6与12脉冲整流器原理.docx
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6与12脉冲整流器原理.docx
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6与12脉冲整流器原理
6与12脉冲整流器原理
一、理论推导
1、6脉冲整流器原理:
6脉冲指以6个可控硅(晶闸管)组成的全桥整流,由于有6个开关脉冲对6个可控硅分别控制,所以叫6脉冲整流。
当忽略三相桥式可控硅整流电路换相过程和电流脉动,假定交流侧电抗为零,直流电感为无穷大,延迟触发角a为零,则交流侧电流傅里叶级数展开为:
(1-1)
由公式(1-1)可得以下结论:
电流中含6K?
1(k为正整数)次谐波,即5、7、11、13...等各次谐波,各次谐波的有效值与谐波次数成反比,且与基波有效值的比值为谐波次数的倒数。
intensivedevelopment.(5)havedifferentemphasis:
fordevelopment,"withdevelopment,theemphasison"way,fromspace,multiplegroupsfromasingleradiation-beltopendevelopment.Spatialstructureof2,theprominentculturalcityprotectionelementsonthedevelopmentofthewholecityandcultureseriessupportingrole,withnaturallandscapesandgreenforthebackground,accordingtothecombinedcity,urbanGrouporganizationstructure,setupadecentralizeddevelopmentpatterns,building...Threerivers:
theYangtze,jinshaRiverandminjiangrivers,citiesinthreeriversbasedondevelopmentalongtheYangtzeRiver,cityontheRiver,Riverinthecity.Multiplegroups:
therelativelycompactarealayout,eachdistrictconsistsofmultiplegroups,andtheareahasbothintegratedurbanfunctions,andhavetheirowncharacteristicsandperimeterformationLiZhuang,LiZhuangdongcharacteristictourareaandHongKongingroup,consistsof17groups.Band:
modernfeaturesgatheringalongtheYangtzeRiverbelt.DvngroupintheupperreachesofthejinshaRiveralongtherivercontinuestotheEasttoSouthstreamgroups,layoutalongthecity'smaincommercial,business,administrative,culturalandcreativeresearchanddevelopmentinscienceandeducationfunctionofmodernserviceandportequipmentmanufacturing,liquor,andotherfeaturesandmodernindustry.2.5-2spatialplanningfigure2.6inYibincity,CentralCityurbandevelopmentvisionvision
图1.1计算机仿真的6脉冲A相的输入电压、电流波形2、12脉冲整流器原理:
12脉冲是指在原有6脉冲整流的基础上,在输入端、增加移相变压器后在
增加一组6脉冲整流器,使直流母线电流由12个可控硅整流完成,因此又称为12脉冲整流。
下图所示I和II两个三相整流电路就是通过变压器的不同联结构成12相整流电路。
12脉冲整流器示意图(由2个6脉冲并联组成)桥1的网侧电流傅立叶级数展开为:
intensivedevelopment.(5)havedifferentemphasis:
fordevelopment,"withdevelopment,theemphasison"way,fromspace,multiplegroupsfromasingleradiation-beltopendevelopment.Spatialstructureof2,theprominentculturalcityprotectionelementsonthedevelopmentofthewholecityandcultureseriessupportingrole,withnaturallandscapesandgreenforthebackground,accordingtothecombinedcity,urbanGrouporganizationstructure,setupadecentralizeddevelopmentpatterns,building...Threerivers:
theYangtze,jinshaRiverandminjiangrivers,citiesinthreeriversbasedondevelopmentalongtheYangtzeRiver,cityontheRiver,Riverinthecity.Multiplegroups:
therelativelycompactarealayout,eachdistrictconsistsofmultiplegroups,andtheareahasbothintegratedurbanfunctions,andhavetheirowncharacteristicsandperimeterformationLiZhuang,LiZhuangdongcharacteristictourareaandHongKongingroup,consistsof17groups.Band:
modernfeaturesgatheringalongtheYangtzeRiverbelt.DvngroupintheupperreachesofthejinshaRiveralongtherivercontinuestotheEasttoSouthstreamgroups,layoutalongthecity'smaincommercial,business,administrative,culturalandcreativeresearchanddevelopmentinscienceandeducationfunctionofmodernserviceandportequipmentmanufacturing,liquor,andotherfeaturesandmodernindustry.2.5-2spatialplanningfigure2.6inYibincity,CentralCityurbandevelopmentvisionvision
(1-2)
桥II网侧线电压比桥I超前30?
