Design And Analysis Of Permanent Magnet Synchronous Motor With Novel Reverse Salient-pole Structure

The source of excitation of permanent magnet synchronous motor(PMSM) is permanent magnet. With the advantage of simple structure, high power density and high efficiency, PMSM has been widely used in industrial area, especially for PMSMs with salient pole effect, who are more widely used for their stronger overloaded capability.But for traditional PMSM with salient pole effect, magnetic reluctance of d-axis is bigger than that of q-axis, so the value of reluctance torque is negative when power angle is smaller than 90 degree, the power angle of the maximum electromagnetic torque is greater than 90 degree, and its permanent magnets run a high risk of demagnetization. Besides, the magnetic path of q-axis is very saturated, so the efficiency of the motor could not be very high because of large core loss.Based on traditional structure PMSM, a novel structure PMSM with revrse silentpole structure is proposed, and design of the proposed motor rated for 15 k W is completed with magnetic circuit method, parameters of the designed motor is calculated by RMxprt, finite element analysis of the novel structure PMSM and corresponding traditional structure PMSM is done with finite element analysis software-Maxwell 2D, d- and q- axis inductance characteristics and torque-angle characteristic curves of both novel and traditional motor are obtained, which prove the rationality and superiority of the proposed PMSM with reverse salient pole structure preliminarily.Based on the introduction of the finite element method, simulation analysis of PMSM was done, no-load magnetic flux-lines of the traditional motor and the novel motor were got, both of their flux lines are distributed in two pole pairs, which is consistent with actual condition. Magnetic flux leakage of the proposed novel PMSM is less than that of the traditional motor, which displays that the design of the proposed motor is reasonable.No-load performance of the motor is analyzed, waveforms of air gap flux density and no-load back EMF and their Fourier analyses are worked out. The results show that gap flux density and no-load back EMF of the proposed PMSM with novel reverse salient pole structure contains less harmonic component, which are more closer to sine wave.The starting performance of two motors with different rotor structure is analyzed, both motors could start from stationary, after going through the asynchronous starting process, their speed could be around the synchronous speed, then both of them could be pulled into synchronous speed finally. PMSM with novel reverse salient pole structure could reach the synchronous speed a little more quickly, which shows stronger starting ability.The electromagnetic torque, current, core loss and copper loss of different loaded status of the proposed PMSM with reverse salient pole structure is analyzed, the results show that the motor could operate stably with any load.Finally, rated status performance comparison between traditional structure PMSM and novel structure PMSM is made, the results show that the rated operation status of novel structure PMSM is basically the same as the traditional one, but its core loss and the copper loss is less than that of the traditional structure PMSM, which shows that the design of its structure is reasonable and has certain feasibility.