Zero voltage, zero current switching power factor correction converter with low conduction loss and low switching loss

A power factor correction converter comprising:

• a resonant unit comprising a first switch, a second switch, and a resonant circuit at least comprising two energy storage elements, wherein said resonant unit is operatively configured to alternatively discharge an electric energy from one of said energy storage elements to a capacitive load;
• and
• a boost unit comprising a boost choke for receiving an alternating current voltage, a rectifying circuit coupled between said boost choke and said resonant unit, a third switch and a fourth switch respectively connected across one of said energy storage elements;
• and
• a power factor correction controller which issues a first switch control signal to drive said first switch to turn on and off when a current flowing through said first switch is zero and issues a second switch control signal to drive said second switch to turn on and off when a current flowing through said second switch is zero, and issues a third switch control signal to drive said third switch to turn on and off when a voltage across said third switch is zero and issues a fourth switch control signal to drive said fourth switch to turn on and off when a voltage across said fourth switch is zero.