Maintain constant Power in varying load

In summary, to maintain constant power in a varying load, the only way is to measure both the voltage and current across the resistor and adjust accordingly. This can be achieved by using a microcontroller or a circuit designed specifically for this purpose. It is also important to measure the temperature of the resistor, as its resistance can change with temperature.
  • #1
weeb0
1
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how to maintain constant Power in varying load

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
 
Last edited:
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  • #2
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.
 
  • #3
.

Maintaining constant power in varying load can be achieved by utilizing a feedback control system. This involves measuring the output power of the resistor and comparing it to a desired setpoint. If there is a difference between the two, the control system will adjust the input voltage or current to the resistor to maintain the desired power output.

One way to do this is by using an operational amplifier (op-amp) to measure the output current of the resistor. This can be done by adding a small resistor (Rsense) in series with the resistor load (RL) and measuring the voltage drop across it. The output current can then be calculated using Ohm's law (I = V/R).

Next, the output current can be multiplied by the output voltage (VRL) to obtain the power output of the resistor (P = I * V). This value can then be compared to the desired power setpoint. If there is a difference, the control system can adjust the input voltage or current to the resistor to maintain the desired power output.

The control system can be implemented using a microcontroller or a dedicated analog circuit. It is important to consider the precision and accuracy of the components used, as well as the response time of the control system. It may also be necessary to add additional components, such as a filter, to ensure stability and prevent oscillations in the control system.

Overall, it is important to carefully design and test the control system to ensure that the power output of the resistor is maintained constant under varying load conditions. I hope this helps and good luck with your project!
 

1. What is constant power in varying load?

Constant power in varying load refers to the ability of a system or device to maintain a consistent power output or consumption, regardless of changes in the load or demand on the system. This is typically achieved through the use of control mechanisms, such as voltage regulators or power converters.

2. Why is it important to maintain constant power in varying load?

Maintaining constant power in varying load is important for ensuring the stability and reliability of a system. Fluctuations in power output or consumption can lead to malfunctions or damage to equipment, and can also cause disruptions in operations or services.

3. What factors affect the ability to maintain constant power in varying load?

Several factors can affect the ability to maintain constant power in varying load, including the design and efficiency of the system, the type of load being applied, and external conditions such as temperature or humidity. The quality and stability of the power source can also play a role.

4. How can constant power in varying load be achieved?

Constant power in varying load can be achieved through various methods, such as using feedback control systems, implementing power management algorithms, or incorporating energy storage devices. The specific approach will depend on the requirements and characteristics of the system.

5. What are some potential challenges in maintaining constant power in varying load?

Some of the challenges in maintaining constant power in varying load include system complexity, limited resources or budget, and changes in load or power demand that are difficult to predict or control. Environmental factors such as temperature or noise can also affect the performance of the system.

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