You can simulate NTCs in Multisim, but you cannot use the RESISTOR_VIRTUAL as a thermistor because it was designed to behave like an RTD. To simulate an NTC Thermistor you will need to :
- Generate a new component with the component wizard (Tools>>Component Wizard)
- If you have any concerns on how to use de Component Wizard, follow the suggestions in the Creating a Custom Component in NI Multisim tutorial.
- Within the Select Simulation Model step, include a resistor model which reflects the thermistor's behavior. For example, you could include the following model for a 1 kΩ thermistor:
.SUBCKT 1KOHM_NTC__THERMISTORS__1__44 1 2 PARAMS: T0=20 R0=1k T1=120 R1=55
R1 1 2 (R0*((R1/R0)^((T0*T1-TEMP*T1)/(TEMP*T0-TEMP*T1))))
How does an RTD resistor behave?
As temperature increases, its resistance rises according to:How does an NTC thermistor behave?
As temperature increases, its resistance gets smaller according to the R vs. T equation:
If you want to derive the equation from known value pairs (T0,R0) and (T1,R1) instead of from the abstract values of K1 and b, the equation reads:
The model suggested in step 3 of the solution section uses this equation as part of the simuation model for a thermistor.