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.