Method for suppressing transient DC bias of three-port isolated DC/DC converter

Abstract

The invention discloses a method for suppressing the transient DC bias of a three-port isolated DC / DC converter, which comprises the steps of firstly, analyzing the formation mechanism of transient DCbias of a TAB (Triple Active Bridge) under the traditional phase shift control, and determining the formation reason of the transient DC bias of the TAB; establishing a DC bias suppression mathematical model based on the formation reason; and determining a driving signal combination method satisfying the DC bias suppression mathematical model so as to suppress the transient DC bias. The establishment of the DC bias suppression mathematical model includes the steps of firstly determining an equivalent circuit of the TAB when the voltage of each port acts independently according to a Y-type equivalent circuit of the TAB, then acquiring a current expression of each port of the TAB according to a superposition theorem, acquiring a current relation before and after the phase shift angle changes if it is assumed that the voltage-second product of positive and negative amplitudes of square-wave voltage of the port 2 and the port 3 within the unit switching period is zero when the phase shiftangle changes and the inductor can still achieve volt-second balance, and thus acquiring the DC bias suppression mathematical model of the TAB. The method solves a problem that the transient DC biasaffects the safe operation of the TAB.

Description

technical field [0001] The invention belongs to the control field of a three-port isolated DC / DC converter, and relates to a method for suppressing a transient DC bias of a three-port isolated DC / DC converter. Background technique [0002] Vigorously developing distributed photovoltaic power generation is an important measure to promote the development and utilization of renewable energy in my country and promote the adjustment of energy structure. The three-port isolated DC / DC converter (triple active bridge, TAB) composed of "PV array + battery + bus load" can realize power transmission and conversion between each two ports, compared with dual active bridge DC conversion For dual active bridge (DAB), the control flexibility is higher and the power supply reliability is better. Among them, the application of high-frequency transformers can not only achieve complete isolation and voltage matching between ports, but also greatly reduce the volume and weight of the device, an...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a method for suppressing the transient DC bias of a three-port isolated DC / DC converter, to solve the problem of the transient adjustment process of the three-port isolated DC / DC converter under traditional phase-shift control due to shifting The phase angle changes, the DC bias current is generated on the inductance of each port of the converter and the transformer core, which affects the safe operation of TAB and its key components, and the existing TAB DC bias suppression method for modal analysis needs to add additional Hardware facilities and can not solve the problem of DC bias of series inductance and transformer excitation inductance at the same time

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