Single‐phase five‐level common‐ground transformerless inverter using switched capacitors for photovoltaic application

Abstract

Transformerless inverters (TLIs) are extensively used in the photovoltaic (PV) grid‐connected system. TLI with a common ground structure exhibits multiple excellent features that improve the efficiency of the inverter, eliminating leakage current and boosting the voltage. The use of TLI eliminates the electrical isolation required between PV and the grid, resulting in a leakage current (LC) issue. The LC affects the power quality of the inverter and creates a safety‐related issue. This paper presents a new TLI topology based on the common ground (CG) structure. This topology uses eight switches and two self‐balanced switched capacitors. Phase disposition pulse width modulation (PD‐PWM) control scheme is used to create a five‐level output voltage. Further, adequate analysis for component selection and loss analysis is carried out to evaluate the efficiency. Its CG configuration certifies that there is minimal LC and common mode voltage (CMV). It also supports the active and reactive power of the grid. Its dual gain makes it suitable for photovoltaic (PV) applications. This topology is simulated for leading, lagging, unity power factor (UPF), and changes in input voltage and load conditions. Later, a corresponding experimental test is carried out on a laboratory prototype (1 kW). An equitable comparison is carried out for the component, stresses, and features like CG, and LC, along with efficiency.

A single‐phase seven‐level buck‐boost common ground transformerless inverter for grid‐connected photovoltaic system

“…11,12 To achieve the above-mentioned functions, several switched capacitor-based MLIs (SC-MLI) with a common ground feature have been presented in the recent literature. 13,14 The leakage current can be eliminated from the TLIs system by providing a connection between the grid neutral to PV negative terminal, as shown in Figure 1C. Moreover, SC-MLI has the inherent capability to boost the input voltage and generate a multilevel output voltage.…”