LLC converter calculator

Screen an LLC operating point before detailed simulation.

An LLC converter uses the resonant tank to shape current and enable soft switching over a useful operating range. Device loss depends on tank current, switching frequency, magnetizing current, dead time, and whether ZVS is actually maintained.

Resonant starting point

fr = 1 / (2π√(LrCr))
Zr = √(Lr/Cr)
Ln = Lm/Lr

These quantities describe the tank but do not by themselves guarantee the required gain range. Turns ratio, load quality factor, input range, output range, and the permitted switching-frequency span must be considered together.

ZVS is an operating condition

Primary MOSFET ZVS requires enough inductive current during deadtime to charge and discharge bridge-node capacitances. The current LLC calculator does not solve the tank or switching-instant current: it uses a hard-switching envelope bound with no ZVS loss credit. The equations above explain tank concepts, not additional solved LLC outputs.

Open the full-bridge LLC calculator