A Novel Method of "Double delta Modulation" on Tracking Control of PWM converters

非线性跟踪控制是SPWM变换器的重要控制策略之一。提出了一种新型双重△调制跟踪控制方法,它由一个无滞环比较器和一个载波周期定时器组成。比较器产生PWM信号的上升沿,使得跟踪控制响应快,精度高;定时器决定PWM信号的下降沿,它保证了开关周期固定不变;文中提出了一个按周期对比较阈值进行预估调节的算法,该算法可使每个周期的平均跟踪误差均为零,同时可以抑制子谐振和跟踪失步。对三相四线电压跌落补偿系统电压跟踪的仿真研究证实了“双重△调制”策略和比较阈值的一步预估算法的有效性。最后对一个单相半桥逆变器的电流跟踪控制给出了实验结果。

A Novel Method of Double Delta Modulation on Tracking Control of PWM Converters

Nonlinear tracking control is one of the important control strategies for PWM converters. A novel method of "double S modulation" for tracking control is proposed first, in which an error hysteresis-less comparator and a switch period timer are only needed. The comparator produces the fore-edges of the output PWM signal, which make faster response and higher precision, and the timer decides the back-edges, which ensure constant switch frequency. A period-by-period predicting arithmetic for the variable threshold of the hysteresis-less comparator is also proposed so that the average tracking error in any switching period is always zero, and the sub-oscillation and step out are suppressed. Simulation researches of voltage tracking control in three-phase four-line voltage sag compensating system validate the new strategy, and finally the experimental results for current tracking in a single-phase half- bridge inverter demonstrate the good tracking control performances.