A Novel Soft Start Method of Super Large Capacity High Voltage Motor

The large current generated by starting directly of super large capacity and high voltage induction motor would have a huge impact on the grid as well as the motor itself.The variation of the power factor and electromagnetic torque during direct start of motors with different capacity and voltage levels are obtained.Aiming at the problem that the secondary impact of auto-transformer starter is too large and the cost of magnetic control starter is too high,the auto-transformer and magnetic control soft start method of super large capacity and high voltage motor is proposed and the basic working principle is analyzed.The calculation formula of cost for magnetic control soft starter and auto-transformer and magnetic control soft starter is deduced,and specific examples are analyzed and compared.It is concluded that the choice of auto-transformer with appropriate tapping ratio can greatly reduce the cost of auto-transformer and magnetic control soft starter compared with the other one.Finally,the simulation and experiment results show that the start method can effectively avoid secondary current impact and constrain the motor starting current to less than 2.5 times the rated current.

Fuzzy-immune control strategy of a hydro-viscous soft start device of a belt conveyor

Considering the control difficulties of a hydro-viscous soft start(HVSS) device of a belt conveyor,a fuzzy-immune control algorithm was derived.A fuzzy-immune PID controller was designed based on immune feedback regulations and adaptability of the fuzzy logic inference.Using MATLAB software,we simulated the controller and compared the HVSS device with a conventional PID controller and a fuzzy PID controller.The simulation results show that the controller is not only very reliable as a PID controller,robust and requires only a short adjustment time of fuzzy control,but possesses also capacity of global optimization of the immune algorithm.To verify our theoretical analysis and simulation,a HVSS test-bed was developed.The experimental results demonstrate that the fuzzy-immune PID controller managed to start the belt conveyor softly and to follow an S-shaped curve while the output speed correctly followed the preset speed with only small fluctuations in speed.

Mechanism of hydro-viscous soft start of belt conveyor

The mechanism of a hydro-viscous soft start is of great importance in the design of a hydro-viscous clutch and its control system. To explain the mechanism of a hydro-viscous soft start, the startup process of a belt conveyor was numerically analyzed with the modified Reynolds equation, an energy equation and a temperature-viscosity equation. The effect of temperature and grooves of the friction disk surface on torque transfer and load capacity of the oil film have also been analyzed. The results show that 1) the grooves are the basis of forming dynamic pressure but they may reduce the capacity of torque transfer to a certain extent, 2) during the startup process, temperature has little effect on torque transfer and load capacity and the variation in load capacity of the oil film is very small, indicating that it is preferable to use the flow rate as a control object than the pressure of the feed cylinder. The results have been verified by an experiment.

Research on the soft start-up performance of hydro-viscous drive

The principle and structure of hydro-viscous drive(HVD) set is introduced. Through theoretical analysis of the HVD set start-up steadiness, the conclusions were obtained that the non-linearity of the pressure performance curve and dynamic pressure instability of the pilot-operated electro-hydraulic pressure relief valve, which is used for the HVD speed regulating purpose and usually works within micro flow-rate and low oil pressure state, are the main causes of the poor start-up steadiness. So a special speed regulating valve for HVD set is developed, with which the start-up steadiness of HVD set is much improved.

Theoretical research on hydroviscous speed-adjusting clutch in soft-start of belt conveyor

Through research on the application of hydroviscous speed-adjusting clutch in belt conveyor, this paper concluded that hydroviscous speed-adjusting clutch has many advantages such as controllable start and stop, overload protection and multi-motor power equilibrium. But its theory when used in large power fan and pump could not meet the needs of belt conveyor soft-start operation. Focusing on the theo- retical analysis of the lubrication oil flow needed by the transmission procedure to form the oil-film. Put forward concrete calculation methods of lubrication flow and how to de- cide number of oil-films used in belt conveyor.

