Bidirectional three-port non-isolated DC converter and control method thereof

Abstract

The invention discloses a bidirectional three-port non-isolated DC converter and a control method thereof and belongs to the technical filed of a power electronic converter. The bidirectional three-port non-isolated DC converter is formed by four switch tubes, one coupling inductor comprising a first winding and a second winding, one high-frequency inductor and an auxiliary capacitor. The bidirectional three-port non-isolated DC converter can be connected with three power supplies of a low-voltage side power supply, a middle side power supply and a high-voltage side power supply and the like simultaneously, and can realize single stage and bidirectional power conversion between any two power supplies. Duty ratio and phase shift control are adopted simultaneously to provide two independent control variables for the system, so that any two ports can be in a controlled state simultaneously, and soft switching of all switch tubes can be realized. The bidirectional three-port non-isolated DC converter has the advantages of simple structure and control, high power density, high efficiency and low cost and the like, and is very suitable for the power systems of hybrid energy storage, electric automobile and DC microgrid and the like, which comprise a plurality of energy storage or a plurality of bidirectional DC buses.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to the technical field of bidirectional non-isolated DC-DC power conversion. Background technique [0002] Bidirectional DC converters can realize bidirectional energy transmission between multiple energy storage devices, energy storage devices and DC buses or between multiple DC buses, and are widely used in renewable energy power generation systems, uninterruptible power supply systems, electric vehicles, hybrid Energy storage and DC microgrid and other systems. With the continuous progress and development of related technologies such as energy storage systems and DC micro-grid power supply systems, new challenges are constantly posed to the bidirectional DC converters connecting the DC bus and energy storage devices, which are mainly manifested in two aspects: (1) It is usually necessary to connect multiple energy storage devices with different voltage levels or multiple DC buse...

AI Technical Summary

Problems solved by technology

[0004] For the traditional non-isolated bidirectional DC converter, it mainly faces two problems when it is applied to the high-voltage DC bus and low-voltage energy storage system: (1) Since the traditional non-isolated bidirectional converter cannot realize soft switching, the switching body diode The reverse recovery of the reverse recovery not only causes very large switching loss and reduces the efficiency of the converter, but also causes a serious voltage spike on the switch tube, which leads to the failure of the switch tube and reduces the reliability of the converter; (2) in order to meet the storage requirements According to the requirements of step-up / step-down ratio between the device and the DC bus, the duty cycle of the switch tube has to work in a limit state close to 1 or 0, which will cause a sharp increase in the voltage and current stress of the switch tube, resulting in a loss of efficiency a substantial reduction in

This solution solves the problems faced by traditional non-isolated bidirectional DC converters to a certain extent, but its ability to improve the step-up / step-down ratio is very limited, and it can only provide two power ports and cannot realize multiple energy storage at the same time Energy transfer between devices or DC bus

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