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Exploring the Dual Subjectivity of Kindergarten's Self-made Play and Teaching Aids Activities from the Perspective of Children's Play Development in China 被引量:1
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作者 Yuwei Zhao 《教育技术与创新》 2024年第1期1-9,共9页
The joint development of teachers and young children is the basis for promoting the development of high-quality preschool education in the new era,and encouraging early childhood teachers to make playthings according ... The joint development of teachers and young children is the basis for promoting the development of high-quality preschool education in the new era,and encouraging early childhood teachers to make playthings according to local conditions is both the fine tradition of China's early childhood education and the direct orientation of China's preschool education policy.Homemade play and teaching aids are some of the methods often used in kindergartens,which skillfully combine young children's daily life objects with toys and early childhood teaching,not only enriching the collective activities of young children but also cultivating children's abilities in various aspects.Kindergarten homemade"play and teaching aids"for early childhood teachers and children have their special educational significance and value,therefore,this paper is based on the children and teachers double subject basis,discussing the homemade"play and teaching aids"for children and teachers of the double subject meanings,and puts forward the realization of the This paper discusses the double-subjective meaning of homemade teaching aids for children and teachers on the basis of the double-subjective foundation of children and teachers,and puts forward specific suggestions for realizing the double-subjectivity of kindergarten homemade teaching aids to enrich the theoretical value and practical significance of homemade teaching aids,to provide theoretical references and support for the relevant staff. 展开更多
关键词 self-made playthings Double subjectivity KINDERGARTEN China
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Process Analysis of Mobile Fermentation of Spent White Hypsizygus marmoreus Substrate with Self-made Mobile Fermentation Bag
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作者 罗茂春 林标声 +1 位作者 邱丰艳 陈柳花 《Agricultural Science & Technology》 CAS 2016年第4期829-832,共4页
The self-made mobile fermentation bag for spent white Hypsizygus marmoreus substrate was developed, and the relevant fermentation process was studied. The results showed that under the condition of single addition of ... The self-made mobile fermentation bag for spent white Hypsizygus marmoreus substrate was developed, and the relevant fermentation process was studied. The results showed that under the condition of single addition of Lactobacillus,nitrogen-free extract was degraded into lactic acid, leading to decreased pH value.On day 10, the fermentation effect reached the best with Lactobacillus abundance of 5.12×10~7/ml, lactic acid content of 0.48% and strong acid flavor. At this time, the fermentation material was moist without mildew and agglomeration, and was suitable for livestock and poultry. However, after 10 days, undesirable acids and mildew generated, a large amount of lactic acid bacteria died, and the fermentation material turned black and agglomerated, and became unsuitable for feeding livestock and poultry. Throughout the fermentation process, the pH value first decreased continuously until to 4.0, and then remained stable. During the fermentation of spent white H. marmoreus substrate, the nitrogen-free extract and crude fiber contents decreased, the crude protein content increased, while other indicators remained unchanged. 展开更多
