摘要
针对Z源三电平NPC逆变器的中点电位偏移问题,提出了一种具有中点电位平衡的SPWM模糊控制算法。该算法将电容电压的偏差与偏差的变化率作为模糊逻辑控制器的输入,直流参考信号的幅值为模糊逻辑控制器的输出。算法按照中点电位偏移的方向与程度,通过模糊控制规则实时调节逆变器的上、下直通时间,从而达到直流侧电容电压中点电位平衡控制,实现在Z源网络升压的情况下,有效地抑制中点电位偏移。同时,该控制算法不会增加额外的开关次数,因此不会增加逆变器的开关损耗。通过MATLAB/Simulink仿真分析,验证了相应抑制中点电位偏移的SPWM模糊控制算法的正确性和可行性。
A SPWM fuzzy control algorithm with neutral-point voltage balance capability is proposed for the neutral-point voltage deviation problem of Z-source three-level NPC inverter. The algorithm takes error and error change rate of the capacitance voltage as input of fuzzy logic controller,and the amplitude of DC reference signal as the output of fuzzy logic controller. According to the direction and extent of the neutral-point voltage deviation,the algorithm regulates the uppershoot-through time and lower-shoot-through time dynamically to achieve the neutral-point voltage balance,which can suppress the neutral-point voltage deviation effectively in the situation of achieving Z-source network boosting. Meanwhile,this algorithm does not increase the extra number of semiconductor commutations,and hence not increase the switching losses of inverter. The correctness and feasibility of the SPWM fuzzy control algorithm to suppress deviation of the neutralpoint voltage is verified through the simulation analysis of MATLAB/Simulink.
引文
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