By submitting this form, you are agreeing to the Terms of Use and Privacy Policy.
Slotless brushless DC (BLDC) motors represent a unique and compelling subset of motors within the larger category of brushless DC motors. They are called “slotless” because typical slotted brushless DC motors contain a stator core of laminated steel composed of slots separated by teeth around which copper wire is wound.
The windings in Slotless BLDC Motor are made possible by specialized winding process technology, such as the Parallex windings. Motors featuring these windings offer several benefits such as low cogging, low vibration and low noise enabling smooth operation, as well as reduced rotational losses enabling higher speeds with reduced heating.
These characteristics are especially advantageous in applications requiring high power output in an ergonomic design, such as high-power hand-held devices like surgical tools.
Most brushless motors (slotted or slotless) utilize a rotating permanent magnet rotor assembly surrounded by fixed windings. The motor’s rotor assembly consists of a steel shaft with permanent magnets, or magnetic ring, secured around the circumference of the shaft.
The magnets produce a magnetic field which interacts with the field produced by the windings. Torque is produced as the product of the forces applied to the magnet, times the moment arm at which it is applied.
The level of torque can thus be affected by many factors, including magnet strength, distance between opposing magnetic fields, winding or stator field strength and the distance from the motor center to field interaction.
The Global Slotless BLDC Motor market accounted for $XX Billion in 2023 and is anticipated to reach $XX Billion by 2030, registering a CAGR of XX% from 2024 to 2030.
LIN Engineering SL013CH026-01 – A typical brushless BLDC motor is constructed using a stator with “slots”; a copper wire is then wound around these slots.
Although this technology works well, it has an inherent problem with cogging (or drag torque), which presents a challenge in applications needing fast response, fast acceleration and smooth operation.
Slotted brushless motors are especially powerful because the teeth around which the copper coils are wound place the iron closer to the magnets. In this way the air gap is minimized and the magnetic circuit is completed more efficiently.
As the air gap between iron and magnets is reduced, the potential torque produced by the motor is increased. However, slotted stators are known to cause cogging due to the teeth in their construction. Cogging occurs when the permanent magnets on the rotor seek a preferred alignment with the teeth and slots of the stator.
Winding copper coils through the slots tends to increase this effect. As magnets pass by the teeth, they have a greater attraction to the iron of the teeth than to the air gaps between them.
This uneven magnetic pull causes the cogging, which ultimately contributes to torque ripple, efficiency loss, motor vibration and noise, as well as prevents smooth motor operation at slow speeds.
