Circuit adaptive zero-voltage switching control method based on switch transistor electroluminescence, electroluminescence detection circuit, and assembly structure thereof

A circuit adaptive zero-voltage switching control method, comprising:

• disposing an opto-sensor to detect whether there is electroluminescence in a switch transistor in a circuit;
• if the disposed opto-sensor does not detect, within a current switching cycle of the circuit, an electroluminescent photon in a body diode (parasitic diode) or an anti-parallel freewheeling diode of the switch transistor that needs to be controlled, reducing switching frequency fsw of the circuit by a variable Δfsw within a next switching cycle, to increase an amplitude of a reverse inductor current, and continuously detecting whether there is electroluminescence;
• and if there is still no electroluminescence detected, continuously reducing the switching frequency by the variable Δfsw within each next switching cycle, and continuously detecting whether there is electroluminescence, until the disposed opto-sensor detects electroluminescence to reach a steady operating state;
• or
• if the disposed opto-sensor detects, within a current switching cycle of the circuit, an electroluminescent photon in a body diode (parasitic diode) or an anti-parallel freewheeling diode of the switch transistor that needs to be controlled, increasing switching frequency fsw by a variable Δfsw within a next switching cycle, and continuously detecting whether there is electroluminescence;
• and if there is still electroluminescence detected, continuously increasing the switching frequency by the variable Δfsw within each next switching cycle, and continuously detecting whether there is electroluminescence, until the disposed opto-sensor detects no electroluminescence to reach a steady operating state;
• and
• repeatedly increasing and reducing the switching frequency of the circuit by the variable Δfsw within successive switching cycles after reaching the steady operating state, wherein electroluminescence occurs at intervals of the successive switching cycles, for the circuit to reach an adaptive zero-voltage switching operating state;
• the variable Δfsw is any value not greater than a difference between switching frequency fsw ii and switching frequency fsw iii;
• the switching frequency fsw ii is switching frequency when an output capacitor of the switch transistor that needs to be controlled in the circuit is just discharged to zero within dead time, at this time an optimal zero-voltage switching interval starts;
• and the switching frequency fsw iii is switching frequency when the switch transistor that needs to be controlled in the circuit is reversely charged at both ends to an on-state voltage of the body diode or the anti-parallel diode within the dead time, at this time the optimal zero-voltage switching interval ends.