变频器解析-变频器结构(gou)与原(yuan)理-KIA MOS管
信息来源:本站 日期:2021-03-23
变(bian)频(pin)器(Variable-frequency Drive,VFD)是应用变(bian)频(pin)技术(shu)与微电(dian)(dian)子技术(shu),通(tong)过改变(bian)电(dian)(dian)机工作电(dian)(dian)源频(pin)率方式来(lai)控(kong)制交流电(dian)(dian)动机的电(dian)(dian)力控(kong)制设备。
变(bian)频(pin)器(qi)主要由整流(liu)(liu)(liu)(交(jiao)流(liu)(liu)(liu)变(bian)直流(liu)(liu)(liu))、滤(lv)波、逆变(bian)(直流(liu)(liu)(liu)变(bian)交(jiao)流(liu)(liu)(liu))、制(zhi)动(dong)单(dan)元、驱动(dong)单(dan)元、检(jian)测(ce)单(dan)元微(wei)处理(li)单(dan)元等(deng)组成。变(bian)频(pin)器(qi)靠内部IGBT的(de)(de)开(kai)断(duan)来调整输出电源的(de)(de)电压和频(pin)率,根据电机的(de)(de)实际需要来提供其所需要的(de)(de)电源电压,进而达(da)到节能、调速的(de)(de)目的(de)(de),另外,变(bian)频(pin)器(qi)还有很多的(de)(de)保护功能,如过流(liu)(liu)(liu)、过压、过载保护等(deng)等(deng)。随着(zhe)工业自动(dong)化(hua)程度的(de)(de)不断(duan)提高,变(bian)频(pin)器(qi)也得(de)到了非常(chang)广泛(fan)的(de)(de)应用。
变(bian)频(pin)器(qi)通常分为4部分:整流(liu)单(dan)元、高容量(liang)电容、逆(ni)变(bian)器(qi)和控制器(qi)。
整流(liu)(liu)单元:将工作频(pin)率固(gu)定(ding)的交流(liu)(liu)电(dian)转换(huan)为直流(liu)(liu)电(dian)。
高(gao)容量电(dian)容:存储转换(huan)后的电(dian)能。
逆(ni)变器:由大功率(lv)开关晶(jing)体管阵列组成电子(zi)开关,将直流电转化成不(bu)同频率(lv)、宽度、幅度的(de)方(fang)波(bo)。
控(kong)制器:按(an)设定的(de)程序工作(zuo),控(kong)制输出方(fang)波(bo)的(de)幅(fu)度与脉宽,使(shi)叠加为近似正弦(xian)波(bo)的(de)交流电(dian),驱动(dong)交流电(dian)动(dong)机。
变(bian)(bian)(bian)频器的(de)发展也同样(yang)要(yao)经历一个徐徐渐进(jin)的(de)过程,最初的(de)变(bian)(bian)(bian)频器并(bing)不是采用(yong)这(zhei)种(zhong)(zhong)交(jiao)(jiao)直交(jiao)(jiao):交(jiao)(jiao)流(liu)变(bian)(bian)(bian)直流(liu)而(er)后(hou)再变(bian)(bian)(bian)交(jiao)(jiao)流(liu)这(zhei)种(zhong)(zhong)拓(tuo)扑,而(er)是直接交(jiao)(jiao)交(jiao)(jiao),无中(zhong)间直流(liu)环节(jie)。这(zhei)种(zhong)(zhong)变(bian)(bian)(bian)频器叫交(jiao)(jiao)交(jiao)(jiao)变(bian)(bian)(bian)频器,目前(qian)这(zhei)种(zhong)(zhong)变(bian)(bian)(bian)频器在超大(da)功(gong)率、低速调速有应(ying)用(yong)。其输(shu)出(chu)频率范(fan)(fan)围为:0-17(1/2-1/3 输(shu)入(ru)电(dian)压频率),所以不能满足许多应(ying)用(yong)的(de)要(yao)求(qiu),而(er)且当时没有IGBT,只有SCR,所以应(ying)用(yong)范(fan)(fan)围有限(xian)。
