Is the stepper motor fast?
The motor rotation speed faster, the back EMF is generated, and the torque is small, until the frequency to a certain extent, the motor torque can overcome the friction when the motor stops rotating, and the motor with a clamor (electromagnetic noise).
The main reason is because the pulse voltage of stepper motor operation, and the pulse voltage keeps changing the direction of the current in the coil, and the frequency change of the voltage of the motor to turn faster, faster, due to changes in current direction within the coil does not stop, the faster change in the direction of the current coil
The speed is much slower than the DC motor, and the 3 thousand rpm is already fast
