Modular dual-CUK step-up-down output anti-parallel combined inverter

Abstract

The invention discloses a modular dual-CUK step-up-down output anti-parallel combined inverter which is formed by combining two SEPIC converters having parallel inputs and anti-parallel outputs. EachCUK converter outputs a half sine wave and two half sine waves are combined into a complete sine wave. The dual-CUK step-up-down output anti-parallel combined inverter is unipolarly modulated. The switching devices S1, S2, S3 and S4 are all full control devices. The switching devices S1 / S2 control on-off of the forward converter. The switching devices S3 / S4 control the on-off of the reverse converter. The switching devices S2 / S4 are used to gate the forward / reverse converters. The switching devices S1 / S3 are used to control the forward / reverse converters to output a half sine voltage. The inverter can realize step-up and step-down inversion, has a wide input voltage range, good adaptability to photovoltaic cell voltage variation, high conversion efficiency and simple system, can be modularly produced, is low in cost and wide in range, and can be widely used for photovoltaic grid-connected power generation systems.

Description

technical field [0001] The invention relates to an inverter in an electric energy conversion device, in particular to a modular dual CUK buck-boost output anti-parallel combined inverter. Background technique [0002] In recent years, in order to cope with the energy crisis and environmental pollution, new energy sources such as solar energy and wind energy have been widely used. New energy is greatly affected by external factors such as climate, weather and environment, which means that its output voltage varies in a large range, requiring the inverter to work normally within a wide input voltage range. In order to solve the above problems, traditional solar photovoltaic power generation systems mostly use two-stage grid-connected photovoltaic inverters, which are mainly composed of a front-stage high-frequency isolation DC / DC converter and a rear-stage grid-side inverter. Before grid-connected power generation, the voltage output by the photovoltaic array is boosted, and ...

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Problems solved by technology

However, since the entire inverter is a whole, if any component is damaged, it needs to be replaced as a whole, and the maintenance is complicated and the cost is high; in addition, since the input voltage values ​​of the first CUK circuit and the second CUK circuit are all external power supplies Half of the voltage value, on the one hand, when the output voltage is constant, the voltage value of the external power supply is too high; on the other hand, the external power supply is divided by capacitors, which may easily cause uneven DC voltage equalization, thereby reducing the quality of the output voltage

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