Fast Transient Modulation for a Step Load Change in a Dual-Active-Bridge Converter with Extended-Phase-Shift Control

Abstract

Abstract:The manipulation of the bidirectional power in a dual-active-bridge converter relies on the adjustment of several phase-shift angles. Improper implementation of those adjustments during the transient process of a step load change may induce transient DC bias current in the transformer and accompanied high peak current, which may result in excess loss and safety issues potentially. The paper proposes a load transient modulation to execute the adjustments of the two phase-shift angles for extended-phase-shift (EPS) control in a predictive manner. An unknown phase-shift is introduced to the gating signals of one bridge arm, and the gating signals of other bridge arms would be modified accordingly to realize the required adjustment of the two phase-shift angles together. With the proper selection of the introduced phase-shift, the power adjustment can be done in less than one high-frequency cycle without resulting in DC bias and overshoot current. Although there are four different operation modes existing in EPS, a universal solution of the unknown phase-shift can be obtained for all possible power transition cases between different modes. Validation of the proposed method is performed by means of both simulation and experimental tests.

Improved Step Load Response of a Dual-Active-Bridge DC–DC Converter

“…The instant currents after the intermediate adjustment are calculated as: To minimize the transient period, the same requirement shown in Equation (15) should be met. Combining Equations (7), (8), (17), (18) and (15), the intermediate switching angles for transition from mode A to mode B are given as:…”

“…Based on SPS control, a transient control named asymmetric-double-side modulation proposed in [16] distributes the required phase-shift adjustment to both two bridges according to an optimized ratio to depress the DC bias current in the transition process. The same technique is then extended to EPS control in [17,18]. However, the obtained results in [17] can not deal with the operation when the converter gain is close to unity.…”

Comprehensive study of fast load modulation with volt‐second balance in a dual‐active‐bridge converter

“…However, the response time to a load change command would be long. In the literature, there are different types of solutions reported [16][17][18][19][20][21][22][23][24][25][26]. The direct flux control is costly with an extra magnetic sensor and associated connection.…”

General Analysis of Switching Modes in a Dual Active Bridge with Triple Phase Shift Modulation

“…This modulation operates by using the Phase-Shift (ϕ) between output voltages of the bridges, as in the PS modulation, along with the pulse width variation of the Bridge 1 output voltage (D 1 ), being D 2 = 1, Figure 2b. EPS modulation reduces the circulating energy and the conduction losses for medium power, therefore improving the performance compared to the PS modulation [15][16][17][18][19], although with a reduced impact for low power.…”