关键词 self-made fermentation bag Mobile fermentation Spent white Hypsizy gus marmoreus substrate Fermentation analysis
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Severe skeletal bimaxillary protrusion treated with micro-implants and a self-made four-curvature torquing auxiliary: A case report 被引量:2
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作者 Rui Liu Wan-Bang Hou +4 位作者 Ping-Zhu Yang Lin Zhu Yong-Quan Zhou Xia Yu Xiu-Jie Wen 《World Journal of Clinical Cases》 SCIE 2021年第3期722-735,共14页
BACKGROUND Bimaxillary protrusion is a clinically common dentofacial deformity,particularly among Chinese patients.This kind of malformation can severely affect facial esthetics and,even in mild cases,is difficult to ... BACKGROUND Bimaxillary protrusion is a clinically common dentofacial deformity,particularly among Chinese patients.This kind of malformation can severely affect facial esthetics and,even in mild cases,is difficult to correct without surgery.Unfortunately,many patients abandon treatment because of fear of surgery.Here,we describe a case of severe skeletal bimaxillary protrusion treated with nonsurgical orthodontic treatments,highlighting an alternative treatment option.CASE SUMMARY A 31-year-old woman wished to address a severe protrusion profile(approximately 8 mm overbite)and gummy smile.Cephalometric analysis and superimposition showed a severe skeletal class II pattern with a mandibular retrusion,and proclined and protrusive mandibular incisors.Panoramic radiograph showed a missing mandibular right third molar.A diagnosis of severe bimaxillary dentoalveolar protrusion was made.Taking into account the patient’s fear of orthognathic surgery,she accepted the proposed alternative treatment using micro-implants and a self-made four-curvature torquing auxiliary.The treatment allowed for maximal en masse anterior tooth retraction,proper relocation of incisors,and alleviation of the skeletal class II pattern.Esthetically,the patient’s lip protrusion was significantly decreased as was the overjet(from 10.5 mm to 1.8 mm),and the results remained stable throughout the 2-year followup.CONCLUSION Nonsurgical treatment using micro-implants and a four-curvature torquing auxiliary may benefit severe cases of skeletal bimaxillary protrusion in adults. 展开更多
关键词 ORTHODONTICS Bimaxillary protrusion Micro-implants self-made fourcurvature torquing auxiliary Teeth Case report
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Self-made wire loop snare successfully treats gastric persimmon stone under endoscopy
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作者 Wen Xu Xiao-Bo Liu +2 位作者 Sheng-Bao Li Wei-Ping Deng Qiang Tong 《World Journal of Clinical Cases》 SCIE 2022年第19期6428-6436,共9页
BACKGROUND Large gastric persimmon stones are generally resistant to standard endoscopic treatments.We applied an alternative endoscopic method using a hand-made snare for the treatment of large gastric phytobezoars.A... BACKGROUND Large gastric persimmon stones are generally resistant to standard endoscopic treatments.We applied an alternative endoscopic method using a hand-made snare for the treatment of large gastric phytobezoars.AIM To explore the clinical efficacy of a self-made wire loop snare to treat giant gastric persimmon stones.METHODS A retrospective study evaluated the clinical data of 38 patients with gastroliths admitted to Taihe Hospital in Shiyan City,Hubei Province,China,between March 2015 and October 2020.The patients were divided into observation(n=23)and control(n=15)groups.Patients in the observation group were treated with selfmade wire loop snares for lithotripsy,and patients in the control group were