针对电压型无线电能传输系统(wireless power transfer,WPT)在实际应用中受外界或系统内部扰动时出现输出电压不稳定以及如何保证控制器对扰动情况迅速做出反应的问题,提出一种基于线性自抗扰控制(linear active disturbance rejection ...针对电压型无线电能传输系统(wireless power transfer,WPT)在实际应用中受外界或系统内部扰动时出现输出电压不稳定以及如何保证控制器对扰动情况迅速做出反应的问题,提出一种基于线性自抗扰控制(linear active disturbance rejection control,LADRC)的WPT系统。首先根据WPT系统SS型谐振网络的T型等效电路建立传递函数模型,分析了各个参数对系统输出的影响,并推导出移相角度与输出电压的关系;其次结合系统模型及自抗扰控制理论,设计一阶LADRC控制器对系统输出电压进行闭环控制,并确定各个环节待整定参数的调节方向;最后搭建了基于LADRC的无线电能传输装置,在多种扰动的情况下比较了LADRC控制器与PI控制器的控制效果。实验结果证明,LADRC控制器能够更好的应对系统扰动的不确定性,保证了WPT系统的恒压输出,具有良好的控制特性。展开更多
针对传统移相全桥零电压开关ZVS(zero voltage switching)变换器存在的例如软开关范围受限、占空比丢失以及寄生振荡问题,提出了一种基于互补占空比调制的改进全桥ZVS直流变换器。通过引入并联辅助谐振网络以实现滞后桥臂开关宽范围的Z...针对传统移相全桥零电压开关ZVS(zero voltage switching)变换器存在的例如软开关范围受限、占空比丢失以及寄生振荡问题,提出了一种基于互补占空比调制的改进全桥ZVS直流变换器。通过引入并联辅助谐振网络以实现滞后桥臂开关宽范围的ZVS,选择较小的谐振电感以减少占空比丢失,引入原边钳位二极管网络以消除寄生振荡。详细阐明了工作原理与特性分析,并进行了仿真对比。结果显示,在20%负载条件下,相较于传统移相全桥变换器,所提改进全桥变换器保证了软开关特性且消除了寄生振荡。展开更多
Functional magnetic resonance imaging has been widely used to investigate the effects of acupuncture on neural activity. However, most functional magnetic resonance imaging studies have focused on acute changes in bra...Functional magnetic resonance imaging has been widely used to investigate the effects of acupuncture on neural activity. However, most functional magnetic resonance imaging studies have focused on acute changes in brain activation induced by acupuncture. Thus, the time course of the therapeutic effects of acupuncture remains unclear. In this study, 32 patients with amnestic mild cognitive impairment were randomly divided into two groups, where they received either Tiaoshen Yizhi acupuncture or sham acupoint acupuncture. The needles were either twirled at Tiaoshen Yizhi acupoints, including Sishencong（EX-HN1）, Yintang（EX-HN3）, Neiguan（PC6）, Taixi（KI3）, Fenglong（ST40）, and Taichong（LR3）, or at related sham acupoints at a depth of approximately 15 mm, an angle of ± 60°, and a rate of approximately 120 times per minute. Acupuncture was conducted for 4 consecutive weeks, five times per week, on weekdays. Resting-state functional magnetic resonance imaging indicated that connections between cognition-related regions such as the insula, dorsolateral prefrontal cortex, hippocampus, thalamus, inferior parietal lobule, and anterior cingulate cortex increased after acupuncture at Tiaoshen Yizhi acupoints. The insula, dorsolateral prefrontal cortex, and hippocampus acted as central brain hubs. Patients in the Tiaoshen Yizhi group exhibited improved cognitive performance after acupuncture. In the sham acupoint acupuncture group, connections between brain regions were dispersed, and we found no differences in cognitive function following the treatment. These results indicate that acupuncture at Tiaoshen Yizhi acupoints can regulate brain networks by increasing connectivity between cognition-related regions, thereby improving cognitive function in patients with mild cognitive impairment.展开更多
文摘针对电压型无线电能传输系统(wireless power transfer,WPT)在实际应用中受外界或系统内部扰动时出现输出电压不稳定以及如何保证控制器对扰动情况迅速做出反应的问题,提出一种基于线性自抗扰控制(linear active disturbance rejection control,LADRC)的WPT系统。首先根据WPT系统SS型谐振网络的T型等效电路建立传递函数模型,分析了各个参数对系统输出的影响,并推导出移相角度与输出电压的关系;其次结合系统模型及自抗扰控制理论,设计一阶LADRC控制器对系统输出电压进行闭环控制,并确定各个环节待整定参数的调节方向;最后搭建了基于LADRC的无线电能传输装置,在多种扰动的情况下比较了LADRC控制器与PI控制器的控制效果。实验结果证明,LADRC控制器能够更好的应对系统扰动的不确定性,保证了WPT系统的恒压输出,具有良好的控制特性。
文摘针对传统移相全桥零电压开关ZVS(zero voltage switching)变换器存在的例如软开关范围受限、占空比丢失以及寄生振荡问题,提出了一种基于互补占空比调制的改进全桥ZVS直流变换器。通过引入并联辅助谐振网络以实现滞后桥臂开关宽范围的ZVS,选择较小的谐振电感以减少占空比丢失,引入原边钳位二极管网络以消除寄生振荡。详细阐明了工作原理与特性分析,并进行了仿真对比。结果显示,在20%负载条件下,相较于传统移相全桥变换器,所提改进全桥变换器保证了软开关特性且消除了寄生振荡。
基金supported by the National Natural Science Foundation of China,No.81173354a grant from the Science and Technology Plan Project of Guangdong Province of China,No.2013B021800099a grant from the Science and Technology Plan Project of Shenzhen City of China,No.JCYJ20150402152005642
文摘Functional magnetic resonance imaging has been widely used to investigate the effects of acupuncture on neural activity. However, most functional magnetic resonance imaging studies have focused on acute changes in brain activation induced by acupuncture. Thus, the time course of the therapeutic effects of acupuncture remains unclear. In this study, 32 patients with amnestic mild cognitive impairment were randomly divided into two groups, where they received either Tiaoshen Yizhi acupuncture or sham acupoint acupuncture. The needles were either twirled at Tiaoshen Yizhi acupoints, including Sishencong（EX-HN1）, Yintang（EX-HN3）, Neiguan（PC6）, Taixi（KI3）, Fenglong（ST40）, and Taichong（LR3）, or at related sham acupoints at a depth of approximately 15 mm, an angle of ± 60°, and a rate of approximately 120 times per minute. Acupuncture was conducted for 4 consecutive weeks, five times per week, on weekdays. Resting-state functional magnetic resonance imaging indicated that connections between cognition-related regions such as the insula, dorsolateral prefrontal cortex, hippocampus, thalamus, inferior parietal lobule, and anterior cingulate cortex increased after acupuncture at Tiaoshen Yizhi acupoints. The insula, dorsolateral prefrontal cortex, and hippocampus acted as central brain hubs. Patients in the Tiaoshen Yizhi group exhibited improved cognitive performance after acupuncture. In the sham acupoint acupuncture group, connections between brain regions were dispersed, and we found no differences in cognitive function following the treatment. These results indicate that acupuncture at Tiaoshen Yizhi acupoints can regulate brain networks by increasing connectivity between cognition-related regions, thereby improving cognitive function in patients with mild cognitive impairment.
