Auto Calibration

by | Mar 6, 2015 | 2 Axis Installation-Group, Brushless Motor-Group, Getting Started, IPm WebControl, Quick Start Guides | 0 comments

Requires version 3.00 and higher

This assumes that all Location (here) and both axis Motor set up has been completed, wiring is completed and you are ready to track the sun.

Sometimes solar trackers can lose position due to mechanical slop, hysteresis or external forces. By enabling and configuring Auto Cal, the Tracker IPm now utilizes the lower limit switch to recalibrate the tracker each day. You store the memorized calibrated value of the limit switch in a non-volatile register which is passed to the present position value “Pv” whenever the switch is closed.

Tech Tip:

This will permit the tracker to recalibrate itself every morning or permit an operator to easily recalibrate remotely. Simply drive the tracker to the lower limit switch in Manual and return it to Auto and it is re-calibrated.

 

Set Up

You do not have to know the exact position of the lower limit switch to set it’s value. Simply estimate and calibrate it using the sun using this procedure.

Azimuth (Disregard for Single Axis or Parabolic Trough)

  1. Ensure the AUTO-MANUAL switch is set to MANUAL before beginning.
  2. Either through the I/O Toolkit’s test I/O (D IN tab, transfer address x118) or the IPWebcontrol site, ENABLE Auto Calibration by turning on AZI01_AUTO_CAL.
  3. Enter the approximate (estimated) azimuth (in degrees) of the minimum limit switch in the AZI01_ZERO transfer (F IN tab, transfer address FI146)
  4. Now you will move the tracker to contact the limit switch. Put the tracker IPm into MANUAL by turning off AZI01_AUTO and turning on AZI01_CALIBRATE (D OUT tab, transfer addresses Y108 and Y109 respectively)
  5. Using the EAST-WEST manual switch, move the tracker EAST until it contacts the minimum limit switch and stops moving. This is indicated by AZI01_ZMIN (D IN tab, transfer address X122) switching to ON
  6. Turn off AZI01_CALIBRATE (D OUT tab, transfer address Y109)
  7. Turn on AZ01_AUTO (D OUT tab, transfer address Y108). This should return the Tracker IPm to automatic tracking. This is when you calibrate the limit switch, and you can do this any time while the tracker is in Auto
  8. If the tracker is not on the sun, enter a value in degrees (including decimals) to AZ01_CORRECTION (F IN tab, transfer address FI144). The number can be a rough estimate and can be plus or minus depending on which direction you want to go. By looking at the results, you can change this number as many times as needed until the tracker is on the sun while AZ01_AUTO is in AUTO. Then you are done with the azimuth Auto Calibration. The next time the tracker contacts the limit switch it will add the correction to the limit switch’s azimuth and render it’s exact position to memory.
  9. The calibration is complete. By repeating steps 3-6 you can prove the accuracy of the calibration.
  10. Return external switch to AUTO

NOTE: The soft limit AZI_MIN_DEG set in I/O Toolkit’s test I/O (F IN tab, transfer address FI108) or Web Control must be a lower value than the calibrated value of the minimum limit switch otherwise the tracker will never reach the limit switch.
Altitude (same procedure)

  1. Either through the I/O Toolkit’s Test I/O (D IN tab, transfer address X117) or the IPWebcontrol site, ENABLE Auto Calibration by turning on ALT01_AUTO_CAL
  2. Enter the approximate (estimated) altitude (in degrees) of the minimum limit switch in ALT01_ZERO (F IN tab, transfer address FI146)
  3. Now you will move the tracker to contact the limit switch. Put the tracker IPm into MANUAL by turning the off ALT01_AUTO and turning on ALT01_CALIBRATE ( D OUT tab, transfer addresses Y100 and Y101 respectively)
  4. Using the UP-DOWN manual switch, move the tracker DOWN until it contacts the minimum limit switch and stops moving. This is indicated by the ALT01_ZMIN (D IN tab, transfer address X120) turning on
  5. Turn off the ALT01_CALIBRATE transfer (D OUT tab, transfer address Y101)
  6. Now turn on the ALT01_AUTO transfer (D OUT tab, transfer address Y100). This should return the Tracker IPm to automatic tracking. This is when you calibrate the limit switch, but you can do this any time
  7. If the tracker is not on the sun, enter a value in degrees (including decimals) to ALT01_CORRECTION (F IN tab, transfer address FI141). The number can be a rough estimate and can be plus or minus depending on which direction you want to go. By looking at the results you can change this number as many times as needed until the tracker is on the the sun while the ALT01_AUTO is in AUTO. The next time the tracker contacts the limit switch it will add the correction to the limit switch’s altitude and render its exact position in memory.
  8. The calibration is complete. By repeating steps 3-6 you can prove the accuracy of the calibration.
  9. Return external switch to AUTO

NOTE: The soft limit ALT_MIN_DEG set in I/O Toolkit’s test I/O (F IN tab, transfer address FI101) or Web Control must be a lower value than the calibrated value of the minimum limit switch otherwise the tracker will never reach the limit switch.