LLC谐振变换器非对称变占空比软启动设计

LLC谐振变换器在传统启动方法中存在浪涌电流过大的问题,为解决此问题,提出一种非对称变占空比的软启动混合控制策略。通过使两个桥臂的对管脉冲保持一致,同时使上、下开关管占空比保持互补导通,得到一种非对称变占空比的软启动方法,再与降频控制方法相结合组成了软启动混合控制策略。搭建了一台LLC谐振变换器实验样机验证方案的可行性。实验结果表明,所提出的混合控制策略能抑制启动过程中的电流冲击,并能保持初级开关管的零电压开通(ZVS)特性。

一种适用于LDO的无过冲软启动电路设计

设计了一种适用于LDO的无过冲软启动电路。其核心是采用线性升压的软启动策略来消除浪涌电流,电路结构简单、易于实现。为了解决超调现象,利用晶体管与正反馈电路设计了一种快速比较器,使得软启动电路输出电压能平滑地过渡到稳定工作状态。为了减小版图面积,利用少量的MOS管设计了斜坡产生电路和输入不平衡比较器电路。该软启动电路集成到一款低压差线性稳压器中,采用SMIC 0.18μm BCD工艺实现,电源电压为4.5 V。仿真结果表明,软启动电路有效地消除了浪涌电流,实现输出电压平稳上升无过冲,并能平滑地过渡到稳定工作状态,无超调现象产生。电路结构简单,版图面积为98μm×60μm,便于片上集成,该电路也可以应用到一般的DC-DC稳压器中。

具有软启动功能的EMI直流滤波器设计

宽禁带半导体器件的应用使电动汽车的电机驱动系统更加小型化和轻量化,但也引发了更为严重的电磁干扰,使得驱动系统的可靠性面临严峻挑战。为此,以24 V/2 A的EMI直流滤波器为例,通过噪声源、滤波器原理及阻抗影响的分析,依据插入损耗指标进行滤波器参数设计。同时,考虑到整车启动时刻的启动冲击,加入软启动电路,进一步提高电动汽车驱动系统可靠性。实验测试验证了滤波器的电磁干扰抑制效果和软启动性能,证明了滤波器设计的可行性和有效性。

新型本质安全电源保护电路设计

为了解决本安电源过流和短路的安全问题,设计了一种用于本质安全电源的新型保护电路。该电路通过电流镜电路按一定的比例复制主路电流,并由副电路采样电流信号,经过放大、移位处理后接入比较器负输入端,比较器正输入端接入短路检测信号。该新型电路的功能是当电源负载发生过流或短路故障时,滞回比较器输出过流或短路控制信号,迅速关断主电流开关,从而实现对负载主电路截断的保护;同时启动微电流开关,检测短路故障是否消除,使得故障消除后能够自动恢复主电流开关电路。此外,电源保护电路的软启动电路可用于解决电源启动过程中的浪涌电流可能会造成过流保护误动作的问题。

双向LLC谐振变换器的数字混合软启动策略

针对双向LLC谐振变换器高压侧启动时产生的巨大浪涌电流可能造成的器件损坏的问题,阐述了启动频率大于谐振频率的必要性和启动频率下的工作模态,并分析了相应的启动初始时刻的状态平面轨迹。据此提出了一种优化谐振变换器启动初始时刻的平面轨迹和指数降频的分阶段数字混合软启动策略,搭建了一台以SPC1168为数字控制芯片的1 440 W样机进行实验,验证了所提出的数字软启动策略的有效性,相较于传统降频启动抑制启动电流的效果提高了25.6%。

一种基于离散变频的三相异步电机软启动控制

针对传统三相异步电机软启动方式存在启动转矩不足,难以适用于部分需要重载启动电机场合的问题,采用一种离散变频的软启动控制方法,将离散变频的方式与传统软启动控制相结合,同时加入功率因数角补偿以提高电机在启动过程中的平稳性。实验表明,该控制方法可在抑制电机启动电流的同时,有效提升电机的启动转矩,同时抑制电机在启动过程中的抖动。

高压干式移磁无级调压软起动装置和就地无功补偿装置在制氧站的应用

以某铅冶炼厂制氧站改扩建项目为例,介绍高压干式移磁无级调压软起动装置和就地无功补偿装置的工作原理及其在罗茨鼓风机上的应用、高压干式移磁无级调压软起动装置和就地无功补偿装置的选型及参数计算、罗茨鼓风机配电系统设计、罗茨鼓风机现场运行效果。

一种混合型飞跨电容三电平Boost装置研制

为适应“双碳”政策驱动下光伏系统朝着高电压等级、高功率密度的发展方向,设计并研制了一款易于软启动的混合型飞跨电容三电平Boost装置(HFCBC)。该拓扑使飞跨电容兼具了从光伏侧和母线侧软启动的能力,降低了过压过流风险。其次,基于状态空间平均法建立了系统小信号模型,设计了带有超前补偿的控制器。最后,搭建了250W的原理样机,验证了所提方案的合理性。

