Suspension capacitance type multi-level bridge circuit and control method thereof

Abstract

The invention provides a suspension capacitance type multi-level bridge circuit and a control method thereof. The three-level Buck circuit of the suspension capacitance type multi-level bridge circuitcomprises an input capacitor, an output capacitor and at least one bridge arm, and each bridge arm comprises a charging unit, a suspension capacitor, two inner tubes, two outer tubes and an inductor,the charging unit is connected to the two ends of the outer tube which is not connected with the low-voltage side in parallel, and when the three-level Buck circuit is connected to a power supply, most voltage in input voltage originally added to the two ends of the outer tube is greatly reduced through voltage division of the charging unit and the suspension capacitor, so that overvoltage damageto the outer tube is avoided; and meanwhile, the charging unit is used for pre-charging the suspension capacitor, so that the problem of overvoltage damage of the other outer tube due to the fact that the outer tube is conducted to charge the suspension capacitor can be avoided, and the safety of the three-level Buck circuit is improved.

Description

[0001] This application claims the priority of the Chinese patent application with the application number 201910859287.6 and the title of the invention "a three-level Buck circuit and its control method" submitted to the China Patent Office on September 11, 2019, the entire contents of which are incorporated by reference in this application. technical field [0002] The invention belongs to the technical field of power electronics, and more specifically, relates to a floating capacitor type multi-level bridge circuit and a control method thereof. Background technique [0003] With the rise of power electronic converter system voltage, the withstand voltage requirements of its related switching devices are also gradually increasing. However, due to the influence of semiconductor process performance and other aspects, the development of cost-effective devices has a certain lag, and it cannot be satisfied in the short term. Therefore, how to use lower voltage level devices and ...

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Problems solved by technology

[0005] In view of this, the object of the present invention is to provide a floating capacitor type multi-level bridge circuit and its control method. The first outer tube is easy to break down due to overvoltage when it is started, resulting in the failure of the first outer tube. Charging and turning on the first outer tube causes the second outer tube to fail due to overvoltage breakdown, which in turn leads to the failure of the three-level Buck circuit

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