变频(pin)(pin)器(qi)其(qi)工(gong)作原理是(shi)将三相(xiang)工(gong)频(pin)(pin)电(dian)(dian)(dian)源(yuan)经(jing)过(guo)几组(zu)相(xiang)控开关控制直接产生(sheng)(sheng)所需要(yao)变压变频(pin)(pin)电(dian)(dian)(dian)源(yuan),其(qi)优点是(shi)效率(lv)高(gao),能(neng)量可以方便返回电(dian)(dian)(dian)网,其(qi)最(zui)大(da)的缺点输出(chu)的最(zui)高(gao)频(pin)(pin)率(lv)必须小(xiao)于输入电(dian)(dian)(dian)源(yuan)频(pin)(pin)率(lv)1/3或1/2,否则(ze)输出(chu)波形太差,电(dian)(dian)(dian)机产生(sheng)(sheng)抖(dou)动,不能(neng)工(gong)作。故交(jiao)交(jiao)变频(pin)(pin)器(qi)至(zhi)今(jin)局(ju)限低(di)转速调(diao)速场合,因而大(da)大(da)限制了它的使用范围。
变频器电路结构框架图
矩阵式(shi)变(bian)频器(qi)是(shi)一种交交直接变(bian)频器(qi),由九(jiu)个直接接于三相输(shu)入(ru)和输(shu)出之间的开关阵组(zu)(zu)成(cheng)(cheng)。矩阵变(bian)换器(qi)没(mei)有中间直流环节,输(shu)出由三个电平组(zu)(zu)成(cheng)(cheng),谐波含量比较小;其功(gong)率(lv)电路简单、紧凑,并可(ke)(ke)输(shu)出频率(lv)、幅值及相位可(ke)(ke)控的正弦负载(zai)电压;矩阵变(bian)换器(qi)的输(shu)入(ru)功(gong)率(lv)因数(shu)可(ke)(ke)控,可(ke)(ke)在四象限工作。
虽(sui)然(ran)矩阵(zhen)(zhen)变换(huan)器(qi)(qi)有(you)很多优点(dian),但是在(zai)其换(huan)流过程(cheng)中不允(yun)许存(cun)在(zai)两个开关同(tong)时导(dao)通的或者(zhe)关断的现(xian)象,实现(xian)起(qi)来比较困(kun)难。矩阵(zhen)(zhen)变换(huan)器(qi)(qi)最大(da)输(shu)出电压(ya)能力(li)低(di),器(qi)(qi)件承受电压(ya)高(gao)也(ye)是此类(lei)变换(huan)器(qi)(qi)一个很大(da)缺点(dian)。
应用在风力发电(dian)中,由于矩(ju)阵(zhen)变换(huan)器的输入输出(chu)不解(jie)耦,即无论是负载还是电(dian)源(yuan)侧的不对称都(dou)会(hui)影响到另一(yi)侧。另外,矩(ju)阵(zhen)变换(huan)器的输入端必(bi)须接滤波电(dian)容(rong)(rong),虽然其(qi)电(dian)容(rong)(rong)的容(rong)(rong)量(liang)比(bi)交(jiao)(jiao)直(zhi)交(jiao)(jiao)的中间储能(neng)电(dian)容(rong)(rong)小,但由于它们是交(jiao)(jiao)流电(dian)容(rong)(rong),要承受开(kai)关频率的交(jiao)(jiao)流电(dian)流,其(qi)体积并不小。
交(jiao)(jiao)-交(jiao)(jiao)变(bian)频就是直接变(bian)频,少了(le)一个(ge)环(huan)节(jie),但是用的(de)器件量很多,三相(xiang)的(de)需(xu)要(yao)36个(ge)晶闸管(guan),控制复杂。我们老师(shi)开(kai)玩笑说谁调通了(le)36个(ge)管(guan)子就可以立即毕业。还有交(jiao)(jiao)-交(jiao)(jiao)变(bian)频只(zhi)能(neng)往工频一下调节(jie)频率,一般调到工频的(de)1/3-1/2,差不多20Hz。
我们把这(zhei)种交(jiao)流(liu)(liu)变(bian)(bian)直(zhi)流(liu)(liu)而后再变(bian)(bian)交(jiao)流(liu)(liu)这(zhei)种变(bian)(bian)频器叫(jiao)交(jiao)直(zhi)交(jiao)变(bian)(bian)频器,分为(wei)两种,一(yi)种是交(jiao)直(zhi)交(jiao)电压型,另外(wai)一(yi)种是交(jiao)直(zhi)交(jiao)电流(liu)(liu)型。其中前者广泛(fan)使(shi)用(yong),现在的(de)通用(yong)变(bian)(bian)频器就(jiu)是采(cai)用(yong)这(zhei)种拓(tuo)扑。
