Alternate Rotor Design for Line-Start Synchronous Reluctance Motor With Minimum Use of Copper

Abstract

Line-start synchronous reluctance motors (LSSynRM) combine the high efficiency of synchronous reluctance Motors (SynRM) with the self-starting capability of induction motors. They operate at synchronous speed in steady state and produce minor rotor losses, thereby providing higher efficiency than induction motors and a higher power density. Despite the simple structure of LSSynRM, its analysis, modeling, and optimal design pose several challenges. In particular, design trends aiming at higher starting capabilities and improved steady-state operation pose significant hurdles. In this study, three synchronous reluctance motors with line-start capability are designed to achieve maximum efficiency at steady-state operation with the optimum amount of copper for starting. The induction cage is constructed using rectangular bars installed in flux barriers to minimize the changes in performance under the steady-state condition. Although different rotor shapes offer similar steady-state performance, they achieve synchronism using different cage bar widths. The rotor with the lowest copper weight is selected for manufacturing. The prototype is constructed based on the optimal design. The experimental results are in good agreement with the simulation results. . INDEX TERMSInduction Cage, Line-Start Synchronous Reluctance Motor, Rectangular Bar, Synchronization NOMENCLATURE 𝐿 𝑠𝑑 d-axis inductance 𝐿 𝑠𝑞 q-axis inductance 𝑝 Pole pairs 𝛿 𝑖 Current angle relative to q-axis 𝐼 Stator current 𝑋 𝑑 d-axis reactance 𝑋 𝑞 q-axis reactance 𝑅 𝑠 Stator phase resistance 𝛿 𝑣 Voltage angle relative to q-axis 𝑉 Voltage 𝑠 Slip 𝜔 Synchronous angular speed 𝛾 Phase of the pulsating torque components 𝑉 𝑠 Stator Voltage 𝑅 𝑟𝑑 Rotor d-axis resistance 𝑅 𝑟𝑞Rotor q-axis resistance 𝐿 𝑚𝑑 d-axis magnetization inductance 𝐿 𝑚𝑞 q-axis magnetization inductance 𝜔 𝑟Rotor angular speed 𝑊 𝑞𝑖 ith flux barrier width along q-axis 𝑊 𝑑𝑖 ith flux barrier width along d-axis ∆𝛼 𝑖 ith flux barrier angle along q-axis 𝑛 𝑟 Number of rotor virtual slots per pole pairs 𝑛 𝑠 Number of stator slots per pole pairs 𝐾 𝑖𝑛𝑠𝑞 Insulation ratio along q-axis I.