treated with traditional foreign body forceps,snares,injection needles,and other tools.Successful stone removal,treatment time,and hospital stay were compared.RESULTS The average operating time was significantly shorter(P<0.001)in the observation group(53.4 min)than that in the control group(172.8 min).The average hospital stay of the observation group(5.4 d)was significantly shorter(P<0.001)than that in the control group(10.3 d).Successful one-time treatment was significantly more frequent(P<0.001)in the observation group(87%)than in the control group(7%).CONCLUSION Self-made guidewire loop snares were successfully used to treat gastrolithiasis, and were significantly more effective than foreign body forceps, snares, and other traditionalmethods. 展开更多
关键词 Gastric persimmon Phytobezoars self-made snare ENDOSCOPY Treatment
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Protective Effects of Self-made Compound Taoren Danshen Decoction on Rats with Acute Liver Injury
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作者 Yuman GUAN Kefeng ZHANG +2 位作者 Ya GAO Jiani LI Lin ZHANG 《Medicinal Plant》 CAS 2018年第5期107-110,共4页
[Objectives] To study the protective effects of self-made Compound Taoren Danshen Decoction( CTDD) on acute liver injury induced by D-galactosamine in rats,and to explore its mechanism. [Methods]An acute liver injury ... [Objectives] To study the protective effects of self-made Compound Taoren Danshen Decoction( CTDD) on acute liver injury induced by D-galactosamine in rats,and to explore its mechanism. [Methods]An acute liver injury model was established by intraperitoneal injection of 500 mg/kg of D-galactosamine. The ALT,AST,MDA,SOD and GSH-Px in serum,as well as serum TNF-α,IL-1β and IL-6 levels were measured,and liver tissue lesions were observed under microscope. [Results] CTDD can significantly reduce ALT,AST and MDA levels,increase SOD,GSH-Px activity,and significantly reduce serum TNF-α,IL-1β and IL-6 levels,and improve liver tissue lesions.[Conclusions]CTDD has a protective effect on D-galactosamine-induced acute liver injury in rats,and its mechanism may be related to inhibition of oxidative stress and inflammatory reaction. 展开更多
关键词 self-made COMPOUND Taoren DANSHEN Decoction(CTDD) D-GALACTOSAMINE Acute liver injury Oxidative stress INFLAMMATORY reaction
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Observation on the Effect of Umbilical Therapy of Herbal Medicine Combined with Self-Made Dysmenorrhea Paste on Primary Dysmenorrhea
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作者 Wen-Ming Cao Xiu-Rong Wang 《Psychosomatic Medicine Research》 2020年第1期1-7,共7页
Objective:To investigate the clinical effect of self-made dysmenorrhea paste combined with umbilical therapy of herbal medicine on primary dysmenorrhea.Methods:160 patients with primary dysmenorrhea were recruited fro... Objective:To investigate the clinical effect of self-made dysmenorrhea paste combined with umbilical therapy of herbal medicine on primary dysmenorrhea.Methods:160 patients with primary dysmenorrhea were recruited from Changle People’s Hospital.Participants were randomly divided into control group and treatment group,with 80 cases in each group.The control group were administered the dysmenorrhea paste sold on the market for 5 days during three menstruation cycles,and the treatment group was given the umbilical therapy of herbal medicine combined with self-made dysmenorrhea paste.The outcome was the intensity of menstrual pain measured by using the visual analogue scale,TCM symptom score and dysmenorrhea symptom score of patients,responder rate.The clinical outcomes were measured on each menstrual cycle at baseline,treatment course(3 cycles),and