Setting up PID on an H100 VFD

Setting up PID on an H100 VFD

PID (which stands for Proportional, Integral, and Derivative) control is a process control loop used to regulate a variable such as temperature or pressure.  In terms of VFDs, this is usually accomplished with a transducer that provides feedback to the VFDs analog input. A set-point is setup in the VFD. The purpose of the PID loop it to automatically adjust and regulate motor speed to achieve a stable feedback as close to the set-point as possible. 
PID example on an HVAC system


Enable PID
  1. Set PID01= Yes

Selecting and Scaling Units
  1. Set PID50 to the appropriate units. these units should match the transducer.
  2. Set the maximum transducer value in PID53.  Example, a 150PSI transducer would be set to 150.
  3. Program the set-point (reference) source in PID10. Most applications use keypad.
  4. Input the desired set-point, the value you want to maintain, in PID11.
Feedback Setup
  1. Set the feedback source in PID20. This is most commonly I2 since transducers are usually 4-20mA
  2. Wire your transducer according to the below diagram. Watch for polarity!

Sleep Function
The sleep function will put the drive to sleep (stop it) when system demand is low.
  1. Set the desired sleep frequency in AP1-08. This is the speed at which the VFD will go to sleep.
  2. A delay time for sleep can be set in AP1-07. 
  3. In order for sleep to work properly a wake-up must be set. AP1-10 is a wake up deviation level. Example: If your set-point is 60PSI and the wake-up is set to 10PSI, the VFD will wake-up at 50PSI. 60-10=50.
  4. Additionally, there is a wake-up delay time set at AP1-09.
Submersible Pumps
Submersible pumps often use a thrust bearing. The pump must ramp up to 30Hz within 1 second in order for the thrust bearing to be properly lubricated. Setup the below parameters on submersible pump applications.
  1. Set ADV60=30Hz.  This is our accel/decel switch frequency.
  2. Set BAS70=1 second and BAS71=1 second. This makes the VFD ramp up to 30Hz in 1 second. It will also ramp down from 30 to 0Hz in 1 second.
PID Loop Tuning
If the PID loop is not responding quickly enough the below parameters are recommended.
  1. The default P-Gain in PID25 is 50%.  It is recommended to set this at 100% for quicker response to feedback changes.
  2. PID26 is the integral time, and defaults to 10 seconds. Decrease this time to about 2 seconds to achieve a tighter PID loop.
Monitoring
The below settings will pin the set-point and feedback to the main monitor display. This will make it easier for tuning and monitoring the system responsiveness.
  1. Set CNF22=18 PID Ref
  2. Set CNF23=19 PID Fbk
LSE PID Guide (Cheat Sheet) for ALL LSE AC Drives
Quick view below or download the spreadsheet attachment.