Ac/dc converter with active capacitor bank

A method of controlling a power converter having an AC-DC converter stage and an active capacitor bank coupled to an output of the AC-DC converter stage, the method comprising:

• comparing an input voltage of the AC-DC converter to a mode selection threshold voltage;
• responsive to the AC input voltage being greater than the threshold voltage, enabling the AC-DC converter stage and operating the active capacitor bank to charge from the output of the AC-DC converter stage;
• and
• responsive to the AC input voltage being less than the threshold voltage, disabling the AC-DC converter stage and operating the active capacitor bank to discharge into the output of the AC-DC converter stage.

A power converter comprising:

• a flyback converter configured to receive an AC input voltage and deliver a DC output voltage;
• an active capacitor bank coupled to the output of the flyback converter, the active capacitor bank including an energy storage capacitor and a plurality of switching devices operable as a bidirectional converter to alternately charge the energy storage capacitor from the DC output voltage or discharge the energy storage capacitor to maintain regulation of the DC output voltage;
• and
• control circuitry responsive to the AC input voltage that:
• enables the flyback converter and operates the plurality of switching devices to charge the energy storage capacitor from the DC output voltage responsive to the AC input voltage being greater than a threshold voltage;
• and
• disables the flyback converter and operates the plurality of switching devices to discharge the energy storage capacitor to maintain regulation of the DC output voltage responsive to the AC input voltage being less than the threshold voltage.