wheel is the rotor of a Permanent Magnet Electric Motor / Generator. The Stator is rigidly mounted with the stator coil(s) enveloping a section of the multiple Permanent Magnet Rotor. I am still studying the fundamentals; and the picture will probably change. I still struggle trying to gain a full understanding of resonant circuits.

The control circuits are tank circuits where the power is controlled by circuit impedance. The frequency of the motor or generator is = Number of permanent magnet poles X RPS. The operator manipulates either/or both the inductance and capacitance of the circuit to control throughput power.

The Maxwell Boostcap Assembly (Storage device) and control circuits are carried in a small pack which is plugged into the bicycle wiring harness.

If properly designed could it have :

a. Infinitely variable torque in power production within the limits of permanent magnet field strength, stator current, and pedal force?

b. Infinitely variable torque in motoring within the limits of permanent magnet field strength, stator current, and tire/road adhesion?

c. Infinitely variable torque in braking within the limits of permanent magnet field strength, storage circuit admittance, and tire/road adhesion?

Hello.

Thanks for the message. I like what you are doing but it is a little complex for me. I just tend to put stuff together without following a plan. If it works, then great but if not, I just try again. I have upsized the battery on my electric bike to 37v 26.8 Ah. If I buy two more 5 cell Turnigy 5000 batteries, that will make it 30Ah at 37v. The hub motor was rusted inside so I am in the process of removing the rust, painting the stator coil with caliper paint, replacing the bearings with stainless steel sealed bearings and re painting the whole thing.

Hydrogenhead;

I wish I lived next door so I could watch your progress.

"replacing the bearings with stainless steel sealed bearings and re painting the whole thing."

How is the rotor and stator electrically insulated?

Will the paint or bearings affect conductivity?

Gav

The stator has no contact with the magnets. This is the magnet ring.

Picture didn't come through I my computer.

I was thinking that the paint might shunt the coil wire?

Or the steel bearing short the stator coils to the axle?

Hopefully not a realistic concern !!

The stator coils are on a static ring as shown. There is no way that painting it could cause a short.

Keep is simple by using existing components. Designing and building custom parts from scratch that can only be used in specific applications will be complex and initially very expensive.

Option1:

DC permanent magnet disk motor (#1). (Efficient, low moment of inertia, high torque, no cogging, size & shape "seems" good for bicycles.)
Buck converter (voltage step-down) for motoring mode (#2). (Switching power supplies are very efficient and readily available at reasonable cost.)
Boost converter (voltage step-up) for braking mode (#3).

Option2:

DC permanent magnet brushless motor and controller (#4 & #5).

Common to both options:

Max Caps for transient energy storage.
Lithium battery pack for bulk energy storage. (Additional cost, but minimal complexity and weight penalty to add a lithium battery at this point in the design.)
Smart microcontroller modes that can adjust performance from pure pedal, to human powered hybrid, to mostly battery mode (#5 & #6), with regen braking and possibly traction control.

**************

Not sure why you are focusing on resonant circuits for this application. Resonant circuits can store energy by shuttling it between the electric field in a capacitor and the magnetic field around an inductor. There is always some loss unless you are using superconductive components (unrealistic for this application). There is a common misconception that resonant circuits can supply energy. Resonant circuits can only store some of the existing energy available and they actually have a very low energy storage per volume density.

I'm NOT trying to stop you from pursuing this project and highly recommend you continue sketching up ideas and concepts AND put them in a dated & initialed notebook. A general idea notebook is fine, but suggest you use a dedicated notebook if this is an important project for you. Keep it on paper for now and continue to research the available technology and market potential.

In my opinion you may have something I refer to as PPTV (Pet Project Tunnel Vision). I've had it MANY times. It is benign (unless you invest ALL your savings) and usually fades as knowledge increases over time. There are billions of people on this planet. Millions of then have similar ideas and dreams. Maybe a few tens of thousands have the resources to investigate and develop their ideas. Only a few dozen people will be lucky enough to develop the "right" idea, at the "right" time, in the "right' location, with the "rights" to profit from it. If you continue to record your ideas and are able to let them grow, evolve, and die, you may become one of those lucky few. Best wishes.


ref:

(#1) http://www.printedmotors.com/e03produkte/e01dc_serie/e378/index_eng.html
(#2) http://en.wikipedia.org/wiki/Buck_converter
(#3) http://en.wikipedia.org/wiki/Boost_converter
(#4) http://en.wikipedia.org/wiki/Brushless_DC_electric_motor
(#5) http://www.goldenmotor.com/hubmotors/MagicPie-Advantages.html
(#6) http://en.wikipedia.org/wiki/Electric_bicycles

Disclaimer: I am not affiliated with any manufacturers listed above. The links are provided for informational purposes only.

Thank You for your comprehensive and gentle reply. You are a kind man.

We will see what the Chinese do with this. An engineer in the electric bicycle industry is a frequent contact of mine. I am waiting to see what kind of reply he may have for me.; if any. Without reviewing his email I believe about 7 million bicycles per year are manufactured in in his geographic proximity.

I don't consider any potential economic gain in my dreaming. Its simply a way to focus my self-study. I share everything far and wide - if its something somebody can pick up and run with then the best of luck to them.

Its obvious to me that you have a much better grasp on the technical challenges regarding power control.

The tank circuits are not used for storage - they are used as a means of controlling energy throughput.

Power is controlled by varying the circuit admittance of the control modules.

Thanks again for your reply.