follow-up period.Results:In this study,there was no significant difference in age and severity of disease between the two groups before treatment.After treatment,VAS score,TCM symptom score and dysmenorrhea symptom score of patients in both groups decreased.The total effective rate was 90.75%in the treatment group and 81.25%in the control group.Conclusion:The treatment of primary dysmenorrhea patients with self-made dysmenorrhea paste combined with application of drugs and moxibustion naval-button method has a significant clinical effect.This method can reduce the pain of patients,improve the quality of life of patients,and homemade dysmenorrhea paste has a good taste,long shelf life,easy to carry,and is worthy of promotion and application. 展开更多
关键词 self-made DYSMENORRHEA PASTE DRESSING and moxibustion UMBILICUS Primary DYSMENORRHEA Therapeutic EFFECT
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Effect of self-made exhaust plaster on patients with gastrointestinal dysfunction after gynecological operation
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作者 Wen-Ming Cao Xiu-Rong Wang Xiao-Xia Wang 《Psychosomatic Medicine Research》 2020年第2期54-59,共6页
Objective:To explore the effect of self-made exhaust patch(SMEP)on gastrointestinal dysfunction after gynecological operation.Methods:A total of 200 patients with gynecological operation in the gynecological ward of S... Objective:To explore the effect of self-made exhaust patch(SMEP)on gastrointestinal dysfunction after gynecological operation.Methods:A total of 200 patients with gynecological operation in the gynecological ward of Shandong Changle People's Hospital were randomly divided into the control group(n=100)and the treatment group(n=100).The recovery time of bowel sounds,the time of first anal exhaust,the duration of abdominal distention,the duration of abdominal pain,the incidence of abdominal distention and abdominal pain and linical efficacy of SMEP were observed.Results:Compared with the control group,the recovery time of gastrointestinal function and the first anal exhaust time in the treatment group were shorter;the duration of abdominal distention and abdominal pain in the treatment group were shorter than those in the control group(P<0.05);Cure rate of abdominal distention in the treatment is 62.5%and cure rate of abdominal pain in the treatment is 60%within 72 hours after operation,which is higher than that in the control group(44.%,45.9%).Conclusion:The results showed that the self-made exhaust patch can improve the clinical symptoms of patients after gynecological abdominal surgery,and the self-made exhaust patch had a significant effect on gastrointestinal dysfunction after gynecological surgery,which was worthy of clinical promotion. 展开更多
关键词 self-made exhaust patch Gynecological operation Gastrointestinal dysfunction Abdominal distention
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Clinical observation on TCM fumigation and washing for treatment of diabetic peripheral neuropathy by self-made water-washing footbath
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作者 Lu Gan Qing Liu +2 位作者 Liping Jin Zheng Yuan Youqiong Zhang 《TMR Clinical Research》 2019年第1期37-42,共6页
