This project allows for manual and automatic temperature control of an aluminum block using a thermoelectric (TE) device. A high-side switch IC is used to turn on and off the device, while the direction of the current through the TE unit is controlled by a 12 V DPDT relay in an H-bridge configuration. This results in an ON/OFF temperature controller with the ability to switch between heating and cooling mode. Two LM35 temperature sensors monitor the ambient room temperature and aluminum block temperature.
The LabVIEW program has both a manual and automatic mode. In manual mode, the current through the TE device is controlled with the “TE Current ON/OFF” and “Heat/Cool” buttons on the program’s front panel. In automatic mode, the program tries to maintain the temperature set point entered by the user. It accomplishes this by first determining whether it needs to heat or cool the block based on the difference between the set point and ambient room temperature. Once the program sets the correct current direction, it simply turns on and off the TE device via the high-side switch when it reaches the desired temperature.
This video shows manual mode operation of the unit after 10 minutes in the “Cool” setting. You can see the ice on the aluminum block melt shortly after the program is set to “Heat”. In automatic mode, this setup is capable of achieving temperature control of ±0.5°C from set point.
Post time: Jun-06-2017