Novel Hybrid Consequent-Pole Brushless Wound Rotor Synchronous Machine for Improving Torque Characteristics

This article introduces a hybrid consequent-pole brushless wound rotor synchronous machine (CP-BL-WRSM). The CP-BL-WRSM installs permanent magnets (PMs) on the alternative rotor poles. Compared with the conventional BL-WRSM and permanent magnet-assisted brushless WRSM (PM-BL-WRSM), the proposed machine provides advantages of high average output torque, high maximum torque, and high starting torque. In addition, the proposed CP-BL-WRSM’s torque ripple is also lower than the conventional brushless WRSM. The volume of PM in the CP-BL-WRSM machine is lower than the conventional permanent magnet synchronous machines (PMSMs) and PM-BL-WRSM. In this brushless topology, the machine uses three-phase stator windings powered by a single inverter, which provides a unique armature current to the stator windings that comprises of fundamental and third-harmonic components. The fundamental current component is used to generate the main stator field, and the third-harmonic current component is used to induce a harmonic current in the harmonic winding. A diode rectifier installed on the rotor is used to rectify the harmonic current. After the rectification, a direct current (DC) is injected into the field winding of the rotor to form a rotor magnetic field and achieve brushless operation. In order to verify the operation of the proposed CP-BL-WRSM topology and analyze its performance, 2-D finite element analysis (FEA) was used in JMAG-Designer. Finally, the performance of the proposed CP-BL-WRSM topology was compared with the conventional BL-WRSM topology and PM-BL-WRSM topology to verify its higher starting torque, higher average torque, and higher maximum torque and higher minimum torque. The proposed topology can replace the existing highly expensive PM synchronous machines (PMSMs) due to its less PM volume and conventional BL-WRSMs due to its better performance.