A circuit configuration and a circuit topologic family of the novel forward mode AC/AC converters with high frequency link are presented. The circuit configuration is constituted of input cycloconverter, high frequenc...A circuit configuration and a circuit topologic family of the novel forward mode AC/AC converters with high frequency link are presented. The circuit configuration is constituted of input cycloconverter, high frequency transformer, output cycloconverter, input and output filters. The circuit topologic family includes eight circuit topologies, such as full-bridge-full-wave mode, etc. The bi-polarity phase-shifted control strategy and steady principles are thoroughly investigated. The output characteristics are obtained. By using the bi-polarity phase-shifted control strategy with phase-shifted control between the output cycloconveter and the input cycloconverter, commutation overlap period of the output cycloconverter, and polarity selection of the output filtering inductance current and the input voltage, the leakage inductance energy and the output filtering inductance current are naturally commutated, and surge voltage and surge current of the cycloconverters are overcome. The converters have such advantages as simple topology, two-stage power conversions(LFAC/HFAC/LFAC), bi-directional power flow, high frequency electrical isolation, good output waveforms, and strong ability to stabilize voltage. The converters lay key technical foundation on a new-type of regulated sinusoidal AC power supplies and electronic transformers. The correction and advancement of the converters are well verified by a principle test.展开更多
植入式脑电刺激技术以特异的解剖学定位点为靶点刺激病灶,在达到良好治疗效果的同时避免了药物治疗带来的全身性不良反应,被广泛应用于重大脑疾病的干预治疗中。传统采用一次性电池供能的植入式脑电刺激方案受电池体积限制,需要采用长...植入式脑电刺激技术以特异的解剖学定位点为靶点刺激病灶,在达到良好治疗效果的同时避免了药物治疗带来的全身性不良反应,被广泛应用于重大脑疾病的干预治疗中。传统采用一次性电池供能的植入式脑电刺激方案受电池体积限制,需要采用长导线来传递电刺激信号,然而这种方式增加了感染和并发症发生的风险。基于近场谐振式电感能量传输(nearfield resonant inductive power transfer,NFR-IPT)的植入式脑电刺激技术可以避免植入一次性电池和长电极引线,易于实现植入设备的全集成,因此受到国内外学者的关注,其高集成度、高效率、高可靠性成为该领域未来发展的主要方向。本文首先讨论了基于NFR-IPT的植入式脑电刺激技术的优势、系统结构和工作原理,然后重点分析了脑电刺激芯片所面临的挑战和其近年来关键技术的研究进展。最后,本文总结了现有技术中所存在的问题,并探讨了基于NFR-IPT的植入式脑电刺激技术未来可能的发展方向。展开更多
Based on planar Si dual-base transistor conception, a novel mesa dual-base heterojunc- tion bipolar transistor ( HBT) is designed and fabricated. Molecule beam extension. selective wet chemical etching, common contact...Based on planar Si dual-base transistor conception, a novel mesa dual-base heterojunc- tion bipolar transistor ( HBT) is designed and fabricated. Molecule beam extension. selective wet chemical etching, common contact photolithography and metal lift-off technique are adopted in the process. The device has particular and distinct voltage-controlled negative differential resistance (NDR) and photo-controlled NDR. The highest peak-to-vally current rate of the voltage-controlled NDR is larger than 148 and the peak current varies with the increase of collector voltage. The device features high speed and high frequency characteristics derived from HBT and intrinsic bistability and self-latching characteristics due to NDR. A single dual-base HBT can be seen as an integration of NDR device, HBT and photoconductive device. Compared with common HBT.the groove is the key factor producing NDR.展开更多
文摘A circuit configuration and a circuit topologic family of the novel forward mode AC/AC converters with high frequency link are presented. The circuit configuration is constituted of input cycloconverter, high frequency transformer, output cycloconverter, input and output filters. The circuit topologic family includes eight circuit topologies, such as full-bridge-full-wave mode, etc. The bi-polarity phase-shifted control strategy and steady principles are thoroughly investigated. The output characteristics are obtained. By using the bi-polarity phase-shifted control strategy with phase-shifted control between the output cycloconveter and the input cycloconverter, commutation overlap period of the output cycloconverter, and polarity selection of the output filtering inductance current and the input voltage, the leakage inductance energy and the output filtering inductance current are naturally commutated, and surge voltage and surge current of the cycloconverters are overcome. The converters have such advantages as simple topology, two-stage power conversions(LFAC/HFAC/LFAC), bi-directional power flow, high frequency electrical isolation, good output waveforms, and strong ability to stabilize voltage. The converters lay key technical foundation on a new-type of regulated sinusoidal AC power supplies and electronic transformers. The correction and advancement of the converters are well verified by a principle test.
文摘植入式脑电刺激技术以特异的解剖学定位点为靶点刺激病灶,在达到良好治疗效果的同时避免了药物治疗带来的全身性不良反应,被广泛应用于重大脑疾病的干预治疗中。传统采用一次性电池供能的植入式脑电刺激方案受电池体积限制,需要采用长导线来传递电刺激信号,然而这种方式增加了感染和并发症发生的风险。基于近场谐振式电感能量传输(nearfield resonant inductive power transfer,NFR-IPT)的植入式脑电刺激技术可以避免植入一次性电池和长电极引线,易于实现植入设备的全集成,因此受到国内外学者的关注,其高集成度、高效率、高可靠性成为该领域未来发展的主要方向。本文首先讨论了基于NFR-IPT的植入式脑电刺激技术的优势、系统结构和工作原理,然后重点分析了脑电刺激芯片所面临的挑战和其近年来关键技术的研究进展。最后,本文总结了现有技术中所存在的问题,并探讨了基于NFR-IPT的植入式脑电刺激技术未来可能的发展方向。
基金Supported by "973" National Key Basic Research Program ( No. 2002CB311905) andYoung Teacher Foundation of Tianjin University.
文摘Based on planar Si dual-base transistor conception, a novel mesa dual-base heterojunc- tion bipolar transistor ( HBT) is designed and fabricated. Molecule beam extension. selective wet chemical etching, common contact photolithography and metal lift-off technique are adopted in the process. The device has particular and distinct voltage-controlled negative differential resistance (NDR) and photo-controlled NDR. The highest peak-to-vally current rate of the voltage-controlled NDR is larger than 148 and the peak current varies with the increase of collector voltage. The device features high speed and high frequency characteristics derived from HBT and intrinsic bistability and self-latching characteristics due to NDR. A single dual-base HBT can be seen as an integration of NDR device, HBT and photoconductive device. Compared with common HBT.the groove is the key factor producing NDR.
