Isolated bridge type three-port DC converter

Abstract

The invention discloses an isolated bridge type three-port DC converter which comprises an inversion unit, an isolation unit, a first output unit and a second output unit, the port at one side of the inversion unit is used for connecting a renewable energy source, the port at the other side of the inversion unit is connected with the isolation unit, the port at one side of the first output unit is connected with the isolation unit, the port at the other side of the first output unit is used for connecting a load, the port at one side of the second output unit is connected with the isolation unit, the port at the other side of the second output unit is used for connecting an energy storage device, the isolation unit is formed by two three-winding transformers, primary-side windings of the two three-winding transformers are connected in series, secondary-side windings of the two three-winding transformers are crossed in a group way and inversely and mutually connected in series, therefore, an output port and the energy storage device share complementary pulse, circulation among the renewable energy source, the energy storage device and the load is eliminated, and energy loss brought by the circulation is reduced.

Description

technical field [0001] The invention belongs to the technical field of direct current conversion, and more specifically relates to an isolated bridge type three-port direct current converter. Background technique [0002] Renewable energy is currently being used more and more widely. However, there are contradictions between the discontinuity and instability of renewable energy and the load that requires stable energy supply. It is necessary to introduce energy storage devices to balance between renewable energy and loads. Generally, a three-port circuit that simultaneously connects renewable energy, energy storage devices, and loads is used to solve this contradiction. [0003] In the prior art, there are the following two three-port circuits: one is a three-port circuit based on two half-bridge structures, in which the primary half-bridge of the isolation transformer is connected to the renewable energy source, the secondary half-bridge is connected to the load, and the st...

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Problems solved by technology

[0003] In the prior art, there are the following two three-port circuits: one is a three-port circuit based on two half-bridge structures, in which the primary half-bridge of the isolation transformer is connected to the renewable energy source, the secondary half-bridge is connected to the load, and the storage The energy device is connected in parallel with the primary side voltage dividing capacitor; the charge and discharge of the energy storage device can be realized by controlling the two switch tubes of the primary side bridge arm; The disadvantage of this structure is that it cannot provide electrical isolation and voltage matching for all three ports, and the working range of its soft switch is limited

[0004] The other is a three-port circuit based on a multi-winding transformer. By connecting the three-winding transformer with three full-bridge structures, and then respectively connecting renewable energy, energy storage devices, and loads, the electrical isolation and communication between the three ports can be realized. The voltage is matched, and the energy flow between the ports can be controlled by controlling the phase relationship between the three full bridges; however, the coupling between the three transformer windings of this structure is serious, and there is a circulating current, resulting in reduced efficiency and complicated control

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