基于APF的简化调制算法及中点平衡策略研究

Simplified PWM Algorithm and Neutral-point Potential Balancing Strategy Based on Active Power Filter

传统三电平SVPWM调制算法以其较高质量的输出电压和较高的直流母线电压利用率获得了广泛的应用,但其存在算法复杂的缺点。针对其缺点,提出了一种基于端电压直接合成的三电平简化PWM调制算法。该算法通过对传统SVPWM算法伏秒平衡式的推导,强化约束条件,获得了新的伏秒平衡规则,简化了计算过程,减少了计算时间。此外,对于三电平APF固有的中点电位不平衡问题,在此算法基础上提出了一种简单、新颖的中点控制方法。最后,通过实验验证了控制算法的正确性和有效性。

SVPWM is widely used for its high quality output voltage and high usage of DC-bus voltage.However,the complexity limits its further applications.In order to overcome the disadvantages of the traditional SVPWM schemes,a simplified three-level PWM strategy based on terminal voltage direct synthesis was studied.A novel voltage second balance rule was obtained by setting a stronger constrain for traditional SVWPM voltage second rule.The new PWM strategy simplified the computational process and could reduce the calculation time.Besides,in order to solve the inherent problem of neutral-point potential offset for three-level APF,a new simplified strategy was proposed.Finally,the validity and correctness of the proposed strategy is verified by experiments.