Upvote:5
You seem to be under the mistaken impression that an invitation is necessary to apply for a visa. It is not.
To accompany you on your business visit, your wife does not need an invitation from her employer, though it may be helpful to include a confirmation of her leave. She does not need anything from your employer other than an acknowledgement that she will be accompanying you on your business visit. The correct type of application, as noted in a comment by Michael Hampton, is "tourism."