Design Considerations of a Permanent Magnetic Spherical Motor Using Spherical Harmonics

Closed-loop magnetic bearing and angular velocity control of a reaction sphere actuator

“…Depending on the practical case, the magnetic flux density model can be formulated with a variety of methods including the distributed multipoles (DMP) methods [33][34][35][36], which consists in modeling both the stator coils and the PMs as distributed multipoles, the charge and current models [27,[37][38][39], where PM are replaced by an equivalent spatial (volume or surface) distribution of ''magnetic charges'' that is in turn used as a source term in the magnetostatic field equations, the finite element analysis [40], which is widely adopted in the design optimization and model verification of spherical actuators, and the harmonic model [19,30,22,17,41], which is derived by solving Maxwell's equations under certain boundary conditions to express the solution as a series of space spherical harmonic function. A particular approach to the harmonic model method consists in employing boundary conditions measured on all the rotor surface to reconstruct the magnetic flux density model [42,43].…”

Analytical calculation of magnetic field of double‐stator permanent magnet spherical motor considering cogging effect and edge effect

“…The existing permanent magnet spherical motor stator structure can be divided into four types: layered stator, nested stator, claw stator and double stator. The layered stator structure is shown in Figure 1a, and its typical feature is that the stator coil has two layers [6, 7] or three layers of coils [8–10] along the axial direction, and each layer of coils is evenly distributed radially or horizontally, with a certain included angle between adjacent layers. By exciting all coils in the circumferential direction, the rotor can rotate around its axis.…”

Trajectory Planning of Multi-dimensional Actuator based on Improved S-shaped Velocity Curve

“…In reference [4], a multi-dimensional spherical wheel motor is proposed and an open-loop controller is designed for its control. In reference [5], [6], based on the principle of spherical harmonic function and equivalent magnetic circuit method, the multidimensional spherical motor with double winding and double excitation is designed respectively. Reference [7] focuses on the application of multi-dimensional actuator and designs an actuator which can be used in curved surface printing technology.…”