Comparison of performance between bipolar and unipolar double-frequency sinusoidal pulse width modulation in a digitally controlled H-bridge inverter system

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.

交错降压式全桥有源电力滤波器

传统全桥有源电力滤波器(active power filter,APF)正常工作时开关管驱动信号中要加入死区时间,这样就会产生死区效应,降低APF的补偿性能。为了解决这个问题,提出一种交错降压式全桥APF,其最大的特点是没有直通隐患,可靠性高,无需设置死区,补偿性能好。针对新型APF电感数目较多的缺陷,采用半波倍频正弦脉宽调制(sinusoidal pulse width modulation,SPWM),有效地减小了单个电感的感值,从而减弱电感数量增加而带来的体积重量影响。仿真和实验验证了理论分析的正确性和新型APF的可行性。