Search

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.

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.

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.

This article proposes a planar magnetic integration technique that combines the grid inductors and transformer in the single-stage E-capless electric vehicle charger into one core. The proposed integration technique reduces the number of magnetic components; therefore, the cost, total magnetic core loss, and volume can be significantly reduced. Using the integrated structure, the overall converter power density increases up to 11.1% compared to the nonintegrated one. This article also presents a detailed analysis of the optimal printed circuit board (PCB) winding arrangement considering both ac resistance and winding stray capacitance. Due to the high dc resistance of PCB winding, Litz wire was also considered for the proposed integrated structure. The effectiveness of the proposed structure was validated by implementing it on a 3.7-kW prototype of a single-stage ac–dc converter. Results show that the prototype with the proposed integrated structure achieved higher efficiency with both PCB winding and Litz wire. Peak efficiency of 97.17% and 6.55-kW/L power density were achieved.

In this article, a three-phase single-stage bidirectional ac–dc converter with low component count is proposed. The single-stage structure is configured by integrating a three-phase ac–dc converter and a three-phase dual active bridge converter. The power factor correction and bidirectional power control are performed by adjusting the modulation index of sinusoidal pulse width modulation (SPWM) and phase-shift angle between the primary and secondary bridges. The low-frequency components generated by SPWM are absorbed by fundamental blocking capacitors connected in series with transformer windings, resulting in true high-frequency isolation. The proposed converter can achieve soft-switching of all switching devices even in continuous conduction mode. A 110 Vac, 3 kW, 100 kHz prototype is implemented to validate the proposed concept and demonstrated 95.34% peak efficiency.

In this article, a single-stage four-phase interleaved totem-pole AC–DC converter for fast charger applications that require high power, wide battery voltage range, and bidirectional operation capabilities is proposed. Due to the four-phase interleaving effect, the grid side switches can operate at duty cycle of 0.25 or 0.5 so that the grid current always achieves ripple-free. A method for secondary side duty cycle generation is proposed for reducing the circulating power and input current total harmonic distortion (THD) under a wide voltage range. The control system is shown to be simple and reliable. An integrated four-phase transformer is designed using one core. Experimental results from a 7.5 kW prototype with an output voltage range of 150 to 750 V are provided to validate the proposed concept.