其(qi)特点是:中间为电(dian)解电(dian)容储存提(ti)供母(mu)线电(dian)压(ya)(ya),前(qian)级采用(yong)二极管不控整流,简单(dan)可靠,逆(ni)变(bian)采用(yong)三相PWM调(diao)制(目(mu)前(qian)调(diao)制算(suan)法是空间电(dian)压(ya)(ya)矢量(liang))。由于(yu)采用(yong)了一定容量(liang)的(de)电(dian)解电(dian)容,所(suo)以直流母(mu)线电(dian)压(ya)(ya)稳定,此时只要控制好(hao)逆(ni)变(bian)IGBT的(de)开(kai)关顺(shun)序(输出相序、频率)和占(zhan)空比(bi)(输出电(dian)压(ya)(ya)大小),就可以获得非常优越的(de)控制特性。
交—直(zhi)—交变(bian)频器(qi)则(ze)是先把交流(liu)(liu)(liu)(liu)电(dian)经整(zheng)流(liu)(liu)(liu)(liu)器(qi)先整(zheng)流(liu)(liu)(liu)(liu)成直(zhi)流(liu)(liu)(liu)(liu)电(dian),直(zhi)流(liu)(liu)(liu)(liu)中间(jian)电(dian)路对整(zheng)流(liu)(liu)(liu)(liu)电(dian)路的(de)输出进行平滑滤波(bo),再经过逆变(bian)器(qi)把这个直(zhi)流(liu)(liu)(liu)(liu)电(dian)流(liu)(liu)(liu)(liu)变(bian)成频率和(he)电(dian)压都可变(bian)的(de)交流(liu)(liu)(liu)(liu)电(dian)。
交(jiao)直(zhi)交(jiao)变频(pin)器又可以(yi)分为电压型(xing)(xing)和(he)电流(liu)型(xing)(xing)两种(zhong),由于控制方法(fa)和(he)硬(ying)件设计等各种(zhong)因素,电压型(xing)(xing)逆变器应用(yong)比较广(guang)泛。传统的(de)(de)(de)电流(liu)型(xing)(xing)交(jiao)直(zhi)交(jiao)变频(pin)器采用(yong)自然换流(liu)的(de)(de)(de)晶闸管作为功率开关,其直(zhi)流(liu)侧(ce)电感比较昂贵,而且应用(yong)于双馈调速中(zhong),在(zai)过同步速时需要换流(liu)电路,在(zai)低转差频(pin)率的(de)(de)(de)条件下性能也比较差,在(zai)双馈异步风力发电中(zhong)应用(yong)的(de)(de)(de)不多。
采用电(dian)压(ya)型交(jiao)直交(jiao)变频器这(zhei)种整流(liu)(liu)变频装置具有结(jie)构简(jian)单(dan)、谐(xie)波含量少(shao)、定转子功率因数可(ke)调等(deng)优异特点,可(ke)以(yi)明显地(di)改善双馈发电(dian)机的运行状(zhuang)态和(he)输(shu)出电(dian)能质量,并且该结(jie)构通过直流(liu)(liu)母线侧(ce)电(dian)容完全实现了网侧(ce)和(he)转子侧(ce)的分离(li)。
电压(ya)型(xing)交直交变频器的双馈发电机(ji)定(ding)子磁场(chang)定(ding)向矢量控(kong)制系统(tong),实现了(le)基于(yu)风机(ji)最大功(gong)率点跟(gen)踪的发电机(ji)有功(gong)和无功(gong)的解(jie)耦控(kong)制,是目前(qian)变速恒频风力发电的一个代表方向。
此外,还有一种并联的交(jiao)(jiao)直交(jiao)(jiao)逆变器(qi)拓扑结(jie)构。这种结(jie)构的主要思想是通过一个(ge)(ge)交(jiao)(jiao)直交(jiao)(jiao)电流(liu)型(xing)和一个(ge)(ge)交(jiao)(jiao)直交(jiao)(jiao)电压型(xing)变频器(qi)并联,电流(liu)型(xing)逆变器(qi)作为主逆变器(qi)负责功率传输(shu),电压型(xing)逆变器(qi)作为辅逆变器(qi)负责补偿电流(liu)型(xing)逆变器(qi)谐波。
