Design Of Low-Speed Direct-Drive Permanent Magnet Synchronous Motor And Research On Anti-Demagnetization Technology

The mud pump transports the mud and water rinses, and sends cooling and circularrinses through alternating role of the inhalation and the discharge valve. In order to adaptto modern oil drilling technology, the development direction of the mud pump is highpower, high efficiency and energy saving. Therefore, the low speed and heavy torque ofpermanent magnet synchronous motor instead of the combination of induction motor andreducer as mud pump impetus is very significant.This paper designs and manufactures permanent magnet synchronous motor for mudpump. According to the experimental stoppage of PMSM, eddy current heatdemagnetization problem is deeply analyzed, and some engineering guiding significantconclusions are reached. The main work is introduced as follows:Part 1: According to the index and performance parameters, this paper designs apermanent magnet synchronous motor. This paper focuses on how to select theelectromagnetic loads, main size of motor and permanent magnet and other parameters.Using finite element software, the paper analyzes the PMSM and gets the simulationdiagram of air gap no-load back emf, flux density wave and magnetic field distribution. A500 kW PMSM with 96 slot is designed, and permanent magnet adopts surface typestructure.Part 2: Based on the stoppage of prototype in the experimental process, permanentmagnet demagnetization is deeply analyzed. This part uses finite element analysis softwareto establish 3D model of PMSM and calculates the eddy current loss. According to theeddy current loss, steady-state temperature field for permanent magnet is analyzed, andmakes the conclusion that eddy current loss causes heat demagnetization.Part 3: This part takes some measures to reduce the eddy current loss in the newprototype, and analyzes the PMSM and gets the simulation diagram of air gap no-loadback emf, flux density wave and magnetic field distribution by finite element software.Then this paper analyzes 3D eddy current field and the steady-state temperature field. The simulation results show that the measures are effective. A 600 kW PMSM with 96 slot isdesigned, and permanent magnet adopts built-in type structure.Part 4: Experiments of no-load, load, and the temperature rise for 600 kW PMSM aretested. Test results show that the performance of prototype meets the design requirementsand the simulation results. This design provides some valuable experience to the relatedmotor.