Series resonance DC/DC converter of photovoltaic system

Abstract

The invention relates to a series resonance DC / DC converter of a photovoltaic system, which comprises a single-pole converter (40), a series resonance circuit (50), a high-frequency isolation transformer (16) and a rapid uncontrollable rectifier (20), wherein the single-pole converter (40) is used for converting a direct voltage (26) of a photovoltaic array (10) into a single-pole pulse voltage; the series resonance circuit (50) is used for converting the single-pole pulse voltage into a sine voltage with a fixed frequency; the high-frequency isolation transformer (16) is used for boosting and isolating as well as protecting; and the rapid uncontrollable rectifier (20) is used for rectifying the high-frequency sine voltage into a stable direct current voltage (28). The converter (100) is only provided with two switching elements, has the advantages of simple control mode and no switching loss, and can be used for boosting and stabilizing the larger photovoltaic array so as to be convenient for synchronizing through a three-phase converter or charging a storage battery.

Description

technical field [0001] The invention relates to a DC / DC converter, in particular to a DC / DC converter with variable input voltage, high frequency, series resonant soft switch and used in a photovoltaic power generation system. Background technique [0002] The DC / DC converter is a conversion circuit that uses semiconductor switching devices to cooperate with inductors, capacitors, transformers and other devices to control the output DC voltage by controlling the rapid on and off of the semiconductor switching devices. , The uncontrollable DC voltage is transformed into a controllable DC voltage that meets the system requirements. In the photovoltaic power generation system, because the output voltage of the photovoltaic array varies drastically with conditions such as temperature and light intensity, it cannot be directly connected to the three-phase inverter to feed power to the three-phase grid. [0003] At present, in domestic and foreign photovoltaic inverter systems, D...

AI Technical Summary

Problems solved by technology

However, the boosting range of the Boost circuit is limited. When the voltage is greatly boosted, the duty ratio of the switching device is large, it is difficult to control the on-off of the switching device, and the output voltage is easily unstable; photovoltaic arrays and three-phase inverters There is no isolation transformer between them, and the two will affect each other, resulting in high harmonic content in the system and affecting the stability of grid connection

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