How to Use a DIAC SPICE Model in PSIM Instead of the Built-in Model?

Jeff_wu · 2025-01-15T15:22:49+00:00

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Hi everyone,

I’m currently working on a project in PSIM that involves using a DIAC. I know that PSIM has a built-in DIAC model, but I’d like to use a custom SPICE model instead to achieve more precise or specific behavior.

Here are my questions:

How can I replace or bypass the built-in DIAC model and use a SPICE model instead?
What are the steps for importing and configuring a DIAC SPICE model in PSIM?

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VSiddhartha

Hi,

The element "SPICE Directive Block" is provided to write SPICE commands, options, models, subcircuit netlist, parametric attributes, and other directives which are not implemented by PSIM schematic. This block can be found in Elements >> SPICE >> SPICE Directive Block.

DIAC spice netlist can be copied and pasted in this block. To know step by step-by-step process and more details, please use following references:

PSIM»»»Help»»»Tutorials»»»"How to Use the SPICE Module"

2. PSIM»»»»Help»»»»Documents»»»»SPICE User Manual

3. PSIM»»»Help»»»Video Tutorials»»»SPICE Device Level

Thank you,

Vishwanatha Siddhartha

Jeff_wu

Hi,

I hope this message finds you well.

I am writing to discuss an issue I encountered while simulating a DIAC circuit. I analyzed the circuit using LTspice, and the results appeared consistent with my expectations. Specifically, the voltage across the capacitor exhibited behavior that seemed reasonable and aligned with the circuit's theoretical operation.

However, when I attempted to replicate the same circuit in PSIM, the results did not match those obtained from LTspice. The capacitor voltage in the PSIM simulation deviated significantly from what I observed in LTspice, leading to confusion about which results might be correct or whether there are inherent differences in how the two software platforms handle the simulation of DIAC behavior.

I have double-checked the circuit parameters, component models, and simulation settings in both software tools to ensure they are identical. Despite this, the inconsistency persists. This leads me to suspect that the discrepancy might be due to differences in the DIAC model implementation or simulation algorithms between LTspice and PSIM.

I would greatly appreciate any insights or suggestions you might have regarding this issue. If you have experienced similar problems or have expertise in these simulation tools, your advice would be invaluable in helping me resolve this.

Thank you for your time and assistance. I look forward to your response.

Best regards,

LTspice_diac.zip

untitled4.psimsch

VSiddhartha

Hi,

I verified both schematics. You are trying to measure at different point from LTspice to PSIM. As shown in figure, the node considered is another end of capacitor, whereas in PSIM schematic voltage measured across capacitor. So, there is a difference between results.

If we measure at same point in PSIM as shown in figure, you will get the same result. Further, you need to keep parameters as shown in figure. This is the main advantage we have in PSIM. We can configure DIAC as ideal and also non-ideal as per requirement.

Thank you,

Vishwanatha Siddhartha