In this article, a new bidirectional single-stage interleaved totem-pole electrolytic capacitorless ac-dc converter with high-frequency isolation and low components count is proposed. The proposed converter is constructed using nonregulating two-phase interleaved totem-pole converter switched with a fixed 50% duty on the grid side and a full-bridge on the dc-side for active power and dc output regulation. This switching method results in a ripple-free grid current regardless of the magnitude of the input inductances. Consequently, a proper design of input inductance secures soft switching for all switches under wide voltage and load ranges without an auxiliary circuit or resonant tank. Hence, the proposed topology overcomes the reverse recovery issue, thereby enabling the use of Si devices in CCM. Moreover, the current spike around the ac main zero-crossing is avoided in the CCM operation due to small rectified voltage around zero-crossing. Furthermore, the instantaneous powers at the grid side and dc-side are identical since the proposed topology is electrolytic capacitorless with inherent second harmonic ripple current at the dc-side. PFC is inherently performed in the proposed converter without a current shaping control loop, and the phase-shift angle is the only control variable. Hence, the control system is simple and reliable. A 3.3 kW prototype of the proposed converter is built and tested in order to verify the performance and the theoretical claims.

This article proposes a modular single-stage electrolytic capacitor-less electric vehicles charger with single and three-phase grid compatibility. The proposed single-stage structure inherently maintains dc charging current for three-phase grid. For single-phase grid, a phase module is reconfigured to operate as a power decoupling circuit, making battery current to be dc. Furthermore, the proposed single-stage on-board charger is able to achieve zero voltage switching under wide grid and battery voltage ranges with only one control variable of phase shift angle. A balancing control method is proposed to ensure pure dc battery charging under unbalanced grid conditions. An optimized design of the planar core with Litz wire for achieving low profile is presented. Finally, a 11-kW prototype of the proposed charger achieved a power density of 5.25 kW/L and demonstrated 97.01% peak efficiency.

In dc microgrid (MG) systems, energy storage systems (ESSs) capable of short- or long-term energy buffering are indispensable for energy management and providing high-quality electric energy. The MG should be able to operate in both islanded and grid-connected modes. A sudden failure of ac utility grids can lead to an inoperable condition of the MG or a large transient phenomenon accompanied by oscillation and overshoot during the mode transition. This paper proposes a control scheme of the bidirectional dc-dc converter for the ESS to resolve the issue associated with mode switching. The proposed control scheme provides autonomous and smooth mode switching, thereby reducing the reliance on the communication with the central controller, and enhancing the reliability of the system. To validate the proposed concept, simulation results and experimental results are provided.

This article proposes an effective integration of APM and OBC providing simultaneous operation without an extra circuit and entire ZVS range of all switches. The integrated circuit of the proposed charger is configured by combining high voltage-side switch legs of the LLC resonant converter of OBC and the PSFB converter of APM. In the simultaneous mode, by operating the common leg as a lagging leg of the phase-shift full bridge (PSFB) converter, the conduction losses of the common leg switches are decreased due to current cancellation effect, and the lagging leg switches of the PSFB converter achieve entire ZVS operation. Further, in the APM standalone mode, entire ZVS operation of the lagging leg switches is also secured by utilizing the magnetizing current of the LLC resonant converter. As a result, the proposed integrated charger achieves comprehensive improvement in terms of efficiency as well as volume and cost. A laboratory prototype combining a 3.7-kW LLC resonant converter with a 1-kW PSFB converter is built and tested in order to verify the performance and theoretical claims.

This paper proposes a high-power density 1.8kW auxiliary power module (APM) for electric vehicles (EVs) based on gallium nitride devices targeting DoE 2025 requirements. A design procedure for the high-frequency phase-shift full-bridge (PSFB) with current-doubler (CD) rectifier using PCB based planar magnetics is proposed. Leakage inductance analysis of the high-frequency pulse-width-modulation (PWM) converter is given to achieve both regulation and zero-voltage-switching turn-on. Then, the magnetics optimization procedure for the customized planar core is proposed with a magnetic figure-of-merit concept to meet the high-power density target. Technical considerations are detailed to meet the extreme temperature constraint imposed on the EVs components. Finally, the proposed APM is demonstrated with a switching frequency of 700kHz and a power density of 8.1kW/L (132.8W/in3).

In this article, one of the very first 800-V fuel cell DC–DC converter (FDC) is developed for the next-generation fuel cell electric vehicles. The higher boost gain ratio and switching loss associated with increasing dc-link voltage, along with gradually increasing power density and efficiency demanded in the next-generation EV power converters, make the conventional boost converter not suitable for 800-V FDC. This article proposes a new design approach in which a zero voltage transition (ZVT) high step-up dual floating output boost converter (DFOBC) is introduced. Due to higher voltage gain, the operating duty cycle of DFOBC is reduced and lies in the vicinity of D = 0.5, which reduces filter size. The ZVT cells greatly reduce switching losses at 300 kHz, which enables using only a single discrete SiC mosfet for the main switch of 25-kW module, contributing to volume and cost reduction. Moreover, the proposed converter successfully demonstrates the possibility of using planar core and printed circuit board (PCB) windings at 100-kW power level, which is rarely seen in previous works. Finally, a 25-kW prototype of the proposed ZVT DFOBC is built and test. The power density of 63 kW/L excluding heatsink is achieved. The peak and full-load efficiency are measured to be 99.0% and 97.7%, respectively.