基于电荷等效电流混合重构的升压型PFC变换器直流母线电容在线估算

The different operating modes of the boost power factor correction converter pose a challenge to accurately estimate dc-link capacitance across a wide power range. In order to meet the requirement of the mixed conduction mode (MCM) and the continuous conduction mode (CCM), an online estimation strategy of dc-link capacitance based on current hybrid reconstruction by charge equivalence is proposed. For obtaining the second harmonic component of capacitor current to estimate capacitance, the current reconstruction models are established in CCM and discontinuous conduction mode (DCM) within a switching cycle based on charge equivalence. By analyzing the effect of the voltage division of boost inductor internal resistance and the misjudgment of operating mode on the current reconstruction within a switching cycle, the capacitor current is reconstructed in different operating modes by the hybrid strategy based on error minimization. In this way, the estimation accuracy of dc-link capacitance can be improved across a wide power range without additional hardware and increasing sampling frequency. Finally, the effectiveness of the proposed strategy is verified on the experimental platform.