Arduino Oven Controller PID
@ January 17, 2012
| Attachment | Size |
|---|---|
| TC_Relay_Controls.tar | 4.08 KB |
| pid_control_result.PNG | 253.58 KB |
This is my Arduino temperature-ramp PID controller, which is running on a hot plate (up to 325 C) and which shall also be tested on a furnace (up to 650 C). This controller integrates some interesting stuff that I didn't make, using libraries I didn't write, but perhaps this will be useful to someone.
Introduction
Common furnace PID controllers focus on reaching temperature set-points and are manually set. This controller allows a final temperature set-point and a rate to be specified using serial commands to an Arduino.
An example command "S300 R10" would set a final temperature of 300C and a rate of 10C/minute, starting from the current temperature. A PID controller aims to match the moving temperature ramp.
The challenge for this controller is to make the relay not switch excessively -- I want to avoid wear on the relay, as it's switching a lot of power and is rated for 100,000 events at its rated power.
Components
- McLaughlin Engineering Thermocouple Shield and Max31855 Library
- Omega K-type Thermocouple (I'm using 0.010" bare wire)
- Relay or Power Switch Tail II on Arduino Pin 7
- Arduino
Arduino Source Code Follows and is attached as "TC_Relay_Controls.tar"
https://github.com/John-NY/Arduino_Oven_Controller_PID
Results for a Hot Plate
The above plot shows a hot-plate test to its maximum temperature.
@ Thu, 2012-01-19 01:32
Collected
Now I've got my eyes open in the lab for a nice hotplate to hack into. Thanks for the "Something Else."
@ Thu, 2012-01-19 01:20
Nice project :-) Being an
Nice project :-) Being an HVACR tech since many years, I didn't know that the Arduino was capable of doing such a task. I have K-Type thermocouple and I would like to try this too. Thanks for sharing and for the tip. Cheers.
@ Fri, 2012-01-20 00:06
Thanks!
I just started using thermocouples, so I took a look around for a "toy" thermocouple application that I could use to check my temperature readings. The idea was that when I get a questionable reading from a thermocouple, I can toss in a second or third sensor to confirm. As it turns out it was pretty educational - I hadn't realized that the thermocouple contact chemistry could be important.