这种结构(gou)主(zhu)逆(ni)变器(qi)有较(jiao)低的(de)开(kai)关频率,辅逆(ni)变器(qi)有较(jiao)低的(de)开(kai)关电(dian)流。同上面(mian)提到(dao)的(de)交直交电(dian)压型逆(ni)变器(qi)相比较(jiao),该拓扑结构(gou)具有低开(kai)关损耗,整(zheng)个系统(tong)的(de)效率比较(jiao)高。其缺点也(ye)是(shi)显而(er)易(yi)见(jian)的(de),大量(liang)电(dian)力电(dian)子器(qi)件的(de)使用导致成本的(de)上升以及更加复杂的(de)控制(zhi)算(suan)法,另外该种结构(gou)电(dian)压利用率比较(jiao)低。
尽管交(jiao)—直—交(jiao)变频(pin)器具有输(shu)出频(pin)率高、功率因数(shu)高等优点,但交(jiao)—直—交(jiao)变频(pin)器仍(reng)存在(zai)许(xu)多待改进的(de)问题(ti):
(1)当前大功率高电(dian)(dian)压电(dian)(dian)力电(dian)(dian)子器件处在发展期,GTO元(yuan)件面(mian)临淘汰,IGBT,IGCT尚(shang)待(dai)成熟;
(2)采用IGCT(或者GTO)、IECT的(de)(de)变(bian)流(liu)(liu)器(qi),器(qi)件(jian)故障(zhang)造成直通短路的(de)(de)保护还是难题;电(dian)源(yuan)侧变(bian)流(liu)(liu)器(qi)如(ru)果发(fa)生直通短路会(hui)造成电(dian)网(wang)短路,所以(yi)变(bian)流(liu)(liu)器(qi)必(bi)须采用高漏抗输(shu)入变(bian)压器(qi),一般要求15%,甚至高达20%;
(3)交(jiao)(jiao)—直—交(jiao)(jiao)变频(pin)(pin)器低频(pin)(pin)运行时过载(zai)能(neng)力减(jian)低,一般运行在5Hz以下时变频(pin)(pin)器过载(zai)能(neng)力减(jian)半;
(4)交—直(zhi)—交变(bian)频器输出PWM调制电(dian)(dian)(dian)压(ya)(ya)波形的(de)(de)电(dian)(dian)(dian)压(ya)(ya)变(bian)化(hua)率du/dt很高(gao)(gao),容易造(zao)成电(dian)(dian)(dian)机(ji)和电(dian)(dian)(dian)器的(de)(de)绝缘疲劳(lao)损伤;输出导线较长时,共模(mo)反(fan)射电(dian)(dian)(dian)压(ya)(ya)会在电(dian)(dian)(dian)机(ji)侧产生很高(gao)(gao)的(de)(de)电(dian)(dian)(dian)压(ya)(ya),如(ru)果是(shi)两(liang)电(dian)(dian)(dian)平(ping)的(de)(de)变(bian)流(liu)器,这(zhei)(zhei)个(ge)电(dian)(dian)(dian)压(ya)(ya)的(de)(de)峰(feng)值是(shi)直(zhi)流(liu)电(dian)(dian)(dian)压(ya)(ya)的(de)(de)两(liang)倍(bei),如(ru)果是(shi)三电(dian)(dian)(dian)平(ping)的(de)(de)变(bian)流(liu)器,这(zhei)(zhei)个(ge)电(dian)(dian)(dian)压(ya)(ya)的(de)(de)峰(feng)值是(shi)中间一半电(dian)(dian)(dian)压(ya)(ya)的(de)(de)三倍(bei);
(5)交—直(zhi)—交变频器PWM调制将(jiang)产(chan)生谐波、噪(zao)声、轴电流(liu)等问题。
