Modeling method, design method, modeling device, design device, modeling system and design system for switched capacitor type direct-current transformer

Abstract

The invention discloses a modeling method, design method, modeling device, design device, modeling system and design system for a switched capacitor type direct-current transformer. In order to improve the accuracy of the modeling of the direct-current transformer under a low switching frequency, a state space averaging method is used to establish the average model of switched capacitor stages inthe switched capacitor type direct-current transformer; the average model is simplified, and a frequency domain small-signal model is built based on the simplified average model; frequency characteristics are analyzed according to the transfer function of a control objective, and a controller is designed, and therefore, the performance of a controlled object can be optimized, and a design processis simple and intuitive. The method of the invention is simple in principle and clear in structure. With the method of the invention adopted, the operation reliability of the direct-current transformer is improved; the accuracy of a direct-current transformer model under a lower switching frequency is improved; and a reasonable basis is provided for parameter debugging before a device is put intooperation.

Description

technical field [0001] The invention belongs to the technical field of power electronics and relates to DC solid-state transformer technology, in particular to a modeling and design method, device and system of a switched capacitor type DC transformer. Background technique [0002] In recent years, with the development of power semiconductor technology and power electronics technology, the technical bottleneck of DC power transmission and distribution has been gradually overcome because of its low line cost, low power loss, high power supply reliability, and access to energy storage and new energy power generation systems. The advantages of low cost have become more and more prominent, and DC power transmission and distribution technology has been paid more attention, and has become a research hotspot in various countries. Among them, as the key equipment for connecting multi-level DC bus, the research and development of DC transformer has great academic value and engineerin...

AI Technical Summary

Problems solved by technology

This early solution mainly has the following disadvantages: 1. The voltage on the series side is not adjustable, and the efficiency of the DC transformer is low when operating under non-rated conditions; 2. When a bipolar short-circuit fault occurs in the DC system, the capacitor of the sub-module is quickly discharged, which will provide A certain fault current; 3. When an internal fault occurs, the operating voltage of the non-faulty sub-module rises after the faulty sub-module is removed, which is not conducive to the safe operation of the DC transformer, and it is difficult to design module redundancy to improve reliability

This method is less accurate at low frequencies, because the half-bridge output voltage as the state average variable does not meet the small ripple criterion in the state average method, so other methods are needed to model the system and design the controller

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