,因网侧线电流比桥I超前30?
(1-3)
故合成的网侧线电流
(1-4)
可见,两个整流桥产生的5、7、17、19、...次谐波相互抵消,注入电网的
、13、23、25等各次谐波,且其有效值只有12k?
1(k为正整数)次谐波,即11
与与谐波次数成反比,而与基波有效值的比值为谐波次数的倒数。
图1.2计算机仿真的12脉冲UPSA相的输入电压、电流波形
intensivedevelopment.(5)havedifferentemphasis:
fordevelopment,"withdevelopment,theemphasison"way,fromspace,multiplegroupsfromasingleradiation-beltopendevelopment.Spatialstructureof2,theprominentculturalcityprotectionelementsonthedevelopmentofthewholecityandcultureseriessupportingrole,withnaturallandscapesandgreenforthebackground,accordingtothecombinedcity,urbanGrouporganizationstructure,setupadecentralizeddevelopmentpatterns,building...Threerivers:
theYangtze,jinshaRiverandminjiangrivers,citiesinthreeriversbasedondevelopmentalongtheYangtzeRiver,cityontheRiver,Riverinthecity.Multiplegroups:
therelativelycompactarealayout,eachdistrictconsistsofmultiplegroups,andtheareahasbothintegratedurbanfunctions,andhavetheirowncharacteristicsandperimeterformationLiZhuang,LiZhuangdongcharacteristictourareaandHongKongingroup,consistsof17groups.Band:
modernfeaturesgatheringalongtheYangtzeRiverbelt.DvngroupintheupperreachesofthejinshaRiveralongtherivercontinuestotheEasttoSouthstreamgroups,layoutalongthecity'smaincommercial,business,administrative,culturalandcreativeresearchanddevelopmentinscienceandeducationfunctionofmodernserviceandportequipmentmanufacturing,liquor,andotherfeaturesandmodernindustry.2.5-2spatialplanningfigure2.6inYibincity,CentralCityurbandevelopmentvisionvision
二、实测数据分析。
以上计算为理想状态,忽略了很多因数,如换相过程、直流侧电流脉动、触发延迟角,交流侧电抗等。
因此实测值与计算值有一定出入。
理论计算谐波表:
某型号大功率UPS谐波实测数据表:
从以上两表对比可得,6脉整流器谐波含量最大为5次谐波、12脉整流器强度最大为11次谐波,与理论计算结果一致。
6脉5次谐波实测值较计算值偏大,12脉11次谐波实测值与计算值相同。
三、谐波分析和改良对策
谐波可能造成配电线缆、变压器发热,降低通话质量,空气开关误动作,发电机喘振等不良后果;谐波按电流相序分为+序(3k+1次,k为0和正整数)、-序(3k+2次,k为0和正整数)、0序(3k次,k为正整数)。
+序电流使损耗加重,-序电流使电机反转、发热,0序电流使中线电流异常增大。
从实测值可见,6脉整流器5次谐波最大,可加装5次滤波器来抑制谐波;12脉整流器11次谐波最大,可加装11次滤波器来抑制谐波。
滤波器原理图如下:
intensivedevelopment.(5)havedifferentemphasis:
fordevelopment,"withdevelopment,theemphasison"way,fromspace,multiplegroupsfromasingleradiation-beltopendevelopment.Spatialstructureof2,theprominentculturalcityprotectionelementsonthedevelopmentofthewholecityandcultureseriessupportingrole,withnaturallandscapesandgreenforthebackground,accordingtothecombinedcity,urbanGrouporganizationstructure,setupadecentralizeddevelopmentpatterns,building...Threerivers:
theYangtze,jinshaRiverandminjiangrivers,citiesinthreeriversbasedondevelopmentalongtheYangtzeRiver,cityontheRiver,Riverinthecity.Multiplegroups:
therelativelycompactarealayout,eachdistrictconsistsofmultiplegroups,andtheareahasbothintegratedurbanfunctions,andhavetheirowncharacteristicsandperimeterformationLiZhuang,LiZhuangdongcharacteristictourareaandHongKongingroup,consistsof17groups.Band:
