基于状态观测器的PWM整流器电流环无差拍控制技术

由零阶保持器及计算时间产生的控制延时是数字控制的固有缺点,将会导致系统振荡以至不稳定.传统电流状态观测器由于其本质是开环观测器,预测效果不甚理想.为补偿延时,一种基于新型状态观测器的方法被提出.该方法首先分析了一个开关周期内的电流变化情况,然后通过在一个开关周期的中间时刻采样获得新输出变量来校正观测误差,据此得到观测器从而预测下一开关周期电流值.此方法消除延时影响不仅使系统稳定,且对给定电流输入可取得无差拍响应.1kW的能量回馈型交流电子负载样机被用于验证该方法,样机采用25kHz的开关频率和TMS320F2812 DSP控制芯片,仿真和样机实验都验证了理论分析的正确性.

Deadbeat Control for Current Loop of PWM Rectifier Based on State-Observer

Inherent disadvantage of digital control is control time delay introduced by the zero-order-hold effect and the computational time delay. It could induce system oscillation and even system stability could be destroyed. Predictive results of conventional current state-observer are not ideal because the state-observer is open-loop in essence. To alleviate this problem, a method based on new state observer is proposed. The current state in a control period is described at first. The new output variable is acquired by sampling in the intermediate instant of the switching period, and then the observer error is corrected by it. The proposed method eliminates the disturbance of time delay so that not only stability is improved but also deadbeat control is fully realized in current loop. A lab prototype of 1kW electronic load with power regeneration ability is set up for the proof of concept. The prototype system is operated at 25 kHz switching frequency and is controlled by a TMS320F2812 DSP. Simulation and experimental results prove the validity of the proposed scheme.