CPS-SPWM级联H桥APF直流侧电容设计

Design of DC-side Capacitor for CPS-SPWM Cascaded H-bridge APF

基于载波移相SPWM(CPS-SPWM)级联H桥的有源电力滤波器(APF)直流侧电容是其正常运行所必需的能量储存设备,该电容大小直接影响APF的谐波及无功补偿效果。这里在级联H桥APF主电路结构及CPSSPWM策略的基础上,建立单个H桥变流器的数学模型,结合开关函数的计算方法,通过分析调制信号、直流侧和交流侧电流三者之间的关系,从理论上推导出直流侧电流和电容电压在稳态下的数学表达式。由电容电压稳态时的脉动要求和直流侧电压控制的动态性能指标,给出直流侧电容参数的设计方法。最后,仿真和实验验证了该方法的可行性和有效性。

As a kind of energy storage equipment, the DC-side capacitor for the cascaded H-bridge active power filter （APF） based on carrier phase shift-sinusoidal pulse width modulation（CPS-SPWM）is necessary, of which the value would directly determine the harmonic and reactive power performance for the APF.Based on the main circuit topology of cascaded H-bridge APF and the CPS-SPWM strategy, firstly, mathematical model for a single H-bridge convert- er is established.Secondly,through concerning the calculation method of switching functions and analyzing the rela- tionship among the modulation signal, the DC-side and the AC-side, mathematical expressions for the DC side current and the capacitor vohage in the steady state are derived theoretically.Then, combined with the capacitor voltage ripple requirements at steady state and the dynamic performance index of DC voltage control, the method for calculating the value of the DC-side capacitor is given.Finally,the simulations and experimental results verify the validity and feasi- bility of the proposed method.