随着国家大力发展城市轨道交通,不间断电源(uninterruptible power supply,UPS)系统作为关键供电装置,具有重要的研究意义和价值。为了满足相关电能质量法规的要求,集成功率因数校正(power factor correction,PFC)输入级是保证轨道交通...随着国家大力发展城市轨道交通,不间断电源(uninterruptible power supply,UPS)系统作为关键供电装置,具有重要的研究意义和价值。为了满足相关电能质量法规的要求,集成功率因数校正(power factor correction,PFC)输入级是保证轨道交通基础设施设备供电的UPS系统的重要要求。三电平Boost PFC在采用传统载波调制时,在一定的输入电压范围内输入电流始终为零,导致变换器功率因数校正效果较差。因此,提出一种基于k值调制的变占空比控制的方法,不仅可以解决高输入电压下传统载波调制存在的问题,且可进一步抑制输入电流的畸变从而提高输入电流波形质量。首先介绍了这种k值调制方法,分析了其原理以及k值对变换器功率因数和电感电流有效值的影响。在此基础上,结合电压平衡策略对k值进行优化,解决直流侧输出电容电压上下不均衡问题。最后,针对高输入电压下输入电流仍然严重畸变的问题,提出一种基于k值调制的可变占空比控制方法,分析了变占空比控制对变换器功率因数、输出功率、电压纹波以及电感电流峰值的影响。最后通过仿真和搭建小功率实验平台,验证了所提控制方法的正确性和有效性。展开更多
本文探讨了榕江“新三变”政策与电子商务结合对农村经济发展的影响。“新三变”即手机变成“新农具”、直播变成“新农活”、数据变成“新农资”,通过现代信息技术与传统农业的深度融合,推动农村经济的转型升级。研究表明,电子商务显...本文探讨了榕江“新三变”政策与电子商务结合对农村经济发展的影响。“新三变”即手机变成“新农具”、直播变成“新农活”、数据变成“新农资”,通过现代信息技术与传统农业的深度融合,推动农村经济的转型升级。研究表明,电子商务显著提升了农民收入,降低了交易成本,提高了农产品的附加值和市场竞争力。政府通过政策支持、技术培训和基础设施建设,帮助农民掌握电商技能,缩小城乡收入差距。榕江县的实践案例展示了政策与科技结合的强大力量,提升了农产品的品牌知名度和销售量,促进了乡村旅游业的发展,为其他地区提供了有益的参考。然而,该模式仍面临技术基础设施和品牌意识不足等挑战。未来,需要持续增加政策和资源投入,以推动农村经济的可持续发展。This article explores the impact of the Rongjiang “New Three Transformations” policy in conjunction with e-commerce on rural economic development. The “New Three Transformations” refer to the transformation of mobile phones into “new agricultural tools”, live streaming into “new farming activities”, and data into “new agricultural materials”. By deeply integrating modern information technology with traditional agriculture, this approach promotes the transformation and upgrading of the agricultural economy. The research indicates that e-commerce significantly enhances farmers’ income, reduces transaction costs, and increases the added value and market competitiveness of agricultural products. The government supports farmers in acquiring e-commerce skills through policy support, technical training, and infrastructure development, thereby narrowing the income gap between urban and rural areas. The practical cases from Rongjiang County demonstrate the powerful synergy of policy and technology, enhancing the brand awareness and sales of agricultural products, and promoting the development of rural tourism, providing valuable references for other regions. However, this model still faces challenges such as inadequate technological infrastructure and lack of brand awareness. In the future, continuous investment in policies and resources is needed to promote the sustainable development of the rural economy.展开更多
文摘本文探讨了榕江“新三变”政策与电子商务结合对农村经济发展的影响。“新三变”即手机变成“新农具”、直播变成“新农活”、数据变成“新农资”,通过现代信息技术与传统农业的深度融合,推动农村经济的转型升级。研究表明,电子商务显著提升了农民收入,降低了交易成本,提高了农产品的附加值和市场竞争力。政府通过政策支持、技术培训和基础设施建设,帮助农民掌握电商技能,缩小城乡收入差距。榕江县的实践案例展示了政策与科技结合的强大力量,提升了农产品的品牌知名度和销售量,促进了乡村旅游业的发展,为其他地区提供了有益的参考。然而,该模式仍面临技术基础设施和品牌意识不足等挑战。未来,需要持续增加政策和资源投入,以推动农村经济的可持续发展。This article explores the impact of the Rongjiang “New Three Transformations” policy in conjunction with e-commerce on rural economic development. The “New Three Transformations” refer to the transformation of mobile phones into “new agricultural tools”, live streaming into “new farming activities”, and data into “new agricultural materials”. By deeply integrating modern information technology with traditional agriculture, this approach promotes the transformation and upgrading of the agricultural economy. The research indicates that e-commerce significantly enhances farmers’ income, reduces transaction costs, and increases the added value and market competitiveness of agricultural products. The government supports farmers in acquiring e-commerce skills through policy support, technical training, and infrastructure development, thereby narrowing the income gap between urban and rural areas. The practical cases from Rongjiang County demonstrate the powerful synergy of policy and technology, enhancing the brand awareness and sales of agricultural products, and promoting the development of rural tourism, providing valuable references for other regions. However, this model still faces challenges such as inadequate technological infrastructure and lack of brand awareness. In the future, continuous investment in policies and resources is needed to promote the sustainable development of the rural economy.
