I don't know this specific VFD, but I see no one else has answered your post either so maybe this will help a little. If you have the manual for the drive, you would read the section on "how to change parameters" and then locate the parameter "accel time" in the parameter list. Accel time is usually expressed as a time constant, usually in "seconds required to accelerate from zero hz to max hz" OR "seconds required to go from min hz to max hz". Increasing this time constant will slow down the acceleration, decreasing it will speed up the acceleration. Speeding it up too much can cause amp draw problems or machinery problems. Motors and machinery have inertial properties that limit how fast they can actually accelerate. If you do not have the manual, try going to the manufacturer's web site. Many of them have documentation you can download. Last resort, get the phone number from the manufacturers web site for "technical assistance" or "contact us", equip youself with something to do while you sit on hold, and take the plunge. I know this VERY general info and you probably already know most of it, but.............
Best of luck,
Stationmaster