Resonant converter and method of operating the same

A method of operating a resonant converter, the resonant converter comprising a transformer and a primary-side circuit, and the primary-side circuit comprising a resonant circuit and a first bridge arm;

• the resonant circuit being coupled to a primary-side winding of the transformer to form a resonant module, and the first bridge arm comprises a first switch and a second switch, the method comprising steps of:
• controlling the primary-side circuit to convert a DC voltage so as to control the resonant converter converting the DC voltage into an output voltage to generate a winding voltage at two ends of the resonant module,
• detecting an output current of the resonant converter, and adjusting a duty cycle of the winding voltage with a variation when determining that the output current is in a current interval between a predetermined current and a rated current, so that the duty cycle does not remain at a predetermined value,
• adjusting the duty cycle to control an operation frequency of the resonant convert to vary within a frequency range, and the frequency range is positively related to the variation,
• providing a first control signal to control the first switch and providing a second control signal to control the second switch, and
• adjusting a dead time between the first control signal and the second control signal to adjust the variation when the output current is in the current interval.