Control method, device and system of full-bridge three-level DC converter

Abstract

The embodiment of the invention discloses a control method, device and system for a full-bridge three-level direct-current converter, and the control method comprises the steps: judging whether a bridge arm switching flag bit is a first preset value or a second preset value or not if a new PWM period is detected; if the bridge arm switching flag bit is a first preset value, updating and configuring PWM driving signals of eight switching tubes of the full-bridge three-level direct-current converter according to a first preset rule so as to perform chopping control on a switching tube Q1 and a switching tube Q4 of a left bridge arm, and updating the bridge arm switching flag bit to a second preset value; and if the bridge arm switching flag bit is a second preset value, updating and configuring PWM driving signals of eight switching tubes of the full-bridge three-level direct-current converter according to a second preset rule so as to perform chopping control on a switching tube Q5 anda switching tube Q8 of a right bridge arm, and updating the bridge arm switching flag bit to the first preset value. The embodiment of the invention not only can effectively balance the power loss ofthe switching tubes corresponding to the left and right bridge arms, but also can improve the thermal stress distribution.

Description

technical field [0001] The present invention relates to the technical field of power electronics, in particular to a control method, device and system for a full-bridge three-level DC converter. Background technique [0002] The full-bridge three-level DC converter has been widely used in the fields of communication power supply, new energy power generation and energy storage system due to its advantages of low voltage stress of switching tube, easy realization of soft switching and high frequency isolation. figure 1 Shown is a common LLC resonant full-bridge three-level DC converter. Various full-bridge three-level DC converters mainly include a three-level neutral point clamped (Neutral Point Clamped, NPC) bridge arm, a resonant network (or inductor / capacitor network), a high-frequency isolation transformer and a rectifier circuit. [0003] Compared with the full-bridge two-level DC converter, the number of switching tubes in the full-bridge three-level DC converter is do...

AI Technical Summary

Problems solved by technology

In the prior art, figure 2 The control method shown is a fixed chopping control for the outer tubes of the left bridge arm (switching tube Q1, switching tube Q4), which is considered to be a better control method, but this control method will always make the left bridge arm The outer tube is turned off when the current is large, and the conduction time of the left and right bridge arm outer tubes is not equal, resulting in inconsistent power loss of the left and right bridge arm outer tubes, resulting in uneven distribution of thermal stress, which in turn affects the full bridge three-level DC Converter Reliability

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