CONTROL OF A HALF BRIDGE RESONANT CONVERTER FOR AVOIDING CAPACITIVE MODE

摘要

This invention relates to improved methods of preventing MOSFET damage in a resonant switched mode power converter (1) by preventing or limiting capacitive mode operation. A combination of response actions (respectively delaying MOSFET switch-on, adjusting switching phase, forcing a switch-on, and increasing frequency) is utilised. In the preferred embodiment, the voltage slope at the half-bridge node (5) is monitored, and in alternative embodiments the same or similar set of response actions is triggered by monitoring different signals, including: the resonant current polarity at switch-off or after the non-overlap time; the voltage of the to-be-switched-on" switch; and the voltage of the "just- switched-of f " switch.