The characteristics analysis and cogging torque optimization of a surface-interior permanent magnet synchronous motor

This paper proposes optimal stator skewed slot analytical method for cogging torque reduction in surface-interior permanent magnet synchronous motor(SIPMSM) and analyzes the characteristics of SIPMSM. The series-parallel equivalent magnetic circuit models(EMCMs) of SIPMSM is built based on the characteristics of magnetic circuits, which is used to design the basic electromagnetic parameters of SIPMSM. Analytical expressions of cogging torque are derived from applying analytical techniques. Stator skewed slot for cogging torque minimum is adopted, and the stator skewed slot pitch is confirmed based on the analytical expressions of the resultant cogging torque. The cogging torque, torque ripple, back electromotive force(back-EMF), power-angle characteristics, efficiency and power factor of SIPMSM are analyzed by establishing 3-dimensional finite element model(3-D-FED) of SIPMSM with stator skewed slot and straight slot. It is shown that the comprehensive performance of optimized SIPMSM is improved as confirmed by finite element analysis and analytical calculation results

Study on the spatial spillover effect of land use type change on carbon emissions

Abstract Land use change affects the terrestrial carbon cycle, a crucial factor in attaining energy conservation and emission reduction under climate change. This study constructs panel data for thirteen Hangzhou districts and municipalities from 2000 to 2020. Using the spatial Durbin model, it analyzes the spatial spillover effect of land use change on carbon emissions. The results show that the spatial distribution of carbon emissions in Hangzhou continues to increase with positive spatial autocorrelation, and the spatial distribution shows "high-high" and "low-low" clustering. The expansion of construction land is the main reason for the increase in carbon emissions, and the inhibitory effect of water area on carbon emissions is more potent than woodland. The area of cultivated land and construction land has a positive spillover effect on carbon emissions, while the woodland area has a negative spillover effect on carbon emissions. To promote urban low-carbon development, maximizing the spatial spillover effect of land use and establishing a collaborative governance system between districts and counties is crucial