外文翻譯--變頻器使用淺談

1、河南科技學(xué)院機(jī)電學(xué)院the frequency converter is used and discussed lightlythe asynchronous motor is such main power equipment of manufacturing enterprise as electricity , chemical industry ,etc. as the high energy consumption equipment, its output power cant be up to the change pro rata of load, majority can o

2、nly turn on through guard or valve degree regulate , but the energy that the motor consumes does not change much, thus cause very great energy to loss . in recent years, one that is with the maturity of the production technology of the frequency converter and range of application of frequency conver

3、ter is extensive day by day, use the frequency converter to carry on technology to transform to the motor power into the energy-conserving , high-efficiency important means of every enterprise.1. frequency conversion adjusts the speed principle n60 f(1s)/p (1) in the type n-rotational speed of the a

4、synchronous motor;f-frequency of the asynchronous motor ;s-the motor is transfered to the difference rate ;p-logarithm very much of the motor。can know by type (1 ) rotational speed n in direct proportion to frequency f , only need change frequency f and change the rotational speed of the motor, moti

5、ve power frequency realize that speed regulate.the frequency converter is mainly adopted and handed in- frank- hand over the side when frequency f changes in the range of 0-50hz, the rotational speed of the motor regulates the range very widely. frequency conversion transfer speed pass person who ch

6、anges electricity , exchange frequently worker power change through the rectifier into a direct current source first just, then change the direct current source into the frequency , exchange power controllable in voltage in order to supply the motor. the frequency converter one there is generally fr

7、om rectification circuit, in the middle of direct current link, go against not becoming and controlling parting of 4 pieces not to make up. rectification part three-phase bridge controlled rectifier, is it change some into igbt three-phase bridge type go against the ng device to go against, and outp

8、ut for pwm wave form, middle direct current for strain wave , direct current energy storage and buffer inactive power link. the wave in harmony is suppressed outstanding problem that frequency converter use whether in harmony wave interfere, as frequency converter when working, output in harmony wav

9、e electric current of electric current will lead to the fact interfering to the power. though every frequency converter producer take measures and reach to frequency converter in harmony administration of wave national standard require basically, question needing to pay close attention to most in bu

10、t the wave in harmony remains the selecting type of the frequency converter and uses. contain other waves in harmony besides base wave in the voltage of output of the frequency converter. low times of in harmony wave usually exert a great influence on electrical machinery load, cause the torque to p

11、ulse, and higher wave in harmony makes the frequency converter export leaking the electric current to increase of the cable again, make electrical machinery exert oneself insufficient, so level times of in harmony wave that frequency converter output must suppress. because the rectification part of

12、the frequency converter adopts the controlled bridge type rectification circuit of diode, the middle strain wave part adopt large electric capacity as wave filter , so introduction of rectifier electric current to charge electric current condenser in fact, it is a steeper pulse wave, its wave in har

13、mony is relatively large in weight. in order to dispel the wave in harmony , adopt the following countermeasure mainly: a. increase frequency converter supply power power impedance generally , interior impedance , power of equipment can is it buffer frequency converter direct current strain function

14、 of inactive power , wave of electric capacity to play. impedance is short circuit impedance of the voltage transformer in this kind. look on power capacity relative capacity little frequency converter as, interior impedance value relative and heavy, the less the content of wave in harmony is; the r

15、elative frequency converter of capacity of the power is the larger in capacity, impedance value is relative low , the larger the content of wave in harmony is. choose frequency converter at supplying power power transformering , had better is it short out impedance heavy voltage transformer to choos

16、e. b. install reactor install reactor to increase from outside frequency converter supply power interior impedance of power actually. installs the reactor or installs at the same time on the exchange side of the frequency converter or the direct current side of the frequency converter, can suppress

17、the electric current of wave in harmony . c. the rectification part of the frequency converter is 6 pulse wave rectifiers that the voltage transformer usually operates heterogeneously, so the wave in harmony produced is relatively big. use heterogeneous operation of voltage transformer, such as make

18、 phase place corner bad y of 30each other y、2 voltage transformers made up are formed and equivalent to 12 pulse wave rectifiers, can reduce the electric current of wave in harmony , play a going to the wave in harmony to suppress role.d. regulate year of the frequency converter bob improve bob in y

19、ear of the frequency converter, can suppress wave in harmony once effectively low . e. use the wave filter wave filter can measure frequency converter in harmony wave amplitude and phase place of electric current, produce the electric current contrary to electric current phase place the same in ampl

