37
Whenever a motor is operated beyond
its optimum operating point, its efficiency
decreases. This results in the energy no
longer being optimally converted, but
rather a proportion of the energy supplied
being converted into heat. Because of
this, the range decreases and the heat
must be discharged. In neodrives motors
this heat is discharged through a large
contact surface inside the motor (stator
carrier) to the dropout or chainstays of
the bicycle frame. Cooling ribs inside and
outside the drive casing additionally ensure
the greatest possible heat exchange with
the surroundings. Heat which cannot be
discharged results in the drive motor being
heated up.
The neodrives wheel hub motors monitor
both the energy supplied and the
temperatures in the motor. Any damage
through overheating owing to overload can
thus be avoided. This, however, results in
the motor performance available to the rider
being reduced to avoid overheating.
If a temperature of 80°C is exceeded in
the motor electronics, the motor control
reduces the supplied power and thus the
assistance. This is indicated in the sMMI by
the thermometer symbol shown opposite
(see section 3.2.11). As the temperature
increases, the power is continually reduced.
This means: the greater the
temperature increase in the motor,
the less drive power can be
obtained and the less assistance
is available. When the motor cools down,
the energy supplied is increased again and
the drive power increases.
This control of drive power according to
the motor temperature is infinitely variable
so that there is always asistance available,
but the motor cannot be damaged by
overheating.
In practice
The above aspects, in practice, lead to
dependence on the outside temperature,
the total weight, incline, terrain, cadence, air
pressure and speed. These factors may lead
to a temperature which causes the power
or assistance to be reduced. This, however,
does not mean that a fault or failure has
occurred in the drive, you can proceed with
less assistance. In extreme cases, a short-
term complete shutoff may occur.
Summary of Contents for Orsted
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