Dual-Active-Bridge Series-Resonant-Converter (DAB-SRC) is widely applied due to its simple circuit structure. A lot of literature has proposed variety kinds of control strategies to ensure the soft switching realization. However, problems such as complex control algorithms, intricate parameter design processes, and a high number of feedback control variables still persist. This paper introduced a variable frequency & single phase shifted (VF&SPS) control strategy based on the time-domain analysis, which employing only two control variables (frequency and phase shifted angle) and only two frequently-used feedback variables (output voltage and current). The soft switching region and the gain model are presented by visualization method so the converter's operating region is clear. By establishing a linear function between normalized frequency fn and the quality factor Q (fn=k*Q+b), the operating track of the converter is restricted and the soft-switching is also ensured even with a constant switching dead-band time. The output is finally regulated by the phase shifted angle ȷ which is generated by a proportional integral compensator. The correctness of the theoretical analysis is verified by a 1.2kW bidirectional prototype with a maximum efficiency of 97.9%.

High switching-speed Silicon Carbide Metal-Oxide-Semiconductor Field-Effect Transistor (SiC MOSFET) has serious crosstalk issues. During the turn-ON transition and turn-OFF transition of the active switch in a phase-leg configuration, the voltage drops across the common-source inductor and the displacement current of the gate-drain capacitor of the OFF-state switch induce a spurious pulse on its gate-source voltage. This paper proposes a new gate driver using two Bipolar Junction Transistors (BJTs) and one diode to connect the gate terminal of SiC MOSFET and the negative driver voltage, which provides a low impedance path to bypass the displacement current of the gate-drain capacitor when crosstalk issues occur. The simulation results prove the proposed driver is valid on suppressing the crosstalk issue. The comparisons between the prior drivers and the proposed driver show the superiority of the proposed driver. Finally, the proposed gate driver is successfully implemented and experimentally verified on a 1.1 kW synchronous buck prototype.

Based on the third generation of semiconductor material, GaN device becomes obvious candidate for new generation POL converters. With the development of integration technology, planar transformer is applied for miniaturization and high power density. LLC resonant converter with EPC eGaN FETs and planar transformer is studies in this paper. First, the difference of LLC resonant converter with eGaN FETs from the one with silicon MOSFETs is analyzed. Second, winding structure of planar transformer is discussed, designed and simulated by Maxwell 2D and 3D finite element analysis (FEA). Finally, LTspice simulation of LLC resonant converter is developed, and a 500kHz/80W prototype is built to verify the analyses.

Due to parasitic parameters existing in Silicon Carbide (SiC) devices application, SiC devices have poor turn-off performances. SiC diode and SiC MOSFET have severe turn-off overvoltage and oscillation. The DC-side snubber is one simple suppressing method. The simplest circuit is the high-frequency decoupling capacitor in parallel with the bridge leg. However, choosing the component value is empirical. Based on the turn-off terminal impedances of the SiC diode and the SiC MOSFET, the suppressing mechanism of this DC-side snubber is analyzed. The guideline selection for the component value is provided. Furthermore, the DC-side snubber with a damping resistor is analyzed based on the terminal impedances. The design principles are provided. Finally, the validity and effectiveness of the DC-side snubbers were proven based on the double-pulse test platform.

This paper presents a single-phase transformerless bidirectional power factor corrector (PFC). A capacitor is inserted into a conventional full-bridge PFC by connecting the ac line terminal and a terminal of DC voltage. The functions of this inserted capacitor have two roles: to bypass the common-mode leakage current from the stray capacitor; to form an LCL filter to reduce the inductor current ripple. A hybrid modulation method is employed in this PFC. The unipolar switching scheme is applied to modulate the PFC, which can achieve high efficiency. Meanwhile, an additional modulation is inserted into the blank time of low-frequency switches to decrease the changing speed of the voltage on the inserted capacitor, and to decrease the spike on the inductor current and leakage current. The performance of the PFC is experimentally verified using a 5 kW prototype.