LLC Resonant Converter Apparatus And Method

An apparatus that controls an LLC resonant converter circuit, the circuit includes a resonant filter, the LLC resonant converter circuit being operated at an operational frequency and having an inverter coupled to the resonant filter that produces a first waveform and a second waveform, the first waveform having a phase shift with respect to the second waveform, the apparatus comprising:

• an interface having an input and an output, the input configured to receive an input voltage to the LLC resonant converter circuit;
• an output voltage of the LLC resonant converter circuit;
• and a load range;
• a processor device coupled to the interface, the controller configured to, based upon a maximum frequency of operation, when the output voltage needs to be adjusted and the operational frequency is below the maximum frequency, adjust the operational frequency via the output of the interface to adjust the output voltage to a desired value, and when the output voltage needs to be adjusted and the operational frequency is above the maximum frequency, adjust the phase shift in the LLC resonant converter circuit via the output of the interface to adjust the output voltage to a desired value.

An LLC resonant converter circuit, comprising:

• an inverter circuit, the inverter circuit producing a first waveform and a second waveform that are summed into a third waveform;
• a resonant filter coupled to the inverter circuit, the resonant filter receiving the third waveform and converting the third waveform into a sinusoidal waveform;
• a transformer isolator that converts the sinusoidal waveform from a first voltage to a second voltage;
• a controller coupled to the inverter circuit;
• a rectifier and output circuit coupled to the isolation transformer;
• wherein the inverter is operated at an operational frequency by the controller and wherein the controller operates such that the first waveform has a phase shift with respect to the second waveform;
• wherein the controller is coupled to the output circuit, the controller configured to, based upon a maximum frequency of operation, when the output voltage needs to be adjusted and the operational frequency is below the maximum frequency, adjust the operational frequency of operation of the inverter circuit to adjust the output voltage to a desired value, and when the output voltage needs to be adjusted and the operational frequency is above the maximum frequency, adjust the phase shift of the first waveform and the second waveform to adjust the output voltage to a desired value.