眾所周知，同步發(fā)電機要用直流電流勵磁。在以往的他勵式同步發(fā)電機中，其直流電流是有附設的直流勵磁機供給。直流勵磁機是一種帶機械換向器的旋轉電樞式交流發(fā)電機。其多相閉合電樞繞組切割定子磁場產生了多相交流電，由于機械換向器和電刷組成的整流系統(tǒng)的整流作用，在電刷上獲得了直流電，再通過另一套電刷，滑塊系統(tǒng)將獲得的直流輸送到同步發(fā)電機的轉子，勵磁繞組去勵磁，因此直流勵磁機的換向器原則上是一個整流器，顯然可以用一組硅二節(jié)管取代，而功率半導體器件的發(fā)展提供了這個條件。將半導體元件與發(fā)電機的軸固結在一起轉動，則可取消換向器、滑塊等滑動接觸部分、利用二極管換成直流電流。直流送給轉子勵磁、繞組勵磁。這就是無刷系統(tǒng)。

下面我們以典型的幾種不同發(fā)電機勵磁系統(tǒng)，介紹它的工作原理。

一、相復勵勵磁原理

左圖為常用的電抗移相相復勵勵磁系統(tǒng)線路圖。由線形電抗器DK把電樞繞組抽頭電壓移相約90°、和電流互感器LH提供的電壓幾何疊加，經過橋式整流器ZL整流，供給發(fā)電機勵磁繞組。負載時由電流互感器LH供給所需的復勵電流，進行電流補償，由線形電抗器DK移相進行相位補償。

二、三次諧波原理

左圖為三次諧波原理圖，對一般發(fā)電機來源，我們需要的是工頻正弦波，稱為基波，比基波高的正弦波都稱為諧波、其中三次諧波的含量最大，在諧波發(fā)電機定子槽中，安放有主繞組和諧波勵磁繞組（s1、s2），而這個繞組之間沒有電的聯(lián)系。諧波繞組將繞組中150HZ諧波感應出來，經過ZL橋式整流器整流，送到主發(fā)電機轉子繞組LE中進行勵磁。

三、可控硅直接勵磁原理

由左圖可以看出，可控硅直接勵磁 是采用可控硅整流器直接將發(fā)電機輸出的任一相一部分能量，經整流后送入勵磁繞組去的勵磁方式，它是由自動電壓調節(jié)器（AVR），控制可控硅的導通角來調節(jié)勵磁電流大小而維持發(fā)電機端電壓的穩(wěn)定。

四、無刷勵磁原理

無刷勵磁主要用于西門子、斯坦福、利萊等無刷發(fā)電機。它是利用交流勵磁機，其定子上的剩磁或永久磁鐵（帶永磁機）建立電壓，該交流電壓經旋轉整流起整流后，送入主發(fā)電機的勵磁繞組，使發(fā)電機建壓。自動電壓調節(jié)器（AVR）能根據(jù)輸出電壓的微小偏差迅速地減小或增加勵磁電流，維持發(fā)電機的所設定電壓近似不變。

中小型三相同步發(fā)電機的技術發(fā)展概況

一．概述

    中小型同步發(fā)電機是中小型電機的主要產品之一，廣泛應用于小型水電站、船舶電站、移動電站、固定電站、應急備用電站、正弦波試驗電源、變頻電源、計算機電源及新能源――風力發(fā)電、地熱發(fā)電、潮汐發(fā)電、余熱發(fā)電等。它對邊（疆）老（區(qū)）貧（窮）地區(qū)實現(xiàn)電氣化，提高該地區(qū)經濟發(fā)展水平和人民的生活水平有著重要的作用，中小型發(fā)電機在船舶、現(xiàn)代電氣化火車內燃機車等運輸設備中也是一個關鍵設備。移動電站對國防設施、工程建設、海上石油平臺、陸上電驅動石油鉆機、野外勘探等也是不可缺少的關鍵裝備之一。應急備用電站在突發(fā)事件中的防災、救護保障人民的生命和財產的安全有著不可替代的作用。開發(fā)綠色能源、可再生能源、減少大氣二氧化碳的含量，小水電、風力發(fā)電、地熱發(fā)電和余熱發(fā)電是重要的組成部分。

