桥门式起重机电机拖动系统能效及其控制研究

发布时间：2018-05-31 01:42

本文选题：桥门式起重机 + 电机拖动系统　；参考：《西南交通大学》2013年博士论文

【摘要】：起重机大车、小车运行机构和起升机构的动力装置多采用三相交流异步电机,实现起重机低能耗、高效率经济运行的关键是对起重机电机拖动系统的有效控制。电机的能效问题包括电机运行时的能源消耗(简称能耗)和工作效率两个方面的问题。电机运行效率、功率因数对电机拖动系统能耗产生直接影响,而负载率是影响电机运行效率和功率因数的重要运行参数。一般,当负载率为30～40%时,能实现电机高效运行,当负载率超过60%时,电机的功率因数接近额定功率因数。相对于功率因数曲线,电机的效率曲线具有更宽的高效率区域。高效运行的电机,其功率因数不一定高,要使两者都接近较高值,应使电机的负载率不低于60%。通过分析电机效率数据得出电机效率与不同电机功率之间的数值拟合关系,电机效率与不同电机功率之间的关系符合指数变化规律。电机效率数值拟合曲线对于电机的生产和工程中电机选型具有理论指导意义。对电机运行的经济性进行有效判定,必须合理确定电机运行的效率、经济负载率。根据电机运行综合效率和额定综合效率的比较,将电机运行的经济性分为非经济运行、基本合理运行、经济运行等三种运行工况。电机综合节电率的计算方法主要有功率计算法、综合效率计算法和累积电能计算法三种。电机综合功率随电机所拖动负载转矩按二次抛物线规律变化,考虑了无功功率引起的线路损耗的情况时,电机的综合效率曲线低于效率曲线,从电机的综合效率曲线也可定义电机三种运行工况。由于考虑了无功引起线路损耗的情况,电机最高效率点向负载率增大的方向偏移,所以经济运行区域相对变小。电机拖动系统节能的重要要求之一就是电机高效运行,这就要求降低电机运行时的内部损耗,尤其是电机内部的电气损耗。为了实现具有恒转矩运行和变工况负载特性的起重机节能运行,基于电机Г型等效电路,将定子铜耗和铁耗看作不变损耗,将转子铜耗看作可变损耗,其中不变损耗仅与定子电压有关,可变损耗仅与起重机负载转矩有关。根据折算前后传动系统动能不变和功率平衡的原则,得到起重机吊重起升机构等效单轴电机拖动系统电机转子侧的等效转动惯量和等效负载转矩。为了方便计算,同时电机平稳运行时,转差率较小,通过求解转差率与负载转矩之间的近似关系,得到随负载转矩按指数规律变化的起重机节能的最优调节电压,以及使电气总损耗最小的目标函数。起重机以380V的恒定电压运行时,轻载工况总损耗最大,以220V恒定电压运行时,在重载工况总损耗最大,按照负载转矩变化适时调整的最优调节电压运行方式时的节能效果是显著的。对电机定子电压和频率同时进行控制,使电机根据负载变化,具有调速平稳、快速起、制动,并且快速跟踪负载转矩的动态性能,对起重机节能控制具有重要意义。为了达到这一目的,针对电机在同步旋转坐标系中的数学模型,基于电机定、转子转差频率设计的电机变频节能控制系统,通过实时测量电机运行转速,计算转速差,经过转速调节器计算定子电流转矩分量,从而计算转差频率,并得到同步旋转坐标系的同步旋转角速度,进而得到空间矢量变换角。定子电压转矩分量和励磁分量由矢量变换角经过两相旋转坐标系到三相静止坐标系变换成电压型逆变器的控制信号,由整流器和逆变器输出电机定子三相变压变频电压,实现电机以给定转速稳定运行,并快速跟踪变化的负载转矩。仿真研究表明：闭环系统的空载起动时间比开环系统快0.34s,并且电机平稳起动,起动阶段开环和闭环系统的峰值电磁转矩差值达148N·m；闭环系统电机消耗的电动率小于开环系统的电机消耗电功率,尤其是在起动阶段开环系统的峰值功率是闭环系统峰值功率的2.5倍,电机具有明显的节能效果。基于矢量变换的矢量变频控制对电机拖动系统的调速范围宽,并且属于转差功率不变型的无极调速方法,结合现代控制理论与方法,既能应用于对调速性能要求较高的场合,对电机拖动系统也具有明显的节能效果。针对基于内扰定义MT坐标系中的电机等效结构设计了起重机电机拖动系统自抗扰控制器,4个一阶自抗扰控制器分别控制磁链方程的磁链、转速方程的转速、励磁电流方程的定子电流励磁分量和转矩电流方程的定子电流转矩分量。闭环系统电机具有良好的起动动态性能。开环系统电机负载起动时的能耗随负载转矩的增大而增大,尤其是在重载和满载时,负载转矩对起动能耗影响较大；对于闭环系统电机负载起动的能耗几乎不随负载转矩的变换而变化；在重载和满载时,闭环系统电机起动时的节能效果是显著的。满载时,闭环系统的节电率可达88%,中等载荷时,节电率可达64%,轻载时,节电率可达55%。
[Abstract]:The key of the crane's low energy consumption and high efficiency economic operation is the effective control of the crane motor dragging system. The energy efficiency of the motor includes two aspects of the energy consumption of the motor (energy consumption) and the working efficiency. It's a problem.
The operation efficiency of the motor has a direct influence on the energy consumption of the motor drive system, and the load rate is an important operating parameter that affects the operating efficiency and the power factor of the motor. Generally, when the load rate is 30 to 40%, the motor can run efficiently. When the load rate exceeds 60%, the power factor of the electric machine is close to the rated power factor. The efficiency curve of the motor has a wider high efficiency area. The power factor of the motor with high efficiency is not necessarily high. To make both of them close to the higher value, the load rate of the motor should not be lower than 60%.. By analyzing the efficiency data of the motor, the numerical fitting relationship between the motor efficiency and the power of different electric machines should be obtained. The efficiency of the motor and the motor efficiency should be obtained. The relationship between different motor powers conforms to the law of exponential change. The numerical fitting curve of the motor efficiency is of theoretical guiding significance to the motor type selection in the motor production and engineering.
The efficiency of motor operation must be determined effectively. The efficiency of motor operation and the rate of economic load must be determined. According to the comparison of the overall efficiency of motor operation and the rated comprehensive efficiency, the economy of motor operation is divided into three operating conditions, such as non economic operation, basic reasonable operation, economic operation and so on. The calculation of the comprehensive electricity saving rate of the motor is calculated. The method mainly includes the power calculation method, the comprehensive efficiency calculation method and the cumulative electric energy calculation method. The comprehensive efficiency curve of the motor is lower than the efficiency curve, and the comprehensive efficiency curve of the motor can also be determined. The total power of the motor is changed with the load torque of the motor by the two parabola law. The overall efficiency curve of the motor is lower than the efficiency curve, and the comprehensive efficiency curve of the motor can be determined. Three For the three operating conditions of the sense motor, the maximum efficiency point of the motor is shifted to the direction of the increase of the load rate because of the loss of the line caused by reactive power, so the economic operation area is relatively smaller.
