Electric bicycle with regenerative braking

[willib]

been thinking about electric bicycles recently

a friend has two.

one is an eBike LE , with a Heinzman electric hub motor.

any way , neither one uses regenerative braking .

i was thinking of using a axial flux alternator to put power back into the the battery when stopping.

i was also thinking that the difference between a three phase axial flux alternator

and a three phase axial flux motor is the controls ,

the controls can be bought from the hobby RC sites

i think it would be fun to make a three phase motor or at least try to make one

i was thinking the regenerative part would use ultra caps to store the power , then switch to a boost set up after braking , to recharge the battery with the power stored in the caps

 sound neat ?

all comments welcome as usual

[RodN]

Several years ago, i think about 7-8, that was the innovaton that made the McLaren winning the F1 world championship. Instead of pumping water with a pump connectet to engine with pulley, they powered it with an electric motor and a battery. Battery then get charged from an alternator, but only when accelerator was released.

This way they gained about 5-7 Hp.

[Nando]

Will:

The RC controls for the brushless motors do not have enough high voltage handling capabilities,also depending on your arrangement you may need a rotor position sensor in reference to the coils, for proper energy pulses to obtain peak "forward" power.

So a circuit with much higher voltage and current capabilities is needed with Hall sensors.

The Smart Drive Motor from F&P is one that has good potential as a 1 HP motor for such project.

This is one of the 100's projects in my folder that may never be done due to those in front of the list and not enough hours in the day or hands and eyes to build it.

Nando

[gizmo]

We did some work a few years ago adapting a Smartdrive to a electric vehicle to race in the World Solar Challenge. We got it all working, but had a few problems with reliability and ran out of time, so opted for a commercial motor and controller. The Smartdrives also work well as a brake, in the washing machine if the user opens the lid, the controller switches the mosfets to dump all the power into a 1000watt water cooled heater element. This could pull up a 20kg load spinning at 1000 rpm in a couple of seconds.

Do a google for 3 phase brushless driver IC, that will find some dedicated driver IC's that will work with any 3 phase perm magnet motor, inc the F&P.

Glenn

[s4w2099]

if you do that your bicycle could have ABS brakes is you install an MPPT. Just think about it. The electronics wont let the wheels lock up. Just a silly thought.

:-D

[rotornuts]

willib,

Last year till it got too cold I commuted to work every day on an electric bike.

This is the bike here,

http://www.fieldlines.com/comments/2006/7/6/234414/0148/5?mode=alone;showrate=1#5

When I first got the bike I often thought about regenerative braking but after using it for some time I discovered that range wasn't the greatest issue and if range was going to become an issue then you are likely riding for extended periods with out slowing down or stopping.

On my commute of 9 KM there are about 10 places where I would need to slow down or stop so if it was to take 4-6 seconds to full stop 10 times I'd have a full 60 seconds of regenerative power peaking only at the very beginning of the braking cycle and diminishing quickly thereafter.

Not allot of potential power I came to realize.

Hardware aside the best way to extend your range is to "soft start". Don't accelerate full throttle from a dead stop. Sounds familiar doesn't it.

Mike

[willib]

Yes i remember that post

Didn't you have a source for the Heinzman  Motors, or was that somone else?

i respect the fact that you have been using an electric Bike for commuting, and for your particular case 10 stoping events  may or may not be worth it , but if you knew that you could get a large portion of the energy back , would you be more inclined to put on the brakes?

as i think about it when you have  to brake , the supercap can store a lot of the power needed to get you going again

"On my commute of 9 KM there are about 10 places where I would need to slow down or stop so if it was to take 4-6 seconds to full stop 10 times I'd have a full 60 seconds of regenerative power peaking only at the very beginning of the braking cycle and diminishing quickly thereafter."

thats doesnt have to be the case. By switching out supercaps or choosing the right ones , there can be as much braking power at the end of the braking cycle as in the beginning.

[rotornuts]

Willib,

I source the kit from ebikeconversions.com.

On my browser the site is displayed as a Google add to the right under the heading "electric power for bikes"

At the moment the greatest shortcomings are flexible charger technology and robust controllers.

The Crystalyte gear is pretty standard in the economy line of electric bike conversions and after test riding some far more expensive kits I think the value is extremely good. the motor is pretty much indestructible but as I mentioned the controllers are very destructible. the biggest favor you could do the E-bike world would be to develop a robust controller that would run on a range of voltages from 36 - 72 and have a built in charger.

My apparent lack of concern for reclaiming power comes from an overriding concern for making the E-bike experience reliable and making configuration changes less expensive.

I started with a 36 volt kit but would like additional speed (up to 40 KMH) so I need to step up to 48 volts at least which requires a move to one additional battery and a new controller that will handle the extra 12 volts along with a new charger. It will cost about 350.00 to make the upgrade.

I think most people are in the same boat of buying in at the top end of the "low voltage" line and are faced with similar problems such a the lack of availability of 48 volt chargers in a small package and burning out controllers.

Mike

[adibrata]

Is anyone know the circuit of regenerative braking???

I have read many source about it, and most of them use MOSFET. They said that the MOSFET is atached paralel with the armarture coil in DC motor. I confuse with that beacuse what i know, if the MOSFET is attached like that, it will burn out. Any solutions??