Dual-mode, ac/dc power converter with power factor correction

An isolated AC/DC power converter having a primary side ground and a secondary side ground, the power converter comprising:

• a rectifier configured to rectify an alternating input voltage;
• a transformer magnetically coupling a primary side and a secondary side of the power converter, the transformer including:
• a primary winding coupled to the rectifier,
• a secondary winding coupled to an output load;
• a dual-mode primary controller having an output (GATE) node and an input node and configured for:
• generating a first output waveform by a critical conducting mode (CrM) module,
• generating a second output waveform by a discontinuous conducting mode (DCM) module,
• receiving a feedback signal by the input node,
• selecting one of the first output waveform or the second output waveform based on the received feedback signal, and
• providing the selected output waveform at the GATE node;
• a switch coupled to the GATE node and commanded by the selected output waveform of the dual-mode primary controller, the switch coupled between the primary winding of the transformer and a primary side ground and configured to control the flow of a current in the primary winding of the transformer;
• and
• a secondary controller coupled to the output load and configured to generate an error voltage and supplying the error voltage as the feedback signal to the dual-mode primary controller.

A method of providing a waveform as an output of a dual-mode controller configured for driving a switch, the method comprising:

• receiving a feedback signal of a voltage or a current at an input node of the dual-mode controller;
• constructing a criterion voltage from the received feedback signal;
• selecting, based on the criterion voltage, one of a critical conducting mode (CrM) module or a discontinuous conducting mode (DCM) module;
• generating, based on the selected module, one of a first output waveform of the CrM module or a second output waveform of the DCM module;
• and
• delivering the generated output waveform at an output of the dual-mode controller, where the method is performed by one of hardware processors or circuits.

A method of controlling an isolated AC/DC power converter, wherein the converter includes a dual-mode primary controller and a secondary controller, the method comprising:

• rectifying an alternating input voltage;
• applying the rectified voltage to a primary winding of a transformer, the primary winding being coupled to a switch and regulated by the switch;
• driving an output load by a secondary winding of the transformer, the load coupled to the secondary controller;
• generating an error voltage by the secondary controller;
• providing the error voltage to the dual-mode primary controller;
• based on the error voltage, providing by the dual-mode primary controller one of
• a first output waveform generated by a critical conducting mode (CrM) module,
• a second output waveform generated by a discontinuous conducting mode (DCM) module;
• and
• controlling output load parameters by applying the provided output waveform of the dual-mode primary controller to the switch.

A dual-mode controller circuit configured to provide pulses for driving a switch on or off for controlling an output of a power converter, the circuit comprising:

• a feedback (FB) node adapted to receive a feedback signal of a voltage or a current;
• a compensation (COMP) node;
• an output (GATE) node configured to provide the pulses;
• an integrator module including:
• a first inverting input node coupled to the FB node of the circuit,
• a second non-inverting input node coupled to a first reference signal of a voltage or a current, and
• a third output node coupled to the COMP node of the circuit, wherein a voltage of the output node of the integrator is an integral of a difference of the signals of the first input and the second input nodes of the integrator;
• a comparator module configured to provide a binary selector (SEL) voltage including:
• a first input node coupled to the COMP node of the circuit,
• a second input node coupled to a threshold voltage, and
• a third output node, wherein the SEL voltage of the output node of the comparator is set based on comparing a voltage of the first input of the comparator with a voltage of the second input of the comparator, and wherein a jump of the SEL voltage includes a curve with hysteresis;
• a critical conducting mode (CrM) module configured to generate a first series of pulses with a first frequency and a first duty cycle adjusted to a voltage at the COMP node of the circuit and adapted for a CrM operation of the power converter, the CrM module including:
• a first input node coupled to the COMP node of the circuit,
• a second input node coupled to the output node of the comparator module and receiving the SEL voltage, and
• a third output node configured to generate the first series of pulses based on the SEL voltage;
• a discontinuous conducting mode (DCM) module configured to generate a second series of pulses with a second frequency and a second duty cycle adjusted to the voltage at the COMP node of the circuit and adapted for a DCM operation of the power converter, the DCM module including:
• a first input node coupled to the COMP node of the circuit,
• a second input node coupled to the output node of the comparator module and receiving the SEL voltage, and
• a third output node configured to generate the second series of pulses based on the SEL voltage;
• and
• a gate driver (DR) module configured to receive one of the first series of pulses or the second series of pulses, the DR module including:
• a first input node coupled to the output nodes of the CrM and DCM modules and configured to receive one of the first series of pulses or the second series of the pulses base on the SEL voltage,
• a second output node coupled to the GATE node of the circuit and configured to provide the received series of pulses at the GATE node of the circuit.