Hi team,
I am writing to inquire about the LLC controller for specific requirements of our system.
We are currently using UCC25660 in a half-bridge LLC configuration with a fixed input voltage of 360VDC and an output voltage of 600VDC. The capacitance of the secondary winding of the transformer is estimated to be within the range of 1nF to 2nF. Given the transformer ratio of 1:4, this capacitance is reflected on the primary side, magnified by N^2 times (16 times). In this condition, under no load, mid-load, and light-load, the capacitance appears to dominate rather than the resistive load.
In the UCC25660 datasheet, it is stated that “In the event of a persistent ZCS condition, the controller ceases switching action and moves to the fault state. A configurable time-out is used to declare a persistent ZCS fault condition.”
However, our specific requirement is to avoid entering the fault condition altogether. Instead, we aim for the controller to tolerate persistent ZCS conditions for an indefinite number of cycles.
Could you please suggest any controllers which satisfy our requirement?
Regards,
Manimuthu