A discrete extended phase shift control method and device for dual active bridge dc-dc converters

Abstract

A discrete expansion phase-shift control method and device for a dual active bridge DC-DC converter, the invention samples the output voltage value U of the dual active bridge DC-DC converter at the beginning of each switching cycle o , and judge U o Which one of the m-level output voltages does it belong to, and the output voltage boundary of each level is U ref ±je ref , set the primary-side inward shift ratio of the dual active bridge DC-DC converters corresponding to the m-level output voltages and the primary-side and secondary-side shifting ratios respectively, and perform phase shifting respectively to obtain m groups of discrete phase-shifting control pulses group, according to U o Select a corresponding group from m groups of discrete phase-shift control pulse groups to control the switching tubes of the dual active bridge DC-DC converter, so that U o Fast and stable at U ref , which speeds up the transient response speed of the system; in addition, the optimization of the return power is also proposed. According to the expected output power and voltage conversion ratio, setting the shift phase corresponding to the control pulse group can reduce the return power, and the control loop of the present invention is simple Reliable without the need for compensation networks and load current loops.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and relates to a discrete expansion phase-shift control method and device for a dual active bridge DC-DC converter. Background technique [0002] In the early 1990s, the dual active bridge (DAB) DC-DC converter was proposed by Doncker. Because of its advantages of high power density, bidirectional energy flow, easy soft switching, and high reliability, it has been widely used in fuel cells, electric vehicles and other fields. The control method determines the steady-state performance and transient performance of the DAB converter. At present, the control mode of DAB converter is mainly phase-shift control, including single-phase-shift (SPS) control, extended-phase-shift (EPS) control and dual-phase-shift (dual-phase-shift) control. shift, DPS) control, etc. The principle of SPS control is simple and easy to implement, but when the voltage conversion ratio is not 1, large return power ...

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Problems solved by technology

[0004] Aiming at the problems of slow dynamic response and large return power in the above-mentioned traditional DAB converter, the present invention proposes a discrete expansion phase-shift control method and device for a dual active bridge DC-DC converter, which only needs to sample the dual active bridge DC -The output voltage of the DC converter is controlled by discrete expansion and phase shifting, without the need to set up an error amplifier and a corresponding compensation network, which reduces the complexity of the system structure, enhances the stability of the system, and speeds up the transient response speed of the system; and Using multi-level discrete control, it has lower output voltage ripple; at the same time, the return power control algorithm is optimized to reduce the return power

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