Control device for a resonant apparatus

A resonant apparatus, comprising:

• a resonant load,
• a switching circuit coupled to the resonant load and including a half-bridge having a high-side transistor and a low-side transistor;
• and
• a control device configured to control the switching circuit, the control device including:
• a driver configured to alternatively set on time periods and off time periods of high-side and low-side transistors of the switching and a dead time of both the transistors to cause the switching circuit to output a periodic square-wave voltage to a resonant load;
• a detector configured to detect the sign of a current flowing through the resonant load;
• and
• a correction circuit configured to extend an operating time period of said transistors in response to at least the current sign detected by the detector.

A control method comprising:

• determining an on time period and an off time period of a high-side transistor and a low-side transistor of a switching circuit of a resonant apparatus;
• determining a dead time of both the transistors so that a periodic square-wave voltage produced by the switching circuit;
• detecting a sign of a current flowing through a resonant load of the resonant apparatus;
• and
• controlling an extension of a current operating time period of said two transistors in response to at least the current sign detected in the detecting step.