A new grid tied transformerless (TL) inverter for photovoltaic (PV) application has been proposed in this paper which works on the switched capacitor (SC) technique and facilitate four times boosting of input voltage with nine level voltage generation. Therefore, this inverter can be a suitable candidate topology for low voltage single stage grid tied PV applications without any additional need of boosting dc/dc intermediate converter stage. Two SC cells are utilized in such a fashion that PV voltage would boost and facilitate nine levels in output voltage. The optional ac decoupling unit at load end, of this proposed inverter topology maintains constant common-mode voltage during two modes. Consequently, leakage current gets reduced sufficiently. H bridge structure at the back end of this topology provides positive and negative half cycle voltage in the output, thus elimination of extra virtual dc-link capacitors (for generating negative half cycle) helps in increasing the efficiency. The Matlab® simulation and experimental findings demonstrate the efficacy and practicality of this proposed inverter.

A new three-level inverter based on the switched capacitor (SC) with a common grounding (CG) configuration has been introduced in this article, which is capable of boosting the input voltage up to three times. Therefore, this inverter is configured without any boost dc/dc converter stage for low voltage PV application. To step up the input PV voltage and facilitate three level in output voltage, two SC cells are connected in parallel. This inverter's common grounding configuration helps in bypassing the stray capacitance, which eliminates the leakage current and consequently reduces electro-magnetic interference (EMI) considerably. Hence, for electro-magnetic compatibility (EMC), this inverter does not require any EMI filter. Additionally, this inverter handles reactive power during the grid's lagging/leading power factor (pf) condition. A proportional resonant (PR) current controller is designed to regulate active and reactive grid power. The proposed modulation strategy helps in balancing capacitor voltages at their base values with allowable ripple. The inverter circuit details, control technique, PWM scheme, thermal modeling, and loss analysis with component design guidelines are described in detail. Experimental results are presented to validate the effectiveness and feasibility of this proposed inverter.

Transformerless grid-connected multi-level photovoltaic (PV) inverter has the major concern of leakage current and buck behavior of output voltage, hence not suitable for low voltage PV applications. A new nine-level quad boost (9L4x) highly efficient inverter based on the switched capacitor (SC) with a common ground (CG) configuration has been proposed in this article, which provides four times the gain of input voltage. Hence, this inverter is preferable for low-voltage PV applications without any boost dc/dc converter intermediate stage. The inverter is designed in such a way that total conducting switches for different level generations are minimum. This technique helps to increase the efficiency of the inverter. Two SC cells are utilized to step-up the input PV voltage and facilitate nine steps in output voltage. The common grounding feature of the proposed inverter topology helps mitigate the leakage current. Additionally, this new inverter can handle reactive power during the grid's lagging/leading power factor (pf) condition. To regulate the active and reactive grid power, a proportional resonant (PR) controller is designed. The proposed modulation strategy balances the voltages of SCs at their base voltage with allowable ripple. The inverter circuit details, control strategy, pulsewidth modulation (PWM) scheme, thermal modeling, and loss analysis with component design guidelines are described in detail. Experimental results are presented to validate the effectiveness and feasibility of this proposed inverter.

A new seven-level common ground (CG) switched capacitor (SC) based grid-tied transformerless inverter has been introduced in this article, which has three times boosting capability of input voltage. Thus, this inverter is preferable for low-voltage PV applications without any boost conversion stage. To step up the input PV voltage and facilitate seven steps in output voltage, two SC cells are connected in parallel. A virtual dc-link capacitor serves a key role for a negative half cycle on behalf of H-bridge and helps in constructing topology with CG. The CG configuration of this inverter helps in bypassing the stray capacitance, which eliminates the leakage current and consequently reduces electromagnetic interference (EMI) considerably. Hence, there is further no requirement of any EMI filter for electromagnetic compatibility. Additionally, this inverter handles reactive power during the grid's lagging/leading power factor condition. To regulate active and reactive grid power, a proportional-resonant current controller is designed. The proposed modulation scheme helps in balancing the capacitor's voltages at their base values with allowable ripple. A detailed comparison also has been presented with other contemporary seven-level inverters. The inverter circuit details, control technique, pulsewidth modulation scheme, thermal modeling, and loss analysis with component design guidelines are described in detail. Experimental results are presented to validate the effectiveness and feasibility of this proposed inverter.

In this article, a new nine-level inverter that offers four times the input voltage gain is proposed. The configuration is designed based on a switched capacitor (SC) along with common ground structure. This inverter could find applications for low voltage PV systems, without using a boost dc/dc converter. Two SC cells are connected in parallel to increase the input PV voltage and enable nine steps in the output voltage. The proposed inverter topology's common ground (CG) structure aids in avoiding parasitic capacitance. As a result, it solves the leakage current issue, which plagues transformerless grid-connected PV inverters frequently. This novel inverter can also manage reactive power whether the grid's power factor (pf) is lagging or leading. The active and reactive grid power are regulated by a proportional resonant (PR) controller. The proposed modulation strategy helps in balancing the voltages of switched capacitors at their base voltage with allowable ripple. Therefore, there is no requirement of extra controller / feedback loop to balance the capacitors' voltage. The novel inverter has the advantages of highest efficiency, low cost and shows robust performance with quad boost CG facility. However, there is slight increase in voltage, current and VA (volt/amp) stress of some devices, which can be observed in comparison to H bridge and half bridge inverter for the same grid voltage. The proposed inverter's specifications, control approach, thermal modeling, PWM scheme, and loss analysis are discussed in depth along with guidelines for component design. Experimental findings are presented to support the viability and efficacy of the newly proposed inverter.

