Polar-Anisotropic Ring Magnets: A Stronger Alternative to Radial Ring Magnets for BLDC Motors
Higher flux density and a naturally sinusoidal field: how polar-anisotropic multipole rings compare with radially magnetized rings in BLDC motor rotors.
Intro: Polar-Anisotropic Ring Magnet
The Polar-Anisotropic ring magnet is a type of multipole ring magnet that, when compared to radial-anisotropic ring magnets with the same material grade and size, demonstrates a higher magnetic flux density. This key advantage has led motor designers to increasingly opt for this innovative multipole ring magnet over its radially magnetized counterpart in various applications.
Orientation of Polar-Anisotropic Ring Magnet
The orientation of this type of multipole ring magnet is similar to the arrangement found in a Halbach array, which is why it is also referred to as a “Halbach multipole ring magnet”. This arrangement leads to an enhancement of magnetic flux density (field strength) on one side of the magnet. As a result, its field strength surpasses that of an identical radial-anisotropic (radially magnetized) ring magnet.
Pros and Cons: Polar-Anisotropic Ring Magnet for E-Motor
- Polar-Anisotropic Ring Magnets boast a higher flux density than their radially oriented equivalents, offering enhanced performance in various applications.
- The magnetic flux density on the outer diameter surface of this multipole ring magnet displays a sine wave without requiring a magnetic shaft, leading to increased motor efficiency and reduced weight of materials.
- The sinusoidal magnetic field on the motor’s circumference reduces cogging torque, leading to quieter and smoother operation.
- The pole flux density variation is higher for these multipole ring magnets than radially oriented ring magnets, which can negatively impact performance in certain applications.
- The manufacturing cost of these multipole ring magnets is higher compared to segment magnets and radially magnetized ring magnets, making them a more expensive option for certain applications.
Applications of Polar-Anisotropic Multipole Ring Magnet
Polar Anisotropic Ring Magnets find extensive applications in various industries that demand high torque or high-speed performance. These magnets prove indispensable in a wide range of fields, including power tools, robotics, home appliances, medical tools, and more. Each application often requires a specific number of poles tailored to its unique requirements. For instance, coreless motors, also known as hollow cup motors, typically employ 4 pole ring magnets to achieve optimal functionality and efficiency. The versatility and adaptability of Polar-Anisotropic Ring Magnets make them a preferred choice in numerous cutting-edge technologies and industrial applications.
