Design and Implementation of Sensorless Capacitor Voltage Balancing Control for Three-Level Boosting PFC

Compared with the conventional boosting PFC converter, the three-level boosting PFC converter has two cascaded switches and two cascaded capacitors across the dc-side voltage. Two capacitor voltages may be different due to their mismatched equivalent series resistance, their mismatched capacitance, and the mismatched conducting time of the corresponding switches. It follows that the controller needs to sense the capacitor voltages to balance both capacitor voltages. In this paper, the sensorless capacitor voltage balancing control (SCVBC) without sensing the capacitor voltages is proposed, and the total number of the feedback signals is saved. The proposed SCVBC is digitally implemented in an FPGA-based system. The provided simulated and experimental results also demonstrate the proposed SCVBC.