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1、 降低电动机高压软起动电网浪涌由于目前国内市场应用的电动机大多是 6kv 和 10kv 电机,做为串接在高压电网和电动机之间的功率执行器件,单只晶闸管还不足以承受 6kv 的高压,虽然单只晶闸管目前已经成熟地 发展 到单只耐压 6500v,但考虑到电网波动、浪涌及耐压余量等可靠性因素,在设计 6kv 高压软起动装置的时候,功率单元采用 3 只晶闸管串联的方式来提高耐压值。同理在设计 10kv 高压软起动装置的时候采用 5 只晶闸管串联组成高压阀组。 Due to the current motor applied in domestic market are mostly 6kV and 10
2、kV motor, as the power is connected in series between the high voltage grid and motor execution device, single thyristor is not enough to withstand the 6kV, although a single thyristor current have been developed to a single pressure 6500v, but considering the fluctuation of the power grid, surge an
3、d pressure allowance when reliability factors, soft starting device in the design of 6kV high voltage, power unit by 3 thyristors in series way to improve voltage. When empathy in the design of 10kv High-voltage soft starter device adopts 5 thyristor series high-pressure valve group.(1)单相 6kv 高压晶闸管功
4、率阀组所示。scr1scr6 http:/ http:/ http:/ http:/ 为大功率高压晶闸管,它们每三个串联后再反并联组成单相功率串联阀组,以实现软起动器对交流电机的控制。这 6 只晶闸管选用同一厂家、同一型号、同一生产批次的产品,以减小其在生产过程中由于生产工艺的不同而产生的自身特性诸如伏安特性、反向恢复电荷、开关时间和临界电压上升率等的差异,影响均压。r1、r2、r3 为静态均压电阻,用以实现晶闸管的静态均压。静态均压电阻选用无感电阻,阻值为晶闸管阻断状态等效阻值的1/40,且功率留有足够大的余量。r4、r5、r6 和 c1、c2、c3共同组成动态均压 网络 ,用以实现动态均压
5、。通过选择,各电阻和电容的参数误差应非常小,电容的取值根据晶闸管的最大反向恢复电荷和最小反向恢复电荷的差值 计算 求得。均压过程主要是由电容 c 完成的。串联的各只晶闸管开关速度不会完全一致,而会稍有差别。电容 c 上的电压在静态情况下数值相同,在开关过程中,由于电容上的电压不能突变,加在各只晶闸管上的压降不会发生跳变。由于开关过程中各只晶闸管中电流不一致所造成的影响由电容 c 的充放电补偿。 (1) single-phase 6kV high voltage thyristor valve group is shown. SCR1 scr6 for high voltage and high
6、 power thyristor, each of them three in series and then connected in parallel to form a single phase power series valve group, to http:/ http:/ http:/ http:/ realize the control of soft starter for AC motor. The 6 thyristors is selected in the same manufacturers, the same type, the same production b
7、atch of products, to reduce the differences in the process of production because of the production process have different characteristics, such as the volt-ampere characteristics of reverse recovery charge, the switching time and the critical voltage rate of rise, impact pressure. R1, R2, R3 for sta
8、tic pressure resistance, is used to realize static thyristor pressure. Static pressure resistance selection of non-inductive resistance, resistance to thyristor blocking state equivalent resistance of 1/40, and the power of a big enough margin. R4, R5, R6 and C1, C2, C3 composed of dynamic voltage b
9、alancing network, to achieve the dynamic pressure. Through selection, parameter error of each resistor and capacitor should be very small, the capacitance value is calculated according to the maximum difference between thyristor reverse recovery charge and minimum reverse recovery charge obtained. T
10、he pressure equalization process is mainly completed by the capacitor C. Each of thyristors in series switch speed is not entirely consistent, but slightly different. The voltage on the C in the static case the same value, in the switch http:/ http:/ http:/ http:/ process, because the voltage on the
11、 capacitor cannot mutation, and drop in not tube each thyristor jump. Since the switching process of the thyristor current inconsistencies caused by the influence of charging and discharging compensation capacitor C.(2)接口单元设计 (2) the design of the interface unit单元包括电压传感器接口、电流传感器接口、光纤传送接口、故障检测酿酒设备接口及
12、人机交互接口等。其中电压信号采用高阻降压方式,并考虑到系统兼容性,将电路设计成 3kv、6kv、10kv 通用,以方便产品生产。电流传感器泰安锅炉采用标准 x/5 电流互感器加高精度电流霍尔的形式,将信号进行相应处理后送到 cpu 进行运算。高压与低压间的信号传送采用光纤传输,既保证信号的实时性及可靠性传输,又起动高低压隔离作用。信号经过接口电路编码后通过光纤传送至触发单元,触发单元将信号解码并经过相应处理后用以触发晶闸管。触发单元的供电采用高位、低位相结合,每只晶闸管的触发电源各自独立。人机接口采用贴膜式软键和液晶显示屏。软件设计是系统控制的核心,直接关系到系统运行的稳定性和可靠性。酿酒设备
13、为了适应各种不同负载的应用,软件设计上设计了多种不同的起动曲线,包括电压斜坡起动、http:/ http:/ http:/ http:/ 限流起动、突跳起动及软停车曲线等。同时设计完善的保护功能,包括短路保护、过流保护、过压、欠压保护、晶闸管过热保护等。电机的参数及各种保护参数可由用户根据现场应用情况自行设定。 Unit comprises a voltage sensor, current sensor interface interface, optical fiber transmission interface, fault detection interface and man-ma
14、chine interface etc. The voltage signal with high resistance voltage drop, and considering the system compatibility, the circuit design of 3KV, 6kV, 10kV general, to facilitate production. Current sensor using standard current transformer x/5 high accuracy current Holzers form, the signal processing
15、 corresponding to CPU. The high voltage and low voltage signal transmission between the use of optical fiber transmission, both to ensure real-time and reliability of transmission signal, and starting high voltage isolation effect. The signal through the interface circuit code through the optical fiber transmission to the triggering unit, the signal decoding and after corresponding treatment is used to trigger the thyristor triggering unit. The triggering unit power supply with high, low combination, each thyristor trigger powe
