User Manual

Motor Channel Parameters
Advanced Digital Motor Controller User Manual 89
The limitation is performed on the Motor current and not on the Battery current. See “Bat-
tery Current vs. Motor Current” on page 28 for a discussion of the differences.
Selectable Amps Threshold Triggering
The controller can be configured to detect when the Amp on a motor channel exceeds a
user-defined threshold value and trigger an action if this condition persists for more than a
preset amount of time.
The list of actions that may be triggered is shown in the table below.
TABLE 7-2. Possible Action List when Amps threshold is exceeded
Action
Applicable
Channel Description
No Action - Input causes no action
Safety Stop Selectable Stops the selected motor(s) channel until command is
moved back to 0 or command direction is reversed
Emergency stop All Stops the controller entirely until controller is powered
down, or a special command is received via the serial port
This feature is very different from amps limiting. Typical uses for it are for stall detection
or “soft limit switches”. When, for example, a motor reaches an end and enters stall con-
dition, the current will rise, and that current increase can be detected and the motor be
made to stop until the direction is reversed.
Programmable Acceleration & Deceleration
When changing speed command, the controller will go from the present speed to the de-
sired one at a user selectable acceleration. This feature is necessary in order to minimize
the surge current and mechanical stress during abrupt speed changes.
This parameter can be changed by using the PC utility. Acceleration can be different for each
motor. A different value can also be set for the acceleration and for the deceleration. The ac-
celeration value is entered in RPMs per second. In open loop installation, where speed is not
actually measured, the acceleration value is relative to the Max RPM parameter. For example,
if the Max RPM is set to 1000 (default value) and acceleration to 2000, this means that the
controller will go from 0 to 100% power in 0.5 seconds. In closed loop Torque Mode the
Acceleration and Deceleration values are entered in miliAmps per second. In case of Safety
Stop the motor will ramp down based on the Fault Deceleration configuration value.
In order to by-pass the ramping process, either the acceleration or the deceleration values
need to be set to 0.
Important Warning
Depending on the load’s weight and inertia, a quick or no acceleration can cause
considerable current surges from the batteries into the motor. A quick or no
deceleration will cause an equally large, or possibly larger, regeneration current
surge. Always experiment with the lowest acceleration value first and settle for the
slowest acceptable value.
Furthermore, by by-passing command ramp the controller cannot protect itself from
high currents.