This is a fairly common trick in Europe and is only for use on dual voltage (for example, 230/460v) motors.
Essentially, you buy a higher voltage (460) drive with the ampacity to cover the motor's lower (230) volt FLA.
Since motor current and torque at a given load is a function of the volts per hertz ratio, you set up the drive for a constant ratio from 0 to 120Hz. That gives the motor the same potential torque output over the whole speed range to 120Hz.
Yes, that does result in twice the motor nameplate hp at 120Hz but remember that the cooling fan is turning twice as fast also. And, motor heating is much more related to current than to hp output.
The end result is a motor with a constant torque speed range up to double nameplate speed and, possibly, (heat and balance permitting) up to twice the nameplate hp.
Crafty, I must say, but you must be a bit carefully that you don't ruin the motor. There is very little in this world that comes for free and that includes the world of drives too!