Transformerless grid-connected PV (photovoltaic) inverters are not suited for low-voltage PV applications because they have serious leakage current, low output voltage, and large filter sizes. In this paper, a new thirteen-level inverter based on the switched capacitor (SC) with an optional ac decoupling circuit is proposed, which offers a gain of input voltage that is six times higher while using fewer switches. Therefore, for low-voltage PV applications, this inverter is preferred without any boost dc/dc converter stages. Three SC cells are used to increase the input PV voltage and enable thirteen steps in the output voltage. The inverter's ac decoupling unit structure serves in keeping CMV (common mode voltage) constant during zero voltage generation operation, which significantly lowers leakage current. The active and reactive grid power are regulated by a proportional resonant (PR) controller. The proposed modulation method assists in balancing the voltages of switched capacitors at their base voltage with the allowed ripple. Details of the inverter circuit as well as the PWM scheme and control technique are also discussed. The proposed inverter's correctness is proven by the results of a Matlab simulation.

A novel nine-level inverter has been proposed in this paper for PV applications. This inverter can boost the input photo-voltaic (PV) voltage up to four times in output without an additional DC/DC converter. Thus, using fewer components, this nine-level quad boost inverter topology with a common ground (CG) feature is the key contribution of this work. Two switched-capacitor (SC) cells are connected in a cascade manner to boost the input PV voltage. SC cells work in a series/parallel manner, i.e., capacitors are charged when connected in parallel and discharged when connected in series with a DC voltage source. Further, this topology can eliminate the leakage current, as it bypasses the parasitic capacitance through a common ground (CG) connection between the negative terminal of the PV panel and the neutral of the grid. Consequently, it does not need an electro-magnetic interference (EMI) filter for electromagnetic compatibility (EMC). The additional feature of the proposed inverter is reactive power handling capability. A proportional + resonant (PR) current controller has been implemented to regulate the active and reactive components of the grid current. The proposed modulation strategy makes the inverter capable of balancing the switched capacitors by charging during its inactive state. The inverter operating principle, operating modes, and modulation scheme have been analyzed in detail. The various claims about the proposed inverter have been verified in MATLAB® simulation, and the results are presented.

Transformerless grid-connected multi-level PV (photovoltaic) inverters are not appropriate for low voltage PV applications due to their substantial concerns regarding leakage current and buck behavior of output voltage. In this study, a new nine-level inverter that offers four times the input voltage gain is proposed. It is based on a switched capacitor (SC) with a common grounding (CG) design. This inverter is therefore preferred for low voltage PV applications since it lacks an intermediary boost dc/dc converter stage. In order to permit nine steps in output voltage, two SC cells are used to step-up the input PV voltage. The proposed inverter topology's shared grounding feature aids in reducing leakage current. This new inverter can also manage reactive power whether the grid's power factor (pf) is lagging or leading. A proportional resonant (PR) controller is developed to govern the active and reactive grid power. There include sections on the PWM scheme, the inverter circuit details, and a comparison analysis. To verify that this proposed inverter is accurate, simulation results are presented.

A novel three-level inverter has been proposed in this paper for PV applications. This inverter can boost the input photo-voltaic (PV) voltage up to three times in output without additional DC/DC converter. Two switched-capacitor (SC) cells are connected in a cascade manner to boost the input PV voltage. Further, this topology can eliminate the leakage current completely, as it bypasses the parasitic capacitance by way of a common ground (CG) connection between the negative terminal of the PV panel and the neutral of the grid. Consequently, it does not need an electro-magnetic interference (EMI) filter for electromagnetic compatibility (EMC). The additional feature of the proposed inverter is reactive power handling capability. A proportional + resonant (PR) current controller has been implemented to regulate the active and reactive components of the grid current. The proposed modulation strategy makes the inverter capable of balancing the switched capacitors by charging during its inactive state. The inverter operating principle, operating modes, and modulation scheme have been analyzed in detail. The various claims about the proposed inverter have been verified in MATLAB® simulation, and the results are presented.

Grid-connected applications of renewable energy sources(solar energy) are increasing day by day. For these applications, transformers play an important role in facilitating galvanic isolation and suitable voltage ratio for interconnection between grid and inverter. However, the omitting of the transformers from the complete power conversion system becomes inevitable because of having large size/weight and cost. Hence transformerless inverters are replacing conventional inverters for grid-connected PV systems at a rapid pace. It has been observed that a transformerless grid-connected H bridge inverter established a common mode resonant circuit with the formation of parasitic capacitance between PV terminals and grounded frame and hence, consequently, leakage current induced in the system. In this paper, a mathematical model has been derived by using source transformation approach for the common-mode resonant circuit of H bridge grid-connected PV inverter, and further, it has been analyzed for both unipolar and bipolar modulation strategies. Finally, a 1kW grid-connected single-phase H bridge PV inverter has been simulated on Matlab and verified with satisfactory results.