变(bian)频(pin)器(qi)节(jie)能(neng)(neng)(neng)主要(yao)(yao)表(biao)现(xian)在(zai)风机(ji)(ji)、水泵的(de)(de)应用(yong)上。为了保证生产的(de)(de)可靠性,各种生产机(ji)(ji)械(xie)在(zai)设计配用(yong)动(dong)(dong)力驱动(dong)(dong)时,都留有(you)一定(ding)的(de)(de)富余(yu)量(liang)(liang)。当(dang)(dang)电机(ji)(ji)不能(neng)(neng)(neng)在(zai)满(man)负荷下(xia)运行(xing)时,除达到动(dong)(dong)力驱动(dong)(dong)要(yao)(yao)求(qiu)外(wai),多余(yu)的(de)(de)力矩(ju)增(zeng)加了有(you)功功率的(de)(de)消(xiao)耗(hao),造(zao)成电能(neng)(neng)(neng)的(de)(de)浪费。风机(ji)(ji)、泵类(lei)等(deng)设备(bei)传统(tong)的(de)(de)调(diao)速(su)方法是通(tong)过调(diao)节(jie)入(ru)(ru)口(kou)或出口(kou)的(de)(de)挡板、阀门(men)开度来调(diao)节(jie)给(ji)风量(liang)(liang)和给(ji)水量(liang)(liang),其输入(ru)(ru)功率大(da),且大(da)量(liang)(liang)的(de)(de)能(neng)(neng)(neng)源消(xiao)耗(hao)在(zai)挡板、阀门(men)的(de)(de)截流过程(cheng)中。当(dang)(dang)使用(yong)变(bian)频(pin)调(diao)速(su)时,如(ru)果流量(liang)(liang)要(yao)(yao)求(qiu)减小,通(tong)过降(jiang)低泵或风机(ji)(ji)的(de)(de)转速(su)即(ji)可满(man)足要(yao)(yao)求(qiu)。
电(dian)(dian)(dian)动(dong)机使用(yong)变(bian)(bian)(bian)(bian)(bian)频(pin)(pin)(pin)(pin)(pin)器(qi)(qi)(qi)的(de)(de)作用(yong)就(jiu)是(shi)为(wei)(wei)了(le)调速(su),并降(jiang)低启(qi)动(dong)电(dian)(dian)(dian)流(liu)(liu)(liu)。为(wei)(wei)了(le)产(chan)生可变(bian)(bian)(bian)(bian)(bian)的(de)(de)电(dian)(dian)(dian)压和频(pin)(pin)(pin)(pin)(pin)率(lv)(lv),该设(she)备(bei)首(shou)先要(yao)把电(dian)(dian)(dian)源(yuan)的(de)(de)交(jiao)流(liu)(liu)(liu)电(dian)(dian)(dian)变(bian)(bian)(bian)(bian)(bian)换为(wei)(wei)直流(liu)(liu)(liu)电(dian)(dian)(dian)(DC),这个(ge)过程叫整(zheng)(zheng)流(liu)(liu)(liu)。把直流(liu)(liu)(liu)电(dian)(dian)(dian)(DC)变(bian)(bian)(bian)(bian)(bian)换为(wei)(wei)交(jiao)流(liu)(liu)(liu)电(dian)(dian)(dian)(AC)的(de)(de)装(zhuang)置(zhi),其科学术(shu)语(yu)为(wei)(wei)“inverter”(逆(ni)(ni)(ni)变(bian)(bian)(bian)(bian)(bian)器(qi)(qi)(qi))。一般(ban)(ban)逆(ni)(ni)(ni)变(bian)(bian)(bian)(bian)(bian)器(qi)(qi)(qi)是(shi)把直流(liu)(liu)(liu)电(dian)(dian)(dian)源(yuan)逆(ni)(ni)(ni)变(bian)(bian)(bian)(bian)(bian)为(wei)(wei)一定的(de)(de)固定频(pin)(pin)(pin)(pin)(pin)率(lv)(lv)和一定电(dian)(dian)(dian)压的(de)(de)逆(ni)(ni)(ni)变(bian)(bian)(bian)(bian)(bian)电(dian)(dian)(dian)源(yuan)。