Study On Core Electromagnetic Characteristics And Loss Of High Speed Permanent Magnet Motor In Ultra-low Temperature Environment

Liquefied natural gas is widely used as a clean and efficient energy,and its transportation needs LNG submersible pump.High speed permanent magnet motor is the core component of submersible pump.The electromagnetic characteristics of the materials constituting the motor will change in low temperature environment.Therefore,it has become an urgent problem to explore the influence of low temperature environment on the performance of component materials,to explore the action mechanism of low temperature conditions on motor characteristics and to form the principle of material selection.This paper focuses on the electromagnetic performance of silicon steel sheet in low temperature environment,stator core loss and rotor eddy current loss of low temperature motor.The electromagnetic characteristics of silicon steel sheet are measured through experiments,and the measurement results are analyzed.Based on the experimental data,the loss of low temperature motor is calculated and its distribution law is studied.In order to study the factors affecting the electromagnetic performance of silicon steel sheet in low temperature environment and establish the basis for the design optimization of low temperature high-speed permanent magnet motor for LNG pump,the low temperature electromagnetic performance measurement experimental scheme of motor material is constructed,and the electromagnetic performance of silicon steel sheet is measured,The basic magnetization curves and loss characteristic curves of silicon steel sheet at different frequencies under normal temperature and low temperature environment,as well as the parameters such as remanence and coercivity are obtained.The influence of low temperature environment on the electromagnetic characteristics of silicon steel sheet is analyzed.Combined with the experimental results of low-temperature performance measurement of silicon steel sheet,the factors of performance change of silicon steel sheet in low-temperature environment are analyzed,the reasons for different variation ranges of electromagnetic properties of silicon steel sheet are explored,and the influence law of low-temperature environment on electromagnetic properties of silicon steel sheet is revealed.The electromagnetic properties of four different series of silicon steel sheets are compared,which provides a reference for the selection of core materials for low temperature and high speed permanent magnet motors.Based on the experimental data and analysis results of electromagnetic characteristics of silicon steel sheet in low temperature environment,taking a low temperature high-speed permanent magnet motor as the research object,the physical model of the motor is established,and the stator core loss of the motor is calculated.The composite structure of stainless steel sheath and metal coating is adopted on the rotor.Combined with the change of electrical conductivity of motor materials in low temperature environment,the eddy current loss of motor rotor is calculated,the weakening effect of sheath and metal coating on eddy current loss is analyzed,and the distribution law of rotor eddy current loss is revealed.The research content of this paper can provide theoretical basis and reference for the design optimization and operation performance analysis of low-temperature motor.