For high-speed applications, such as drills, grinders, or tattooing instruments, the slotless BLDC motor DS16 from Nanotec is a highly efficient solution. The stator of the DS16 consists of ring-shaped plates with a flat winding on the inside. Since the windings don't have an iron core, the motor's inductance is very low and the current rises rapidly. In addition, the amount of iron lost is greatly reduced and the motors have a high efficiency rating. During slow operation, the lack of torque ripple has a positive effect. Unlike standard BLDC motors, the magnetic field isn't reinforced at the pole shoes and there is no cogging torque.
DS16 is available in size S with a power output of 3.7 W at max. 27,000 rpm, in size M with a power output of 10 W at max. 30,000 rpm, and in size L with a power output of 25 W at max. 29,000 rpm. The low inductance of these slotless motors, combined with the PWM frequency of the controller, can lead to high current ripple generating additional heat. Therefore, additional motor throttles need to be used between the controller and motor.