the quality of life seriously,and even lead to more servere complications.On the base of the well-controlled blood glucose,improving the symptoms of both lower limbs timely will has positive significance for enhancing... the quality of life seriously,and even lead to more servere complications.On the base of the well-controlled blood glucose,improving the symptoms of both lower limbs timely will has positive significance for enhancing the life quality of patients and preventing complications of limbs.This article makes a comprehensive study on the application of self-made water-washing footbath in the treatment of DPN by Chinese medicine fumigation.From March 2018 to April 2018 in our hospital 20 cases of DPN patients were collected and they were divided into observation group(treated by self-made water-washing footbath with herbs)and control group(treated by conventional barrels),10 cases in each.The results showed that Chinese medicine fumigation on both lower limbs has clinical curative effect to improve the symptoms of arthromyodynia caused by diabetes.It provide an alternative method of external treatment for DPN patients with numbness in both lower limbs which could alleviate their suffering and improve the quality of life significantly. 展开更多
关键词 self-made water-washing footbath Chinese medicine fumigation and washing Diabetic peripheralneuropathy Clinical observation
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Observation on Curative Effect of Self-made Wubeizi Decoction Combined with rhaFGF in Promoting Postoperative Wound Healing in Patients with Anal Fistula
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作者 Yingnan YANG Dan GAN +2 位作者 Zhiqiang YUAN Dongqin WANG Yu CHEN 《Medicinal Plant》 CAS 2023年第3期74-77,81,共5页
[Objectives]To explore the curative effect of Self-made Wubeizi Decoction combined with recombinant human acidic fibroblast growth factor(rhaFGF)in promoting postoperative wound healing in patients with anal fistula.[... [Objectives]To explore the curative effect of Self-made Wubeizi Decoction combined with recombinant human acidic fibroblast growth factor(rhaFGF)in promoting postoperative wound healing in patients with anal fistula.[Methods]A total of 82 patients with anal fistula who underwent anal fistula resection+use of setons in Luodian Hospital during January and March of 2020 were randomly divided into observation group and control group with 41 cases in each group.The control group was given rhaFGF external application regimen,and the observation group was treated with Self-made Wubeizi Decoction on the basis of the control group.After 3 weeks of treatment,the differences in curative effects of TCM syndromes were compared between the two groups.Besides,the changes in TCM symptom scores,inflammatory mediators[interleukin-12(IL-12),tumor necrosis factor-α(TNF-α),interferon-γ(IFN-γ)],anorectal functions[anal resting pressure(ARP),maximal systolic pressure(MSP)and maximum tolerated volume(MTV)of the anal canal],quality of life[GQOLI-74 scores]were compared.[Results]After 3 weeks of treatment,the total effective rate of the observation group was significantly higher than that of the control group(P<0.05);the levels of TCM symptom scores,IL-12,TNF-α,IFN-γ,ARP,MSP,and MTV in both groups were significantly lower than those before treatment,and these levels in the observation group was significantly lower than that in the control group at the same time(P<0.05).The GQOLI-74 scores of both groups were significantly higher than those before treatment,and the observation group was significantly higher than the control group(P<0.05).[Conclusions]The Self-made Wubeizi Decoction combined with rhaFGF therapy has a significant effect in promoting postoperative wound healing in patients with anal fistula.It can effectively inhibit the local inflammation of patients,facilitate the recovery of anorectal function and improve the quality of life,thus has high clinical application value. 展开更多
关键词 self-made Wubeizi Decoction Recombinant human acidic fibroblast growth factor(rhaFGF) Anal fistula Anal fistula resection Wound healing Inflammatory mediators Anorectal function Quality of life
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考虑Chopper保护的双馈电机短路电流计算 被引量:7
