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  Definition of series hybrid cycles
In a '''series hybrid cycle''' (SH) or "electronic bicycle"
human power is converted into electric power using a '''pedaled generator'''.
In "chainless" SH cycles chain or
shaft drives are substituted by pedaled generators.
SH cycles can be bicycles, tricycles or quadracycles, or they can have the form of boats or other kinds of machines.

How series hybrid cycles work
For maximum efficiency, during the ride, pedaling power is fed directly
into the electric motor, not into the battery. The battery however delivers
current while the pedaled generator accelerates from stand still to nominal
cadence. The motor of a SH cycle delivers about twice the torque of a
parallel hybrid cycle motor because the SH cycle has to start (on hills)
without the help of a chain or a shaft drive. With SH cycles every mode of
operation is possible between 0 and 100% pedaling effort.

History
The first publication known is from May 1975 and is by Augustus Kinzel (US
Patent 3'884'317). However since there are no power electronics Kinzel's
version of the electrically powered cycle had difficulties to start and
would only work at elevated speed of pedaling and rolling.
The first persons to understand that technology is mature enough for series
hybrid human powered vehicles were Bernie Macdonalds and Thomas Müller in
1994 and 1995. Macdonalds and Müller recognized that brushless electric
machines with modern, strong permanent magnets and power electronics allow
to actually build efficient series hybrid drives. The power electronics load
the generator and allow recuperation of kinetic energy by loading the motor
during braking of the vehicle.
The Electrilite by Macdonalds is not a cycle, but a lightweight commuter
sports vehicle with two seats. The concept dates from 1994 and 1995.
Thomas Müller designed a "Fahrrad mit elektromagnetischem Antrieb" in his
diploma thesis from winter 1994/95 as an industrial designer and actually
built a sporty mountain-bike like bicycle which was test-ridden already at
this time!

At Berne University of Applied Sciences Jürg Blatter and Andreas Fuchs built
a ridable bicycle with pedal generator to simplify a complex
electro-mechanical human-electric hybrid drive of an ultra-lightweight
mobile somewhat similar to Electrilite but with only one passenger seat,
built during winter 1995/96. The early work is documented in "Bicycling
Science" 3 by D.G. Wilson, third edition, or in the proceedings of the 1999
Velomobile Seminar on "Assisted Human Powered Vehicles". In 1998 the drive
with pedal generator was mounted onto a Leitra chassis where it continued to
work reliably for years.
In the 1999 Velomobile Seminar proceedings Harald Kutzke describes his
concept of the "active bicycle". Part of the concept is that an active
bicycle compensates the losses and the drag associated with the bicycle, but
not of the rider: Aim is to electronically approach the ideal bicycle
weighing nothing and having no drag at all. In Hannes Neuperts book "Das
Powerbike" Kutzke wrote about this topic under the title of the so called
"Electronic-Bike".


Since a pedaled generator can be built as lightweight as a chain drive it
has very low rotational inertia and therefore, upon start of pedaling, the
pedal starts much faster than on a bicycle with chain. Such acceleration is
too quick to be ergonomical. Therefore Andreas Fuchs worked on solutions to
this problem which is described e.g. in patent EP 1165188.
For Swissmove, Peter Lacher built power electronics which allow to sufficiently brake the pedal of a two-wheeled working model so that ergonomical starting behavior of a series hybrid bike can be realized using a reasonably sized electric machine. In 2008, Peter Lacher also implemented CAN Open for communication with a well working motor controller. This step allowed to improve the two-wheeler which now runs very well.
Until 2008 five series hybrid bikes, trikes and quadracycles with ever
improving components have been built. According to experiences from test rides range per Watt-hour battery capacity is as good
as in traditional electric bicycles because human and electric drive
do not interfere by mechanical means.

Andreas Fuchs, update June 3, 2012  


 
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