Hello Brad,
There are a lot of examples in the www. I found this 3rd party .NET assembly utility for you:
Write to XLS, XLSX, ODS, CSV or HTML Files from your .NET applications
You can integrate it into your PB .NET application
There is a feature to convert any type of format:
GemBox.Spreadsheet Samples - Convert
But I'm not sure if it is free of charge 
Hope this helps
Jacob