Discrete expansion phase shift control method and device for dual-active-bridge DC-DC converter

Abstract

The invention discloses a discrete expansion phase shift control method and device for a dual-active-bridge DC-DC converter. The method comprises the steps of: sampling an output voltage value Uo of the dual-active-bridge DC-DC converter at the starting moment of each switching period, judging which stage of m-stage output voltage the Uo belongs to, and enabling the boundary of each stage of output voltage to be Uref+ / -jeref, setting a primary side inward phase shift ratio and an outward phase shift ratio between primary side secondary sides of the dual-active-bridge DC-DC converter corresponding to m levels of output voltages respectively, and performing phase shift respectively to obtain m groups of discrete phase shift control pulse groups, according to the judgment result of the Uo, selecting a corresponding group from the m discrete phase shift control pulse groups to control a switching tube of the dual-active-bridge DC-DC converter, thus rapidly stabilizing the Uo at Uref, and increasing the transient response speed of the system; in addition, optimization of the backflow power is further provided, the phase shift ratio corresponding to the control pulse group is set according to the expected output power and the voltage conversion ratio, the backflow power can be reduced, the control loop is simple and reliable, and a compensation network and a load current loop are notneeded.

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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