Photovoltaic inverter with no transformer

Is a transformer-less grid-connected PV inverter possible?

This paper proposes a new transformer-less grid-connected PV inverter. A closed-loop control scheme is presented for the proposed transformer-less inverter to connect it with the power grid. The proposed transformer-less inverter reduces extra leakage current and holds the common-mode voltage at a constant point.

Why are transformer-less inverters used in photovoltaic systems?

To solve the problems of efficiency, cost and size of inverters, transformer-less inverters were introduced. Removing the transformer causes a galvanic connection between the photovoltaic system and the power grid. Thus, the common mode leakage current may follow through the parasitic capacitors between photovoltaic system and ground .

Are transformerless PV inverters safe?

Consequently, the grid connected transformerless PV inverters must comply with strict safety standards such as IEEE 1547.1, VDE0126-1-1, EN 50106, IEC61727, and AS/NZS 5033.

Does transformerless inverter have a low current THD?

Even at 50% of the rated condition and 220 V of PV, the inverter has a low current THD of 3.7%. The proposed method is also validated with Hardware-in-the-Loop (HIL) test using OPAL-RT 4510 Simulator. Many transformerless inverter (TLI) topologies are developed for low-voltage grid-tied PV systems over the last decade.

What are transformer-less PV inverter topologies?

Several transformer-less PV inverter topologies, such as H5 [ 11 ], oH5 [ 12 ], HERIC [ 13 ], and H6 [ 14 ], have been reported and applied to improve efficiency and reduce leakage current. In these topologies, the galvanic isolation method is used, in which the ground of the photovoltaic source is separated from the inverter ground.

Does a transformerless inverter have galvanic isolation?

As the transformerless inverters are connected directly to the electrical grid, there is not galvanic isolation between the PV system and the electrical grid dealing in new problems to be solved. Figure 2. PV inverter with high frequency transformer (HFT).