maintain constant Power in varying load


by weeb0
Tags: constant, load, maintain, power, varying
weeb0
weeb0 is offline
#1
Sep21-07, 11:10 PM
P: 1
Hi,

I'm having some questions about the way I could achieve to maintain the power in a resistor constant. My problem, is that the resistor is quite small (less than 100ohm at room temperature). When running, the resistor, a heating resistor, heats up to 300celcius.

So, the resistor change in function of the temperature. So, to maintain that temperature, I want to keep the power of the resistor constant.

I have some ideas to achieve this, but I have some misunderdstanding so I miss something.

Here is my mind :

RL = Resistor Load (heating resistor)


1. find IRL : adding an Rsense of about 1ohm serially with the RL. 1A = 1V on the ouput of the opamp
2. multiply the IRL with the VRL. Obtain Power 1W = 1V.
3. find delta Power (substract Power_Setpoint from Power (step2))
4. ?????? -> using (step 3) change the current or the voltage applied to the Rsense to obtain the perfect power.


I though to use a microcontroller to control this, but I was wondering some precision issues...

So, do somebody have some suggestions ?
Do some circuit do this ?
Am I doing this right ?

Thank you for your help
Phys.Org News Partner Engineering news on Phys.org
Lifting the brakes on fuel efficiency
PsiKick's batteryless sensors poised for coming 'Internet of things'
Researcher launches successful tech start-up to help the blind
alvaros
alvaros is offline
#2
Sep22-07, 04:34 PM
P: 167
I want to keep the power of the resistor constant.
The only way is to measure both the voltage and the current across the resistor.

So, to maintain that temperature,
The only way is to measure the temperature of the resistor. If the resistance of the resistor changes with temperature ( like all resistors ) one way is to measure, again, the voltage and the current across the resistor.


Register to reply

Related Discussions
how does Lorentz transformation manage to maintain the speed of light constant? Special & General Relativity 6
Does WMAP disprove a time-varying cosmological constant? General Physics 2
Does WMAP disprove a time-varying cosmological constant? General Physics 2
Varying Fine Structure Constant? High Energy, Nuclear, Particle Physics 12