聚氨酯保温管的应力松弛及蠕变分析

随着当前我国现代工业社会经济的快速进步和大力发展,聚氨酯保温管在当今人们的工业生产和日常生活中占据不可取代的重要地位,因其本身具有良好的机械稳定性能和保温绝热稳定性能,已得到广泛应用。聚氨酯保温管失效多源于蠕变和应力松弛,本文对聚氨酯保温管的压缩蠕变和应力松弛进行深入探讨,有助于评估力学性能和运行寿命。

Model predictive current control for PMSM driven by three-level inverter based on fractional sliding mode speed observer

Based on the fractional order theory and sliding mode control theory,a model prediction current control(MPCC)strategy based on fractional observer is proposed for the permanent magnet synchronous motor(PMSM)driven by three-level inverter.Compared with the traditional sliding mode speed observer,the observer is very simple and eases to implement.Moreover,the observer reduces the ripple of the motor speed in high frequency range in an efficient way.To reduce the stator current ripple and improve the control performance of the torque and speed,the MPCC strategy is put forward,which can make PMSM MPCC system have better control performance,stronger robustness and good dynamic performance.The simulation results validate the feasibility and effectiveness of the proposed scheme.

管道防腐生产线运管板链同步控制系统

近年来,随着工业技术水平的不断发展,多台异步电动机共同驱动方式在轧钢、传动、纺织、动车牵引等领域得到了广泛的应用。因此,研究并改善多台异步电动机同步控制系统的性能以及提高同步控制精度对于满足各种制造设备以及产品质量需求具有十分重要的理论和现实意义。本文介绍了管道防腐生产线运管板链同步控制的一种方法,建立了以PLC为主站,变频器为从站,以两台异步电机的转速同步为研究对象的控制系统。对其在实际应用中出现的问题进行了分析,提出改进措施。