Control method of isolated two-stage dc/ac converter with bidirectional support of AC and DC interconnection
A control method and isolation transformer technology, applied in the direction of DC power input conversion to DC power output, AC power input conversion to DC power output, control/regulation system, etc., can solve problems such as difficult to achieve two-way support, poor flexibility of voltage matching, etc. , to achieve the effects of reducing loops, improving response speed, and highly reliable power supply
Active Publication Date: 2021-12-14
ZHEJIANG UNIV
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Problems solved by technology
Traditional isolated two-stage DC / AC converters mostly use AC power frequency transformers to step down the AC voltage to match the requirements for DC voltage levels, and use droop control for DC / AC converters to realize the interconnection of AC and DC sub-networks. The control method is less flexible for voltage matching and it is difficult to achieve two-way support
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[0041] Below in conjunction with accompanying drawing, the present invention is described in further detail:
[0042] The topology of the isolated two-stage DC / AC converter is shown in figure 1 As shown, it consists of two parts: where the DC / DC module consists of S 1 -S 8 The H-bridge composed of these eight switching tubes, the isolation transformer with a turn ratio of 1:n, and the primary and secondary capacitor C 1 、C 2 and the resonant inductance L r1 , L r2 and resonant capacitor C r1 、C r2 composition. While the DC / AC module consists of S 9 -S 14 The three-phase half-bridge composed of these six switching tubes is connected to the AC bus through the LC filter.
[0043] The bidirectional power support control block diagram of the isolated two-stage DC / AC converter is shown in figure 2 As shown, its specific implementation steps are:
[0044] (1) Measure the AC side voltage v ac And through the phase-locked loop PLL phase locking to obtain the exchange freq...
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The invention relates to the field of power electronics, and aims to provide a control method for an isolated two-stage DC / AC converter with AC-DC interconnection bidirectional support. The present invention uses an isolated two-stage DC / AC converter to realize the connection between the AC subnet and the DC subnet, wherein the bidirectional DC / AC converter module is used to realize equal sharing of active power on the AC side and the DC side and can realize bidirectional voltage support , the bidirectional resonant DC converter module is used to realize voltage matching and current isolation between the AC side and the DC side. The proposed control strategy normalizes the two heterogeneous information of AC frequency and DC voltage in the bidirectional DC / AC system, and takes the normalized value equal as the control target. The present invention realizes bidirectional power support and seamless connection between AC and DC subnets of different voltage levels without switching control strategies, improves the plug-and-play control characteristics of AC and DC hybrid subnets, and reduces the impact on AC subnets. The voltage requirements of the DC sub-network connection have good control performance.
Description
technical field [0001] The invention relates to a control method of an isolated two-stage DC / AC converter supported by AC and DC interconnection bidirectionally, belonging to the field of power electronics. Background technique [0002] The AC-DC hybrid microgrid connects the DC subnet and the AC subnet through the converter, makes full use of the advantages of AC power supply and DC power supply, reasonably regulates the AC-DC distributed power supply and load, minimizes the intermediate conversion links, and improves the system efficiency. At present, there are mainly two types of connecting AC subnet and DC subnet: non-isolated DC / AC converter and DC / AC converter with AC power frequency transformer. Among them, the non-isolated single-stage DC / AC converter has poor safety, the DC / AC converter with AC power frequency transformer has low overall efficiency and occupies a large area, and the bidirectional full-bridge DC / DC converter has a high degree of modularization , can...
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IPC IPC(8): H02J5/00H02J3/36H02M3/335H02M7/5387
CPCH02J5/00H02J3/36H02M3/33576H02M7/5387Y02E60/60
Inventor 李悦彭勇刚韦巍
Owner ZHEJIANG UNIV