Research On Core Loss Model Of Motor Close To Service Condition

The relevant statistic information from the National Energy Administration shows that the industrial electricity consumption in China accounts for 67% of the entire social electricity consumption.More than 70% of industrial electricity consumption comes from motor power consumption.Accurate calculation of motor loss is of great significance for high-quality motor design and performance optimization.As one of the main sources of motor loss,core loss generally accounts for 15% to 40% of the total loss.The internal physical process of motor is very complicated under actual service condition,which involves multi-physical fields coupling.These factors such as magnetization,stress and temperature will directly affect the accuracy of core loss calculation.Therefore,it is necessary to consider the effects of related physical factors in core loss calculation process.In this thesis,the self-developed vector magnetic characteristic measuring device of electrical steel sheet under complicated working condition is utilized to measure loss characteristics of electrical steel sheet under simultaneous action of multiple physical factors.Through data analysis,the influences of different physical factors on core loss are obtained.Based on these,the core loss model of motor close to service condition is established and the accuracy of model is proved by comparing the calculated results with the experimental data.The model is applied to core loss analysis of a Y-series motor,the specific application process of the model is given.Firstly,the theory of core loss separation and the generation principle of three core losses are described and core loss models are classified and summarized.By analyzing the methods of different core loss models that take into account the three physical factors of magnetization,stress and temperature are analyzed,the advantages and disadvantages of these models are investigated and necessity of establishing a core loss model close to service condition is clarified.Secondly,the hardware structure and measurement principle of the self-developed vector magnetic characteristic measuring device of electrical steel sheet under complicated working condition are introduced.By analyzing the loss characteristic of electric steel sheet under complex working conditions,the core loss curves of 50W600 non-oriented electric steel sheet under different magnetization trajectories axial ratios,different stresses and different temperatures are obtained.The influence method of rotational magnetization,stress and temperature on the loss of electrical steel sheet is clarified.The correction methods of different physical factors in core loss model are proposed.The core loss model of motor close to service condition that can overall consider the effects of rotational magnetization,stress and temperature is established.Using the measured data,the calculation results of the improved model and the trinomial loss separation model are compared,which validates the accuracy of the motor core loss model close to service condition.Finally,an induction motor is simulated and analyzed.The magnetization characteristics of different positions on stator core are obtained by magnetic field simulation;The stress distribution of stator interference assembly is obtained by stress field simulation;The temperature distribution after steady operation of the motor is obtained by temperature field simulation.The simulation data is extracted to the motor core loss model close to service condition.The model is used to calculate core loss of the induction motor and compared with other models to verify the practical application value of the improved model.