Leakage current suppression method and suppression device for single-phase non-isolated cascaded h-bridge inverter

Abstract

This application discloses a leakage current suppression method and a suppression device for a single-phase non-isolated cascaded H-bridge inverter. The inverter is formed by cascading 1-2k H-bridge modules, and the number i is the same as the number 2k-i+1. The H-bridge modules are collectively referred to as a module, i=1,2,...,k; the method includes: obtaining the DC side voltage of each H-bridge module; calculating the sum of the DC-side voltage errors of the two H-bridge modules in each module ;Follow to make the module with the larger sum of the DC side voltage errors of the two internal H-bridge modules obtain greater output power, keep the output power of the two H-bridge modules in the same module equal and keep the total parasitic capacitance voltage Based on the constant principle, the modulation signal of each H-bridge module is calculated; the calculated modulation signal is sent to the corresponding H-bridge module, thereby suppressing the leakage current.

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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