电磁发射直线感应电机多约束改进间接矢量控制策略

Improved indirect vector control strategy with multi-constraints of linear induction motor for generalized electromagnetic launch

针对高加速、短行程、非周期瞬态运行的电磁发射技术,在不同应用场景下具有负载特性迥异、发射能源电压电流等级受限以及对直线电机驱动的抗扰性、通用性和推力输出性能要求较高等特性,以短初级双三相直线感应电机为研究对象,基于次级磁场定向探究电机输出推力与dq轴电流、运动速度之间的耦合变化关系,提出一种通用化的直线感应电机多约束改进间接矢量控制策略,在逆变器电流约束、直流电压约束以及电机行程约束下,控制转矩/励磁电流比例系数k恒为1,实现电机在设定电流等级下的最大推力安培比输出与最大推力运行,使负载在最短行程内加速至目标速度。与传统基于查找表的恒/变滑差间接矢量控制方法相比,提出的改进策略可有效避免查表法引入的最优滑差离散误差,使电机在相同电流等级下以理论最大平均输出推力运行,进一步降低负载的行程需求,从而减小直线感应电机的体积重量,提高电磁发射系统的通用性。

For the characteristics of electromagnetic launch(EML) technology with high acceleration, short stroke and non periodic transient operation that under different application scenarios, the load characteristics are very different, the voltage and current levels of emission energy are limited, and the requirements for immunity, versatility and thrust output performance of linear motor drive are high. Taking the short primary dual three-phase linear induction motor(LIM) as the research object, based on the secondary field orientation, it explored the coupling relationship between the output thrust and dq-axis currents, motion velocity. A generalized multi-constraints improved indirect vector control strategy for LIM was proposed. Under the constraints of converter current, DC voltage, and motion distance, it controlled the torque per Ampere ratio coefficient k to be constant as 1, and achieved the maximum thrust per Ampere output and maximum thrust operation of the motor under the set current level, to accelerate the load to the target speed in the shortest stroke. The improved strategy is simpler and easier to be implemented and effectively avoids the optimal slip dispersion error introduced by look-up table method compared with the traditional constant/variable slip indirect vector control method. Under the same current level, the LIM operates in the theoretical maximum average output thrust to further shorten the moving distance of emission load, which can significantly reduce the volume and weight of LIM, and improve the universality of the EML system.