带脉冲功率负载的直流供电系统现已广泛应用于电动车、舰船及航空等领域。当脉冲负载发生突变时,整流发电机端电压会随之变化,对整个供电系统的稳定性造成负面影响,此时,滤波电容起到了关键作用。直流供电系统中的滤波电容通常采用电解...带脉冲功率负载的直流供电系统现已广泛应用于电动车、舰船及航空等领域。当脉冲负载发生突变时,整流发电机端电压会随之变化,对整个供电系统的稳定性造成负面影响,此时,滤波电容起到了关键作用。直流供电系统中的滤波电容通常采用电解电容。电解电容存在寄生参数等效串联电阻(equivalent series resistance,ESR),会引起输出电压波形畸变及电压大小的变化。为此,该文提出一种考虑滤波电容寄生参数ESR的双三相整流发电机带脉冲负载的瞬时电压计算方法。首先,建立考虑滤波电容寄生参数ESR的带脉冲功率负载的双三相整流发电机等效瞬态数学模型;其次,通过双三相整流发电机瞬态有限元仿真同负载突变实验进行对比,验证所提出的考虑滤波电容寄生参数ESR的双三相整流发电机等效模型负载突变的瞬时电压计算方法的必要性与可行性;最后,分析滤波电容C及其寄生参数ESR对双三相整流发电机直流侧电压的影响。结果表明,建立的等效模型具有较高的准确性,同时,表明考虑滤波电容寄生参数ESR对整流发电机直流测电压的研究对提高整个直流供电系统电能质量具有重要意义。展开更多
The effects of high-volume slag-fly ash cement with different particle sizes on hydration degree,microstructure and mechanical properties were systematically studied,by means of laser particle size(DLS),X-ray diffract...The effects of high-volume slag-fly ash cement with different particle sizes on hydration degree,microstructure and mechanical properties were systematically studied,by means of laser particle size(DLS),X-ray diffraction (XRD),comprehensive thermal analysis (TG-DTA),scanning electron microscopy(SEM) and mechanical properties tests.The results show that suitable particle size distribution of cementitious material has significantly promoting effects on hydration reaction rate and mechanical properties.Compared with slag without further grinding,the slag after ball milling for 4 h has an obvious improvement in reactivity,which also provides a faster hydration rate and higher compressive strength for the cementitious material.When the slag milled for 1 and 4 h is mixed at a mass ratio of 2:1 (i e,slag with D_(50) of 7.4μm and average size of 9.9μm,and slag with D_(50) value of 2.6μm and average size of 5.3μm),and a certain amount of fly ash is added in,the most obvious improvement of compressive strength of cement is achieved.展开更多
文摘带脉冲功率负载的直流供电系统现已广泛应用于电动车、舰船及航空等领域。当脉冲负载发生突变时,整流发电机端电压会随之变化,对整个供电系统的稳定性造成负面影响,此时,滤波电容起到了关键作用。直流供电系统中的滤波电容通常采用电解电容。电解电容存在寄生参数等效串联电阻(equivalent series resistance,ESR),会引起输出电压波形畸变及电压大小的变化。为此,该文提出一种考虑滤波电容寄生参数ESR的双三相整流发电机带脉冲负载的瞬时电压计算方法。首先,建立考虑滤波电容寄生参数ESR的带脉冲功率负载的双三相整流发电机等效瞬态数学模型;其次,通过双三相整流发电机瞬态有限元仿真同负载突变实验进行对比,验证所提出的考虑滤波电容寄生参数ESR的双三相整流发电机等效模型负载突变的瞬时电压计算方法的必要性与可行性;最后,分析滤波电容C及其寄生参数ESR对双三相整流发电机直流侧电压的影响。结果表明,建立的等效模型具有较高的准确性,同时,表明考虑滤波电容寄生参数ESR对整流发电机直流测电压的研究对提高整个直流供电系统电能质量具有重要意义。
基金Funded by the National Natural Science Foundation of China(No.52172025)。
文摘The effects of high-volume slag-fly ash cement with different particle sizes on hydration degree,microstructure and mechanical properties were systematically studied,by means of laser particle size(DLS),X-ray diffraction (XRD),comprehensive thermal analysis (TG-DTA),scanning electron microscopy(SEM) and mechanical properties tests.The results show that suitable particle size distribution of cementitious material has significantly promoting effects on hydration reaction rate and mechanical properties.Compared with slag without further grinding,the slag after ball milling for 4 h has an obvious improvement in reactivity,which also provides a faster hydration rate and higher compressive strength for the cementitious material.When the slag milled for 1 and 4 h is mixed at a mass ratio of 2:1 (i e,slag with D_(50) of 7.4μm and average size of 9.9μm,and slag with D_(50) value of 2.6μm and average size of 5.3μm),and a certain amount of fly ash is added in,the most obvious improvement of compressive strength of cement is achieved.
