This paper presents a novel structure of the transformer-less grid-connected inverters. The proposed inverter is combined with six power switches and two power diodes which can generate six voltage levels at the output. Furthermore, the proposed inverter can overcome the leakage current issue in the photovoltaic (PV) system, which is the major problem in grid-tied PV applications. Additional significant features include- reduced filter size, lower total harmonic distortion (THD) of the injected current to the grid, and voltage boosting ability. Moreover, the proposed topology provides full reactive power support to the grid. A control strategy is designed and implemented to provide a voltage boost ability without using any additional dc-dc boost converter. Finally, the performance of the proposed inverter is validated by the 770 W laboratory prototype.
Due to the benefits of achieving low cost, light weight, and high performance, transformer-less inverters are frequently employed in grid-tied solar photovoltaic (PV) generation systems. However, additional steps must be taken to prevent security issues including ground fault currents and leakage currents, which can be prevented by connecting the PV panel to the ground through a parasitic capacitor. The proposal for new topologies with their control techniques and the modulation schemes have been inspired by the reduction of leakage currents issues. In this paper, improved topologies of single-phase transformerless inverter are proposed to reduce the leakage current and total harmonic distortion (THD) of grid current. These new topologies are named as H9 and H10 inverters according to the number of the switching devices in the inverter. Pulse width modulation (PWM) method is used for the inverters to suppress harmonics at the output grid current. The proposed H9 and H10 topologies can
Now-a-days, transformer-less grid connected solar photovoltaic (PV) inverters have attracted significant attention due to their special benefits such as higher efficiency, lower cost, and easy set up mechanism. A new transformer-less inverter topology with reduced leakage current and improved performances has been presented in this paper. This inverter circuit has been fabricated with eight semiconductor devices and an LCL filter at the output side. Three switches are used in the common mode voltage (CMV) clamping brunch to enhance inverter efficiency. In the freewheeling brunch, one switch is used so that the leakage current spikes get avoided. In the freewheeling mode common mode voltage is kept constant. While zero voltage state, CMV is clamped to half of the input voltage. The proposed inverter provides only a total of 10.18 mA leakage current. The grid current THD and grid voltage THD are found to be 1.42% and 0.37%, respectively. Unipolar SPWM method has been used to control the