高压软启和高压变频在铁合金烧结主抽风机上的应用

在原有主抽风机同步电动机高压软启动控制基础上,增加高压变频器,实现高压软启和高压变频技术并用于主抽风机同步电动机启动与控制,更加利于工艺控制。应用后可根据实际情况,频繁启停风机,最大限度节能降耗。

电压源型高压变频器兼容电流源型变频器高炉鼓风机电动机软起动改造方案

介绍高炉鼓风机电动机软起动方式及发展趋势。介绍TMEIC电压源型高压变频器(VSI)兼容包头钢铁炼铁厂3台高炉鼓风机电动机负载换向式电流源型变频器(LCI)软起动改造方案及效果。VSI及LCI软起动系统均具备软起动现场高压电动机的功能,二套软起动系统互为备用、互不干扰,能保证一套软起动系统断电断开状态时、另一套软起动系统能正常稳定运行,实现二拖三变频软起动功能。

同步电机静止变频软起动及其电枢电流谐波分析

同步电机软起动是由静止变频器(Static Frequency Converter,SFC)将同步电机从静止逐渐拖动至额定转速。但SFC短时和频繁起动会造成大量谐波,该谐波施加在同步电机电枢绕组对同步电机造成不可逆的危害。本文首先图解分析了同步电机软起动低速和高速阶段的换相过程,由此推导出各阶段电枢电流模型,从而分析得出电枢电流谐波特性。最后,搭建出同步电机软起动的Matlab/Simulink模型,验证本文推导的准确性。

梳棉除尘系统恒压吸风智能控制技术

为保证清梳联连续稳定生产、减少资源浪费,介绍梳棉除尘系统的组成,分析管网、除尘机组、梳棉除尘系统存在能耗高、智能化程度低、设备开停频繁启动、滤尘器间歇控制等不足及原因,提出除尘系统进行恒压吸风智能控制改造思路,即在除尘主风机加装变频器、梳棉负压主管道端加装压力变送器和负压保护装置,在除尘机组增加管网控制装置,在集尘风机加装软启动,改进滤网收集系统等方案;通过对比除尘系统改造前后的实际效果,表明改造后梳棉机恒压为800 Pa~900 Pa,用电量减少5.68%。指出:应用梳棉除尘系统恒压吸风智能控制技术,可实现人机智能控制,达到稳定吸风工艺质量的效果,用电效率提高、用电成本降低,保护电机、节能降耗。

东芝三菱变频器软启动同步切换技术在京博石化烷烃脱氢装置压缩机的应用

本文简单叙述了对京博石化烷烃脱氢装置进行的技术改造,将原东芝三菱变频运行用的高压变频器,改造为变频运行加上能软启动同步切换的变频器,可以将电机无扰切换到电网上工频运行。简单叙述了改造的必要性,改造的基本思路和方案,以及改造后的实际效果。

智能永磁直驱技术在矸石山提升机中的应用

枣庄矿业集团公司高庄煤矿矸石山绞车采用永磁直驱系统,控制实现主从跟随,转矩和速度平衡,并且可通过调节频率,实现软启、软停,永磁直驱系统将机械传动效率提高到98.5%,电动机额定效率可达96%。在控制方式上,采用全矢量控制,实现转矩和速度调节,对节能增效、减轻检修人员的劳动强度具有重要意义。

相位模糊下基于软判决的卷积码识别方法

QPSK数据流通常具有相位模糊的问题,传统方法常采用卷积码遍历识别码字起始位置的译码算法,这将导致算法计算量大、资源占用高等诸多问题。因此,提出一种基于软判决的卷积码起始位置识别与QPSK相位模糊消除的译码方法,以有效提升译码算法性能。首先,推导了卷积码编码序列与校验矩阵之间的数学表达式,明晰了卷积码码字起始位置与相位模糊的逻辑关系;然后,求解CCSDS标准卷积码的校验矩阵,以方程成立的概率作为判决的度量,该方法适用于各种码率的删除卷积码,具有工程实用性;最后,通过仿真分析验证了所提出方法的有效性。研究表明该方法无需遍历卷积码的码字起始位置和相位模糊,且鲁棒性较强,所需数据量较小,随着数据量的增大和卷积码码率的降低,识别准确率逐渐提高。