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Can I simulate an NTC thermistor with the RESISTOR_VIRTUAL component in Multisim?

Primary Software: Electronics Workbench>>Multisim
Primary Software Version: 12.0
Primary Software Fixed Version: N/A
Secondary Software: N/A

Problem: If I place a RESISTOR_VIRTUAL in Multisim, I am given temperature paremters such as TC1, TC2 and TNOM. Is it possible to set these parameters to make it behave like a thermistor?

Solution:

In Multisim, you can simulate NTCs, but you cannot use the RESISTOR_VIRTUAL as a thermistor as it behaves like an RTD.


 How Does a 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 not from the abstract values K0 and b, but from known value pairs (T0,R0) and (T1,R1), the equation reads:

Simply generate a new component with the component wizard (Tools>>Component Wizard) and within the step Select Simulation Model include a resistor model which contains this behaviour.

For example the SPICE model f 1kOhm 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))))
.ENDS
See also the attached thermistor for use in Multisim.



Related Links: KnowledgeBase 40D2DFFE: How can I simulate a Pt100 RTD with Multisim?


Attachments:

NTC_Thermistor.zip 



eq_RTD.gif - eq_RTD.gif
eq_NTC.gif - eq_NTC.gif
eq_NTC_recalc.gif - eq_NTC_recalc.gifTHERMISTOR_NTC_1kOm.zip - THERMISTOR_NTC_1kOm.zip


Report Date: 08/23/2006
Last Updated: 07/31/2012
Document ID: 40M88VFE

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