A single-stage isolated bidirectional AC-DC converter

Abstract

The invention discloses a single-stage isolation type bi-directional AC-DC convert, comprising three AC-side inductor, three AC-side capacitors, three-phase full bridges, three bidirectional switches,a positive bus single-phase full bridge, a negative bus single-phase full bridge, two isolation transformers, a rectifier / inverter single-phase full bridge, a DC-side filter inductor and a DC-side filter capacitor. The invention realizes the rectifying mode of the step-down type, avoids the start-up impact of boost rectifier mode in the past, At that same time, the problem in the prior art that atwo-stage structure has to be used when the three-phase bi-directional AC / DC converter converts a three-phase 380V AC voltage to a low-voltage DC voltage or converts a low-voltage DC voltage to a three-phase 380V AC voltage is solved, and the electric isolation is realized only by a single-stage power conversion circuit.

Description

technical field [0001] The invention relates to the technical field of AC / DC bidirectional converters, in particular to a single-stage isolated bidirectional AC-DC converter. Background technique [0002] As a new form of power supply, the research and application of DC microgrid with new energy as the core is still in the stage of rapid development, and there are still many problems to be solved. DC microgrid is the product of the integration of power electronics technology, information electronics technology and power system, involving multiple research fields such as converter devices, operation control, fault protection, power supply planning, system architecture and communication protocols. Among them, the interface AC / DC converter between the DC microgrid and the AC grid, as the link connecting the two networks, is responsible for regulating the energy balance of the entire microgrid, and is one of the focuses of DC microgrid research. In high-power occasions, a three...

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Problems solved by technology

In addition, the rectification mode of the voltage source AC / DC converter is a boost (boost) type, which has the problem of start-up shock. It is necessary to add a start-up current limiting measure in the power transmission path, which affects the efficiency and power density of the converter. At the same time, the boost When the type circuit is working with no load or light load, the closed-loop control of the system is also difficult, and it is difficult to take into account the stability of the control and the fast dynamic response characteristics.

[0005] Isolated AC / DC converters usually require a two-stage structure. One is to add a power frequency isolation transformer in the front stage, which will lead to a large volume, weight and high cost of the converter; the other is to add a high frequency isolation transformer in the rear stage. Bidirectional DC / DC converter, but the two-stage power conversion has a great negative impact on system efficiency, and the existing high-frequency isolated bidirectional DC / DC converter has poor characteristics under the condition of wide voltage variation range, this conversion It is difficult for the converter to adapt to the application requirements of wide input and output voltage changes

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