20、itude of wave in harmony, thus absorb effectively .3. match of load3.1 square torque load air blower, pump load whether industry use equipment most live, frequency converter at most application at the load. it plants square torque load . generally speaking , have u/f =const control frequency convert

21、er of mode can meet the demand of load basically, below foundation the main characteristic question that need notice when introducing personning who select of frequency converter. 3.1.1 have avoided loadingair blower difficult overload as water pump, guarantee it greater than or mean the capacity of

22、 the motor slightly at the capacity to choose frequency converter; overload capacity of frequency converter that choose at the same time require to be lower even , up to 120% generally, 1min. but should notice when the function parameter of the frequency converter is chosen and presetted, because th

23、e load one hinders the torque in direct proportion to the square of rotational speed, when the operating frequency is higher than the specified frequency of the motor, to hinder torque can exceed the specified torque load, overfreight motor. so is it control supreme operating frequency can exceed th

24、e specified frequency of the electrical machinery strictly to want.3.1.2 match that the frequency converter accelerates time and moderates time while opening / stoppingbecause air blower and load of pump rotate inertia to be heavy, it start and when stopping with to accelerate time and moderate time

25、 it matches to be one important problem very frequency converter. person who select when using , should calculate to accelerate time and moderate according to load parameter time choose short time most frequency converter in frequency converter, in order to take place situation that voltage trip whe

26、n the frequency converter has not flowed to trip while starting and the frequency converter is moderated . but in the production technology sometimes , demand to be very strict to the start-up time of air blower and pump, if above-mentioned time that calculate can at meeting demanding , should redes

27、ign the selecting type to the frequency converter. 3.1.3 avoid the resonance because frequency converter through change power frequency of motor is it change electrical machinery rotational speed realize energy-conserving result to come, possible under a certain electrical machinery rotational speed

28、 and load some resonance , axle of department, resonance frequency coincident, cause load axle vibration that department can tolerate , cause equipment stoppage in transit or equipment damage sometimes, so when the function parameter of the frequency converter is chosen and presetted , should follow

29、 the resonance frequency of the axle department of load , through is it jump some frequency and width to establish , prevent system from the resonance phenomenon take place. 3.1.4 suppress and press it with water hammer effect pump load easy to is it suppress keep and water hammer effect to happen i

30、n the course of operating actually, so at the time of the selecting type of the frequency converter, should establish alone to this question when the function is established . a. suppress and press while running at a low speed , because it export the door to make the pressure rise to close in pump l

31、oad, thus cause the vapour of the pump to lose. when the function of the frequency converter is established , through limit minimum frequency of frequency converter is it limit minimum rotational speed of critical point , pump of flow to come, can avoid the emergence of this kind of phenomenon . b.

32、water hammer effect pump load flows backwards because of liquid gravity in the pump pipeline while suddenly cutting out. is it stop valve to be tight against stop valve , leading to the fact electrical machinery overturn , make frequency converter break down or burn out because the electrical machin

33、ery generates electricity to go against. in the systematic design of the frequency converter , should make the frequency converter stop according to the contours of moderating , disconnect the main circuit after the electrical machinery totally stops, or establish the cutting out and moderating stop

34、ping function, can avoid the emergence of this phenomenon . 3.2 permanent torque load the bringing type conveyer is a typical example of permanent torque load. the basic characteristic of permanent torque load is, in a situation that load is certain, it depends on the friction obstruction and radius

35、 of the cylinder among the belt and cylinder that load hinders the torque . this kind of load torque has nothing to do with the speed of the rotational speed, so in the course of regulating the rotational speed, the hindering the torque of load keeps intact. permanent torque load, while choosing fre

36、quency conversion to adjust the speed systematically, except according to the routine demand, should choose the frequency converter control method . a. adjusting the speed range of load. in case of adjusting the speed range not big , choose the frequency converter of comparatively simple and easy v/

37、f control method. when adjusting the speed range very largly , should consider adopting vector control method feedbacked . b. just load hinders the torque not to change in with certain load cases in permanent torque load, but their transfer to distance yet vary with load when changing to load. when

38、not quite on the torque change range, can choose the frequency converter of comparatively simple and easy v/f control method , to torque change range heavy load , should is it adopt vector control method feedbacked to have to consider. c. if does not have high expectations for mechanical characteris

