Over the past decade, brushless DC motors (BLDC) have increasingly replaced brush DC motors, especially in applications where high speed (Over 12,000 rpm ) and long service life are required.
However, brushless DC motors do not have all the advantages: Brush DC motors offer simple control and no cogging, while the complex structure of brushless DC motors means higher costs - conventional brushless DC motors are slotted designs, with coils wrapped in slots around the stator.
As a result, a brushless DC motor with a slotless design was developed, which has four major advantages over conventional slotted brushless DC motors.
Smaller size: The stator teeth in slotted brushless DC motors prevent the overall size of the motor from being minimized, while the slotless design has diagonal or axial windings fixed on the cylindrical stator core, making it easier to reduce the size .
Lower cost: The slotless design reduces complexity and the stator core is easier to manufacture, thus providing cost advantages.
High power density: The slotless BLDC motor has high power density because the slotless rotor has a two-pole permanent magnet design and the core loss is relatively small under high-speed operation.
Better overload capability: The toothless design has no magnetic saturation and therefore provides better overload capability.
Although slotless BLDC motors have many advantages, they are not always the optimal choice in practical applications. For example, low inductance brings challenges to motion control, requiring control devices with higher switching frequencies or series compensation inductors to alleviate the low inductance problem.
In fact, different brushless DC motor technologies are suitable for different applications. Slotted brushless DC motors are suitable for applications such as electric vehicles or home appliances where a higher pole count is required and final size is not an issue. They are also preferred in harsh environments because the slotted design coils are easier to protect and are mechanically held in place by the stator teeth. And for applications that require high speed and small size, such as in medical equipment or portable industrial tools, slotless BLDC motors are a better choice and can provide the best solution.
