Post-assembly magnetization of ferrite magnets in permanent magnet synchronous machines using an inverter

Date

2025-6-19

Author

Filiz, Halid

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Permanent magnet synchronous machines (PMSMs) utilize permanent magnets (PMs) embedded in the rotor to establish a magnetic field, replacing conventional rotor windings. One of the primary challenges encountered in manufacturing PMSMs is placing these magnets onto the rotor, which becomes especially difficult due to the strong magnetic attraction forces involved. Among the materials suitable for PMs, ferrite—a ferromagnetic ceramic material—presents a low-cost alternative to rare-earth magnets. Ferrite magnets are easier to magnetize and more readily available, albeit with lower magnetic performance. This thesis investigates the feasibility of performing post-assembly magnetization (PAM) utilizing the inverter and stator windings to magnetize ferrite PMs while they are inside the motor, aiming to eliminate the need for external magnetization equipment. To evaluate this, both a capacitor discharge impulse magnetizer and a two-level, three-phase inverter are designed and implemented. The design methodologies and the reasoning behind key circuit decisions are presented in detail. Experimental validation is performed through a permanent magnet-assisted synchronous reluctance motor equipped with ferrite PMs, on which PAM is attempted using both the capacitor discharge circuit and the inverter. Results demonstrate that up to 96% of the pre-magnetized magnet performance can be achieved when a current, which is approximately ten times the motor’s rated current, is applied. The findings suggest that PAM using the designed inverter circuit is viable, as long as the power source supplying the inverter can provide sufficient current.

Subject Keywords

Post-assembly magnetization, Three-phase inverter, Capacitor discharge impulse magnetizer, Permanent magnet assisted synchronous reluctance motor, Sintered ferrite permanent magnets

URI

https://hdl.handle.net/11511/115468

Collections

Graduate School of Natural and Applied Sciences, Thesis