Apparatus and methods for sensing resonant circuit signals to enhance control in a resonant converter

A hod of controlling an output power delivered by a resonant converter to a load, comprising:

• applying an input power comprising an input voltage to an input of the resonant converter;
• providing a switched power signal to a resonant transformer input port, the switched power signal comprising a switching cycle and a switching frequency;
• providing a buffered primary port signal from the resonant transformer input port to a control module with a parallel coupled buffer circuit coupled to the resonant transformer input port, the buffered primary port signal comprising comprehensive signal information relating to the input power and the output power of the resonant converter;
• level shifting an alternating current (ac) component of the buffered primary port signal;
• converting the ac component into a sense interface signal;
• and
• controlling the output power in response to the sense interface signal.

A method of resonant power conversion in a resonant converter, comprising:

• applying an input power to the resonant converter;
• providing a switched power signal to a resonant transformer input port;
• providing a buffered primary port signal from the resonant transformer input port to a control module with a parallel coupled buffer circuit coupled to the resonant transformer input port, the buffered primary port signal comprising comprehensive signal information relating to the input power and an output power of the resonant converter;
• level shifting an alternating current (ac) component of the buffered primary port signal;
• converting the ac component into a sense interface signal using a sense interface circuit;
• and
• delivering the output power to a load in response to the sense interface signal, the output power comprising an output current and an output voltage.

A resonant converter, comprising:

• a resonant transformer having a resonant transformer input port, the resonant transformer input port including a series coupled leakage inductance and magnetizing inductance to provide a primary port signal having a first voltage range;
• a buffer circuit coupled in parallel with the resonant transformer input port to provide a buffered primary port signal in response to the primary port signal, the buffered primary port signal comprising comprehensive signal information relating to an input power and an output power of the resonant converter;
• and
• a sense interface circuit configured to receive the buffered primary port signal and convert the buffered primary port signal into a sense interface signal having a second voltage range.