Frameless Brushless Motor
Frameless motors are a unique motor type that omits the housing and rotor found in traditional electric motors. This allows them to be built directly into a machine’s structure.
When used with a feedback device (encoder, hall sensor) they form a complete servo system. They provide precise performance while minimizing size, weight and inertia.
Power density
The frameless motor consists of just the rotor and stator, eliminating the need for housings, end bells, bearings and rotor shafts. This allows engineers to integrate the rotor and stator directly into the machine’s mechanical design. Compared to traditional motors, this design allows for greater power density in an extremely compact and lightweight form factor.
Kollmorgen’s frameless motor kits can be configured with multiple different options to achieve the performance characteristics required for your application. Select from a variety of frame sizes, stack lengths and Frameless brushless motor winding variations to create an optimal performance fit within your design. For example, the KinetiMax HPD outer-rotor brushless motors offer high-torque, low-cogging, space-saving integration and are available in six frames with three stack lengths per size.
These compact frameless motors can be used in applications where a minimal size and weight are essential, such as robotic joints, sensor gimbals, weapon stations and UAV propulsion and guidance systems. They also improve the dexterity, versatility and speed of surgical robots, humanoid robots and exoskeletons and industrial cobots.
Frameless motors can also be incorporated into hygienic machines that need to resist harsh environmental conditions, such as semiconductor processing and radiation-producing medical devices. They can be modified with materials that prevent outgassing and premature degradation, and they can be sealed to ensure washdown fluids never touch the motor.
Efficiency
One of the primary advantages of a frameless motor is its high efficiency. Frameless motors produce more power in the same physical space than a traditional electric motor, which is a result of eliminating unnecessary components such as the housing and bearings. These motors are also designed to have a larger diameter, which allows them to fit more windings in the same space. This results in a lower cost, lower maintenance, and higher performance in the same footprint as a traditional motor.
Another advantage of a frameless motor is its ease of installation. Rather than needing a special mounting system, these motors can be integrated directly into the machine structure, which reduces the size and weight of the assembly. This makes them ideal for applications requiring minimal inertia and high torque density such as collaborative robots.
In addition, a frameless motor’s unique electromagnetic design provides greater shaft and coupling efficiencies compared to other available permanent magnet synchronous motors. Moreover, a frameless motor can be configured with a high pole count pancake stator that produces exceptionally low cogging torque.
Furthermore, a frameless motor is typically embedded directly into the machine’s structure, which allows it to be protected from caustic washdown fluids, environmental exposure, and weather conditions. This helps ensure reliable operation and long-term reliability. This type of robust construction is also important for machine manufacturers looking to minimize maintenance costs and downtime.
Customization
Since a frameless motor lacks the housing, end bells, bearings, rotor shaft and cable connectors found on housed servo motors, it can be more easily integrated directly into machine or application designs. This offers flexibility for system architects to create unique machine features and functions not possible with a standardized housed motor design.
Integrating a frameless motor can also reduce overall machine inertia. This can improve move and settling times to increase system bandwidth. For high-speed, precise motion, a frameless motor can be directly coupled to compact, low or zero backlash planetary, harmonic or cycloidal gearing. This can significantly Frameless brushless motor manufacturer improve the load response time to changing drive input demands while delivering unsurpassed torque density.
For applications requiring extreme environment resilience, a frameless motor can be modified with materials that resist outgassing and premature degradation. This can be important in hygienic applications such as food & beverage production and packaging. In high-vacuum or high radiation environments, a frameless motor can be modified to provide an air or liquid cooling system for efficient heatsinking.
The most significant challenge of integrating a frameless motor is the precision required during mounting to ensure that the rotor and stator are coaxially aligned. A properly maintained air gap between the rotor and stator is essential for optimum performance. If this is not achieved, the rotor can generate an alternating magnetic field that produces a jittering error signal that is detected by the amplifier as position control errors.
Challenges
The growing emphasis on green solutions has led manufacturers to design frameless motors that are more energy-efficient and eco-friendly. This trend, along with a global push to reduce carbon footprints, is expected to drive demand for these motors. Furthermore, the compact design of frameless servo motors helps reduce the overall size of motion systems. This enables the integration of these motors in devices with limited space, such as robot machines and drones.
As industries from manufacturing to healthcare delve into automation, the demand for efficient and compact motors is rising. This is propelling the growth of the frameless brushless motor market, presenting a myriad of opportunities for players.
Moreover, the emergence of electric vehicles, both fully electric and hybrid, will drive the use of frameless motors in their propulsion systems. This is owing to their high power density and efficiency, which makes them ideal for these applications.
Additionally, the growing adoption of robotics in various sectors is also boosting the demand for these motors. These motors offer precise control and reliability, making them the perfect choice for robotic applications. In the medical sector, they are used in devices that require precision and reliability, such as pumps and prosthetics. However, the initial cost of integrating these motors can be expensive for small and medium enterprises, deterring their widespread adoption.
