Halbach Array

Ι What Is Halbach Array?

A Halbach array, whether circular or linear, consists of multiple magnets, typically uniform in size within each array. Circular Halbach arrays employ arc or trapezoidal magnet shapes for curved field focusing, while linear arrays use rectangular shapes for straight-line applications. These magnets, often called Halbach array magnets, vary in magnetization direction to concentrate the magnetic field. A Halbach array becomes more efficient with a smaller magnetization direction difference and more elements, yielding a stronger, more uniform magnetic output. However, this increases machining costs for the magnets and assembly expenses for the array. Beyond a certain point, manufacturing challenges—such as precision shaping and alignment—outweigh the benefits of enhanced magnetic strength, leading to diminishing returns in high-performance applications.

Halbach array motors, advanced permanent magnet motors, leverage a Halbach array to boost performance. By incorporating Halbach arrays, these motors enhance magnetic flux density in the air gap while minimizing flux in the rotor yoke, making them ideal for internal or external rotor designs with surface-mounted magnets. This setup reduces motor size and weight, increasing power density for greater efficiency. Lower rotor yoke flux allows reduced ferromagnetic material, decreasing rotor weight and inertia. In a Halbach array, magnets with varying magnetization directions achieve an operating point above 0.9, optimizing magnet utilization. The air gap’s near-sinusoidal flux distribution cuts cogging torque and ripple, enabling fractional-slot concentrated windings without skewed stator slots, ensuring smoother operation with low harmonic content in high-precision applications.