China’s National Intellectual Property Administration had published four BYD patent applications by December 14, 2025, outlining mechanisms intended to improve electric-motor efficiency by adjusting rotor magnetic flux. The applications were filed in May 2024.
Two applications, CN121055630A and CN121055631A, identify high-speed torque and efficiency limitations in permanent-magnet synchronous motors as problems their designs seek to address. Both claim wider constant-power and high-efficiency operating ranges while maintaining high torque and power density. Their abstracts do not quantify those claimed gains.
Four approaches to adjusting magnetic flux
CN121055622A describes a flux-adjustment assembly positioned at one or both axial ends of the rotor. The assembly can change position around the rotor’s circumference, in the radial direction, or both. Its abstract describes using that movement to regulate magnetic flux through the rotor and adjust the motor’s working magnetic field. The application identifies the additional space needed for axial movement as a limitation of existing adjustment arrangements.
CN121055630A proposes a movable, magnetically conductive component at one or both axial ends of the rotor. A connected drive mechanism moves the component closer to or farther from the rotor. The abstract says this changes magnetic flux through a bypass circuit formed by the component and rotor, allowing adjustment of the main magnetic field.
CN121055623A focuses on movement along the rotor’s axis. A flux-adjustment assembly sits at one or both axial ends and moves toward or away from the rotor. Its abstract describes that movement as a way to regulate rotor magnetic flux and the motor’s working magnetic field.
CN121055631A describes a rotor with a magnetically conductive portion extending along its axis and protruding beyond the rotor body. An adjustment assembly changes the area over which it and the protruding portion face each other in the radial direction. The abstract says varying this facing area changes flux through a magnetic bypass circuit, regulating the main magnetic field.
