SINEWAVE GRINFINEON CONTROLLER MANUAL
Rev 2.1
-16-
The geared motor in Figure 16 has 32 magnets and a 7:1 gear reduction. In this
case, the maximum speed in sensorless mode would be 28000 eRPM / 16 / 7 =
250 rpm. In a 26” wheel that would correspond to 31 kph. Below this speed the
bike would run fine but any faster and the controller is liable to shut down in a
fault mode.
Figure 16: Direct Drive and Geared Hub Motor eRPM examples
The maximum speed when running with hall sensors is much higher, but at
values over 50,000 eRPM the commutation timing can be off and motor
performance will suffer.
4.2
Power Oscillations at Full Throttle when Sensored
In sensored sine wave mode, the motor controller is always attempting to
interpolate the exact motor position at any given moment in between hall sensor
events.
With certain geared hub motor installations, the controller can be prone to having
large power fluctuations at full throttle while this interpolation overshoots and
undershoots. This can be triggered by sudden changes in motor RPM (such as
hitting a pothole or popping a wheelie) and it may require releasing and
reapplying the throttle to smooth out. If the motor setup is prone to this behavior,
we recommend unplugging the halls and running the sensorless.
