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Abstract The transient DC bias current will be generated when the input voltage or load of the dual active bridge (DAB) converter suddenly changes, resulting in the excessive peak value of the inductor current and saturation of the transformer core. An improved three‐phase‐shift (ITPS) strategy based on double integral sliding mode‐direct power control (DISM‐DPC) is proposed in this paper to suppress DC bias current without additional hardware. The proposed ITPS determines the steady‐state phase shift ratio through an inductor RMS current optimisation strategy. The transient phase shift strategy can be determined by the transient DC bias current model, which eliminates the DC bias within one switching cycle and effectively reduces the current impact. In addition, a dual‐loop compensation control method of power inner loop and output voltage outer loop is proposed. Compared with the steady‐state control method, the transient optimisation method of double‐loop compensation control can stabilise the output voltage quickly, effectively reduce the transient impact of the current and improve the dynamic performance of the circuit operation. The experimental results verify the theoretical analysis and prove the effectiveness of the scheme.

The transient DC bias current will be generated when the input voltage or load of the dual active bridge (DAB) converter suddenly changes, resulting in the excessive peak value of the inductor current and saturation of the transformer core. An improved three‐phase‐shift (ITPS) strategy based on double integral sliding mode‐direct power control (DISM‐DPC) is proposed in this paper to suppress DC bias current without additional hardware. The proposed ITPS determines the steady‐state phase shift ratio through an inductor RMS current optimisation strategy. The transient phase shift strategy can be determined by the transient DC bias current model, which eliminates the DC bias within one switching cycle and effectively reduces the current impact. In addition, a dual‐loop compensation control method of power inner loop and output voltage outer loop is proposed. Compared with the steady‐state control method, the transient optimisation method of double‐loop compensation control can stabilise the output voltage quickly, effectively reduce the transient impact of the current and improve the dynamic performance of the circuit operation. The experimental results verify the theoretical analysis and prove the effectiveness of the scheme. [ABSTRACT FROM AUTHOR]

Dual-active-bridge (DAB) circuit is an excellent candidate for a high-efficiency, high-power density, and bidirectional electric vehicle charger. Unlike resonant circuits employing auxiliary inductors and capacitors, DAB minimizes the usage of passive components. The challenge, however, lies in the difficulty of securing zero-voltage switching (ZVS), particularly at light-to-medium load when using the conventional single-phase-shift (SPS) control. This is of utmost importance not only for the sake of the efficiency, but also for minimizing the switch-bridge crosstalk caused by the hard switching-on, thereby enhancing the system reliability. Although dual-phase-shift (DPS) and triple-phase-shift (TPS) can be the answer, they do introduce side effects such as larger switching-off current. This article systematically integrates SPS, DPS, and TPS to maximize full-power ZVS range for both steady state and transient operations in EV chargers. This article plots ZVS boundaries over the full power range, categorizes all operations into nine modes, and proposes a smooth transition method among all operation modes. Dead band is also incorporated in the ZVS boundary setting. Experimental results on a SiC-based charger validate the effectiveness of this method of widening ZVS range for output voltage of 200–450 Vdc and power of 0–20 kW, achieving smooth transitions among various operation modes, and suppressing the switch crosstalk, thereby securing high charger reliability. [ABSTRACT FROM AUTHOR]

Dead time between the complementary driving signals is needed to avoid short circuit in voltage source inverters (VSIs), however, this raises issues such as voltage distortion and harmonic generation. In wireless power transfer (WPT) systems, the ratio of dead time versus operating period becomes more problematic due to the high frequency, where the dead time can cause serious concerns regarding the phase errors and control performance deterioration. Therefore, this paper presents a comprehensive analysis of the dead-time effect for WPT systems based on a series–series (SS) topology. Firstly, it is found that voltage distortion appears in two regions in comparison with the three in one active bridge WPT system, and seven regions, as compared to the eight in dual active bridge (DAB) WPT system. Afterwards, a novel pulse width modulation (PWM) method is proposed, where the driving signals of the same phase leg are no longer complementary to each other. By employing the proposed method, the dead-time effect can be addressed up to a certain extent, and the desired voltage can be obtained in all the regions. In addition, the proposed method is not influenced by the system parameters, and can be easily applied to other high-frequency resonant converters. Simulated and experimental results are added to verify the feasibility and efficacy of the proposed control scheme.