A symmetric single phase diode assisted dual boost Z-source switched capacitor seven level inverter with modified SPWM

This paper introduces an advanced symmetric single phase transformerless double boost Z-source inverter (DB-SC7LI) that incorporates a modified modulation strategy. The circuit layout of the DB-SC7LI is meticulously designed to mitigate leakage current effectively. A significant reduction in the number of passive elements within the impedance network of the proposed topology, relative to identical counterparts, simplifies the associated control scheme. To address the restricted shoot-through (ST) states at the zero-voltage level, a refined modulation approach is devised to enable ST states at multiple voltage levels; inherently minimizing fluctuations in the inverter's output voltage (Δv). Additionally, the DB-SC7LI supports reactive power management and continuously draws current from the DC source. By generating a staircase output voltage and requiring a lower ST duty ratio (d), the topology significantly reduces total harmonic distortion (THD) in the grid-injected current, which also leads to a smaller filter size. Furthermore, the integration of impedance source networks with switched capacitor multilevel inverters (SC-MLIs) effectively mitigates inrush current issues, enhances voltage gain, and strengthens immunity-key benefits of Z-source topologies. Finally, the proposed design is validated through simulation with PSIM software for changing solar radiation conditions and a 1 kW laboratory prototype.