对于逆(ni)(ni)(ni)变(bian)(bian)(bian)(bian)(bian)为(wei)(wei)频(pin)(pin)(pin)(pin)(pin)率(lv)(lv)可调、电(dian)(dian)(dian)压可调的(de)(de)逆(ni)(ni)(ni)变(bian)(bian)(bian)(bian)(bian)器(qi)(qi)(qi)我们称为(wei)(wei)变(bian)(bian)(bian)(bian)(bian)频(pin)(pin)(pin)(pin)(pin)器(qi)(qi)(qi)。变(bian)(bian)(bian)(bian)(bian)频(pin)(pin)(pin)(pin)(pin)器(qi)(qi)(qi)输(shu)出(chu)的(de)(de)波(bo)形是(shi)模拟(ni)正(zheng)弦波(bo),主(zhu)要(yao)是(shi)用(yong)在(zai)三相异步电(dian)(dian)(dian)动(dong)机调速(su)用(yong),又叫变(bian)(bian)(bian)(bian)(bian)频(pin)(pin)(pin)(pin)(pin)调速(su)器(qi)(qi)(qi)。对于主(zhu)要(yao)用(yong)在(zai)仪器(qi)(qi)(qi)仪表的(de)(de)检测设(she)备(bei)中(zhong)的(de)(de)波(bo)形要(yao)求(qiu)较高的(de)(de)可变(bian)(bian)(bian)(bian)(bian)频(pin)(pin)(pin)(pin)(pin)率(lv)(lv)逆(ni)(ni)(ni)变(bian)(bian)(bian)(bian)(bian)器(qi)(qi)(qi),要(yao)对波(bo)形进行(xing)整(zheng)(zheng)理,可以输(shu)出(chu)标准的(de)(de)正(zheng)弦波(bo),叫变(bian)(bian)(bian)(bian)(bian)频(pin)(pin)(pin)(pin)(pin)电(dian)(dian)(dian)源(yuan)。一般(ban)(ban)变(bian)(bian)(bian)(bian)(bian)频(pin)(pin)(pin)(pin)(pin)电(dian)(dian)(dian)源(yuan)是(shi)变(bian)(bian)(bian)(bian)(bian)频(pin)(pin)(pin)(pin)(pin)器(qi)(qi)(qi)价格的(de)(de)15--20倍。由(you)于变(bian)(bian)(bian)(bian)(bian)频(pin)(pin)(pin)(pin)(pin)器(qi)(qi)(qi)设(she)备(bei)中(zhong)产(chan)生变(bian)(bian)(bian)(bian)(bian)化的(de)(de)电(dian)(dian)(dian)压或(huo)频(pin)(pin)(pin)(pin)(pin)率(lv)(lv)的(de)(de)主(zhu)要(yao)装(zhuang)置(zhi)叫“inverter”,故(gu)该产(chan)品本身就(jiu)被命名为(wei)(wei)“inverter”,即:变(bian)(bian)(bian)(bian)(bian)频(pin)(pin)(pin)(pin)(pin)器(qi)(qi)(qi)。
变频(pin)(pin)(pin)不是(shi)(shi)到处可以省(sheng)电(dian),有不少场合用变频(pin)(pin)(pin)并不一定能(neng)省(sheng)电(dian)。 作为电(dian)子电(dian)路,变频(pin)(pin)(pin)器本身也要耗电(dian)(约额定功率的3-5%)。一台1.5匹的空调自身耗电(dian)算(suan)下来也有20-30W,相当于(yu)一盏长明(ming)灯. 变频(pin)(pin)(pin)器在(zai)工频(pin)(pin)(pin)下运(yun)行,具(ju)有节电(dian)功能(neng),是(shi)(shi)事实。但是(shi)(shi)他(ta)的前提条件是(shi)(shi):
第(di)一、大功率并且为风机(ji)/泵类负载;
第(di)二(er)、装置本身具有节电功能(软(ruan)件支(zhi)持);
