Hello,
I want to modelise a generator with an equivalent thevenin generator in Spice. My generator will send impulsion in a switch mode power supply. I make simulation in time domain.
I have the Vco (open-circuit voltage) and the Zs (source impedance) in fonction of the frequency.
I translate the Vco in time domain with a TDF to use it in spice in a voltage generator using a file. My file is composed of the Vco amplitudes and the times.
For the Zs I need your help. I have the Zs in fonction of the frequency. How is it possible to include it in Spice ? Does exist a function where I could insert my frequency Zs file ?
Thank you in advance
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Hello,
It is my understanding that you want to define a frequency dependent impedance. For that I recommend you to read the PSpice Application Note "Modeling Impedances with ABM". You find it in the "Learning Pspice" resources. Just open OrCAD Capture and click on Help Learning PSpice.
I hope it helps.
Regards
Hello,
Yes, I want to define a frequency dependent impedance. I measured my impedance with a network analyser and so I have a file of three columns. The first one with the frequency, the second one with th real part of the impedance and the last one with the imaginary part of the impedance. I want to include it in PSpice. I don't think the application note could help me.
Thank you again in advance
Hello,
Then I think this option will help you. You could use the component EFREQ, where you can select a table with three inputs. First one for the frequency, second one for the real part and the thrid one for the phase. If you want to use Decibels, then in the property write MAGUNITS=DB, if not just write MAGUNITS=MAG.
Regards
Hello,
I don't understand the component EFREQ. And I don't know if I explain really good my problem. I have a CSV file in which the first column is the frequence between 1kHz and 100 MHz, the seconde one with the real part of the impedance and the third one with the imaginary part of the impedance. And I would like to implement this impedance dependinf of the frequency in Orcad (pspice) to simulate my circuit in the time domain. In serie with this impedance I will place a voltage generator in which I use a csv file of my thevenin generator Vco (open circuit voltage of the equivalent thevenin generator).
Thank you again
Hi,
Thanks for all the information. I do not know personally a way to integrate a CSV file with your features in PSpice. It is possible to integrate time-voltage pairs CSV files.
That is why, the option I considered to generate the resistor you need was to use the EFREQ to "convert" your data (freq, MAG, Phase) to voltage and then whit this component connected to a GVALUE component, it could be possible to generate your desired impedance.
Maybe someone in the forum has other alternatives.
Regards
Hello,
Ok thanks, I will try this.
I have another problem. For my open-circuit voltage Vco of my equivalent thevenin generator I use a VPWL_F_RE_N_TIMES in which I use my csv file.
I want to coupling my pulse (thevenin generator) on the sector voltage (VSIN 230Veff) but I don't know how I make it.
I try to place my VPWL in serie with the sector VSIN but in this case my switch mode power supplie don't run ... I don't have my sinus with my pulse in addition (coupled on my sinus) at a some time.
I don't know if it is clear.
Thank you again
Hi,
If I understood properly you want to couple your source (VPWL) with a VSIN in a particular moment in a switch power supply, but it is not working. Could you share your circuit? Could you specify a little bit more the problem you are facing?
Regards
Yes, you well understood. And if I place my VPWL in serie with my VSIN at the input of the switch mode power supply it don't work because in output I don't have the worker voltage (19V).
If I delete the VPWL and I just place only the VSIN at the input I have well the output voltage of 19V. I can't couple my pulse (VPWL) with the VSIN at the input of the SMPS. I don't know how I can do it.
Thank you again
To include the frequency-dependent source impedance (Zs) in blossom word game, you can use the built-in behavioral sources or use a combination of passive components to approximate the impedance characteristics.
To model a generator with an equivalent Thevenin generator in Spice, you can use the following steps. Spice, which stands for Simulation Program with Integrated Circuit Emphasis, is widely used for electronic circuit simulation.
Define the Voltage Source: Assume you have a voltage source representing your generator. In Spice, you can define a voltage source using the "V" element. For example:
spice
V1 N1 N2 DC 10VThis line creates a voltage source named V1 between nodes N1 and N2 with a value of 10V.
Add Internal Resistance: A Thevenin equivalent includes an internal resistance. Add a resistor to represent the internal resistance of your generator. For instance:
spice
R1 N2 N3 5 OhmThis line adds a resistor R1 between nodes N2 and N3 with a resistance of 5 Ohms.
Connect Load Resistance: To complete the Thevenin equivalent, connect a load resistor to the circuit. This resistor represents the load connected to your generator.
spice
R_load N3 N4 10 OhmGround Reference: Specify a ground reference for your circuit. This is essential for simulation.
spice
0 N1 0Simulation Commands: Include simulation commands to define the analysis you want to perform, such as a DC operating point analysis or a transient analysis.
spice
.DC V1 0V 10V 1V .PRINT DC V(N4) .ENDIn this example, a DC sweep is performed on the voltage source V1 from 0V to 10V with a step of 1V. The voltage at node N4 (output) is printed during the analysis.
The above steps provide a basic example. Depending on your specific generator and application, you may need to modify the circuit accordingly. Always refer to the Spice documentation for precise syntax and options.
Remember to replace the values and node names in the example with your actual circuit parameters. Spice simulation tools can help you analyze the behavior of your generator modeled with a Thevenin equivalent circuit under different conditions Sinistea.