[SOLVED] control algorithms on heater

[mohamed.elsabagh]

I would like to design a heater controlled by microcontroller, and I don't want to use PID control algorithm because the initial temperature of this heater is not constant or unknown (calculated during run time).

 

[horace1]

how are you going to set the temperature at run time, e.g. keypad, potentiometer, etc? In any case PID is probably overkill, proportional is usually sufficent unless one has a very sophisticated system. e.g. as the temperature gets closer to the set point you reduce the power going into the heater (PWM is a useful technique for this)

 

[andre_luis]

mohamed.elsabagh,

To control manage heating devices, is most used histeresis loopback, that works like thermostat.

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[mohamed.elsabagh]

I am not going to set the temperature at the run time, I will give you an example if 2 heaters are going to heat a body the first heater is going to heat up the body to temperature x given by the user, the next step the second heater will heat the body from temperature x up to temperature y, each heater should be controlled by a separate algorithm for example PID.

 

[horace1]

I am not sure what you problem is. In your first post you stated "I don't want to use PID control algorithm ...". If so you can use simple ON/OFF (with hysteresis as indicated by andre_teprom). In you last post you said you would have two heaters both controlled by PID. Which are you interested in ON/OFF or PID control ? In practice I have found proportional control (using PWM) is satisfactory for water heating systems, etc.