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作者 潘文霞 刘明洋 +5 位作者 杨刚 潘学萍 张艺博 郭家圣 杨建军 孙科 《中国电机工程学报》 EI CSCD 北大核心 2017年第18期5454-5460,共7页
直流母线串入直流卸荷电路(Chopper)保护是双馈风力发电机(double fed induction generators,DFIG)常用的保护措施。Chopper保护动作对DFIG的暂态过程及其暂态短路电流有着重要影响,为此,该文针对Chopper启动后的双馈风力发电系统暂态... 直流母线串入直流卸荷电路(Chopper)保护是双馈风力发电机(double fed induction generators,DFIG)常用的保护措施。Chopper保护动作对DFIG的暂态过程及其暂态短路电流有着重要影响,为此,该文针对Chopper启动后的双馈风力发电系统暂态过程建立含Chopper保护元件的暂态等值电路,通过分析Chopper保护投入后DFIG磁链、电压的变化,推导出DFIG三相短路电流最大值以及周期分量有效值的计算模型。最后对比PSCAD/EMTDC的仿真结果,验证了文中建立的三相短路电流计算模型的准确性。 展开更多
关键词 双馈风力发电机 三相短路电流 chopper保护 PSCAD/EMTDC
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综合Crowbar和Chopper保护的双馈风机低电压穿越仿真研究 被引量:12
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作者 曹鹏飞 邹博 +1 位作者 吴林林 黄家栋 《华北电力技术》 CAS 2017年第2期49-54,共6页
为了优化双馈风电机组的低电压穿越(LVRT)性能,在现有LVRT技术的基础上,充分借鉴和参考了撬棒(Crowbar)保护、直流卸荷回路(Chopper)保护和定、转子变流器控制(RSC)在LVRT过程中的突出优点,提出了利用Crowbar保护抑制转子回路过流,发挥C... 为了优化双馈风电机组的低电压穿越(LVRT)性能,在现有LVRT技术的基础上,充分借鉴和参考了撬棒(Crowbar)保护、直流卸荷回路(Chopper)保护和定、转子变流器控制(RSC)在LVRT过程中的突出优点,提出了利用Crowbar保护抑制转子回路过流,发挥Chopper电路稳定直流母线电压的作用,及时退出Crowbar电阻并重新激发RSC,使之及时向电网提供无功支持,并结合仿真对综合保护控制策略的状态特性进行了分析。 展开更多
关键词 低电压穿越 Crowbar保护 chopper保护 转子变流器控制 无功功率
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基于混合型Chopper电路的MMC-UPFC故障渡越方案 被引量:2
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作者 郑涛 王赟鹏 +3 位作者 李厚源 吕文轩 张成绮 马家璇 《电力自动化设备》 EI CSCD 北大核心 2021年第2期97-103,117,共8页
当交流系统发生短路时,基于模块化多电平控制器的统一潮流控制器(MMC-UPFC)串、并联侧MMC均会受到故障冲击,存在两侧换流器过流闭锁,MMC-UPFC完全退出运行的风险。对此,以交流系统发生最严重的三相短路故障为例,分析了MMC-UPFC串、并联... 当交流系统发生短路时,基于模块化多电平控制器的统一潮流控制器(MMC-UPFC)串、并联侧MMC均会受到故障冲击,存在两侧换流器过流闭锁,MMC-UPFC完全退出运行的风险。对此,以交流系统发生最严重的三相短路故障为例,分析了MMC-UPFC串、并联侧MMC故障特性;在此基础上,借鉴风电场交流故障渡越的Chopper电路,并结合MMC-UPFC不同运行方式对故障特性的影响,提出了基于混合型Chopper电路的MMC-UPFC故障渡越方案。该方案能够在交流系统发生故障后隔离并联侧MMC与串联侧MMC之间的联系,从而抑制串联侧馈入并联侧MMC的故障电流。仿真结果表明在MMC-UPFC的不同运行方式下,所提方案均能避免故障后并联侧MMC闭锁,MMC-UPFC将切换至静止同步补偿器(STATCOM)工作模式,为交流系统提供无功功率支撑。 展开更多
关键词 UPFC MMC 换流器 交流系统三相短路 故障渡越 混合型chopper电路
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基于Matlab的Boost-Buck Chopper的建模与仿真 被引量:1
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作者 孟庆波 崔刚 《信息技术》 2012年第2期97-100,共4页
对Matlab进行了简单介绍,建立了IGBT的仿真模型,运用Matlab/Simulink和PowerSystem工具对Boost-Buck Chopper进行建模、参数选择和仿真分析。与常规电路分析方法相比,该方法具有很大的优越性。
关键词 MATLAB SIMULINK BOOST-BUCK chopper 建模 仿真
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Crowbar和Chopper保护对双馈风机低电压穿越的影响分析 被引量:2
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作者 杨晋岭 陈富强 张一博 《太原科技大学学报》 2021年第5期393-398,共6页
针对在电网低电压故障期间,双馈风力发电机因硬件保护出现离网问题,研究基于Crowbar阻值和增加Chopper保护电路对DFIG的影响。首先,在转子交流侧采用主动型Crowbar电路,可保护转子侧变流器减少暂态冲击电流的影响,直流侧配备卸荷(Chopp... 针对在电网低电压故障期间,双馈风力发电机因硬件保护出现离网问题,研究基于Crowbar阻值和增加Chopper保护电路对DFIG的影响。首先,在转子交流侧采用主动型Crowbar电路,可保护转子侧变流器减少暂态冲击电流的影响,直流侧配备卸荷(Chopper)电路,可在暂态过程中维持直流侧电压稳定;其次,在分析电网电压跌落过程中双馈风机的暂态特性基础上,采用基于定子电网电压定向的控制策略,合理的选取Crowbar阻值范围,并分析Crowbar和Chopper投切时刻对双馈风力发电机安全低穿的影响,在MATLAB/Simulink仿真平台中建立1.5 MW双馈风力发电机组模型,验证了Crowbar和Chopper保护电路的有效性。 展开更多
关键词 低电压穿越 Crowbar阻值 chopper电路 参数整定
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大功率Chopper整流系统的应用研究
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作者 吴伟 王云芳 傅新华 《上海大学学报(自然科学版)》 CAS CSCD 2004年第2期153-157,共5页
文章首先介绍了大功率IGBT模块的构成及chopper电路的基本原理;然后介绍了Chopper整流系统的并联均流的方法;最后研究了Chopper整流的几种结构,如6脉波整流多输出、12脉波整流多输出、24脉波整流高压输出及大电流低电压输出,并给出Chop... 文章首先介绍了大功率IGBT模块的构成及chopper电路的基本原理;然后介绍了Chopper整流系统的并联均流的方法;最后研究了Chopper整流的几种结构,如6脉波整流多输出、12脉波整流多输出、24脉波整流高压输出及大电流低电压输出,并给出Chopper整流系统的优点:输出电流纹波低、动态响应快、电压闪变小、整个功率范围内功率因数高、整个系统电效率高、体积小、成本低. 展开更多
关键词 大功率 交流变换器 电源
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电网电压不对称暂降下考虑Chopper动作的双馈风机转子电流分析 被引量:10
