Output capacitance voltage-sharing control system and control method for three-level DC converter

Abstract

The invention discloses an output capacitance voltage-sharing control system and control method for a three-level DC converter and belongs to the field of electronic engineering. The output capacitance voltage-sharing control system comprises a PV analog power supply for supplying power to a Boost DC converter and is characterized in that voltage and current signals of the input end of the Boost DC converter are sent to an input conditioning circuit; voltage signals of the output end of the Boost DC converter are sent to an output conditioning circuit; the signal output end of the input conditioning circuit and the signal output end of the output conditioning circuit are both connected with the signal input end of a digital signal processor; the signal output end of the digital signal processor is connected with a drive circuit; the drive circuit controls power tubes in the Boost DC converter to be turned on or turned off. Through the output capacitance voltage-sharing control system and control method for the three-level DC converter, the problem that midpoints are unbalanced due to the fact that modulation strategies, parameters of the circuit and drive delay are inconsistent can be solved; when the output capacitance voltage-sharing control system is applied to a two-stage non-isolated grid-connected generation device, the electricity generation quality of a back-stage inverter can be guaranteed.

Description

technical field [0001] The invention relates to a DC converter, in particular to a voltage equalizing device for output capacitors of the DC converter, and belongs to the technical field of electronic engineering. Background technique [0002] Before the present invention, in the two-stage non-isolated three-level grid-connected power generation device, the existing three-level Boost DC converter output capacitor voltage equalization control methods mainly include the following: [0003] One is the method of realizing midpoint potential balance through the inverter side: mainly by improving the modulation strategy of the inverter and the corresponding control method to achieve midpoint potential balance. However, when the grid-connected inverter is started, the back-stage inverter circuit is not working yet, so this method cannot solve the problem of unbalanced midpoint potential during the start-up process. [0004] The second is to use the table look-up method to determin...

AI Technical Summary

Problems solved by technology

However, when the grid-connected inverter is started, the back-stage inverter circuit is not working, so this method cannot solve the problem of unbalanced midpoint potential during the start-up process.

[0004] The second is to use the table look-up method to determine the on and off of the upper and lower switch tubes according to the change of the voltage of the upper and lower capacitors on the DC side of the output DC side of the three-level Boost DC converter, so as to achieve the balance of the voltages of the two capacitors on the DC side , this method is relatively simple, but the dynamic performance is not very ideal

However, due to a large number of parasitic parameters in the actual circuit, as well as factors such as asymmetric capacitance parameters and sudden power changes, the parameters of the PI regulator need to be adjusted repeatedly, and a set of adjusted PI parameters is difficult to cope with sudden power changes.

Images