August 17, 1998 Design News
Drive's auxiliary PID loop controls
John Lewis, Northeast Technical Editor
APIControl's centennial controller series uses 40-bit
DSP technology to control brushless-servo and induction-motor
torque and velocity. Moreover, API President Greg Woods
claims the built-in programmable PID controller is ideal
for controlling and maintaining tension or pressure
without using a separate controller outside the drive.
The drive controls 1.5 axes of motion while running
concurrent PLC tasks on its auxiliary PID loop using
±10V analog or step-type commands and encoder feedback. The
PID controller runs in tandem with all the other control
loops (position, velocity, current, spline and CAM)
within the drive and executes at 10,000 times per second.
APImateTM, the setup, programming, and diagnostic
tool, features a virtual oscilloscope that captures
and plots internal drive data. This is especially useful
when using the PID controller, explains Woods, as the
reference, feedback, and output of the PID controller
can be monitored and plotted over time.
Centennial drives use DeviceNet or RS-232/485 communications,
and include dynamic-adaptive compensation, cam profiling,
master/slave mode, and offer a large complement of programmable
I/O and the ability to run concurrent I/O tasks. Line-operated,
the controllers don't need a separate power supply or
transformer. Fully protected against typical operational
hazards, the device uses battery-backed program storage,
and is UL- and CE-compliant.