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Drives Instructions (INTG, PI, PMUL, SCRV, SOC, UPDN)
The SOC instruction can be used in a torque or tension regulating application
where a load cell or force transducer is used as feedback and the output of the
regulating scheme operates directly on the torque (current) minor loop of the
drive. In many such applications, the controlled system may be mechanically
under-damped and have a natural frequency which is difficult to stabilize as it
becomes reflected through the feedback device itself.
load
motor
drive
torque
signal
Using the SOC instruction, PID tuning is simplified because the regulating
terms can be arranged so that you have WLead and ZLead as inputs to the
SOC instruction, rather than Kp, Ki, and Kd values. In this manner, the corner
frequencies of the controller/regulator are easier to adjust and setup against
the real world process. During startup, the natural frequency of the system and
the damping factor can be measured empirically or on-site. Afterward, the
parameters of the regulator can be adjusted to match the characteristics of the
process, allowing more gain and more stable control of the final process.
second order controller
second order lead (WLead)
moves gain from -1 to +1
Publication 1756-RM006D-EN-P - May 2005
process
system natural
frequency