In this paper,new SVPWM switching sequences for six-phase asymmetrical induction motor drives are derived with the aim to reduce inverter’s switching losses.Total three switching sequences are introduced in this pape...In this paper,new SVPWM switching sequences for six-phase asymmetrical induction motor drives are derived with the aim to reduce inverter’s switching losses.Total three switching sequences are introduced in this paper.These sequences are derived such that the phases get continuously clamped when a current of the phases is around its peak magnitude and hence reduced switching losses are recorded.The comparative performances of these modulation techniques are studied with two existing switching sequences.Simulation,analytical and experimental results are presented.Based on these results,it is found that new switching sequences reduce switching losses effectively in dual three phase inverters.展开更多
The heat treatment process of a gear made of AISI 9310 carburized steel is modeled using the commercial heat treatment simulation software DANTE.Both carburization and quenching processes affect the residual stress di...The heat treatment process of a gear made of AISI 9310 carburized steel is modeled using the commercial heat treatment simulation software DANTE.Both carburization and quenching processes affect the residual stress distribution and distortion of heat-treated parts,which are important to service quality and fatigue life.DANTE/VCARB is used to design the boost/diffuse schedule of a vacuum carburization process.Oil quenching is modeled following the vacuum carburization process.Thermal gradient and phase transformation are two main sources of distortion and residual stresses in quenched parts.The relation of the carbon distribution,thermal gradient,and phase transformations during quenching is studied through the gear modeling example.Because of geometry,the residual stress distribution after quenching is non-uniform along the gear surface.In general,the root fillet has higher residual compression than either the root or tooth face locations after traditional oil quenching of carburized gears.The predicted residual stresses from the oil quenching model are imported into a single tooth fatigue bending model.The gear stresses under bending load indicate the possible cracking locations during the bending fatigue test.The importance of heat treatment residual stresses during gear design is pointed out,and it is commonly ignored in the gear design and manufacturing industry.展开更多
直接数字合成器(direct digital synthesizer,DDS)是近年来迅速发展起来的频率合成技术,具有频率分辨率高、频率捷变等诸多优点.但其缺点是杂散抑制性能较差.分析了理想DDS的频谱结构,给出了杂散频谱的产生机理,并据此开发了图形化的频...直接数字合成器(direct digital synthesizer,DDS)是近年来迅速发展起来的频率合成技术,具有频率分辨率高、频率捷变等诸多优点.但其缺点是杂散抑制性能较差.分析了理想DDS的频谱结构,给出了杂散频谱的产生机理,并据此开发了图形化的频谱分析与杂散预测软件包.测试结果与理论值的对比说明了该软件包的正确性,并对基于DDS技术的频率源设计具有一定的实用性和指导意义.展开更多
文摘In this paper,new SVPWM switching sequences for six-phase asymmetrical induction motor drives are derived with the aim to reduce inverter’s switching losses.Total three switching sequences are introduced in this paper.These sequences are derived such that the phases get continuously clamped when a current of the phases is around its peak magnitude and hence reduced switching losses are recorded.The comparative performances of these modulation techniques are studied with two existing switching sequences.Simulation,analytical and experimental results are presented.Based on these results,it is found that new switching sequences reduce switching losses effectively in dual three phase inverters.
文摘The heat treatment process of a gear made of AISI 9310 carburized steel is modeled using the commercial heat treatment simulation software DANTE.Both carburization and quenching processes affect the residual stress distribution and distortion of heat-treated parts,which are important to service quality and fatigue life.DANTE/VCARB is used to design the boost/diffuse schedule of a vacuum carburization process.Oil quenching is modeled following the vacuum carburization process.Thermal gradient and phase transformation are two main sources of distortion and residual stresses in quenched parts.The relation of the carbon distribution,thermal gradient,and phase transformations during quenching is studied through the gear modeling example.Because of geometry,the residual stress distribution after quenching is non-uniform along the gear surface.In general,the root fillet has higher residual compression than either the root or tooth face locations after traditional oil quenching of carburized gears.The predicted residual stresses from the oil quenching model are imported into a single tooth fatigue bending model.The gear stresses under bending load indicate the possible cracking locations during the bending fatigue test.The importance of heat treatment residual stresses during gear design is pointed out,and it is commonly ignored in the gear design and manufacturing industry.
文摘直接数字合成器(direct digital synthesizer,DDS)是近年来迅速发展起来的频率合成技术,具有频率分辨率高、频率捷变等诸多优点.但其缺点是杂散抑制性能较差.分析了理想DDS的频谱结构,给出了杂散频谱的产生机理,并据此开发了图形化的频谱分析与杂散预测软件包.测试结果与理论值的对比说明了该软件包的正确性,并对基于DDS技术的频率源设计具有一定的实用性和指导意义.
