A New Neutral-Point Clamped Based LLC Converter with Self-Sustained Resonant Controller

摘要

This paper proposes a new neutral-point clamped based LLC resonant converter, which is controlled by a modified self-sustained control system. The presented neutral-point clamped based topology comprises only four switches, which improves efficiency and reduces the cost of implementation. The arrangement of the power switches is such that this converter is also appropriate for connection to high DC voltage because the clamp diodes limit the voltage across power switches to the half of DC-link voltage. The proposed self-sustained resonant controller provides zero-voltage switching (ZVS) and zero-current switching (ZCS) for power switches to reduce the switching losses further. This converter has galvanic isolation due to employing high-frequency step-down transformer and includes a center-tapped full-wave rectifier. Simulation results evaluate the proposed topology and its control network. Simulations are done for 500V/48V/1.5kW converter. Results indicate that this topology operates with ZVS and ZCS, and works with low-voltage and low-current stresses.