这是(shi)体(ti)现节电效(xiao)果的三个条件(jian)。除(chu)此之外,无所谓节不节电,没(mei)有什么意义。如果不加(jia)前提条件(jian)的说变频器工(gong)频运(yun)行节能(neng),就(jiu)是(shi)夸大或是(shi)商(shang)业炒作。知道了原(yuan)委,你会巧妙的利(li)用(yong)他为(wei)你服务。一(yi)定(ding)要注意使用(yong)场合和使用(yong)条件(jian)才好正确应用(yong),否则就(jiu)是(shi)盲(mang)从、轻(qing)信而(er)“受骗上当”。
无(wu)(wu)(wu)功(gong)(gong)功(gong)(gong)率(lv)不但增(zeng)加(jia)线损和设(she)备的发热(re),更主要(yao)的是功(gong)(gong)率(lv)因数的降低(di)导致电(dian)网有功(gong)(gong)功(gong)(gong)率(lv)的降低(di),大量的无(wu)(wu)(wu)功(gong)(gong)电(dian)能消耗在线路当中,设(she)备使用效率(lv)低(di)下,浪费严重(zhong),使用变(bian)(bian)频(pin)(pin)调速(su)装置后,由于变(bian)(bian)频(pin)(pin)器内部滤波(bo)电(dian)容的作用,从而减少(shao)了(le)无(wu)(wu)(wu)功(gong)(gong)损耗,增(zeng)加(jia)了(le)电(dian)网的有功(gong)(gong)功(gong)(gong)率(lv)。
1:电(dian)机硬启(qi)动(dong)对(dui)电(dian)网造(zao)成严重的(de)(de)(de)(de)冲击,而且还会对(dui)电(dian)网容(rong)(rong)量要(yao)求过高,启(qi)动(dong)时产生(sheng)的(de)(de)(de)(de)大电(dian)流(liu)和(he)(he)震动(dong)时对(dui)挡板和(he)(he)阀门的(de)(de)(de)(de)损(sun)害极大,对(dui)设(she)备、管路的(de)(de)(de)(de)使用寿(shou)命(ming)极为不(bu)利。而使用变频节能(neng)(neng)装置后(hou),利用变频器(qi)的(de)(de)(de)(de)软启(qi)动(dong)功(gong)能(neng)(neng)将使启(qi)动(dong)电(dian)流(liu)从零(ling)开始,最大值也不(bu)超(chao)过额(e)定电(dian)流(liu),减(jian)轻了(le)(le)对(dui)电(dian)网的(de)(de)(de)(de)冲击和(he)(he)对(dui)供电(dian)容(rong)(rong)量的(de)(de)(de)(de)要(yao)求,延(yan)长了(le)(le)设(she)备和(he)(he)阀门的(de)(de)(de)(de)使用寿(shou)命(ming)。节省(sheng)了(le)(le)设(she)备的(de)(de)(de)(de)维护费用。
2:从理论上讲,变(bian)频(pin)器(qi)可以(yi)用(yong)在(zai)(zai)所有带(dai)有电(dian)(dian)动(dong)(dong)机(ji)的(de)机(ji)械设备(bei)中,电(dian)(dian)动(dong)(dong)机(ji)在(zai)(zai)启动(dong)(dong)时,电(dian)(dian)流会(hui)(hui)比额定(ding)高5-6倍的(de),不但会(hui)(hui)影(ying)响(xiang)电(dian)(dian)机(ji)的(de)使(shi)用(yong)寿命而(er)且消耗较(jiao)多的(de)电(dian)(dian)量.系统在(zai)(zai)设计时在(zai)(zai)电(dian)(dian)机(ji)选型上会(hui)(hui)留有一定(ding)的(de)余(yu)量,电(dian)(dian)机(ji)的(de)速度是(shi)固定(ding)不变(bian),但在(zai)(zai)实际使(shi)用(yong)过程中,有时要以(yi)较(jiao)低或者较(jiao)高的(de)速度运(yun)行(xing),因此进行(xing)变(bian)频(pin)改造是(shi)非常有必要的(de)。变(bian)频(pin)器(qi)可实现电(dian)(dian)机(ji)软启动(dong)(dong)、补偿功率因素。
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