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This article proposes a dual-input mismatch power processing LLC converter for microinverter application. The proposed converter has two photovoltaic (PV) input interfaces in series, so that when the power of the two PV panels is mismatched, the LLC converter is still in good working conditions. The dual control of pulsewidth modulation and pulse frequency modulation achieves independent power flow control of two input ports to eliminate the impact of mismatched power. In addition, through the structure of flying capacitor, the voltage stress of all primary switches is reduced. This article also proposes a control strategy for active voltage balancing of flying capacitors to balance the voltage stress of all primary switches. All switches in the converter operate under zero voltage switching conditions, and all diodes operate under zero current switching conditions. Besides, the switches on the main power circuit have a fixed 0.5 duty cycle, which gives it a lower current stress under any working condition. Finally, a 500 W laboratory prototype was constructed for experiments to verify the effectiveness of the theory.

The bootstrap gate driver circuits are widely used for bridge-arm-type high-current and high-power-density converters due to their low cost and compact structures. In high-current applications, improper bootstrap parameters and circuit design will cause start-up gate–source voltage oscillation, bridge-arm shoot-through, and gate–source voltage overshoot. Because of the lack of research and detailed model on the above three aspects in high-current applications, this article proposes a full-parameter model of the driver circuit through a detailed analysis of the driver circuit and summarizes a set of systematic design methods, which provides a reference for the parameters and circuit design of bootstrap gate driver for Si-based or GaN-based converters. This article will help tackle the challenges encountered in the bootstrap gate driver circuit design for high-current and high-power-density converters.

In this article, a quad-active-bridge (QAB) converter with one single inductor is presented for the modular photovoltaic inverter, which is able to achieve ac/dc power decoupling in magnetic paths without increasing the size of the power transformer, thus reducing the bus capacitance. The single inductor QAB structure simplifies the circuit design of the QAB. In addition, a detailed analysis was conducted on the influencing factors of the double-line frequency voltage ripple for the presented topology, revealing that the parasitic circuits have a very significant impact on its performance, which makes it impractical for real-world applications. Therefore, a control strategy based on the power balancing and phase-shifting principles is proposed to suppress the voltage ripple caused by the inevitable parasitic circuit resistance and leakage inductance. The effectiveness of the analysis and the control strategy is validated by simulation and experimental results.