Grid-connected inverter capable of reducing electrolytic capacitance

Abstract

The invention discloses a grid-connected inverter capable of reducing electrolytic capacitance, belonging to the field of inverters in power electronic converters. The inverter comprises a direct current (DC) power source, a DC / DC converter, a DC / AC converter, a bidirectional DC / DC converter, a DC-link capacitor and an energy storage capacitor. The output end of the DC power source is connected with the DC / DC converter in series, then is connected with the DC-link capacitor in parallel and finally is connected with the bidirectional input end of the bidirectional DC / DC converter and the input end of the DC / AC converter respectively. The bidirectional output end of the bidirectional DC / DC converter is connected with the two ends of the energy storage capacitor and the output end of the DC / AC converter is connected into the grid. When the instantaneous output power of the DC / AC converter is greater than or smaller than that of the DC power source, the energy storage capacitor correspondingly outputs or absorbs power. The grid-connected inverter uses less electrolytic capacitance as far as possible or does not use electrolytic capacitance and the service life of the whole inverter is lengthened.

Description

technical field [0001] The invention relates to an inverter, in particular to a grid-connected inverter capable of reducing electrolytic capacitance, and belongs to the field of inverters in power electronic conversion devices. Background technique [0002] Due to the global energy and economic crisis, major developed countries in the world have begun to pay attention to the research on the utilization of renewable energy, such as the research on distributed power generation systems of renewable energy such as solar energy and wind energy is of great significance. In the photovoltaic grid-connected power generation system, since the output power of the photovoltaic array is smooth DC, and the output power of the grid-connected inverter presents periodic pulsations, in the existing two-stage grid-connected power generation system, the DC / DC converter and the DC / AC converters usually need a capacitor with a large enough capacity to compensate the instantaneous power differenc...

AI Technical Summary

Problems solved by technology

Due to the large capacity of the capacitor, it is usually necessary to use an electrolytic capacitor. However, as the working time of the electrolytic capacitor increases, the electrolyte will slowly volatilize, and the capacitor capacity will gradually decrease, which will affect the filtering effect and reduce the grid-connected inverter. service life of the machine

[0003] Therefore, in the actual photovoltaic power generation system, in order to ensure the filtering effect and improve the service life of the grid-connected inverter, the electrolytic capacitors are usually derated, which increases the cost of the system

Images