Three-level DC converter output capacitor voltage equalization control system and its control method

Abstract

The invention discloses a three-level DC converter output capacitor voltage equalization control system and its control method in the field of electronic engineering, including a PV analog power supply for the Boost DC converter, and the voltage and current signals at the input end of the Boost DC converter are sent to the input Conditioning circuit, the voltage signal at the output terminal of the Boost DC converter is sent to the output conditioning circuit, the signal output terminal of the input conditioning circuit, and the signal output terminal of the output conditioning circuit are connected to the signal input terminal of the digital signal processor, and the signal of the digital signal processor The output end is connected with a drive circuit, which controls the switching of the power tube in the Boost DC converter. The present invention can eliminate the midpoint unbalance problem caused by the inconsistency of the modulation strategy, the parameters of the circuit itself, and the drive delay. When the present invention is applied to When used in a two-stage non-isolated grid-connected power generation device, it can ensure the power generation quality of the rear-stage inverter.

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...

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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.

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