Reduced stopping time with a soft starter

I have an application where the load (industrial grinding machine) is presently started by a soft starter. We normally free wheel stop, but now want to consider safety and try and stop the grinder more quickly. I have done some investigation and am considering "plug braking" by reversing the motor phasing and starting the soft starter again. I guess I will need a zero speed detector of some sort to prevent the motor load from ramping up in the reverse direction.

I don't need to stop the grinder as quickly as it starts so was considering using a lower current limit when "plug braking". Does the motor produce the same torque/current vs speed profile when doing this? Is is possible to work out what the stopping time is for a given current limit? I have all the load details such as motor info, gear ratio and load inertia.

Also, the soft starter has DC injection braking on it. The maximum current that it can inject is 100% for 60secs. I don't know if the 100% relates to the soft starter size or the motor size. Will 100% current be sufficient to help stop the motor? I read another thread on DC injection and this helps explain what goes on in the motor but I was wondering is there any formula for working out the actual stop time? As mentioned above we don't have to stop it as quickly as it starts. (it starts in 43 secs with 350% FLC. I hope to stop it in 180secs)

Our site safety comittee needs me to state some figures. If they approve then I will have to make it stop in the time I give.

Any help would be appreciated.
BigTrev1