Design and Analysis of a Novel Dual-Rotor Toroidally Wound Slotted Limited-Angle Torque Motor With Flat Wire for Torque Improvement

Existing research on toroidally wound limited-angle torque motors (LATMs) prefer to adopt slotless structures to obtain the advantages of shorter coil ends, lower torque ripple, and simpler structure. However, such toroidally wound slotless LATMs still require further improvement due to their relatively low torque density, which is mainly limited by insufficient permanent magnets (PMs) utilization, low winding utilization, and restricted power density. To overcome these defects, this article proposes a novel dual-rotor toroidally wound slotted LATM employing the flat wire winding. The proposed LATM consists of a dual-rotor structure formed by two toroidal rotor cores with surface-mounted PMs, a toroidal stator core featuring odd-numbered rectangular open slots on both its inner and outer radial sides, and a toroidally wound double-layer flat-wire winding. This design represents a significant improvement over conventional LATMs—retaining their advantages while effectively addressing their limitations—thereby significantly enhancing the electromagnetic loading and achieving higher torque output. First, the topology evolution and operating principle of the proposed LATM are introduced. Subsequently, the preliminary design of the motor is proposed, and the key parameters of the design are further optimized under critical constraints. Based on finite element analysis, both the electromagnetic and thermal performance are then evaluated and compared with the existing LATM. Finally, the prototype has been fabricated for experimental validation. Both simulation, comparison, and test results confirm that the proposed LATM significantly improves torque density while maintaining a wide constant-torque range.