In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperatur...In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.展开更多
SnO_(2)is used as electrode material with excellent properties,but it has some disadvantages such as slow reaction kinetics,low inherent conductivity and complex preparation process.Here,SnO_(2)@carbon nanotubes(SnO_(...SnO_(2)is used as electrode material with excellent properties,but it has some disadvantages such as slow reaction kinetics,low inherent conductivity and complex preparation process.Here,SnO_(2)@carbon nanotubes(SnO_(2)@CNTs)is synthesized through an efficient method of one-pot alternating current electrochemical dispersion.By using heat treatment at 400℃,the SnO_(2)@CNTs-400 composite material with abundant mesoporous structure is obtained,while the crystal particles are grown,and a strong bonding effect is formed with CNTs via powerful Sn-O-C bond.Benefiting from the introduction of high electrical conductivity CNTs and outstanding structural characteristics,as prepared composite material(SnO_(2)@CNTs-400)exhibit enhanced diffusion dynamics,lithium-ion transmission rate and structural steadiness.The specific capacity of SnO_(2)@CNTs and SnO_(2)@CNTs-400 as anodes for lithium-ion batteries can reach 690.2 mA·h/g and 836.5 mA·h/g,respectively,after 100 cycles at 0.5 A/g.The abundant chemical bonds and porous structure can be formed in composite via alternating current synthesis method,which takes significant in improving electrochemical properties.展开更多
用于中高压直流电网互联和隔离的模块化多电平直流变压器(modular multilevel DC transformer,MMDCT)在传输功率变化的过程中会出现电流欠阻尼振荡的问题,从而降低了装置的稳定性,因此文中对振荡抑制展开了研究。首先,通过差模和共模电...用于中高压直流电网互联和隔离的模块化多电平直流变压器(modular multilevel DC transformer,MMDCT)在传输功率变化的过程中会出现电流欠阻尼振荡的问题,从而降低了装置的稳定性,因此文中对振荡抑制展开了研究。首先,通过差模和共模电路中的振荡现象分析,并基于状态空间平均法建立数学模型,从而揭示了MMDCT中的电流振荡机理;进一步提出了一种基于共模和差模分离的电流振荡抑制方法,利用变副边交流侧电压占空比的方式实现漏感电流振荡的抑制,同时采用变桥臂电压占空比的方式进行环流电流振荡的抑制,并给出了相应控制器参数设计依据。最后,通过仿真和实验验证了所提控制方法的有效性,结果表明在基于共模和差模分离的振荡抑制方法下,MMDCT可以在功率变化过程中快速实现电流稳定,有利于提升装置稳定性。展开更多
基金supported by the National Natural Science Foundation of China(No.62271109)。
文摘In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.
基金Project(2023JЛ10041)supported by the Distinguished Young Scholar Fund Project of Hunan Province Natural Science Foundation,ChinaProject(22A0114)supported by the Hunan Provincial Education Office Foundation of China+2 种基金Projects(GX-ZD20211004,GX-ZD20221007)supported by the Science and Technology Program of Xiangtan,ChinaProject(R24-5979269037)supported by the RSC Research Fund Grout,EnglandProject(S202310530037X)supported by the National College Students Innovative Experimental Program Funding Project,China。
文摘SnO_(2)is used as electrode material with excellent properties,but it has some disadvantages such as slow reaction kinetics,low inherent conductivity and complex preparation process.Here,SnO_(2)@carbon nanotubes(SnO_(2)@CNTs)is synthesized through an efficient method of one-pot alternating current electrochemical dispersion.By using heat treatment at 400℃,the SnO_(2)@CNTs-400 composite material with abundant mesoporous structure is obtained,while the crystal particles are grown,and a strong bonding effect is formed with CNTs via powerful Sn-O-C bond.Benefiting from the introduction of high electrical conductivity CNTs and outstanding structural characteristics,as prepared composite material(SnO_(2)@CNTs-400)exhibit enhanced diffusion dynamics,lithium-ion transmission rate and structural steadiness.The specific capacity of SnO_(2)@CNTs and SnO_(2)@CNTs-400 as anodes for lithium-ion batteries can reach 690.2 mA·h/g and 836.5 mA·h/g,respectively,after 100 cycles at 0.5 A/g.The abundant chemical bonds and porous structure can be formed in composite via alternating current synthesis method,which takes significant in improving electrochemical properties.
文摘用于中高压直流电网互联和隔离的模块化多电平直流变压器(modular multilevel DC transformer,MMDCT)在传输功率变化的过程中会出现电流欠阻尼振荡的问题,从而降低了装置的稳定性,因此文中对振荡抑制展开了研究。首先,通过差模和共模电路中的振荡现象分析,并基于状态空间平均法建立数学模型,从而揭示了MMDCT中的电流振荡机理;进一步提出了一种基于共模和差模分离的电流振荡抑制方法,利用变副边交流侧电压占空比的方式实现漏感电流振荡的抑制,同时采用变桥臂电压占空比的方式进行环流电流振荡的抑制,并给出了相应控制器参数设计依据。最后,通过仿真和实验验证了所提控制方法的有效性,结果表明在基于共模和差模分离的振荡抑制方法下,MMDCT可以在功率变化过程中快速实现电流稳定,有利于提升装置稳定性。
