This research investigated the outputting circulation current inhibition characteristic which are controlled by the instantaneous feedback voltage in inverter parallel driving of the mine hoist. We established a trans...This research investigated the outputting circulation current inhibition characteristic which are controlled by the instantaneous feedback voltage in inverter parallel driving of the mine hoist. We established a transfer function of the parallel inverters controlled by the close-loop adjustment of instantaneous voltage feedback. The influence of the parameters of the close-loop feedback circuit to the inhibition effects to the outputting circulation current is observed. After analyzing the circulating current inhibition characteristics, the proportion integration （PI） controller is introduced into the close-loop adjustment by instantaneous voltage feedback. The characteristics equation is gained to determine the PI parameters by drawing the Bode plots. The inhibition effects of the proposed controller are examined by the established simulation model of parallel inverter system. The harmonic distortion rate at the outputting voltage frequency value of 4, 10, 20, 41 and 50 Hz, are all lower than 2.32 % by the instantaneous outputting voltage feedback.展开更多
With the development of the social economy, Chinese tourism will surely change from medium scale to massive scale. As people are more and more focusing on the inner values of life style, new types of tourist demands w...With the development of the social economy, Chinese tourism will surely change from medium scale to massive scale. As people are more and more focusing on the inner values of life style, new types of tourist demands will emerge at anytime, and the spatial structure of tourist demands will show new characteristics as well Until now there is few study on tourist demand, especially on its spatial pattern. Study on spatial characteristics of tourist demand will contribute to spatial optimization and adjustments of tourist flow and supply. So this article has put forward the spatial pattern of tourist demand in China and measures of spatial adjustments and grade system of the spatial adjustment of tourists demand.展开更多
文摘This research investigated the outputting circulation current inhibition characteristic which are controlled by the instantaneous feedback voltage in inverter parallel driving of the mine hoist. We established a transfer function of the parallel inverters controlled by the close-loop adjustment of instantaneous voltage feedback. The influence of the parameters of the close-loop feedback circuit to the inhibition effects to the outputting circulation current is observed. After analyzing the circulating current inhibition characteristics, the proportion integration （PI） controller is introduced into the close-loop adjustment by instantaneous voltage feedback. The characteristics equation is gained to determine the PI parameters by drawing the Bode plots. The inhibition effects of the proposed controller are examined by the established simulation model of parallel inverter system. The harmonic distortion rate at the outputting voltage frequency value of 4, 10, 20, 41 and 50 Hz, are all lower than 2.32 % by the instantaneous outputting voltage feedback.
文摘With the development of the social economy, Chinese tourism will surely change from medium scale to massive scale. As people are more and more focusing on the inner values of life style, new types of tourist demands will emerge at anytime, and the spatial structure of tourist demands will show new characteristics as well Until now there is few study on tourist demand, especially on its spatial pattern. Study on spatial characteristics of tourist demand will contribute to spatial optimization and adjustments of tourist flow and supply. So this article has put forward the spatial pattern of tourist demand in China and measures of spatial adjustments and grade system of the spatial adjustment of tourists demand.
