Bidirectional DC-DC converter and control method thereof

Abstract

The invention discloses a bidirectional DC-DC converter and a control method thereof. The converter is mainly applied to an aerospace power system, a shipboard power supply, a DC motor driving system, a storage battery system, a DC uninterruptible power system and a compound energy storage system of a vehicle. The method of the invention is applied to the bidirectional DC-DC converter which comprises an input side full bridge circuit and an output side full bridge circuit. The method comprises the steps that when the primary side current of a transformer is equal to the critical current of a nonlinear inductor, the inductance of the nonlinear inductor changes suddenly, the slope of the primary side current change of the transformer is increased, the primary side current of the transformer is raised, the reset time is reduced, and the slope of the primary side current change is increased; through internal shift comparison, the voltage of a primary side of the transformer is zero, and the cycle energy of the bidirectional DC-DC converter is zero. The efficiency of the bidirectional DC-DC converter is greatly improved, and the structure and control of the converter are simple and easy to realize.

Description

technical field [0001] The invention belongs to the application field of power electronics, and in particular relates to a bidirectional DC-DC converter used for composite energy of pure electric vehicles and a control method thereof. Background technique [0002] With the increasingly prominent problems of energy and environmental protection in the current society, electric vehicles have become a new type of vehicle that has developed rapidly in recent years, and are the most promising green and clean vehicles in the 21st century. Under the existing technical conditions, the performance of the power battery is the main bottleneck in the development of electric vehicles, and the bidirectional direct-current (DC-DC) converter can optimize the motor control and improve the overall efficiency and performance of electric vehicles. Bi-directional DC-DC can not only realize the cooperation between battery and supercapacitor to achieve the optimal configuration of power, but also r...

AI Technical Summary

Problems solved by technology

[0004] From the above introduction, it can be seen that L is a fixed value, which can be set according to experience, but the value of L cannot be selected too small, otherwise the switching action of the lagging arm of the converter will not be able to ensure soft switching

Therefore, in order to ensure the soft switching inductance of the lagging arm must be relatively large, but this brings another problem: the rise of the primary current and the reset time must also increase, which causes the energy transmitted by the converter to change within one cycle. small, affecting the efficiency of the converter

So circulating energy is meaningless, but there is a loss in the flow

This also reduces the efficiency of the converter

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