Split induction three-level photovoltaic grid-connected inverter and control method thereof

Abstract

The invention discloses a split induction three-level photovoltaic grid-connected inverter and a control method thereof and belongs to the technical field of a power electric transformer. The inverter comprises a power supply circuit (A), a first converting branch (B) and a second converting branch (C), wherein the power supply circuit (A) consists of a direct current power supply and two voltage-dividing capacitors; the first converting branch (B) and the second converting branch (C) respectively consist of a power diode, a split inductance and two power switching tubes. The inverter can be expanded into a three-phase circuit structure according to the capacitance requirement and has the same principle with the single-phase structure. The control method of the inverter comprises two parts which respectively are the hysteresis ring width frequency-fixing control of the inverter side inductance current and the early closing of the high-frequency switch driving signal. The invention does not generate high-frequency leakage current when working in the single-polar PWM modulation mode, and does not have the bridge arm direct-connection danger, and the voltage stress of the power switching tubes and the diode are respectively equal to or smaller than one half of the input voltage.

Description

technical field [0001] The invention relates to an inverter, in particular to a split inductor three-level non-isolated photovoltaic grid-connected inverter and a control method thereof, belonging to the technical field of power electronic converters. Background technique [0002] The energy crisis and environmental degradation have made countries around the world actively develop renewable energy sources including photovoltaics and wind energy. With the popularization and utilization of photovoltaic power generation, the topology and control methods of inverters suitable for parallel connection of solar arrays and power grids have been extensively studied. The non-isolated photovoltaic grid-connected inverter has the advantages of high efficiency, small size, light weight and low cost, but due to the existence of parasitic capacitance of the solar panel to the ground, the switching action of the switching device of the grid-connected inverter may generate high frequency Th...

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Problems solved by technology

Patent CN 100431255C replaces the power switch tube in the double-buck half-bridge inverter with a diode-clamped three-level switch unit, and obtains the main circuit topology of the three-level double-buck half-bridge inverter. Although the topology reduces the voltage stress of the power switch tube, the freewheeling diode of the bridge arm still bears the input voltage, which is not suitable for the application of higher voltage input occasions. Although it can be further replaced by introducing a diode-clamped three-level diode unit, the This will make the circuit structure more complex

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