三电平逆变器异步电动机直接转矩控制系统(I)——单一矢量法

Direct Torque Control of Induction Motor Fed by Three Level Inverter(I)——Single Vector Method

三电平中点钳位逆变器(NPC)广泛应用于中压变频调速系统,具有对器件耐压要求低,输出谐波含量低,控制性能好等优点。其主要问题是如何避免中点电压的漂移,以及防止输出电压有过高的瞬时跳变。提出一种三电平异步电动机直接转矩控制(DTC)系统,即基于单一矢量的控制算法。该方法有效地控制了三电平逆变器的中点电压,并抑制了输出电压的跳变,从而满足了实际运行的要求。仿真结果表明,本文的方法在三电平逆变器供电的异步电动机上有效地实现了DTC系统,并能达到较好的控制性能。

Three-level neutral-point-champed(NPC) inverter is widely used in medium-voltage adjustable speed drive applications, while the direct torque control of induction motor presents the advantages of simple structure, fast torque response, and high robustness to the variation of parameters. In this paper, a three-level DTC system is presented based on single vector selection table which resolves the problems of voltage unbalance of neutral point and high dv/dt of output voltage, typical in multilevel inverters. Also the DTC control algorithm is implemented digitally in a DSP system. Finally, simulations show good performance of proposed control strategy of induction motor fed by three-level inverter.