A power supply and protection circuit for a three-level inverter switching power supply

Abstract

The invention discloses a power supply and protection circuit of a three-level inverter switch power supply. The structure of the circuit comprises a resistance voltage-sharing unit, an energy storage capacitance energy discharge unit and an input voltage clamping unit. The switch power supply of the invention is applied in a three-level inverter. The resistance voltage-sharing unit makes two energy storage capacitance voltages of a direct current side of the three-level inverter during normal working be equal. When a power grid is powered down, the capacitance energy discharge unit can rapidly release energy on an energy storage capacitor of the direct current side of the inverter. The voltage clamping unit makes the switch power supply adopt an alternating current of the power grid to provide power when a main system of the inverter is powered on. When the inverter works normally, a direct current on the energy storage capacitor of the direct current side of the inverter is used to provide power. An input voltage of the circuit of the invention is a half of a direct current side voltage of the three-level inverter. When the main system of the inverter is powered down suddenly, the switch power supply can still work for a while so that protection motion after power is lost is guaranteed to be performed reliably and security of the main system of the inverter is increased.

Description

technical field [0001] The patent of the invention belongs to the field of three-level inverter, and in particular relates to a power supply and protection circuit of a switching power supply of a three-level inverter. Background technique [0002] Energy is the material basis for human survival and development, and plays a key role in social development. However, with the development of society and economy, on the one hand, people's demand for energy is increasing day by day. Environmental pollution caused by energy consumption is a huge challenge, and new energy power generation technology has become a research hotspot at home and abroad to seek solutions to energy problems. New energy power generation technology is being widely promoted and applied. At present, most new energy power generation is integrated into the grid through inverters. For high-power inverter systems, three-level inverters have become a popular research object because of their low withstand voltage ...

AI Technical Summary

Problems solved by technology

However, in practical applications, it is difficult for the switching power supply to meet such a wide input voltage requirement, and it is impossible to meet the system power demand at all times, so that the switching power supply cannot be started normally, or although the switching power supply can be started, it cannot reach the required wide input voltage. Voltage range, and the high voltage on the DC side also brings difficulties to the selection of switch tubes

[0006] The third is that the two ends of a voltage dividing capacitor of the DC side voltage of the three-level inverter are directly connected to the input end of the switching power supply. The problem that the input voltage of the switching power supply is not high enough

However, since this switching power supply only takes power from one DC-side voltage-dividing capacitor, the voltage on the other voltage-dividing capacitor will be relatively large when the inverter is working.

At this time, there may be uneven voltage division of the voltage dividing capacitor on the DC side of the inverter, resulting in low power quality after inversion, and even unable to meet the requirements of grid connection.

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