Variable-Magnetization Interior Permanent Magnet Motor Yield Widely Variable Flux due to Small Magnetizing Current and Operating at High Power over a Wide Speed Range

In electric vehicles, power consumption and a wide speed range with high motors power are essential. Permanent magnet (PM) motors exhibit high capacity and efficiency. However, the flux-weakening control technique may cause significant iron and copper losses and high harmonic iron losses to decrease the back-EMF at high-speed. This paper proposes a variable-magnetization technique for PM in the interior permanent magnet (IPM) motor by a field due to the small magnetization current to achieve variable back-EMF and describes the proposed IPM motor using its technique produces high power over a wide speed range. Our results indicate that the proposed PM motor can vary the de- and re-magnetization and achieve compatibility between a wide variable back-EMF range and a small magnetization current. Furthermore, our analysis results confirm that the proposed IPM motor can produce high torque over a wide speed range by varying the magnetization state of PM.