Bidirectional isolated non-resonant DAB DC-DC converter for ultra-wide input voltage range applications

Abstract

This paper details efficiency optimized operation and design of a bi-directional and isolated five-level Dual Active Bridge (5LDAB) converter for an application that requires ultra-wide voltage and power ranges. The rated power of the considered converter is 7.5 kW, the specified input voltage range is 150 V ≤ V dc1 ≤ 800 V and the output voltage is constant, V dc2 = 700 V. In order to achieve high efficiency levels in a wide operating range, a modulation scheme is proposed to minimize the transformer rms current. Results of transformer rms currents and of efficiencies are presented for the 5LDAB and compared with the results obtained for an efficiency optimized conventional Dual Active Bridge (DAB) converter. Compared with the DAB topology, the 5LDAB converter can achieve an overall reduction of transformer rms currents and of conduction losses in the higher voltage regime of the operating range.Index Terms-DC/DC, Dual active bridge, DAB, Multilevel, Wide voltage range, Efficiency.

A voltage doubler circuit to extend the soft-switching range of dual active bridge converters

“…In Fig. 3(a) when t = t 2 , v coss,Q2 = v coss,Q3 = V h , thus the dynamic equations of the parasitic capacitors and the series inductor can be obtained as (5) and (6).…”

“…Various modulation strategies have been proposed in the literature to extend the soft-switching range, e.g. the phase shift modulation with one duty ratio (or hybrid phase shift modulation) and the phase shift modulation with two duty ratios [5][6][7]. By introducing duty ratios, these modulations can realize triangular or trapezoidal transformer current.…”

A Dual Active Bridge Converter With an Extended High-Efficiency Range by DC Blocking Capacitor Voltage Control

“…Under light load conditions, switching frequency of the DAB may also become extremely high, in order to guarantee soft switching. Consequently, most modulation strategies in the literature have retained a fixed switching frequency [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], while exploring other means for widening the soft-switching range and reducing circulating power in the DAB, in order to increase its efficiency. One technique extended from SPS is to lower the duty ratio of one full bridge to below 0.5.…”

“…To retain symmetry with the same duty ratios set for both full bridges, Dual Phase Shift (DPS) modulation has been proposed [14], [15]. Compared with EPS, no extra complexity has been introduced by DPS, despite its improved performances, which can still be optimized by adding a third control parameter to form the Triple Phase Shift (TPS) modulation [16][17][18][19][20][21][22]. Control parameters of TPS are thus the two independent duty ratios of the two full bridges, and the phase angle between them.…”

Derivation of operation mode for flying capacitor topology applied to three-level DAB converter

“…Moreover, the voltage balance control is required. On the other hand, a three-level DAB converter applied with T-type topology has been proposed in order to achieve the minimum inductor current [10]. The switching pattern of the three-level inverter is determined by the relationship among the turn ratio of the transformer and the input/output voltage.…”