基于遗传-双模糊控制的异步电机直接转矩控制及DSP实现-机械设计及理论专业论文.docxVIP

摘 摘 要 -I-万方数据 -I- 万方数据 摘 要 直接转矩控制凭借其结构简单、电机参数不太敏感、易于实现等优点被广泛应用 于交流调速领域。但低速时磁链观测精度低、转速响应慢、转矩脉动较大等缺陷仍亟 需解决。本文首先对电机低速下的动、静态特性作了深入研究与仿真分析，并提出相 应的改进控制策略，最后利用 DSP 实验平台对整个系统进行了全数字化实现和实验论 证。 ⑴ 在传统 u?i 磁链观测局限性的基础上，引入一种改进型的自适应磁链补偿观 测器，很好地解决了低速时的直流偏移和零漂等问题。 ⑵ 利用遗传算法对 PI 控制参数、模糊规则进行在线优化与修正，提出一种新的 转速控制策略，并采用另一模糊决策表对空间电压矢量进行最优选择。双模糊控制器 的建立，使得转速响应时间小于 0.05s，磁链波动小于 0.23%，平均转矩脉动仅为 5%， 从而提高了电机低速运行时的整体性能。 ⑶ 在伪降阶磁链观测器的基础上，以定子电流和转子磁链为状态变量，设计出 一种新型的转速观测器，并能对定、转子电阻进行辨识。针对三个参数之间存在耦合， 同时辨识时难于收敛其真实值，提出一种转子电阻估值跟随定子电阻估值按一定规律 变化的补偿措施。仿真结果表明，补偿后的转速估计误差小于 10%，并能提高电机低 速运行时的稳定性。 ⑷ 以 TMS320F2812 为控制核心搭建实验硬件平台，采用 C 语言编写程序主要完 成：A/D 采样、磁链和转矩观测、模糊自适应 PI 速度调节、MRAS 速度辨识、SVPWM 生成等功能。论文最后对遗传-双模糊直接转矩控制系统进行了联机调试，实验结果 表明，低速时转速平均误差小于 3%，定子磁链波动范围小于 1%，平均转矩脉动为 8.5%， 在全速度范围内表现出良好的动、静态性能。 关键词：直接转矩控制;遗传算法;模糊控制;无速度传感器;TMS320F2812. -II-万方数据 -II- 万方数据 Abstract Direct torque control is widely used in AC variable speed field by virtue of its simple structure, less sensitive to motor parameters and easy realization. However, some drawbacks are still urgently solved at low speed such as the low precision flux observer, the slow speed response and the large torque ripple. In this paper, firstly the static and dynamic performance of motor is in-depth studied by numerical simulation analysis at low speed, and some improved control strategies are proposed as well. Finally, the fully digital implementation and experimental demonstration have been completed for the whole system by DSP experiment platform. ⑴ Based on limitation of the traditional u-i flux estimation, a modified adaptive flux compensating observer has been introduced, which can solve well the DC offset and zero drift at low speed. ⑵ A new speed control strategy has been proposed. In other words, on the one hand, genetic algorithm (GA) is used to on-line optimize and revise PI control parameters and fuzzy rules. On the other hand, another fuzzy decision table is used to select the optimal space voltage vector. The establishment of double fuzzy controller, which m