Hybrid series H-bridge multi-level grid-connected inverter direct current bus voltage control method

Abstract

The invention discloses a simple and easy method for realizing instruction voltage distribution between cascade different high and low voltage modules by using a hybrid multi-level modulation method to achieve distribution of active power absorbed by the modules so as to stabilize voltage of a direct current side of the high and low voltage modules to be close to a given value, without extra auxiliary device. As seen from a simulation result, voltage balancing control over the voltage of a direct current side of the high and low voltage modules can be excellently realized. Meanwhile, a small-sized experimental prototype consisting of a high-voltage H-bridge module and a low-voltage H-bridge module connected in series in each phase and having capacity of 5 kVa is erected in a laboratory; experimental verification is performed on the method; and both the simulation result and an experimental result prove that the method is correct and reliable and provides excellent reference value for engineering application.

Description

technical field [0001] The present invention relates to the research field of grid-connected inverter and hybrid multi-level, in particular to hybrid multi-level modulation and a voltage equalization control method between a high-voltage module and a low-voltage module of a hybrid multi-level grid-connected inverter, specifically The hybrid multi-level modulation method is used to realize the command voltage distribution among different cascaded high and low voltage modules to achieve the purpose of making full use of different performance power electronic devices and ensuring the DC bus voltage balance of high and low voltage modules. Background technique [0002] Power electronics technology has very broad application prospects in power systems, and its typical applications include static var generators, dynamic voltage restorers, static voltage compensators, static phase compensators, power flow controllers, active power filters and High frequency rectifier etc. [1] . C...

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Problems solved by technology

However, using a hybrid multi-level grid-connected inverter cascaded with multiple H-bridge modules with different voltage levels, there is no literature that proposes a good method to control the DC side voltage of each H-bridge module.

Literature [19] conducts research on DC side bus voltage control of hybrid cascaded multi-level active power filters, but it can be seen from the experimental results that its modulation strategy makes it possible for low-frequency power modules to generate high-frequency modulation, which does not have Practicality

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