研究了一种不间断电源(uninterrupted power supply,UPS)均流控制方法,在有功功率和无功功率控制逆变基准电压幅值和相位的基础上加入了输出滤波电感电流的直流分量控制。有功功率和无功功率以及电感电流直流分量通过CAN总线进行传输,...研究了一种不间断电源(uninterrupted power supply,UPS)均流控制方法,在有功功率和无功功率控制逆变基准电压幅值和相位的基础上加入了输出滤波电感电流的直流分量控制。有功功率和无功功率以及电感电流直流分量通过CAN总线进行传输,提高了并联系统的抗干扰能力和可靠性。滤波电感电流直流分量控制的加入可以有效地提高整个并联UPS系统的均流特性以及稳定性。2台DSP控制的30 kVA三相四线UPS并联系统验证了该方法的可行性,实验证明该控制方法可以取得良好的并联均流效果和稳定性。展开更多
The failure of the key parts, such as gears, in cutter head driving system of tunneling boring machine has not been properly solved under the interaction of driving motors asynchronously and wave tunneling torque load...The failure of the key parts, such as gears, in cutter head driving system of tunneling boring machine has not been properly solved under the interaction of driving motors asynchronously and wave tunneling torque load. A dynamic model of multi-gear driving system is established considering the inertia effects of driving mechanism and cutter head as well as the bending-torsional coupling. By taking into account the nonlinear coupling factors between ring gear and multiple pinions, the influence for meshing angle by bending-torsional coupling and the dynamic load-sharing characteristic of multiple pinions driving are analyzed. Load-sharing coefficients at different rotating cutter head speeds and input torques are presented. Numerical results indicate that the load-sharing coefficients can reach up to 1.2-1.3. A simulated experimental platform of the multiple pinions driving is carried out and the torque distributions under the step load in driving shaft of pinions are measured. The imbalance of torque distribution of pinions is verified and the load-sharing coefficients in each pinion can reach 1.262. The results of simulation and test are similar, which shows the correctness of theoretical model. A loop coupling control method is put forward based on current torque master slave control method. The imbalance of the multiple pinions driving in cutter head driving system of tunneling boring machine can be greatly decreased and the load-sharing coefficients can be reduced to 1.051 by using the loop coupling control method. The proposed research provides an effective solution to the imbalance of torque distribution and synchronous control method for multiple pinions driving of TBM.展开更多
On the basis of capacity flow model, a new model is developed for a load-sharing k-out-of-n： G system consisting of different components, to describe the increase of the same component＇s failure rates under differen...On the basis of capacity flow model, a new model is developed for a load-sharing k-out-of-n： G system consisting of different components, to describe the increase of the same component＇s failure rates under different loads. All components have exponential life distributions and are nonrepairable in the system. Reliability of load- sharing 2-out- of-3： G system is calculated and some special cases for the system are discussed. The calculation and discussions show that the model is right and practical.展开更多
在航空航天等要求高可靠性的系统中,通常采用并联形式来提高系统的可靠性。当并联系统中某个元件失效后,由于负载重新分配,导致剩余正常元件的工作环境劣化。针对这一问题,建立基于载荷共享的并联可修复系统可靠性评估模型既适用于元件...在航空航天等要求高可靠性的系统中,通常采用并联形式来提高系统的可靠性。当并联系统中某个元件失效后,由于负载重新分配,导致剩余正常元件的工作环境劣化。针对这一问题,建立基于载荷共享的并联可修复系统可靠性评估模型既适用于元件故障率相同又适用于元件故障率不同的并联可修复系统。当载荷共享因子取值为1时,该模型可退化为传统马尔可夫模型。算例结果表明,文中方法和传统方法求得的系统瞬态可用度变化趋势相同;相比传统方法的评估结果,当考虑载荷共享时系统的稳态可用度减小幅度不大,而平均故障间隔时间(mean time between failure,MTBF)将大幅减小。因此,利用传统马尔可夫模型给出的MTBF来衡量系统可靠性以及确定维修间隔需慎重。展开更多
文摘研究了一种不间断电源(uninterrupted power supply,UPS)均流控制方法,在有功功率和无功功率控制逆变基准电压幅值和相位的基础上加入了输出滤波电感电流的直流分量控制。有功功率和无功功率以及电感电流直流分量通过CAN总线进行传输,提高了并联系统的抗干扰能力和可靠性。滤波电感电流直流分量控制的加入可以有效地提高整个并联UPS系统的均流特性以及稳定性。2台DSP控制的30 kVA三相四线UPS并联系统验证了该方法的可行性,实验证明该控制方法可以取得良好的并联均流效果和稳定性。
基金supported by National Basic Research Program of China(973 Program, Grant No. 2013CB035402)
文摘The failure of the key parts, such as gears, in cutter head driving system of tunneling boring machine has not been properly solved under the interaction of driving motors asynchronously and wave tunneling torque load. A dynamic model of multi-gear driving system is established considering the inertia effects of driving mechanism and cutter head as well as the bending-torsional coupling. By taking into account the nonlinear coupling factors between ring gear and multiple pinions, the influence for meshing angle by bending-torsional coupling and the dynamic load-sharing characteristic of multiple pinions driving are analyzed. Load-sharing coefficients at different rotating cutter head speeds and input torques are presented. Numerical results indicate that the load-sharing coefficients can reach up to 1.2-1.3. A simulated experimental platform of the multiple pinions driving is carried out and the torque distributions under the step load in driving shaft of pinions are measured. The imbalance of torque distribution of pinions is verified and the load-sharing coefficients in each pinion can reach 1.262. The results of simulation and test are similar, which shows the correctness of theoretical model. A loop coupling control method is put forward based on current torque master slave control method. The imbalance of the multiple pinions driving in cutter head driving system of tunneling boring machine can be greatly decreased and the load-sharing coefficients can be reduced to 1.051 by using the loop coupling control method. The proposed research provides an effective solution to the imbalance of torque distribution and synchronous control method for multiple pinions driving of TBM.
基金the Natural Science Foundation of the Education Department of Sichuan Province([2006]A067)the Talent Introduction Foundation of Sichuan Normal University.
文摘On the basis of capacity flow model, a new model is developed for a load-sharing k-out-of-n： G system consisting of different components, to describe the increase of the same component＇s failure rates under different loads. All components have exponential life distributions and are nonrepairable in the system. Reliability of load- sharing 2-out- of-3： G system is calculated and some special cases for the system are discussed. The calculation and discussions show that the model is right and practical.
文摘在航空航天等要求高可靠性的系统中,通常采用并联形式来提高系统的可靠性。当并联系统中某个元件失效后,由于负载重新分配,导致剩余正常元件的工作环境劣化。针对这一问题,建立基于载荷共享的并联可修复系统可靠性评估模型既适用于元件故障率相同又适用于元件故障率不同的并联可修复系统。当载荷共享因子取值为1时,该模型可退化为传统马尔可夫模型。算例结果表明,文中方法和传统方法求得的系统瞬态可用度变化趋势相同;相比传统方法的评估结果,当考虑载荷共享时系统的稳态可用度减小幅度不大,而平均故障间隔时间(mean time between failure,MTBF)将大幅减小。因此,利用传统马尔可夫模型给出的MTBF来衡量系统可靠性以及确定维修间隔需慎重。
