长初级双边直线感应电动机分段推力协同控制和测速算法

Thrust Cooperative Control and Speed Measurement Algorithm of Segmented Long Primary Double-Sided Linear Induction Motor

为提高分段长初级双边直线感应电动机(LP-DSLIM)的推力平稳性,提出一种多变流器驱动的分段推力协同控制策略和测速算法。基于分段LP-DSLIM单元电机数学模型,研究了一台变流器控制一段单元电机的特性,设计了多变流器驱动多段电机的协同控制策略;根据直线电机运动方程和多分段LP-DSLIM推力计算值构造了线性扩张状态观测器(LESO)以观测速度,速度观测值噪声小且无滞后,用于推力协同控制时推力波动小且无推力损失,有效地改善了推力控制效果。仿真和实验验证了推力协同控制策略和LESO测速算法的有效性。

Long primary double-sided induction motors(LP-DSLIM)are widely used in rail transit and linear motor based electro-magnetic launch system,with the advantages of large thrust weight ratio and small dynamics longitudinal end effect during high-speed operation.To reduce the voltage and capacity of the inverter and to improve the power factor of LP-DSLIM,the long primary is segmented into several primary segments and the power supply mode of multiple inverters is adopted.However,the thrust characterization method and high-performance cooperative control strategy of segmented LP-DSLIM powered by multiple inverters have to be studied deeply.Besides,in the field oriented control,the speed participates in the field orientation and the speed measurement accuracy will directly affect the thrust control effect.It is necessary to increase the speed measurement accuracy in motor drive.This paper proposes a thrust cooperative control strategy of segmented LP-DSLIM powered by multiple inverters and a linear speed measurement algorithm.Firstly,the characteristics of one inverter driving a unit motor are studied basing on unit motor mathematical model of segmented LP-DSLIM.When the d axis currents of all unit motors are equal to isd and the q axis currents of all unit motors are equal to isq,the secondary flux equation and electromagnetic thrust equation of segmented LP-DSLIM powered by multiple inverters are similar to that of rotating induction motor.When isd is a constant value,the secondary flux linkage is kept constant and the electromagnetic thrust is controlled by isq.The thrust of each unit motor is naturally proportional to the length of the coupling secondary,which realizes cooperative thrust control.Then,according to the linear motor motion equation and the thrust model,the linear extended state observer(LESO)is established to observe the speed.The speed observer is compared with the tracking differentiator(TD)speed measurement algorithm.Simulation results and experimental results verified the effectiveness of the established speed observer and the proposed thrust cooperative control strategy.When the filter factor h0 in TD is small,the observed velocity noise is large and the thrust fluctuation is large.When h0 in TD is large,the observed velocity lags seriously and the thrust loss is large.The constructed speed observer can simultaneously meet the requirements of low noise and no lag,small speed measurement error.Meanwhile,the thrust fluctuation is small and there is less thrust loss when the observation speed of constructed speed observer is applied for field oriented control.Under the proposed control strategy,the thrust of each unit motor is proportional to the length of its coupling secondary,the total thrust is kept constant.The following conclusions can be drawn:①Under the proposed cooperative control strategy,the secondary flux equation and electromagnetic thrust equation of segmented LP-DSLIM powered by multiple inverters are similar to that of rotating induction motor.The thrust of each unit motor is naturally proportional to the length of the coupling secondary.The cooperative control strategy is suitable to electromagnetic thrust system.②The low noise and small lag of TD velocity measurement algorithm cannot be obtained simultaneously,which will lead to large thrust noise or thrust loss in the field oriented control.The speed measurement algorithm of the constructed speed observer is simple with low noise and no lag.When the constructed speed observer is used for field orientation,the thrust fluctuation is small,the thrust loss is small,and the control effect is better than that of the TD speed measurement algorithm.