Bidirectional three-level soft switch DC/DC for superconducting energy storage and its voltage side pulse width controlling method

Abstract

The dual-way tri-level soft switch DC / DC for superconductance energy-storage comprises a voltage unit composed by two tri-level semi-bridges with midpoint clamping diode, a transformer unit, and a current unit with structure decided by the last unit, total-bridge / total-wave current source inverter for common transformer / transformer with middle tap. Wherein, paralleling capacitors on top and bottom switch tubes of the semi-bridge, but not on two tubes on middle; or paralleling capacitors on all tubes; connecting midpoints of semi-bridge and clamping diode to midpoint of connecting line of two voltage-dividing capacitors. This invention can overcome the unbalance problem of midpoint voltage.

Description

technical field [0001] The invention relates to a DC converter for superconducting energy storage and a control method thereof, in particular to a bidirectional three-level soft switch DC / DC for superconducting energy storage and a control method thereof. Background technique [0002] In recent years, with the development of superconducting material technology, the application of superconducting materials in the field of electric power has attracted more and more attention and attention, and countries all over the world have carried out research on superconducting electric power technology. Among them, superconducting energy storage technology has attracted people's attention because it can realize multiple functions such as pulse energy regulation and power system stability control, and has become the only commercialized superconducting power technology at present. Superconducting energy storage technology is generally divided into two types: voltage source type and current...

AI Technical Summary

Problems solved by technology

Although these patents adopt different topological structures, they do not solve two key problems: 1. The soft switching problem of the switching tube

These DC / DCs realize the charging and discharging of superconducting magnets through hard switching. The switching stress and loss of the switching tube are large, which not only greatly shortens the life of the switching tube, but also reduces the working efficiency of the system.

2. The DC voltage terminal voltage is low, and there is only one DC terminal voltage interface, which cannot be connected with advanced multi-level voltage source inverters

It realizes the charging and discharging of the superconducting magnet through the hard switching of the switch tubes 17a and 17b, the stress of the switch tube is large, and the loss is also large; at the same time, it has only one DC terminal voltage interface, as shown in the figure, the two ends of the capacitor 9 The DC voltage interface provided, in order to reduce harmonics, it can only be connected to the high voltage power system through multiple voltage source converters

However, multiple voltage source converters need to use multiple bulky and expensive power frequency transformers

Not only greatly increases the volume of the system, but also greatly increases the cost of the system

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