Leakage current suppression method and suppression device of single-phase non-isolated cascaded H-bridge inverter

Abstract

The invention discloses a leakage current suppression method and suppression device of a single-phase non-isolated cascaded H-bridge inverter. The inverter is formed by cascading one to 2k H-bridge modules, an i(th) H-bridge module and an (2k-i+1) H-bridge module form a module assembly, and i is equal to 1, 2 until k. The method comprises the teps of acquiring the voltage of a DC side of each H-bridge module; calculating error sum of the voltages of the DC sides of two H-bridge modules in each module assembly; calculating a modulation signal of each H-bridge module by following a principle that larger output power is acquired by the module with larger error sum of the voltages of the DC sides of the two H-bridge modules, the output powers of the two H-bridge modules in the same module assembly are equal and the total parasitic capacitance voltage is maintained constant; and sending the modulation signal obtained by calculation to the corresponding H-bridge module, so that the leakage current is suppressed.

Description

technical field [0001] The invention relates to the technical field of power electronics, and more specifically, to a leakage current suppression method and suppression device for a single-phase non-isolated cascaded H-bridge inverter. Background technique [0002] The single-phase non-isolated cascaded H-bridge inverter is formed by cascading multiple H-bridge modules, and its topology is as follows: figure 1 As shown: the DC side of each H-bridge module is connected to an independent photovoltaic panel, and the AC side of each H-bridge module is connected in series and then connected to the power grid through a filter inductor. The single-phase non-isolated cascaded H-bridge inverter obtains the maximum utilization rate of photovoltaic energy through independent MPPT (Maximum Power Point Tracking) control of each photovoltaic panel. [0003] In a single-phase non-isolated cascaded H-bridge inverter, there is a direct electrical connection between the grid and the photovol...

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Problems solved by technology

[0003] In a single-phase non-isolated cascaded H-bridge inverter, there is a direct electrical connection between the grid and the photovoltaic panels, resulting in the parasitic capacitance of the photovoltaic panels (i.e. figure 1 Capacitance C in P1 ~C Pn ) under the action of common mode voltage and differential mode voltage will produce a certain leakage, which not only brings conduction and radiation interference, increases the harmonic content of the incoming current and system loss, but also may endanger the safety of related equipment and personnel

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