Modular multilevel dynamic switching DC-DC transformer

Abstract

The invention discloses a modular multilevel dynamic switching DC-DC transformer which is composed of N DC-DC sub modules connected in series. Each DC-DC sub module is a symmetric structure which is composed of two half-bridge sub modules and isolating switches S1 and S2 arranged between the two sub modules and can realize bidirectional power flow. Capacitors C1 and C2 are arranged in parallel between the half-bridge sub modules and the isolating switches. The power input end is used as the primary side of the DC-DC transformer, and the power output end is used as the secondary side of the DC-DC transformer. The half-bridge sub modules are primary sub modules when on the primary side of the DC-DC transformer, and are secondary sub modules when on the secondary side of the DC-DC transformer. The primary and secondary sub modules are switched on or off by turning on or off a switching device. Compared with the prior art, the switching ratio of primary to secondary sub modules can be changed dynamically; the transmission power can be controlled flexibly, and the DC-DC transformer has DC power flow control ability; and the number of sub modules is greatly reduced, the advantage of economical performance is significant, the size of the DC-DC transformer is reduced, and the DC-DC transformer can be easily promoted and applied.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a dynamic switching design scheme of a modularized DC-DC transformer. Background technique [0002] Due to the volatility and intermittent characteristics of renewable energy, the large-scale integration of new energy sources such as wind energy and photovoltaics into the power grid will have a profound impact on the safe and stable operation of the AC power grid. Flexible direct current transmission technology provides effective solutions for large-scale centralized access of wind energy and photovoltaic power generation, interconnection of power grids, and power supply for cities and islands. DC-DC transformer is the key equipment to realize DC multi-voltage level conversion and DC power flow control. [0003] At present, scholars at home and abroad have proposed many DC-DC transformer conversion topologies. Isolated modular multi-level DC-DC transformers are widely accepted, ...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the DC voltage level conversion and power flow control problems that need to be solved in the current flexible DC system, taking into account the equipment volume and economy, the present invention proposes a modular multi-level dynamic switching DC-DC transformer, and designs a DC-DC transformer based on primary and secondary DC transformer with independent dynamic switching of side sub-modules

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