    我國小型同步發(fā)電機的第一代產品是1956年電工局在上海組織的統(tǒng)一設計并于1957年完成的TSN、TSWN系列農用水輪發(fā)電機。第二代產品是在進行了大量試驗研究和調查研究的基礎上于1965年開始的T2系列小型三相同步發(fā)電機統(tǒng)一設計，該水平達到六十年代國際先進水平，為B級絕緣的有刷三相同步發(fā)電機。在這段時間還開發(fā)了ST系列有刷單相同步發(fā)電機，此系列電機出口量較大。1979年開始進行TFW系列三相無刷同步發(fā)電機和TFDW系列單相無刷同步發(fā)電機的統(tǒng)一設計，1982年10月通過了樣機鑒定工作,并推廣生產,此兩系列主要性能指標達到或接近當時的國際先進水平,此系列仍采用B級絕緣結構。

    進入八十年代末、九十年代初，隨著我國改革開放不斷發(fā)展，我國的電機行業(yè)的部分企業(yè)開始引進先進工業(yè)國的中小型同步發(fā)電機，有的按生產許可證方式進行技術引進，有的引進軟件技術（或生

產技術），有的按合作生產方式引進國外的先進技術，其先后有德國西 門子公司的IFC5和IFC6系列、德國AEG公司的DKBH系列、英國彼特普公司E系列、美國馬拉松公司的MP系列發(fā)電機、英國的斯坦福公司BC、HC系列等發(fā)電機，這些發(fā)電機的絕緣等級為F級或H級，采用隱極式或整體凸級結

構，其技術經濟指標較先進，可靠性較高，其制造工藝水平較先進，這些產品的引進，對提高我國的中小型發(fā)電機水平和制造工藝水平有較大的促進作用。比如，無錫電機廠、汾西機械廠、柳州電機廠

引進了德國西門子公司1FC5、1FC6系列無刷發(fā)電機，蘭州電機有限責任公司（以下簡稱蘭電）引進了德國AEG公司DKBH系列船用、陸用無刷發(fā)電機，福州發(fā)電設備廠引進了美國麥格乃泰克公司無刷發(fā)電機制造技術等等。近年無錫電機廠又引進了西門子公司最近開發(fā)的1FC2系列無刷三相同步發(fā)電機，該電機為整園凸極沖片，克服了原西門子公司1FC5、1FC6隱極結構體積偏大，重量偏重的不足。90年代，無錫電機廠與新時代公司、上海革新電機廠與馬拉松公司合資辦了企業(yè)，使我國中小型三相同步發(fā)電機水平又有了進一步的提高，使國內三相同步發(fā)電機生產的主要企業(yè)產品達到了國際先進水平。蘭州電機廠在引進德國AEG公司DKBH系列基礎上，90年代中期，又開發(fā)了自己的新一代產品：TZHW系列（陸用）、TFXW-H系列（船用）無刷三相同步發(fā)電機，使其性能有了進一步的提高，更加適合國情、廠情，提高了市場競爭力。

Generator principle and structure -- the generator excitation system

As everyone knows, synchronous generator with direct current excitation. In the past he excitation synchronous generator, the DC current is supplied with DC exciter. DC exciter is a kind of mechanical commutator armature type alternator. The multi phase closed armature winding cutting stator magnetic field produced a polyphase alternating current, due to mechanical commutator and brush composed of rectification system in the rectification, brush obtained by DC, and then through another set of brushes, slider system will be the DC transmission to the synchronous generator rotor, the excitation winding to excitation, thus the DC exciter commutator is in principle a rectifier, apparently by a group of two joints of pipe to replace the silicon, and the semiconductor power devices are provided for the development of this condition. The semiconductor element and the shaft generator are combined together to rotate, can cancel the commutator, a sliding contact portion, using diode into DC current. DC excitation winding exciter rotor, to. This is the brushless system.

Below we give several typical different generator excitation system, introduces its working principle.

One, the phase compound excitation principle

The common reactance phase shift phase compound excitation system circuit diagram. By linear reactor DK armature winding tap voltage phase shift for 90 degrees, and a current transformer LH voltage supplied by the geometric overlay, through a bridge rectifier ZL rectifier, supply generator excitation winding. When the load is composed of a current transformer LH provide the desired compound excitation current, current compensation, by linear reactor DK phase by phase compensation.

Two or three harmonic theory

The three harmonic diagram, on the general generator source, we need is sinusoidal, known as the fundamental, base wave sine wave is called a harmonic, of which three harmonic content is maximum, in a harmonic generator stator slot, which are the main winding and harmonic excitation windings ( S1, S2), and the winding without electric contact. Harmonic winding winding in150HZ harmonic induction, after ZL bridge rectifier, is sent to the main generator rotor winding in LE excitation.

