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Tuning
Draw a simplified 3 cascade PIP control loop. What are the advantages of using this structure over a traditional PID control loop?
PIP is easier to tune, can use feed forward and gain scheduling is also possible.
What are the 5 main steps of the composer wizard tuning process?
Current gain tuning, commutation, digital inputs and outputs, velocity gain tuning and position tuning
What types of communications are available for the drive? What is the baud rate of each?
RS232 – up to 57,600 bps
CAN bus – up to 1 Mbps
What is auto phasing? When is it used?
To obtain the proper commutation angle each time the drive is switched on. This is done when no absolute sensor is available.
What is the method for manual velocity tuning?
Set KP=0 and KI=0. Set a range of movement (±1000 counts) and a velocity (±1000 counts/second), and observe the velocity command with respect to the actual velocity. Double KP until there is a 25% overshoot, decrease KP by 75% to start KI and obtain the rise time. Take KP/Rise time and start KI. Increase until the velocity command and the velocity track well.
What is a good indication for instability of the system in the step response?
Signal Oscillation, high overshoot and undershoot.
What would you do in the case of current saturation during the step response tuning of the drive?
Slightly lower the speed of travel. If the saturation is large, decrease it significantly.
What is KI of the velocity used for?
To stabilize the velocity during steady state motion (0 velocity error).
What is the position error (PE)?
The difference between the commanded position with respect to the position feedback, i.e., PCMD-Px.
What is the rise time of a step input?
The time it takes for the velocity to go from 10% of the desired velocity to 90% of the desired velocity.
What types of advanced filters are available in the Composer?
Encoder jitter filters (main and auxiliary), DI LPF, notch filter, low pass single and double pole, lead lag.
Describe the tuning process in 4-5 brief, bullet point steps
Set KP=0 and KI=0. Set a range of movement (±1000 counts) and a velocity (±1000 counts/second), and observe the velocity command with respect to velocity. Double KP until there is a 25% overshoot, decrease KP by 75% to start KI and obtain the rise time. Take KP/Rise time and start KI. Increase until the velocity command and the velocity track well.
Add position tuning: (0.5/Rise time x KP)
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