Proceedings of the 6th European Seminar on Velomobile

[paultrafalgar]

http://www.liggecykelforeningen.dk/Designseminar/Proceedings
A list of papers to download is included.

 

[Miles]

Thanks Paul

 

[paultrafalgar]

No Serious Students of ebikes should fail to read this:
http://www.liggecykelforeningen.dk/Designseminar/ParallelHybridDrive
Download the pdf and study it!
"
Abstract

This paper discusses the basic configurations of drive systems for human electric hybrid vehicles.

The e-bikes on the market today are parallel hybrids (PHEB, parallel hybrid electric bicycle). In parallel hybrids it is attempted to mechanically add the highly variable torque of a pedalling human with a constant torque of an electric motor. Some vehicles have the motor near the bottom bracket, while others use motors near or in the front or rear wheel. A special case of a parallel hybrid is Michael Kutters drive system where electric and human power are added using a planetary gearset in the rear wheel hub.

In a series hybrid human electric hybrid (SHEB, series hybrid electrical bicycle) human power is converted into electric power using an electric generator driven by the pedals. Mechanical drive power to move the series hybrid vehicle is produced by a motor driving the wheel just as in the case with the parallel hybrids having either a front wheel or rear wheel (hub) motor.

The different kinds of hybrid drives and their disadvantages and benefits with respect to use in recumbents and velomobiles as well as in upright cycles are discussed.
Paper

Download PDF: vmsem6-fuchs--parallel-hybrid-drive.pdf (English, 2884 KB)


Conclusions
Various ways to couple human and electric machine are possible, using mechanical
and electrical methods.
The data from performance measurements show that bottom bracket motor systems
do not necessarily perform as well both in the flats and on slopes as do front wheel
hub motors, although one would expect that, based on the fact that the motor can
also use the mechanical gears of the human power transmission via chain. More
research is needed to identify the real reasons for this effect.
One hypothesis of the author is, that since the motor is mechanically coupled to the
pedals, it is not allowed to run freely (e.g. on a power hyperbola) according to the
needs of the drive situation. So not the full dynamic range of the motor is used. The
bottom bracket motor is loaded variable only in the dimension of torque, but not in the
dimension of speed (rpm). Doubling electric drive power therefore leads to
quadrupled energetic losses in bottom bracket motors.
Hub wheel motors perform well, at least if in the front wheel. More reasearch, maybe
using younger e-cycle models than those from 2002, could eventually reveal the
reasons why the rear wheel hub motors performed so poorly on the hills.
Final conclusions regarding the potential of the series hybrid drive system for
dynamic riding and energetic efficiencies can not be made yet because no fully
developed products exist at this moment.
"

 

[vanilla ice]

The data from performance measurements show that bottom bracket motor systems
do not necessarily perform as well both in the flats and on slopes as do front wheel
hub motors, although one would expect that, based on the fact that the motor can
also use the mechanical gears of the human power transmission via chain.

Whaaaa? One would expect that? No one wouldn't.