BLDC Motor Drive control
Are you able to accelerate the motor from 0rpm to 7500rpm in one second? If not you will not be able to perform the reverse action in that time. 

It may very well be time to consider why you believe you need to stop in one second. This level of performance may not be possible with the motor, load and type of drive electronics that you are using. 

A more normal operational scenario would be to anticipate ahead of time when you need to stop the motor and then start the deceleration curve at such time that the 0rpm condition occurs at your needed stopping point. You could compare this to operating your car. As you are approaching a red light at 50kph you do not keep up that velocity until you are right on top of the intersection. Instead you anticipate the need to stop and start braking well before the intersection. 

Finding the characteristics of your system and learning what maximum acceleration and deceleration are possible is part the tuning study that needs to be done during the design and development phase. Proper selection of the motor, power system and driving subsystem are all part of this process.