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作者 林瑞星 马晓阳 +3 位作者 常晓青 徐琳 丁理杰 杨洪耕 《电力系统及其自动化学报》 CSCD 北大核心 2019年第4期106-112,117,共8页
针对电网电压不对称暂降下双馈感应发电机直流侧卸荷Chopper电路的投入,分析了其动作后双馈感应发电机的转子三相不对称电流,双馈感应发电机在机端电压不对称故障时表现出极为复杂的电磁暂态特性。首先建立了正反向旋转坐标系下双馈感... 针对电网电压不对称暂降下双馈感应发电机直流侧卸荷Chopper电路的投入,分析了其动作后双馈感应发电机的转子三相不对称电流,双馈感应发电机在机端电压不对称故障时表现出极为复杂的电磁暂态特性。首先建立了正反向旋转坐标系下双馈感应发电机的正序、负序模型,然后基于序分量叠加法把不对称故障时复杂电磁暂态过程中出现的暂态量等效分解为正序、负序和自由分量,推导了不对称故障下Chopper投入后转子暂态短路电流精确解析表达式。利用Matlab/Simulink仿真软件对所提方法进行验证,仿真结果验证了机端电压不对称跌落过程中双馈感应发电机转子不对称短路电流变化特性。 展开更多
关键词 双馈感应发电机 chopper保护 不对称故障 转子电流
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A 16bit 96kHz Chopper-Stabilized Sigma-Delta ADC 被引量:1
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作者 曹楹 任腾龙 洪志良 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第8期1204-1210,共7页
A 16bit sigma-delta audio analog-to-digital converter is developed.It consists of an analog modulator and a digital decimator.A standard 2-order single-loop architecture is employed in the modulator.Chopper stabilizat... A 16bit sigma-delta audio analog-to-digital converter is developed.It consists of an analog modulator and a digital decimator.A standard 2-order single-loop architecture is employed in the modulator.Chopper stabilization is applied to the first integrator to eliminate the 1/f noise.A low-power,area-efficient decimator is used,which includes a poly-phase comb-filter and a wave-digital-filter.The converter achieves a 92dB dynamic range over the 96kHz audio band.This single chip occupies 2.68mm2 in a 0.18μm six-metal CMOS process and dissipates only 15.5mW power. 展开更多
关键词 sigma-delta modulation chopper stabilize decimator poly phase wave digital filter on-chip noise
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半/全桥混合型DC Chopper拓扑及其控制策略 被引量:5
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作者 陈晴 严佳男 +3 位作者 谢瑞 宋伟宏 杨文斌 林磊 《高电压技术》 EI CAS CSCD 北大核心 2021年第11期4013-4022,共10页
DC Chopper能在海上风电柔性直流输电系统主网侧发生短路故障时耗散系统的盈余功率,并实现故障穿越。针对全桥型集中式模块化DC Chopper使用IGBT和二极管数目多的问题,提出了一种半桥/全桥混合型集中式模块化DC Chopper拓扑。该拓扑采... DC Chopper能在海上风电柔性直流输电系统主网侧发生短路故障时耗散系统的盈余功率,并实现故障穿越。针对全桥型集中式模块化DC Chopper使用IGBT和二极管数目多的问题,提出了一种半桥/全桥混合型集中式模块化DC Chopper拓扑。该拓扑采用半桥子模块替换桥臂中一部分仅起到电压支撑作用的全桥子模块,并根据桥臂电流单向性的特点,省略掉子模块中部分IGBT,仅保留其反并联二极管,大幅降低了设备的成本。在此基础上,针对现有的集中式模块化拓扑控制策略精确度低的问题,进而提出了一种利用方波正半波幅值调节耗散功率、利用占空比平衡桥臂能量的控制策略,实现了对耗散功率和桥臂能量的精确控制。在Matlab/Simulink中开展了海上风电柔性直流输电系统故障穿越的仿真研究,验证了所提出的DC Chopper拓扑及控制方案具有良好的故障穿越效果。 展开更多
关键词 柔性直流输电系统 故障穿越 集中式模块化DC chopper 半桥子模块 全桥子模块 桥臂能量平衡 功率耗散
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一种风电变流器Chopper装置的测试方法 被引量:2
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作者 吴伟亮 封阿明 简优宗 《电气技术》 2018年第8期59-62,共4页
为保证电网低电压穿越故障下风电机组能正常运行,需要在风电变流器直流母线接入Chopper装置进行短暂能量控制。本文提出一种利用现有功率测试平台和软件模拟电网低电压穿越故障的方法来测试Chopper装置的电气性能。测试方法经济实用,具... 为保证电网低电压穿越故障下风电机组能正常运行,需要在风电变流器直流母线接入Chopper装置进行短暂能量控制。本文提出一种利用现有功率测试平台和软件模拟电网低电压穿越故障的方法来测试Chopper装置的电气性能。测试方法经济实用,具有很好的应用前景。实验结果验证了此方法的可行性。 展开更多
关键词 风电变流器 chopper装置 低电压穿越 能量循环 经济实用
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考虑Chopper动作的双馈风电机组三相短路电流分析 被引量:10
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作者 唐浩 郑涛 +1 位作者 黄少锋 杨国生 《电力系统自动化》 EI CSCD 北大核心 2015年第3期76-83,共8页
直流母线并接直流卸荷电路(Chopper)以保护转子侧变频器(RSC)是一种较常用的双馈风电机组低电压穿越改造方案。目前对称故障下双馈风电机组短路电流特性研究以故障后投入撬棒(Crowbar)电阻为主,Chopper动作下双馈风电机组短路电流特性... 直流母线并接直流卸荷电路(Chopper)以保护转子侧变频器(RSC)是一种较常用的双馈风电机组低电压穿越改造方案。目前对称故障下双馈风电机组短路电流特性研究以故障后投入撬棒(Crowbar)电阻为主,Chopper动作下双馈风电机组短路电流特性研究几乎没有,故而难以分析其作用下双馈风电机组短路电流特性对系统中保护动作可靠性和设备安全的影响。类比双馈风电机组故障后投入Crowbar电阻的分析思路——转子回路串入电阻,通过分析对称故障后Chopper动作下的转子电流回路,将被闭锁的RSC和Chopper等效为可变电阻,分析了该等效电阻阻值随电压跌落程度和故障前转差率的变化规律。根据故障后双馈感应发电机的磁链、电压关系,通过数学解析得到Chopper动作下对称短路电流解析表达式。在MATLAB/Simulink中搭建配置Chopper的双馈风电机组模型,仿真验证了该表达式的有效性。 展开更多
关键词 双馈感应发电机 对称故障 直流卸荷电路 短路电流特性
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