modernfeaturesgatheringalongtheYangtzeRiverbelt.DvngroupintheupperreachesofthejinshaRiveralongtherivercontinuestotheEasttoSouthstreamgroups,layoutalongthecity'smaincommercial,business,administrative,culturalandcreativeresearchanddevelopmentinscienceandeducationfunctionofmodernserviceandportequipmentmanufacturing,liquor,andotherfeaturesandmodernindustry.2.5-2spatialplanningfigure2.6inYibincity,CentralCityurbandevelopmentvisionvision
图:
常用的LC滤波器原理图
某型号大功率UPS加装滤波器后谐波对比表如下:
从上表可以看出,加装滤波器对谐波抑制作用非常明显。
需要特别指出的是:
6脉冲+5次谐波滤波器的配置可以达到9,左右的谐波要求,但是由于5次谐波(250Hz)滤波器的电容容值较大,在UPS负载较轻(<15%额定负载)时,整流器输入电流会超前输入电压,如果发电机的励磁绕组采用自励方式,很容易产生电枢正反馈效应,发电机输出电压会异常升高,导致发电机进入保护状态而停机。
因此6脉冲+5次谐波滤波器方案不建议在UPS负载较轻时使用。
当实际负载较轻时,可将5次谐波滤波器从整流器上脱出。
而单独的12脉整流器也可达到10,左右的电流谐波指标,但是没有大电容
的LC电路,避免了与发电机的励磁正反馈效应。
采用12脉冲整流器+11次谐波器可达到小于4.5%的电流谐波指标。
单次谐波和总谐波含量均满足IEC61000-3-4的指标要求。
附表1:
在配置不同负载条件下,输入电流谐波总含量数据
附表2:
某型号400KVA12脉冲+11次滤波器UPS输入电流总谐波含量表intensivedevelopment.(5)havedifferentemphasis:
fordevelopment,"withdevelopment,theemphasison"way,fromspace,multiplegroupsfromasingleradiation-beltopendevelopment.Spatialstructureof2,theprominentculturalcityprotectionelementsonthedevelopmentofthewholecityandcultureseriessupportingrole,withnaturallandscapesandgreenforthebackground,accordingtothecombinedcity,urbanGrouporganizationstructure,setupadecentralizeddevelopmentpatterns,building...Threerivers:
theYangtze,jinshaRiverandminjiangrivers,citiesinthreeriversbasedondevelopmentalongtheYangtzeRiver,cityontheRiver,Riverinthecity.Multiplegroups:
therelativelycompactarealayout,eachdistrictconsistsofmultiplegroups,andtheareahasbothintegratedurbanfunctions,andhavetheirowncharacteristicsandperimeterformationLiZhuang,LiZhuangdongcharacteristictourareaandHongKongingroup,consistsof17groups.Band:
modernfeaturesgatheringalongtheYangtzeRiverbelt.DvngroupintheupperreachesofthejinshaRiveralongtherivercontinuestotheEasttoSouthstreamgroups,layoutalongthecity'smaincommercial,business,administrative,culturalandcreativeresearchanddevelopmentinscienceandeducationfunctionofmodernserviceandportequipmentmanufacturing,liquor,andotherfeaturesandmodernindustry.2.5-2spatialplanningfigure2.6inYibincity,CentralCityurbandevelopmentvisionvision
影响电网的是谐波电流的绝对值,而不是谐波电流的百分比。
由上表可以看出,在满载情况下,谐波电流绝对值最大;在半载及轻载情况下,谐波电流绝对值均不超过100%满载谐波电流绝对值。
12脉冲+11次谐波滤波器具有最小的效输入电流总谐波,同时还可避免有源滤波器“误补偿”、系统效率低等缺点,因12脉冲+11次谐波滤波器此对电网的污染最低,适用于可靠性要求较高的场合使用。
四、性能对比:
从上表可以看到,12脉冲整流器在多项性能指标上均优于6脉冲整流器。
12脉冲整流技术自70年代诞生自今,经过不断改进和完善,现已逐渐成为大功率UPS整流器的优选技术。
全球主流的大功率UPS厂商均推出了12脉冲UPS产品
intensivedevelopment.(5)havedifferentemphasis:
fordevelopment,"withdevelopment,theemphasison"way,fromspace,multiplegroupsfromasingleradiation-beltopendevelopment.Spatialstructureof2,theprominentculturalcityprotectionelementsonthedevelopmentofthewholecityandcultureseriessupportingrole,withnaturallandscapesandgreenforthebackground,accordingtothecombinedcity,urbanGrouporganizationstructure,setupadecentralizeddevelopmentpatterns,building...Threerivers:
theYangtze,jinshaRiverandminji
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