One of the important requirements for the energy saving of the motor drive system is the efficient operation of the motor. This requires the reduction of the internal loss of the motor, especially the electrical loss in the motor. In order to achieve the energy saving operation of a crane with constant torque operation and variable load characteristics, the copper consumption and iron consumption of the stator are considered based on the equivalent circuit of the electric machine. The constant loss is regarded as a variable loss, in which the constant loss is only related to the stator voltage, and the variable loss is only related to the load torque of the crane. According to the principle of kinetic energy constant and power balance of the transmission system, the equivalent rotation of the rotor side of the crane lifting lifting mechanism equivalent to the single axis motor drag system is obtained. In order to be convenient for calculation, when the motor runs smoothly, the transfer rate is small. By solving the approximate relationship between the transfer rate and the load torque, the optimal regulating voltage of the crane energy saving with the load torque changing according to the exponential law and the objective function to minimize the total electrical loss are obtained. The crane is constant with the 380V. When the voltage runs, the total loss is maximum in the light load condition. When the 220V constant voltage runs, the total loss is maximum in the heavy load condition. The energy saving effect is remarkable when the optimal regulation voltage is adjusted according to the change of the load torque.
Control the voltage and frequency of the motor stator at the same time, so that the motor is stable, fast, braking, and fast tracking the dynamic performance of the load torque according to the change of the load. In order to achieve this goal, the mathematical model of the motor in the synchronous rotating coordinate system is based on the motor setting. The frequency conversion and energy saving control system of the rotor is designed. By measuring the speed of the motor in real time and calculating the speed difference, the stator current torque component is calculated by the speed regulator, and the frequency of the rotation is calculated, and the synchronous rotation angular velocity of the synchronous rotating coordinate system is obtained, and then the space vector transformation angle is obtained. The stator voltage torque is divided into the stator voltage and torque. The quantity and excitation component are transformed from the vector transformation angle to the three-phase static coordinate system to the control signal of the voltage inverter. The three-phase variable frequency voltage of the motor stator is output by the rectifier and the inverter to realize the stable operation of the motor at a given speed, and the load torque is rapidly followed by the change of the load. The unloaded starting time of the loop system is faster than that of the open loop system, and the motor starts smoothly. The peak electromagnetic torque difference between the open loop and the closed loop system is 148N m. The electromotor consumption of the closed loop system is less than that of the open loop system, especially in the starting stage, the peak power of the open loop system is a closed loop system. 2.5 times the peak power, the motor has obvious energy saving effect.
Vector conversion based VVVF control has a wide range of speed regulation for the motor drive system, and it belongs to the non variable rotating speed control method. Combined with the modern control theory and method, it can not only apply to the situation where the speed regulation performance is high, but also have obvious energy saving effect on the motor drive system. The MT based on the internal disturbance definition. The motor equivalent structure in the coordinate system designs the auto disturbance rejection controller for the crane motor drag system. The 4 first order auto disturbance rejection controllers control the magnetic chain of the magnetic chain equation, the speed of the speed equation, the stator current excitation component of the excitation current equation and the stator current torque component of the torque current equation. The closed-loop system motor has good performance. Starting dynamic performance. The energy consumption of the motor load starting in the open loop system increases with the increase of load torque, especially when heavy load and full load, the load torque has great influence on the starting energy consumption; for the closed-loop system, the energy consumption of the motor load starting almost does not change with the load torque transformation; in the heavy load and full load, the closed loop system motor is used. The energy saving effect is remarkable when starting. When the load is full, the power saving rate of the closed loop system can reach 88%. When the medium load is applied, the power saving rate can reach 64%. When the load is light, the power saving rate can reach 55%..
【学位授予单位】：西南交通大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TM343.2;TH21

【参考文献】