基于单周期控制的三相PFC整流器在输入电压不对称时的改进策略

An Improved Control Strategy of the One Cycle Control Three-Phase PFC Rectifier Under Unbalanced Conditions

分析了基于单周期控制技术的双并联升压型三相PFC整流器在电网电压不对称时输入电流跟踪输入电压不良的问题,提出了一种有效的改进措施,通过计算相电压不对称系数,对占空比计算公式进行修正,以消除不对称电压对输入电流波形跟踪不良的影响,使每相电流均和各自的电压同相,从而实现单位功率因数和低电流畸变。在任意时刻,该整流器只需要两个开关管工作在高频状态,从而使开关管的总体损耗程度进一步降低。最后通过硬件实验验证了该控制策略的正确性。

The input current waveforms of the three-phase rectifier with a parallel-connected dual boost topology based on one cycle control are analyzed under unbalanced input voltage conditions, and a modified effective method is proposed. By dynamically calculating the unbalanced parameters of the unbalanced input voltages, the original duty rate equations of three-phase PFC controller are modified correspondingly. This will eliminate the input current displacement caused by the unbalanced input voltages, and make the input currents in-phase with the input voltages, which results in unity power factor. The switching losses of the proposed controller are significantly reduced since only two switches are controlled at any time. Experimental results are presented to verify the theoretical analysis.