Resonant power conversion circuit and control method thereof for balancing duty cycles of high-side transistor and low-side transistor

A control method for controlling a resonant power conversion circuit, wherein the resonant power conversion circuit comprises a resonant capacitor coupled between a resonant node and a ground, a transformer comprising a primary coil and a secondary coil, a high-side transistor providing an input voltage to a switch node, a low-side transistor coupling the switch node to the ground, a regulation circuit regulating a current flowing through the secondary coil to an output voltage, and a feedback circuit generating a feedback voltage based on the output voltage, wherein the primary coil is coupled between the switch node and the resonant node, wherein the control method comprises:

• generating a current detection signal by using a first current detection circuit to detect a current flowing through the resonant capacitor;
• integrating the current detection signal based on a reference voltage to generate an integral signal;
• full-wave rectifying the integral signal to generate a rectified signal;
• and
• driving the high-side transistor and the low-side transistor based on the rectified signal and a feedback voltage;
• wherein the first current detection circuit comprises a first capacitor and a first resistor;
• wherein the first capacitor is coupled between the resonant node and a first detection node, and the first resistor is coupled between the first detection node and the ground;
• wherein the current detection signal is generated at the first detection node.