By deriving the discrete-time models of a digitally controlled H-bridge inverter system modulated by bipolar sinu- soidal pulse width modulation （BSPWM） and unipolar double-frequency sinusoidal pulse width modulation （UDFSPWM） respectively, the performances of the two modulation strategies are analyzed in detail. The circuit parameters, used in this paper, are fixed. When the systems, modulated by BSPWM and UDFSPWM, have the same switching frequency, the stabil- ity boundaries of the two systems are the same. However, when the equivalent switching frequencies of the two systems are the same, the BSPWM modulated system is more stable than the UDFSPWM modulated system. In addition, a convenient method of establishing the discrete-time model of piecewise smooth system is presented. Finally, the analytical results are confirmed by circuit simulations and experimental measurements.
如何在单相畸变电网中快速准确的获取基波以及所需的特定次谐波信息,对并网型电力电子变换器的控制系统而言是十分重要的。针对这一问题,提出了一种基于通用信号延迟叠加算子(generalized delayed signal superposition operator,GDSS)的单相锁相环结构,用于恶劣电网下系统基波以及多重谐波信息的检测。这种锁相环结构包含了多个具有很强频率选择特性的GDSS算子,能够在半个基波周期内从输入信号中分离出所需要的基波以及多个谐波频率信息,并且其参数以及GDSS算子个数还能够根据实际控制系统需求灵活调整。在各种工况下的仿真及实验表明,所提的锁相方法能够在恶劣电网下快速准确的获取基波及多重谐波信息,并且面对电网常见扰动时具有很强的鲁棒性。
