Análise da tensão do ponto neutro para o inversor ANPC de três portas: uma abordagem vetorial

Abstract

The ANPC topology with secondary bi-directional DC port (ANPC-3P) allows the connection of energy storage systems (ESS) directly to the topology on a secondary DC port, assigning an additional task to the inverter. In this work, the issues of low frequency ripple and the balance of the neutral-point voltage for the three-phase ANPC-3P inverter are investigated from the perspective of the space vector modulation considering the three nearest vectors approach. The theoretical analysis presents the procedures for calculating the average neutral point current, the limits for the controllability of the ESS currents, the impact of ESS integration for eliminating the low frequency ripple of the neutral-point potential and how this relates to parameters and operating conditions. Additionally, a space vector modulation is proposed that experimentally demonstrated its capacity of synthesizing the reference voltage at the output, controlling the ESS currents and balancing neutral-point voltage with reduced low frequency ripple. Experimental results are presented for several points and operation modes. To evaluate the effectiveness of the proposed space vector modulation in reducing the low frequency ripple of the neutral-point voltage, a carrier-based modulation with geometric approach is used for comparison.