无轴承异步电机的直接转矩控制技术研究

针对无轴承异步电机气隙磁场定向算法控制复杂、存在失稳转矩及高度非线性等局限性，将直接转矩控制算法引入到无轴承异步电机解耦控制中。利用小信号模型分析了转矩绕组电流波动对无轴承异步电机麦克斯韦力的影响，研究了一种基于空间矢量脉宽调制(space vector pulse width modulation，SVPWM)的直接转矩控制算法，转矩PI环和磁链PI环的输出分别为磁链的相位角增量和幅值增量，经过相位角增量校正环节解决了转矩环和磁链环的干扰问题，对SVPWM的谐波系数进行了分析。针对一台无轴承异步电机，利用数字信号处理器TMS320F2812 DSP实现了电机在两种直接转矩控制(direct torque control，DTC)算法下的悬浮。实验结果表明该算法降低了电流的总谐波系数，减小了电机转矩的脉动，提高了电机的悬浮性能。

Direct Torque Control of Bearingless Induction Motor

Due to the limitations such as complexity, unsteady torque and nonlinearity in the gap flux direction algorithm, this paper introduces the direct torque control in the bearingless induction motor decoupling control. In this paper, small signal model is used to analyze the influence of torque current ripple on Maxwell force and a space vector pulse width modulation (SVPWM) direct torque control algorithm is studied further. The outputs of torque PI modulator and flux PI modulator are flux phase angle increments and amplitude increments respectively and a regulator for phase angle increment is adopted to solve the disturbance problems in torque loop and flux loop. The total harmonic distortion (THD) of SVPWM is analyzed in this paper. In the experiments on a bearingless induction motor, DSP (TM320F2812) was adopted to realize the suspending control which based on the two direct torque control (DTC) algorithms. The experimental results validate that the studied algorithms have a better performance in reducing disturbances of current and torque. Thus the suspending performance of motor is improved.