静止坐标系下电流型PWM整流器电流环控制策略研究及其参数设计

A Novel Control Strategy and Its Parameter Design of the Current-loop in a Stationary Frame for Current-source PWM Rectifiers

通过分析三相脉宽调制电流型整流器(current source rectifier,CSR)在两相静止坐标系中的数学模型,利用瞬时功率理论建立电压定向的CSR功率控制策略。为了有效抑制整流器输入侧LC滤波器产生的并联谐振,文中引入电容电压反馈有源阻尼控制环路。采用频域法对电流内环开环传递函数进行研究,针对静置坐标系下电流内环在动态响应和稳定性方面的限制,提出电流内环级联滞后补偿控制方法。详细研究电流内环比例谐振控制器及各参数对其性能的影响,并根据性能指标要求确定系统参数。利用根轨迹分析滤波电感变化对电流内环稳定性影响,并明确有源阻尼反馈增益与系统鲁棒性的关联性,最后对控制器进行离散化处理以实现数字控制。仿真和在60 kVA三相CSR样机实验结果表明,所提出的控制方法能够实现良好的动、静态性能,单位功率因数以及有效抑制网侧电流畸变。

By analyzing the mathematical model of the three-phase pulse width modulation （PWM） current-source rectifier （CSR） in a stationary reference frame based on the instantaneous power theory, a voltage-oriented CSR power control strategy was proposed. As an alternative approach for active damping, the proportional capacitor-voltage feedback was used to damp the inductor-capacitor filter （LC） resonance. The system transfer function of the inner-current loop was analyzed using the frequency response method. In order to improve the limitations on dynamic response and stability of the controller,a new cascaded lag compensation method for inner-current loop was presented. The impacts of proportional resonant （PR） controller and its parameters in the inner-current loop were analyzed. Then, the parameter values of the controller were chosen according to the performance indicators. Stability against the filter inductance variation was studied by means of the root locus analysis, the correlation between active damping feedback gain and system robustness had been established. Finally, the controllers were discretized with the Tustin transformation. Simulations of a 60 kVA laboratory prototype shows that the proposed control method is able to generate excellent dynamic and steady-state performances, improve power factor, and reduce the input-current distortion.