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This article proposes a new isolated three-port dc–dc converter (TPC) named dual floating dual active bridge (DAB) three-port converter. The proposed converter combines an isolated DAB converter and an interleaved nonisolated dual floating boost (DFB)converter. As the power demand of auxiliary loads in the vehicles rapidly increases due to autonomous and entertainment systems, a dual auxiliary voltage (48 and 12 V) system is introduced to mitigate the burden of high current. The high voltage gain feature of the DFB converter ensures that the operating duty remains around 0.5, reducing filter size, turn-off current, and circulating current, and increasing the power transfer capability from the high voltage side. Additionally, the lower voltage stress on the low-side switches allows for the use of switches with lower RDS,on, reducing conduction losses. To validate the theoretical claims, a 6.1 kW, 100 kHz prototype of the proposed TPC has been built. The prototype operates with a wide HV-port voltage range of 400–840 V and a 12 V-port voltage range of 9–16 V while providing a fixed 48 V to the 48 V-port. The prototype achieves a power density of 9.14 kW/L and a peak efficiency of 96.6%.

This article proposes a high-step-down dc-dc converter for electric vehicles with an 800 V battery system. The proposed converter significantly reduces the current rating requirement for the dc blocking capacitor on the secondary side by reconstructing the secondary side circuit. The maximum duty cycle of the proposed converter is larger than the phase-shift full-bridge converter, which allows the use of larger leakage inductance. This turns out to be a crucial advantage to achieve the wide range zero voltage switching (ZVS) in high switching frequencies over 500 kHz. In addition, with a three-level structure, the voltage rating of the primary side switch is determined as half the input voltage and the energy to achieve ZVS turn-on is reduced, so it is suitable for high-frequency operation using a gallium nitride (GaN) device. The two transformers are integrated with partial flux cancelation, resulting in 10.3% of power loss and 27.7% of footprint reduction. Finally, a 700 kHz GaN-based 1.2 kW prototype achieved a power density of 10.2 kW/L and a peak efficiency of 93.4%.

This article proposes an all-in-one magnetic structure that integrates a leakage inductor, two filter inductors, and a transformer in the phase shift full bridge (PSFB) current doubler converter for the auxiliary power module (APM). The proposed integration technique significantly reduces the number of magnetic components, not only achieving a 17.5% reduction in the magnetic volume and a 26% reduction in the magnetic loss but also simplifying the manufacturing processes. Considering the coupling effect in the proposed integrated structure, the zero voltage switching (ZVS) energy is increased. An optimized coupling coefficient is proposed to cover the entire ZVS range, considering the increase in RMS current associated with an elevated coupling coefficient. To validate the effectiveness of the proposed structure, a 3-kW and 200-kHz prototype APM with an input range of 360–800 V and an output voltage range of 11.5–15.3 V is built and tested. The achieved peak efficiency is 95.5%, and the power density reaches 8.4 kW/L.

Fault-tolerant (FT) methods have been recognized for improving the reliability of multiphase bidirectional dc-dc converters. Few FT methods for current-fed dual-active-bridge (CF-DAB) converter have been developed, because it becomes more challenging due to the asymmetrical structure between primary and secondary sides. In this article, the behaviors of the CF-DAB converter are comprehensively analyzed when an open-circuit fault (OCF) occurs in different fault scenarios. An analysis and the proposed FT method are aimed to determine the open-circuit cases, which can recover full conversion power after the fault occurs. Moreover, this article also proposed an auto-balancing control method to prevent the converter from being out of control. The proposed balancing control method can be utilized for general multiphase current-fed converters. A 6-kW prototype is built to verify the proposed method.

In this article, a new single-stage bridgeless totem-pole ac–dc converter is proposed. The proposed converter is composed of two single-stage boost half-bridge ac–dc converters with the interleaved operation. Besides, while preserving the advantages of the L-type half-bridge-based single-stage totem-pole ac–dc converter, the proposed converter has the ability of phase-shedding operation, which helps to increase the total efficiency of the converter due to reduced switching and core losses by half under medium and light loads. A hybrid harmonic injection in phase shift and duty cycle according to battery voltage is proposed, which not only improves total harmonic distortion to smaller than 4% under the whole load range but also extends the zero-voltage switching range of the converter under a wide voltage range. The proposed control method can be utilized in the general dual-active-bridge-based single-stage converter. Experimental results from a 1.5-kW prototype are provided to validate the proposed concepts.