Study On Calculation Methods Of Core Loss In Small And Medium-sized Asynchronous Motors

With the rapid development of national economy, the government put forward thedecision of "Energy Conservation and Emissions Reduction" in the new century. As themost widely used type of motor industry, small and medium-sized asynchronous motor,provides a great help for the prosperity of our country economy in all walks of life. As ahuge energy consumption of energy economy in our country, Motor’s loss standard isbecoming more and more high. As variable frequency power supply used more widely,deeply study of motor’s core loss especially the iron loss prediction and calculation seemsto be very necessary during motor’s design phase.At first, this paper introduced the hysteresis losses, the eddy current losses andabnormal losses from the characteristics of ferromagnetic material. And because of thedifferences between core loss of motor and the one of ferromagnetic material, the paperalso discussed the other factors that affect core loss. Secondly, in view of the domesticmotor iron loss rough calculation method in engineering, under the condition of sinusoidalvoltage power supply, magnetic circuit analysis method is established based on the classiccore loss trinomial discrete calculation model. Under the condition of SPWM power supply,harmonic analysis method has been used to improve the core loss model under sine powersupply, so as to adapt to the calculation of core loss under variable frequency. Then, thispaper used the time step finite element method (FEM) of the two kinds of power supplywhen motor is under no-load running condition, and got its core loss results. Finally, thepaper made two comparisons. One is between the engineering simple method’s calculationresults and the model’s results under sine power supply, the other one is between thewaveform coefficient method’s calculation results and the model’s results. It also calculatedthe respectively deviation value comparison of the model calculation results with the finiteelement method’s results, which proved that the core loss calculation model is reliable andhas some practical value in engineering.