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Hi, my company produces wire-wound power resistors. We want to simulate the temperature of the wire inside the resistor housing and outside the resistor housing. We use a R-C circuit. but... I need the R and the C change with the temperature, that is the voltage in the electric equivalent circuit. here's my public circuit: https://www.circuitlab.com/circuit/9f86cg/rc_base1/

Can anybody help me ?

thank you for your support

Andrea www.fairfild.com

Hi Andrea,

I've made an example circuit to demonstrate the basics of doing non-linear simulations with R and C values that vary with other voltages/currents in the system are as follows:

This shows how to use a "behavioral voltage source" to simulate a non-linear resistance, and how to use a "behavioral charge store" to simulate a non-linear capacitance.

You can also use a CSV Voltage Source to model the input to your system, although in your case (a thermal equivalent system), you probably want the input to be a current source to represent a particular thermal power flux.

Do you have existing equations / models of the thermal system? I'm sure we could help you fit them in to the simulator.

Mike

P.S. those look like serious power resistors!