Five-level H-bridge converter and pre-charging method thereof

Abstract

The invention discloses a five-level H-bridge converter, which is topologically of a five-level H-bridge single-phase output structure, adopts modular design, can form a multi-phase output system, andadopts an absorption loop to effectively reduce voltage spikes and oscillation on a specific switching device. By controlling the switching sequence of the switching devices, in the power-on processof the converter module, a load is connected to a DC bus to carry out segmented pre-charging on a capacitor bank in a circuit, and the current passing through the capacitor bank is prevented from being too large; and when the voltage of each segment of the capacitor bank is detected to reach a preset value, the pre-charging process is ended, the switching tube is controlled to cut off the connection between the load and the DC bus, and the converter enters a normal working mode. In comparison with a circuit topology used by the existing high-voltage five-level converter, the voltage spikes andthe oscillation caused by stray inductance existing in a high-voltage line on a specific switching device can be effectively reduced, capacitor banks in a circuit are effectively pre-charged in a segmented mode, and the voltage of each capacitor bank is controlled.

Description

technical field [0001] The invention belongs to the field of high-voltage and large-capacity power electronic converters such as electric drives and power systems, and specifically relates to a five-level H-bridge converter and a precharging method thereof. Background technique [0002] At present, with the development of high-voltage and large-capacity power electronics technology in the fields of high-voltage power systems and high-power motor control, the topology and control technology of five-level inverters have been widely used. Due to the limited withstand voltage capability of current power electronic devices, in order to realize the function of using low withstand voltage switches to output high voltage, the capacity of the system is usually increased by means of series and parallel connection of power electronic devices or power electronic bridge arm modules. Moreover, compared with the traditional two-level converter, the five-level converter has the characterist...

AI Technical Summary

Problems solved by technology

When this kind of converter is used in high-voltage occasions, often due to the long line, the stray inductance on the line is very large, which will cause specific switching devices (switching devices S5 and S11 marked as 4 in the figure) , withstand large voltage spikes and oscillations, if the voltage spikes are not absorbed and limited, it is easy to cause damage to the switching device

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