The whole analysis process of pneumatic stressed membrane structure contains nine states and seven analysis processes.The zero-stress state is the corner-stone of analysis and design of pneumatic stressed structure,an...The whole analysis process of pneumatic stressed membrane structure contains nine states and seven analysis processes.The zero-stress state is the corner-stone of analysis and design of pneumatic stressed structure,and has significant impact on the pre-stressed state and load state.According to the logical model of the whole numerical analysis process of pneumatic stressed structure,a numerical analysis method to solve the zero-stress state from the elasticized equilibrium state was firstly proposed,called linear compatibility matrix M-P inverse method.Firstly,the pneumatic membrane stressed structure was transferred into grid structure by using membrane link to simulate membrane surface.Secondly,on the basis of equilibrium matrix theory of pin joint structure and small deformation assumption,compatibility equation of system was established.Thirdly,the unstressed length and elongation of links were calculated from the tension and material parameters of elasticized equilibrium state.Finally,using compatibility matrix M-P inverse,the nodal displacement was calculated by solving compatibility equation,the configuration of zero-stress state could be obtained through reverse superposition,and the stress was released.According to the algorithm,the program was coded with MATLAB.The correctness and efficiency of this method were verified by several numerical examples,and it could be found that one elasticized equilibrium state corresponded to one configuration of the zero-stress state.The work has theoretical significance and practical guidance value for pneumatic membrane structural design.展开更多
随着双有源桥开关频率的不断提高,开关损耗在总损耗中的占比逐渐增大。零电压开关(zero voltage switching,ZVS)控制策略已成为降低开关损耗的主要手段。然而,传统ZVS控制策略在考虑死区时间时,存在ZVS区域不连续和移相比突变的问题,影...随着双有源桥开关频率的不断提高,开关损耗在总损耗中的占比逐渐增大。零电压开关(zero voltage switching,ZVS)控制策略已成为降低开关损耗的主要手段。然而,传统ZVS控制策略在考虑死区时间时,存在ZVS区域不连续和移相比突变的问题,影响系统稳定。为了解决该问题,提出一种在全功率范围内移相比非突变的ZVS和电流应力优化策略。在中等功率范围内,由于死区时间的影响,所有开关器件的ZVS无法完全实现,以牺牲第1个桥臂开关器件的ZVS为代价,确保移相比的连续变化。在高功率范围内,以移相比连续变化为目标,重新调整分界线,实现中等功率范围与高功率范围的无缝切换。理论分析表明,提出的优化策略能够在全功率范围内保证移相比的连续性。通过搭建小功率实验平台,实验结果验证了所提优化策略的正确性和有效性。展开更多
为解决双有源桥(dual active bridge,DAB)变换器在采用传统控制策略时存在的动态响应慢、电流应力大及零电压开关(zero voltage switch,ZVS)范围受限等问题,笔者提出一种三重移相调制(triple phase shift,TPS)与模型预测控制(model pred...为解决双有源桥(dual active bridge,DAB)变换器在采用传统控制策略时存在的动态响应慢、电流应力大及零电压开关(zero voltage switch,ZVS)范围受限等问题,笔者提出一种三重移相调制(triple phase shift,TPS)与模型预测控制(model predictive control,MPC)的协同控制策略。该方法构建考虑ZVS约束的多模式电流应力模型,并设计包含电压跟踪、电流应力最小化及ZVS约束的复合代价函数;MPC实时求解最优移相角组合,实现TPS占空比的动态优化与实时校验。仿真结果表明:与传统TPS+PI控制策略相比,所提TPS-MPC协同控制策略在负载阶跃扰动下,动态响应速度提升约70%,电流应力降低约7.16%,且输出电压的恢复时间更短、波动幅值显著减小。该策略能有效优化DAB变换器的动态性能与效率,可为实现高功率密度、高效率电力电子变压器提供可行的控制解决方案。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 50878128, 50808122)
文摘The whole analysis process of pneumatic stressed membrane structure contains nine states and seven analysis processes.The zero-stress state is the corner-stone of analysis and design of pneumatic stressed structure,and has significant impact on the pre-stressed state and load state.According to the logical model of the whole numerical analysis process of pneumatic stressed structure,a numerical analysis method to solve the zero-stress state from the elasticized equilibrium state was firstly proposed,called linear compatibility matrix M-P inverse method.Firstly,the pneumatic membrane stressed structure was transferred into grid structure by using membrane link to simulate membrane surface.Secondly,on the basis of equilibrium matrix theory of pin joint structure and small deformation assumption,compatibility equation of system was established.Thirdly,the unstressed length and elongation of links were calculated from the tension and material parameters of elasticized equilibrium state.Finally,using compatibility matrix M-P inverse,the nodal displacement was calculated by solving compatibility equation,the configuration of zero-stress state could be obtained through reverse superposition,and the stress was released.According to the algorithm,the program was coded with MATLAB.The correctness and efficiency of this method were verified by several numerical examples,and it could be found that one elasticized equilibrium state corresponded to one configuration of the zero-stress state.The work has theoretical significance and practical guidance value for pneumatic membrane structural design.
文摘随着双有源桥开关频率的不断提高,开关损耗在总损耗中的占比逐渐增大。零电压开关(zero voltage switching,ZVS)控制策略已成为降低开关损耗的主要手段。然而,传统ZVS控制策略在考虑死区时间时,存在ZVS区域不连续和移相比突变的问题,影响系统稳定。为了解决该问题,提出一种在全功率范围内移相比非突变的ZVS和电流应力优化策略。在中等功率范围内,由于死区时间的影响,所有开关器件的ZVS无法完全实现,以牺牲第1个桥臂开关器件的ZVS为代价,确保移相比的连续变化。在高功率范围内,以移相比连续变化为目标,重新调整分界线,实现中等功率范围与高功率范围的无缝切换。理论分析表明,提出的优化策略能够在全功率范围内保证移相比的连续性。通过搭建小功率实验平台,实验结果验证了所提优化策略的正确性和有效性。
文摘为解决双有源桥(dual active bridge,DAB)变换器在采用传统控制策略时存在的动态响应慢、电流应力大及零电压开关(zero voltage switch,ZVS)范围受限等问题,笔者提出一种三重移相调制(triple phase shift,TPS)与模型预测控制(model predictive control,MPC)的协同控制策略。该方法构建考虑ZVS约束的多模式电流应力模型,并设计包含电压跟踪、电流应力最小化及ZVS约束的复合代价函数;MPC实时求解最优移相角组合,实现TPS占空比的动态优化与实时校验。仿真结果表明:与传统TPS+PI控制策略相比,所提TPS-MPC协同控制策略在负载阶跃扰动下,动态响应速度提升约70%,电流应力降低约7.16%,且输出电压的恢复时间更短、波动幅值显著减小。该策略能有效优化DAB变换器的动态性能与效率,可为实现高功率密度、高效率电力电子变压器提供可行的控制解决方案。
