Research of five-phase ferrite permanent magnet assisted synchronous reluctance motor under single-phase open fault

When the single-phase open fault of the traditional three-phase permanent magnet synchronous motor happens,the output torque's ability of the motor is greatly reduced and the torque ripple is large. The five-phase permanent magnet synchronous motor has the outstanding advantages of small torque ripple and strong fault tolerance. It is widely used in electric vehicle,military and servo motor occasions. Because the cost of the five-phase motor increases with the increase of the number of phases and the price advantage of ferrite,the ferrite magnetic aid structure is used in the rotor of the five-phase motor. In order to study the fault-tolerant performance of the five-phase ferrite permanent magnet assisted synchronous reluctance motor after single-phase open fault,a fault-tolerant control strategy was adopted based on the principle of invariant magneto-motive force after single-phase open fault. And the performance of the motor after single-phase open fault was discussed by adjusting the amplitude and phase of the remaining four-phase current reasonably. A finite element analysis (FEA) model of five-phase ferrite permanent magnet assisted synchronous reluctance motor (PMa-SynRM) was established. The torque ripple,efficiency,unbalanced radial magnetic pull of rotor,the demagnetization of ferrite and the temperature rise of the five-phase motor in the conditions of health,single-phase open fault and fault-tolerant control (FTC) strategy were analyzed and compared. The results show that the torque ripple of the motor and the unbalanced radial magnetic pull of the rotor increase under the condition of singlephase open fault. After adopting fault-tolerant control,the torque fluctuation of motor,the unbalanced radial magnetic pull of rotor and the demagnetization risk of ferrite are improved,but the efficiency of motor is reduced and the overall temperature is increased due to the increase of copper consumption. The temperature distribution of windings under single-phase open fault and fault-tolerant control conditions is uneven. Based on the research of five-phase motor under single-phase open fault conditions,it provides the basis for future research on five-phase and more phases" motor.