The Design Techniques Of Permanet Magnet Motors With Multiple Poles And Few Slots Used For Escalator

The appearance of the escalator has brought great convenience to human daily life. Itsappearance also becomes an important sign of the modern material civilization. At thisstage, the mainly requirement of the drive system of escalator is that it should have highefficiency in a wide load range, low torque ripple and low noise. Direct drive system withpermanent magnet can be very good to meet the requirements above. So this paper apply itin the escalator system by designed an8.8kW permanent magnet synchronous motor(PMSM). And an experiment has been done based on it.Firstly, in order to reduce the noise of the escalator, so in this paper, electromagneticnoise of PMSM has been studied. Orders and frequencies of the radial magnetic force indifferent slot/pole combinations have been deduced firstly. In this process, the conditionsof producing unbalanced magnetic force have been presented. And the solution has beenproved by an experiment. Then the main orders and frequencies have been suggested andan8poles36slots motor has been analyzed based on it. The slot/pole combination of8.8kW escalator motor has been chosen used the theory stated above.Secondly, in order to suppress torque ripple of the escalator motor, cogging torque ofPMSM has been studied. A new evaluation formula in the view of cogging torque ofmotors with different slot/pole combinations has been proposed. This paper uses8kinds ofslot/pole combinations for the design of the8.8kW escalator motor. And cogging torquehas been optimized in the process. The slot/pole combination of the escalator motor hasbeen chosen in the view of cogging torque.Thirdly, based on the studied forward the paper, different structural styles have beenused in the process of escalator motor design. At last, surface mounted inner rotor NdFeBPMSM which slot/pole is20poles and24slots has been chosen thinking of efficiency, cost,torque ripple and electromagnetic noise. Good performances have been achieved after thesuitable optimization. Finally, the prototype has been made and an experiment has been done based on it.The main performance indicators such as Efficiency, noise and cogging torque have beentested in the experiment. The result shows that all performance of the prototype meets therequirement.