Single-input half-bridge inverter and control method thereof

Abstract

The invention discloses a single-input half-bridge inverter and a control method thereof. The inverter comprises a photovoltaic cell, a three-terminal converter, an input capacitor, an intermediate capacitor, a filter inductor, a first switch tube, a second switch tube and a power grid or a load. The control method includes the steps that the three-terminal converter works in an open loop, and theduty ratio of the switch tubes in the three-terminal converter is 0.5; the first switch tube and the second switch tube of the single-input half-bridge inverter work in a closed loop and are high-frequency switches. The inverter is applicable to the occasion of a photovoltaic inverter; since a photovoltaic cell plate of the inverter is directly connected to the load or the power grid, the parasitic capacitance of the photovoltaic cell panel to the ground is short-connected with the ground to fundamentally eliminate the common mode leak current.

Description

technical field [0001] The invention relates to an inverter and a control method thereof, in particular to a single-input half-bridge inverter and a control method thereof. Background technique [0002] Since the non-isolated photovoltaic inverter has no isolation between the photovoltaic module and the grid, common mode leakage current may flow through the parasitic capacitance of the photovoltaic module to the ground. This common-mode leakage current will cause electromagnetic interference, increase system loss, and even pose a threat to personal safety. The German VDE-0126-1-1 standard stipulates that the effective value of common-mode leakage current of non-isolated photovoltaic inverters should be less than 30mA. If the system detects that it exceeds this value, the non-isolated PV inverter will stop. Experts and scholars at home and abroad have conducted a series of fruitful research on how to suppress the common-mode leakage current of non-isolated photovoltaic inve...

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Problems solved by technology

However, the effect of the above method to suppress the common-mode leakage current is easily affected by the parasitic capacitance of the photovoltaic module to the ground and the change of circuit parameters. Therefore, it is necessary to study the inverter topology and its control method that can fundamentally eliminate the common-mode leakage current.

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