Using its patented FiberPrinting technology that brings advanced levels of magnetic impact, Alva Industries, a Norweigian manufacturer of frameless motors, has expanded its SlimTorq series of slotless frameless motors with new diameters –25mm, 85mm and 160mm size variants expanding their versatility across an even broader range of precision applications.
Attendees at automation fairs in Europe have been getting first looks at them recently where Alva has been showcasing the new products and its specialized technology, including Smart Production Solutions held in Nuremberg in November and Automatica held in Munich in June. Applications for the motors include high precision gimbals, medical devices and surgical robots, defense and satellite communications, marine propulsion.
The engineers at Alva have also developed a new 3-phase Hall-effect sensor option, available across the entire SlimTorq lineup. They feature open-drain output, a built-in 1.2kΩ pull-up resistor, and 5VDC supply voltage, enabling reliable and straightforward integration for applications requiring commutation or simple speed and position feedback.
SlimTorq is a thin and light torque motor range for high-precision and high-speed applications on land, sea, air and space. The company’s FiberPrinting enables ironless and slotless motor windings with up to 60% copper fill factor designed to bring new capabilities in precision, torque density and adaptability.
“FiberPrinting allows us to break through the limitations of conventional motor manufacturing,” says Nicolas Giraudo, Chief Commercial Officer of Alva, which is located in Trondheim. “With SlimTorq, our customers benefit from a unique combination of slim design, high torque density, linearity and scalability – all while reducing weight and optimizing heat dissipation.” The process enables Alva to rapidly design and manufacture ironless & slotless windings with high copper fill factor for virtually any electric motor or generator.
The company cites several key attributes:
- High Copper Fill Factor
The primary limitation of traditional ironless & slotless motors lies in their poor performance in terms of power & torque density, explains Alva. This is mainly attributed to the low copper fill factor which compromises phase resistance and voltage constant. FiberPrinting addresses this limitation by enabling high copper fill and short end-windings. The features can significantly boost the performance of slotless motors, allowing them to even challenge slotted motors in terms of performance.
- Non-Skewed Windings
Traditional ironless & slotless winding methods can only produce skewed windings that generate a magnetic field which is misaligned with the rotor’s magnetic field, resulting in a lower motor constant (Km), notes the company. FiberPrinting, however, allows for the production of non-skewed stator windings with a magnetic field that is perfectly aligned with the rotor’s magnetic field, improving performance in power and torque density.
- Halbach Rotors
Alva also manufactures Halbach Array rotors to further refine motor performance. They feature radial and tangential magnets meticulously arranged to maximize magnetic field strength, offering a stronger magnetic field relative to the magnetic mass and volume compared to traditional radial arrays.
- Perfect pole positioning
Halbach rotors are notoriously difficult to manufacture due the large magnetic forces between the radial and tangential magnets, however, Alva’s process allows them to assemble the rotors with perfect magnet positioning in a rapid and repeated manner. Incorporating Halbach Array rotors into their slotless motors, Alva achieves advanced levels of torque-density and efficiency, even rivaling the performance of the best slotted motors, it says.
- Precision of slotless motors
The motors exhibit a perfectly linear behavior in all nominal conditions due to the absence of cogging torque, low back-EMF THD. Essentially, they never saturate. This allows for ultra-precise angular control with simple control electronics and algorithms. The motor has zero cogging torque due to the symmetrical magnetic interaction between the stator and rotor. A symmetrical magnetic interaction is achieved since the laminations around the stator are perfectly cylindrical. Due to the geometrical simplicity of the motor in combination with a Halbach array rotor, the stator and rotor can be optimized to generate an almost perfect sinusoidal back-EMF even at high torque-levels and temperature fluctuations.
- Performance of slotted motors
Their slotless motors exhibit the same motor-constant vs. mass ratio as a slotted motor, providing equivalent power & torque density. With virtually no saturation of the stator, they enable a peak torque well beyond that of an equivalent slotted motor, allowing OEM design engineers to transition from slotted motors to improve precision without incurring any performance or weight penalty. Additionally, they can replace legacy precision slotless motors to enhance both performance and weight. For more info, see www.alvaindustries.com.
