【正文】 電壓?jiǎn)?dòng)設(shè)計(jì)中，帶式輸送機(jī)驅(qū)動(dòng)軸通過(guò)齒輪傳動(dòng)直接連接到電機(jī)。此種控制方式功率可達(dá)到 750kW。DC 驅(qū)動(dòng)系統(tǒng)在機(jī)械上是簡(jiǎn)單的，但設(shè)計(jì)的電子電路，監(jiān)測(cè) 和控制整個(gè)系統(tǒng)，相比于其他軟啟動(dòng)系統(tǒng)的選擇是昂貴的，但在轉(zhuǎn)矩、負(fù)載均分和變速為主要考慮的場(chǎng)合，它又是一個(gè)可靠的，節(jié)約成本的方式。 固定充液液力偶合器 固定充液液力偶合器是在結(jié)構(gòu)較簡(jiǎn)單和僅3 具有有限的彎曲部分的輸送裝置中最常用的軟啟動(dòng)裝置，其結(jié)構(gòu)相對(duì)比較簡(jiǎn)單，成本又低，對(duì)現(xiàn)在使用的大多數(shù)輸送機(jī)能提供優(yōu)良的軟啟動(dòng)效果。此種液力偶合器需要在工作腔以外設(shè)置導(dǎo)管 (也稱勺管 )和導(dǎo)管腔，依靠調(diào)節(jié)裝置改變勺管開(kāi)度 (勺管頂端與旋轉(zhuǎn)外 殼間距 )人為的改變工作腔的充液量，從而實(shí)現(xiàn)對(duì)輸出轉(zhuǎn)速的調(diào)節(jié)。 VFC 控制器可以容易地裝在小功率輸送機(jī)驅(qū)動(dòng)上。 2. AV 逆變器每個(gè)開(kāi)關(guān)只需要一個(gè) HVIGBT[2,3]。若對(duì)輸入諧波有 更高的要求，可以使用 24 脈沖二極管整流器作為輸入變流器。 產(chǎn)生的諧波盡可能的小，使用盡可能低的開(kāi)關(guān)頻率以最小化開(kāi)關(guān)損耗 。在這些選擇中，可變頻率控制 (VFC)的方法顯現(xiàn)出在將來(lái)長(zhǎng)距離輸送中帶式輸送機(jī)扮 演了重要的角色。s rotor windings. the modified motor control System controls motor torque. For conveyor starting, resistance is placed in series with the rotor for low initial torque. As the conveyor accelerates,the resistance is reduced slowly to maintain a constant acceleration torque. On multipledrive systems. an external slip resistor may be left in series with the rotor windings to aid in load sharing .the motor systems have a relatively simple a ,the control systems for these can be highly plex, because they are 9 based on puter control of the resistance switching. Today, the majority of control systems are custom designed to meet a conveyor system39。 P N and 0 are the do bus points. The phase U, for example, is in state P (positive bus voltage)when the switches S1uand S2u are closed, whereas it is in state N (negative bus voltage) when the switches S3u and S4u, are closed. At neutral point clamping, the phase is in 0 state when either S3u, conducts depending on positive or negative phase current polarity, respectively. For neutral point voltage balancing, the average current injected at 0 should be zero. 2. 2 Line side converter For standard applications. a 12pulse diode rectifier feeds the divided DClink capacitor. This topology introduces low harmonics on. the line side. For even higher requirements a 24pulse diode rectifier can be used as an input converter. For more advanced applications where regeneration. capability is necessary, an active front. end converter can replace the diode rectifier, using the same structure as the inverter. 2. 3 Inverter control Motor Control. Motor control of induction machines is realized by using a rotor flux. oriented vector controller. Fig. 2 shows the block diagram of indirect vector controlled drive that incorporates both constant torque and high speed fieldweakening regions where the PW M modulator was used. In this figure, the mand generated as function of speed. The feedback speed is added with the feed forward slip mand signalψ,the resulting frequency signal is integrated and then the unit vector signals(cosθe and sinθ e)are generated. The vector rotator generates the voltage Vs and Angle θe mands for the 14 PW M as shown. PWM Modulator. The demanded voltage vector is generated using an elaborate PWM modulator. The modulator extends the concepts of spacevector modulation to the threelevel inverter. The operation can be explained by starting from a regularly sampled sinetriangle parison from twolevel inverter. Instead of using one set of reference waveforms and one triangle defining the switching frequency, threelevel Modulator uses two sets of reference waveforms Uand U and just one triangle. Thus, each switching transition is used in an optimal way so that several objectives are reached at the same time. Very low harmonics are generated. The switching frequency is low and thus switching losses are minimized. As in a twolevel inverter, a zerosequence ponent can be added to each set of reference waveform s in order to maximize the fundamental voltage ponent. As an additional degree of freedom, the position of the reference waveform s within the triangle can be changed. This can be used for current balance in the two halves of the DClink. 3 Testing results After Successful installation of three 750 kW /2. 3 kV threelevel inverters for one 2. 7 km long belt conveyor driving system in Cheng zhuang Mine. The performance of the whole VFC system was tested. Fig. 3 is taken from the test, which shows the excellent characteristic o