PWM电压源逆变器非线性因素迭代学习补偿

An Iterative-learning-based Compensation for PWM VSI Nonlinearities

脉宽调制(pulse width modulation,PWM)电压源型逆变器(voltage source inverter,VSI)的非线性因素会导致输出电压和电流的波形畸变、基波分量幅值减小,其驱动永磁同步电机会造成转矩波动,低速运行不平稳等现象。为了解决VSI非线性因素对永磁同步电机调速系统运行性能的影响,建立上述非线性因素的数学模型,将非线性因素对系统的影响看成一个扰动电压。通过坐标变换和时域到角度域的转换,在同步旋转坐标系下,扰动电压是由关于转子位置的周期扰动和常值扰动组成的。提出在角度域内采用迭代学习和前馈的复合补偿来分别消除周期扰动和常值扰动,该方法无需系统精确模型,实现简单,只需电流传感器。仿真和实验结果标明,所提复合补偿能有效地减小电流谐波,提高低速运行平稳性,且适用于不同转速。

The nonlinearities of pulse width modulation voltage source inverter（PWM-VSI） lead to output voltage and current distortion, fundamental wave amplitude decrease, torque ripple that may cause instability in the low-speed range of permanent magnet synchronous machine（PMSM） drives. To eliminate the influence on PMSM drives due to the nonlinearities of the VSI, models of the above nonlinearities were established and their influence was treated as a total disturbance voltage. Through coordinate transformation and time domain to angle domain transformation, the voltage disturbance is comprised of a periodic disturbance with regard to the rotor position and a constant disturbance in the synchronous rotating reference frame. A composite compensation strategy, composed of the iterative learning control and feed-forward, was proposed to eliminate the periodic disturbance and constant disturbance respectively in the angle-domain. The proposed method is easy to implement without the knowledge of the system accurate model, attaining effective compensation by only using current sensors. Simulation and experimental results demonstrate that the proposed composite compensation can reduce the current harmonic effectively, improve the stability in low-speed range and is applicable to the different speed operations.