In three, the controllable silicon excitation principle

As can be seen by the controllable silicon excitation, is the use of silicon controlled rectifier directly to the generator output any phase of a portion of the energy, the rectifier is sent to the field winding to the excitation mode, it is composed of automatic voltage regulator ( AVR ), SCR conduction angle to adjust the excitation current size and maintain generator terminal voltage stability.

Four, the principle of brushless excitation

Brushless excitation is mainly used for Siemens, Standford Lilley, brushless generator. It is the use of AC exciter, the stator remanence or permanent magnet ( permanent magnet machine set voltage ), the AC voltage by the rotating rectifier has rectified, into the main generator excitation winding, so that the generator voltage build. Automatic voltage regulator ( AVR ) based on the output voltage of the minimal deviation rapidly decreasing or increasing the excitation current, maintain the generator set by the approximate constant voltage.

Small three-phase synchronous generator technology development

A. An overview

Small and medium synchronous generator in small-sized motor is one of the main products, widely used in small hydropower stations, ship power station, mobile station, fixed station, emergency power, sine wave test power supply, variable frequency power supply, computer power and new energy - wind power, geothermal power, tidal power, waste heat power generation. It to the side ( border ) and old ( area) poverty ( poor ) region to achieve electrification, improve the level of economic development and people's living level has an important role, medium and small generator in ship, the modern electrified train locomotives and other transporting equipment is a key apparatus. Mobile power station on the national defense facilities, engineering construction, offshore oil platforms, onshore oil drilling rig electric drive, field exploration is an indispensable key equipment. Emergency standby power station in the event of an emergency, rescue and protect people's lives and property safety plays an irreplaceable role. The development of green energy, renewable energy, reduce atmospheric carbon dioxide content, small hydropower, wind power, geothermal power and heat generation is an important part of the.

Our country medium and small synchronous generator of the first generation product is electrical engineering 1956Bureau in Shanghai organization of unified design and completed in 1957 for the TSN, TSWN series of farm water turbine generator. Second generation products are made in a large amount of experimental study and on the basis of the investigation began in 1965of the T2 series of small synchronous generator uniform design, the level achieved sixty time international advanced level, for class B insulation brushless three-phase synchronous generator. During this period of time also developed the ST series brushless single phase synchronous generator, this series motor export volume of the larger. Beginning in 1979 for TFW series three-phase brushless synchronous generator and TFDW series single-phase brushless synchronous generator with unified design, in 1982October passed the prototype identification work, and promote the production of the two series, the main performance indexes reach or approach the international advanced level, this series still uses the B class insulation structure.

In eighty time end, at the beginning of ninety time, as our country reforming and opening development, China's motor industry enterprises began to introduce advanced industrial country small and medium synchronous generator, some of the production license for the introduction of technology, the introduction of software technology ( or students

Production technology ), some of the cooperation mode of production of the introduction of foreign advanced technology, it has the German company SIEMENS IFC5series and the IFC6, Germany AEG company 's DKBH series, E series, the British Peterp USA marathon MP series generators, Britain's Standford BC, HC series generator, the generator insulation class F or class H, the implicit pole type or integral convex class node

Structure, its technology economic norms is more advanced, higher reliability, the manufacturing technology level is advanced, the product introduction, to improve China's medium and small generator level and manufacturing technology level has bigger stimulative effect. For example, motor factory in Wuxi, Fenxi machinery factory, Liuzhou electric plant

The introduction of Germany Siemens company 1FC5,1FC6 series brushless generator, Lanzhou Electrical Machinery Company Limited ( hereinafter referred to as the blue electric ) AEG introduction of the German company DKBH series marine, marine brushless generator in Fuzhou power plant, the introduction of the United States MEG Tektronix Inc brushless generator machine manufacturing technology and so on. In recent years, Wuxi electric plant and the introduction of Siemens company recently developed 1FC2series three-phase brushless synchronous generator, the motor for the entire park salient pole laminations, to overcome the original Siemens company 1FC5,1FC6non-salient pole structure in large volume, weight overweight deficiency. In 90, Wuxi electric factory and new Time Inc, Shanghai electrical machinery plant innovation and marathon joint-venture enterprise, make our country small and medium sized three-phase synchronous generator level had rise further, make domestic three-phase synchronous generator and production of major products reached the international advanced level. Lanzhou motor factory in the introduction of the German company AEG based on the DKBH series,90 time metaphase, and the development of their new generation of products: TZHW series ( land ), TFXW-H series ( Marine ) brushless three-phase synchronous generator, so that the performance is further improved, more suitable for the national conditions, conditions of the plant, improve the market competitiveness.