Non-isolated type three-phase three-level photovoltaic inverter modulation method

Abstract

The present invention discloses a non-isolated type three-phase three-level photovoltaic inverter modulation method. The modulation method can effectively inhibit leakage currents of two types of NPIC inverters provided by the present invention. The technical scheme adopted by the modulation method has the key points of: firstly, performing subtraction on any two of modulation signals (reference to the specification) of the NPIC inverters to obtain modulation signals (reference to the specification); then respectively multiplying the modulation signals by a coefficient K to obtain modulation signals (reference to the specification); performing zero-sequence component calculation by (reference to the specification) to obtain zero-sequence signals v0; respectively adding (reference to the specification) and the zero-sequence signals v0 to obtain modulation signals (reference to the specification); and comparing modulation signals (reference to the specification) with a triangular carrier wave VC by means of a comparator to obtain logical signals X,Y,Z; and performing a logical operation provided by the present invention on the X,Y,Z to obtain a logical expression of a switching signal. The modulation method provided by the present invention has the beneficial effects that the switching signal is generated by means of the logical operation, and the implementation manner is simple. The method solves the problem of excessive complexity for implementation of conventional multi-carrier wave modulation and spatial vector modulation, also ensures a constant common-mode voltage of a system, and effectively suppress the leakage currents.

Description

technical field [0001] The present invention relates to the field of power electronics, in particular to a modulation method for a non-isolated three-phase three-level photovoltaic inverter, which can effectively suppress the two non-isolated three-phase three-level photovoltaic inverters provided by the present invention device leakage current. Background technique [0002] Because the traditional photovoltaic inverter contains a power frequency or high frequency transformer, the entire inverter is large in size, high in cost and low in efficiency. The non-isolated photovoltaic inverter overcomes the above technical defects and has become one of the research hotspots in the academic and industrial circles. However, due to the parasitic capacitance between the photovoltaic panel and the ground, the high-frequency operation of the inverter will cause a large leakage current on the parasitic capacitance, causing grid-connected current distortion and threatening personnel safe...

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Problems solved by technology

However, this method belongs to SVPWM, the implementation is more complicated, and the common-mode voltage has a small range of changes, this method cannot effectively suppress the leakage current

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