Transformerless Quasi-Z-Source Inverter to Reduce Leakage Current for Single-Phase Grid-Tied Applications

Abstract

The conventional single-phase quasi-Z-source (QZS) inverter has a high leakage current as it is connected to the grid. To address this problem, this paper proposes a transformerless QZS inverter, which can reduce the leakage current for single-phase grid-tied applications. The proposed inverter effectively alleviates the leakage current problem by removing high-frequency components for the common-mode voltage. The operation principle of the proposed inverter is described together with its control strategy. A control scheme is presented for regulating the DC-link voltage and the grid current. A 1.0 kW prototype inverter was designed and tested to verify the performance of the proposed inverter. Silicon carbide (SiC) power devices were applied to the proposed inverter to increase the power efficiency. The experimental results showed that the proposed inverter achieved high performance for leakage current reduction and power efficiency improvement.

A Novel Single-Stage Common-Ground Transformerless Buck–Boost Inverter

“…Using (1), ( 2), ( 4), ( 5), (7), and ( 8), applying the volt-second balance principle on L 1 and L 2 , the inductors L 1 and L 2 currents can be calculated using ( 17) and (18).…”

“…According to (17), (18), and ( 12), the peak value of inductors L 1 and L 2 currents can be given by ( 19) and (20).…”

“…Compared with two-stage configurations, single-stage configurations have more benefits, including compactness, lower device count, lower costs, and greater efficiency [16]. From this point of view, single-stage inverters are reported in the literature, and their comprehensive review is given in [17][18][19][20][21][22][23][24][25][26][27]. Common-ground transformerless inverter topologies were introduced in [21][22][23][24][25][28][29][30], which directly connect the ground of the grid to the negative of the DC input source.…”

Power Converters in Power Electronics: Current Research Trends

“…In order to increase the voltage gain, a multiplier cell technique is applied to the quasi-switched boost inverter with low input current ripple [5]. The applications of the ISI for grid connection [6] and photovoltaic [7] are presented.…”

Multiport Isolated link with Current-Fed Z-Source Converters to Manage Power Imbalance in PV Applications

“…The operation principle of the ZSI and current-fed topologies mentioned consist in apply a shoot-through state to overlap the H-bridge branches (0V) which provides natural protection against short-circuits, making it suitable for large-scale applications. After its presentation, variations on the topology were proposed for many applications such a grid-tied converters without galvanic isolation [16][17][18], with galvanic isolation [19][20][21], and finally for grid-tied PV systems [22][23][24].Z-sources topologies are interesting for PV applications because they can operate as voltage and current source. Additionally, Z-source converters operating as current source can be better applied in medium-high power applications due to the restriction of <1 kV in PV arrays terminals.…”