Cycle Analyst V3.1 User Manual
Rev 1.0
These features are most often used to make setups comply with local ebike
regulations that stipulate maximum speed for motor assistance, and sometimes a
different limit when pedaling versus just using the throttle. A 3 term PID control
algorithm is employed in firmware to enable a smooth rollback of motor power as
target speed is reached without oscillation. The default feedback settings work
well for most ebike systems with common PWM controllers, but they may need to
be decreased for powerful ebikes, or increased by a factor of 2 or 3 for ebikes
running a torque-based controller like the Phaserunner or Baserunner.
The use of regen speed limiting is a useful feature for those who want a speed
governor behavior when riding downhill. It enables the system to automatically
enter proportional regen mode when the speed limit is exceeded without needing
to activate ebrakes.
6.7 Setup Power Limits
There are many reasons for using a Cycle Analyst to limit the power of an ebike
beyond the controller's native limits. This can be done to reduce stress on a
battery cells for better cycle life, to extend the range you are able to get on a
charge, to prevent inadventent overcurrent tripping of a BMS circuit, to limit the
risk of motor overheating, and to reduce mechanical stress to drivetrains on mid-
drive systems.
Power can be limited either with a battery current limit in amps, or a power limit in
watts. Both have similar effect, though with an amps limit the power will decline
as the battery depletes and drops in voltage, while with a watts limit it remains
constant. In general, the use of an amps limit is most appropriate when the goal
is protection of the battery pack, while a watts limit makes most sense when you
are wanting to protect the motor or mechanical drivetrain.
When the CA device is limiting power because one of these limits is active, the
diagnostics screen will capitalize the associated a or w limit flag. If the power
output becomes jerky and oscillates at this point that it is a sign that the
associated feedback gain term needs to be adjusted downwards until the
behavior is smooth via the WGain and AGain feedback terms.
If no limiting is desired, then these limits can be left at their default high values
(99 Amps and 9990 Watts) where they will not come into play.
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