Grid Voltage Sensorless Control of 3.2kW Bridgeless Totem-Pole PFC Converter with Pre-Estimation and Seamless Mode-Transition

This paper proposes a current control method for bridgeless totem-pole power factor correction (BTPPFC) converters without a grid voltage sensor. The grid voltage is pre-estimated through a discontinuous conduction mode (DCM) start-up technique before executing closed-loop current control. The pre-estimated grid voltage is used as a feed-forward term into the current controller. This is achieved by initializing the digital states of the current controller just before activation of the closed-loop current control, enabling a seamless transition. The proportional-resonant (PR) current controller is utilized both for current control and grid angle estimation. The error between the estimated and actual grid angles is below 0.3º at steady state. The validity of the proposed grid voltage sensorless current control method is verified by experiments with a 3.2 kW SiC MOSFET-based BTPPFC converter.