39、tic , can consider choosing the frequency converter of comparatively simple and easy v/f control method in load, and is requiring higher occasion , must adopt arrow feedbacked. 變頻器使用淺談異步電動(dòng)機(jī)是電力、化工等生產(chǎn)企業(yè)最主要的動(dòng)力設(shè)備。作為高能耗設(shè)備，其輸出功率不能隨負(fù)荷按比例變化，大部分只能通過(guò)擋板或閥門的開度來(lái)調(diào)節(jié)，而電動(dòng)機(jī)消耗的能量變化不大，從而造成很大的能量損耗。近年來(lái)，隨著變頻器生產(chǎn)技術(shù)的成熟以及變頻器應(yīng)

40、用范圍的日益廣泛，使用變頻器對(duì)電動(dòng)機(jī)電源進(jìn)行技術(shù)改造成為各企業(yè)節(jié)能、高效率的重要手段。1.變頻調(diào)速原理n60 f(1s)/p (1)式中n異步電動(dòng)機(jī)的轉(zhuǎn)速； f異步電動(dòng)機(jī)的頻率； s電動(dòng)機(jī)轉(zhuǎn)差率； p電動(dòng)機(jī)極對(duì)數(shù)。由式(1)可知，轉(zhuǎn)速n與頻率f成正比，只要改變頻率f即可改變電動(dòng)機(jī)轉(zhuǎn)速，動(dòng)機(jī)電源頻率實(shí)現(xiàn)速度調(diào)節(jié)的。變頻器主要采用交直交方當(dāng)頻率f在050hz的范圍內(nèi)變化時(shí)，電動(dòng)轉(zhuǎn)速調(diào)節(jié)范圍非常寬。變頻調(diào)速就是通過(guò)改變電式，先把工頻交流電源通過(guò)整 器轉(zhuǎn)換成直流電源，然后再把直流電源轉(zhuǎn)換成頻率、電壓均可控制的交流電源供給電動(dòng)機(jī)。變頻器的電路一般由整流、中間直流環(huán)節(jié)、逆變和控制4個(gè)部分成。整流部分為三相

41、橋式不可控整流器，逆變部分為igbt三相橋式逆變器，輸出為pwm波形，中間直流環(huán)節(jié)為濾波、直流儲(chǔ)能和緩沖無(wú)功功率。2.諧波抑制 變頻器使用的突出問(wèn)題就是諧波干擾，當(dāng)變頻器工作時(shí)，輸出電流的諧波電流會(huì)對(duì)電源造成干擾。雖然各變頻器廠家對(duì)變頻器諧波的治理均采取了措施且基本達(dá)到國(guó)家標(biāo)準(zhǔn)要求，但諧波仍然是變頻器選型和使用中最需要關(guān)注的問(wèn)題。 變頻器的輸出電壓中含有除基波以外的其他諧波。較低次諧波通常對(duì)電機(jī)負(fù)載影響較大，引起轉(zhuǎn)矩脈動(dòng)，而較高的諧波又使變頻器輸出電纜的漏電流增加，使電機(jī)出力不足，故變頻器輸出的高低次諧波都必須抑制。 由于變頻器的整流部分采用二極管不可控橋式整流電路，中間濾波部分采用大電容作為

42、濾波器，所以整流器的輸入電流實(shí)際上是電容器的充電電流，呈較陡的脈沖波，其諧波分量較大。為了消除諧波，主要采用以下對(duì)策：a.增加變頻器供電電源內(nèi)阻抗通常情況下，電源設(shè)備的內(nèi)阻抗可以起到緩沖變頻器直流濾波電容的無(wú)功功率的作用。這種內(nèi)阻抗就是變壓器的短路阻抗。當(dāng)電源容量相對(duì)變頻器容量越小，內(nèi)阻抗值相對(duì)越大，諧波含量越??；電源容量相對(duì)變頻器容量越大，則內(nèi)阻抗值相對(duì)越小，諧波含量越大。所以選擇變頻器供電電源變壓器時(shí)，最好選擇短路阻抗大的變壓器。 b.安裝電抗器安裝電抗器實(shí)際是從外部增加變頻器供電電源的內(nèi)阻抗。在變頻器的交流側(cè)或變頻器的直流側(cè)安裝電抗器或同時(shí)安裝，可抑制諧波電流。c.變壓器多相運(yùn)行通常變頻器的整流部分是6脈波整流器，所以產(chǎn)生的諧波較大。應(yīng)用變壓器的多相運(yùn)行，如使相位角互差30的y、組合的2臺(tái)變壓器構(gòu)成相當(dāng)于12脈波整流器，則可減小諧波電流，起到諧波抑制作用。d.調(diào)節(jié)變頻器的載波比提高變頻器載波比，可有效抑制低