Convert IPN to PDF

Autodesk Inventor presentations (.ipn) are used to demonstrate a single 2D view or a 3D rotation of certain part or assembly, as such these can be usually exported as videos (.mp4, .wmv) and not as PDF documents, which is why a direct ipn to pdf conversion seems somewhat unlikely.

You would have to access the original source that was used to create the presentation (.ipt file) and use that file in order to create a PDF or 3D PDF document from it. In any case, you will need Inventor for this.

Simply put, it is impossible to convert IPN to PDF directly.
Thus, there is no so-called ipn to pdf converter or a free online .ipn to .pdf converter to be found.