A Novel Squirrel-Cage Rotor Permanent Magnet Adjustable Speed Drive With a Non-Rotary Mechanical Flux Adjuster

Permanent magnet adjustable speed drive (PMASD) has been widely applied to regulate the speeds of large pumps and fans for energy-saving. For improving the torque density and simplifying the actuator of traditional PMASD, a novel squirrel-cage rotor (SCR-) PMASD with a non-rotary mechanical flux adjuster (MFA) is proposed in this paper. An analytical model considering the slot effect and the MFA shifting is established to analyze the magnetic field and the output torque efficiently for the initial design of the proposed drive. The air-gap flux density distributions obtained by the analytical model are verified by two-dimensional (2D-) finite element analysis (FEA). During the speed regulation process, the torque characteristics, power, loss, and efficiency of the drive under different MFA shifting distances are compared with the 2D-FEA and experimental results. The analysis and measured results show that the proposed drive can achieve a wide speed regulation range.