Dynamic demagnetisation investigation for less‐rare‐earth flux switching permanent magnet motors considering three‐phase short‐circuit fault

Abstract

This study presents dynamic demagnetisation investigations of less-rare-earth (LRE) flux switching permanent magnet (LRE-FSPM) motor under three-phase short-circuit (SC) fault. Owing to relatively low coercivity of ferrite PMs, it is necessary to investigate demagnetised risk of LRE PM motors. Actually, motors suffer from larger demagnetising risk under SC faults than normal conditions. Hence, it is essential for LRE PM motors to comprehensively investigate and enhance antidemagnetisation capability during design stage. Here, by integrating electrical-magnetic field calculation and driving control circuit, dynamic demagnetisation characteristics of the LRE-FSPM motor under SC faults are calculated as an example. To fairly evaluate demagnetisation withstand capability of LRE-FSPM motor, the non-rare-earth (NRE)-FSPM motor is also presented and compared as a referenced motor. Then, the dynamic demagnetisation characteristics of two motors are analysed and compared, including demagnetising d-axis current, operating points, and demagnetised area. It is found that, the proposed LRE-FSPM motor exhibits improved operating points and less demagnetised area, which is only about one-third of that of NRE-FSPM motor. Finally, the demagnetisation calculation results not only verify the validity of dynamic demagnetisation investigation approach, but also prove the reasonability of LRE-FSPM motor, which provide a promising research path for the design of LRE PM motors.

Design and Analysis of Permanent Magnets in a Negative-Salient Permanent Magnet Synchronous Motor

“…Generally, LM can be determined according to the axial length of the motor, so only hM and bM need to be determined in the motor design. The initial values of hM and bM are given in (15)…”

“…According to (14) and (15), the initial hM and bM can be determined, and the final hM and bM can be determined by FEM. The inductance varies with hM, as shown in Fig.…”

“…Literature [14] calculated the flux density of PM via a bidirectional magnetic network. Literature [15]- [16] investigated demagnetization of PM under short-circuit faults.…”

Performance analysis of asymmetrical less‐rare‐earth permanent magnet motor for electric vehicle

“…However, the rare‐earth materials are non‐renewable resources [10]. With the over‐exploitation of human beings, the price of the rare‐earth materials continues to rise, and the situation of short supply is constantly serious, which further restricts the research and development of rare‐earth PMs [11]. Therefore, the current hotspot in motor research is to reduce the use of rare‐earth materials under the premise of ensuring motor performance.…”

Non‐linear analytical modelling and optimisation of a 12/8 rotor excited flux‐switching machine

“…Rare‐earth PM is not used in the former topology which leads to a cost‐effective machine. However, the latter topology offers high value of power density by using rare‐earth PMs [9, 10]. Moreover, hybrid excited FSMs have been proposed which use both excitation windings and PMs gaining advantages of the both topologies simultaneously [11].…”