Slotless Motor
Silent & Powerfull
Slotless Motor
A slotless motor is a Brushless Direct Current (BLDC) motor that doesn’t have the typical slotted iron core stator. Instead, the copper windings are wound in a pattern and potted in for example epoxy, to hold the shape. This stator is then combined with a rotor and this creates a motor that is lighter, more compact and has specific properties compared to a slotted motor. For example, the slotless motors don't have the slotted iron core and therefore experiences less torque saturation, and virtually no cogging.
The Alva slotless motors take this even further by introducing the FiberPrinting™ technology that increases the copper fill factor and has non-skewed windings as stators. These two features, combined with the overall simplicity and compactness of the design, allows for very thin, lightweight and efficient stators.
These stators are then combined with Halbach array rotors, that maximise magnetic flux to increase the torque output. These technologies make slotless motors, not only much more powerful than regular slotless but also capable of rivaling slotted ones for the same volume, while being much lighter.
SlimTorq™
Slotless Motors
Alva offers a range of slotless motors in the SlimTorq™ standard product line. These motors are used for all types of applications and they come in many sizes (from 25 mm to 160 mm in outer diameter). To be able to match the specific need in each project, every motor can be manufactured with different winding configurations that tailor the power consumption, speed and torque capabilities of that particular motor. Most of the variants are also capable of being configured in a lightweight alternative (L) and a more power focused alternative (M).
Additionally there are different sensor options like temperature sensors and Hall effect sensors, and the terminal areas can protrude either radially or axially. These and many more options have been thought to meet every customer's specific demand. To learn more about Alva motors, more information can be obtained contacting or having a look at the product catalog or the product selector.
Custom Slotless Motors
The FiberPrinting™ technology makes it possible to create custom slotless motors. Not only is it possible to create different diameters and lengths, it’s also possible to optimize for different attributes. In simple terms this is achieved by tweaking the design of the stator windings, and the size of the magnets. For example, the stator windings can be made longer, which creates a larger diameter, or wider, which creates a longer motor. Also, the winding configuration can be tweaked to create a different number of poles and a completely different torque constant. It all depends on the requirements and what is the main focus of the design.
In addition to the adaptable manufacturing technique, Alva has developed a design tool, called RDT (Rapid design tool) to iterate and create these motor designs quickly. In this tool it’s possible to optimize the motor for different specifications, for example low weight, high motor constant or something else. If you’ve ever looked for a motor you couldn’t find, let us know and we can possibly create it.
| Header | Header | Header | Header |
|---|---|---|---|
| Cell | Cell | Cell | Cell |
| Cell | Cell | Cell | Cell |
| Cell | Cell | Cell | Cell |
| Cell | Cell | Cell | Cell |
Alvas SlimTorq™ products cover a broad range of slotless motor specifications. In the product catalog, all the necessary data can be found, including technical drawings, electrical specifications and torque-speed curves. In case anything is missing or a specific case needs Alva’s attention, reach out to us to discuss with our experts.
Slotless Motor Applications
Slotless motors can be found in many applications. Wherever there is a need for a precise, compact, lightweight and efficient electric motor, a slotless motor is a good alternative. This could mean applications like:
- Precision Gimbals
- UAV payloads
- Exoskeletons
- Surgical robots
- Aerospace applications
- Rim thrusters
- UGVs
- Reaction Wheels
- Gyroscopes
The larger inner diameter creates valuable space for integration with gears, encoders, sensors or for routing cables and tubes. The topology of actuators created with inrunner slotless motors also makes sense since the stator sits on the outside which makes it easier to keep the motor at a balanced heat level and it is much easier to mount. Also, because the slotless motors experience virtually no cogging, high precision applications see many benefits of slotless motors compared to slotted ones.
Typically 6-8 weeks.
Typically 16-20 weeks from confirmed specifications to first prototype.
NTC Temperature sensor or Hall effect sensors.
-40 to 80 degrees celsius ambient temperature for standard motors. Extended temperature versions are possible as custom designs.
All motors can be delivered with either a radial or an axial cable routing alternative.
Get in Touch
Talk to an engineer or request a quote today.
All rights reserved ©2025