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algorithms necessary for vector drive technology are
computationally intense, it was generally not practical to implement
them in an affordably priced brushless servo motor drive in the past.
The same DSP technology that makes vector drive technology a
reality in all Axiom brushless servo drives, makes all digital control
loop tuning and other advanced features practical in all Axiom
brushless servo motor drives. These drives are designed and built to
provide enhanced performance and years of dependable service.
The first performance improvement incorporated into Axiom PV
and DV series drives is an enhanced commutation scheme known as
Space Vector Commutation. This commutation scheme is similar to
sine commutation except that it uses a more computationally
intense algorithm that gains back some of the bus voltage utilization
lost in sine commutation. Axiom PV and DV series drives will
typically provide 12.5% more speed at a given torque than the
theoretical maximum possible with sine commutation.
Furthermore, as a Vector Drive, all Axiom PV and DV series drives
provide closed loop motor control of torque producing current.
They accomplish this by first accurately measuring motor current in
each motor phase leg 10,000 times each second. This information is
used to calculate the actual torque producing current vector being
produced in the motor.
Because this is a true vectored closed loop current control system,
torque errors due to tolerances and R-L time constant induced
phase lag are automatically compensated for in the algorithm. All
Tol-O-Matic MRV motors can be driven from zero speed to full rated
speed with negligible torque ripple or loss of torque due to tolerance
or current phase lag issues.
In addition to the enhanced drive features built into all Axiom series
drives, the Axiom Plus PV series incorporates a 1.5 axis motion
controller in the same package. This controller has a sequential
program thread that executes the motion commands. It also has a
scanned “PLC” ladder logic thread to allow I/O and control logic
functions to run asynchronously with respect to the sequential
program.
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