简述船上变频系统(Variable Frequency Drive, VFD)在设计、设备选型和安装应用等方面的一些具体要求,简单说明变频系统产生谐波的原因和如何消除谐波对船舶运营的影响。对电缆的选用和安装敷设进行详细说明,这是在船上应用时要重点关...简述船上变频系统(Variable Frequency Drive, VFD)在设计、设备选型和安装应用等方面的一些具体要求,简单说明变频系统产生谐波的原因和如何消除谐波对船舶运营的影响。对电缆的选用和安装敷设进行详细说明,这是在船上应用时要重点关注的部分;同时,对变频系统的变压器、变频器、设备密封件和末端接线处理等进行简述。变频系统中各设备间是相互关联的,任何设备选型或安装不满足技术要求都会带来不可预知的影响。掌握变频系统的设计应用,为今后更广泛的应用提供参考。展开更多
Conventional vacuum control in a milking system is accomplished by using a vacuum pump, sized for the maximum air flows into the milking system, running at a full speed. The difference between the pump capacity and th...Conventional vacuum control in a milking system is accomplished by using a vacuum pump, sized for the maximum air flows into the milking system, running at a full speed. The difference between the pump capacity and the necessary flow of air is compensated by allowing air to enter the system through a regulator. The solution presented in this paper uses a VFD （variable frequency driver） in order to drive the vacuum pump at a controlled speed, so that the air removed equals the air entering the milking system. The VFD technology is able to adjust the rate of air removal from the milking system, by changing the speed of the vacuum pump motor. The VFD is controlled by a computer using a virtual instrument in order to emulate a PID （proportion integration differentiation） regulator. The tests aimed to evaluate the vacuum regulator characteristics and vacuum stability. A statistical analysis of the experimental results was performed and it showed that there was a significant difference between the experimental results obtained for the two methods of vacuum regulation （with vacuum regulator and VFD controller respectively）. The experimental results proved that the used of the VFD controller led to a higher vacuum stability in terms of the error between the set vacuum value and the achieved values.展开更多
文摘简述船上变频系统(Variable Frequency Drive, VFD)在设计、设备选型和安装应用等方面的一些具体要求,简单说明变频系统产生谐波的原因和如何消除谐波对船舶运营的影响。对电缆的选用和安装敷设进行详细说明,这是在船上应用时要重点关注的部分;同时,对变频系统的变压器、变频器、设备密封件和末端接线处理等进行简述。变频系统中各设备间是相互关联的,任何设备选型或安装不满足技术要求都会带来不可预知的影响。掌握变频系统的设计应用,为今后更广泛的应用提供参考。
文摘Conventional vacuum control in a milking system is accomplished by using a vacuum pump, sized for the maximum air flows into the milking system, running at a full speed. The difference between the pump capacity and the necessary flow of air is compensated by allowing air to enter the system through a regulator. The solution presented in this paper uses a VFD （variable frequency driver） in order to drive the vacuum pump at a controlled speed, so that the air removed equals the air entering the milking system. The VFD technology is able to adjust the rate of air removal from the milking system, by changing the speed of the vacuum pump motor. The VFD is controlled by a computer using a virtual instrument in order to emulate a PID （proportion integration differentiation） regulator. The tests aimed to evaluate the vacuum regulator characteristics and vacuum stability. A statistical analysis of the experimental results was performed and it showed that there was a significant difference between the experimental results obtained for the two methods of vacuum regulation （with vacuum regulator and VFD controller respectively）. The experimental results proved that the used of the VFD controller led to a higher vacuum stability in terms of the error between the set vacuum value and the achieved values.
