Design And Study On Dual-Redundancy Permanent Magnet Synchronous Motor With Dual Y Shift 30 Degree

For systems requiring high safety and reliability,dual-redundancy permanent magnet synchronous motor(DRPMSM)is adopted frequently.Base on the traditional dual Y shift 30 degree DRPMSM with double-layer and fractional slot concentrated winding(FSCW),a new DRPMSM with no electromagnetic coupling among the phase windings is proposed in this paper,by adding a small teeth in the common slot centre between two adjacent phase windings.With this machine,the slot-pole combination selection,the influence of small teeth on the electromagnetic performance and vibration,as well as on-line detection method for the inter-turn short-circuit fault(ISCF)are studied.The new DRPMSM with dual Y shift 30 degree combines the advantages of fault-tolerant permanent magnet synchronous motor(PMSM)and multi-phase PMSM.When FSCW is used in PMSM,no electromagnetic coupling can be realized by selecting reasonable slot-pole combination and using single-layer winding.However,the goal of no electromagnetic coupling can also be achieved by adding a small teeth in the common slot centre between two adjacent phase windings under appropriate combination of the slot-pole and double-layer winding.Compared with the former method,the latter has shorter end-winding,as well as smaller eddy current loss,lower saturation level of magnetic field and smaller vibration noise caused by lower order harmonics.The winding with dual Y shift 30 degree has fewer magnetic field harmonics in the air gap than the one with dual Y and no phase shift.As a result,the rotor loss and torque ripple amplitude can be reduced,and the motor performance can be improved.In the design of new DRPMSM,a parameterized model based on the width of small teeth and slot opening is proposed,with which the influence of small teeth on the electromagnetic performance could be considered comprehensively.Within the range of small teeth and slot opening,the optimization is done to maximize the fundamental winding coefficient of back electromotive force(EMF)and minimize the amplitude of cogging torque after their theoretical formulas are deduced.The results of finite element simulation show that under the optimization approaches above,the cogging torque,EMF and electromagnetic torque can get quite ideal values,and there is almost no mutual inductance among phase windings.In addition,the reason why adding small teeth can double the cogging torque cycle is revealed,and the correctness of the theoretical derivation is verified by simulation and experiment.For the stator of new DRPMSM after adding small teeth and the ratio of teeth width to teeth tip width,a quadratic Fourier decomposition method is proposed to analyze the modulation effect of small teeth on the radial electromagnetic force in the air gap and inner surface of yoke.Combined with modal analysis,the influence of small teeth on electromagnetic vibration is analyzed.The analytic expression of the radial electromagnetic force about DRPMSM in air gap is derived,and its sources are summarized.The simplified stator teeth model of the traditional and new DRPMSM are established,by which the modulation effect of small teeth on different orders of radial electromagnetic force is analyzed.The simulation of modal and harmonic response is carried out,and the results are verified by experiments.In order to guarantee the low amplitude of vibration at full load for DRPMSM,the width of the small teeth should be small enough.Based on the arithmetic mean for the ratio of the squared amplitude difference between two sets of space voltage vectors to squared frequency,a new online detection method for ISCF of DRPMSM with small teeth is proposed to avoid serious damage of motor and reduce system reliability.The electromagnetic relationships in DRPMSM without mutual inductances are analyzed theoretically upon occurrence of the ISCF.By the difference between the EMF and impedance of the dual winding,the arithmetic mean for the ratio of the squared amplitude difference between two sets of space voltage vectors to squared frequency is used to identify the faulty winding.The simulation and experimental results verify the effectiveness of the proposed method.