基于新型变结构控制策略的直接转矩控制系统研究

Research of Direct Torque Control Based on a New Variable Structure Control Strategy

提出一种新型变结构控制策略,以解决感应电机直接转矩控制系统转矩波动大,低速性能差,以及逆变器开关频率不固定等问题。在变结构控制中采用带有线性区间的非线性控制结构,既能利用非线性特性抵偿内外扰的影响,又能实现系统在原点附近无抖振,在保证变结构控制快速性和鲁棒性的同时,有效改善了系统的性能。结合电机数学模型设计了相应的控制律,通过Lyapunov分析证明了系统的全局渐近稳定性。仿真结果证明了本文所提控制策略的有效性和可行性。

A new variable structure control （VSC） strategy is proposed in this paper to solve problems of DTC for induction motor drives,such as large torque ripple,difficulty to control at low speed range,and the switching frequency is variable. The nonlinear control technology with linear region is adopted in VSC to counteract the effect of disturbance,and achieve zero chattering right around system origin. The robustness and quickness of VSC are maintained,and the performance is significantly improved by the new strategy simultaneously. According to mathematical model of induction motor,control law is designed in this paper,and global asymptotic stability of the system is proved in the Lyapunov sense. Simulation results confirm the validity and feasibility of the proposed strategy.