Digital Current Sensorless Control for Dual-Boost Half-Bridge PFC Converter With Natural Capacitor Voltage Balancing

To improve the efficiency of the conventional boost-type power factor correction (PFC) converters with the diode bridge circuit, the PFC converters of bridgeless category are often used. Due to no series-connected switches and no short-through risks, the dual-boost half-bridge (DBHB) circuit is used as the PFC converter in this paper. In order to simplify the conventional two-loop control scheme and reduce the number of sensors, the behaviors of the DBHB PFC converter are studied and its equivalent single-switch model is developed. Then, the current sensorless control for the DBHB PFC converter is proposed to achieve voltage regulation and yield sinusoidal input current in phase with the input voltage without sensing any current. In addition, the proposed method is able to balance capacitor voltages naturally without adding any voltage balancing control loop. An 800-W DBHB PFC prototype is implemented to evaluate the control performance. Both simulation and experimental results are provided to demonstrate the proposed current sensorless control method.