Enhancement of DC-Bus Voltage Regulation in Totem-Pole Bridgeless PFC by a New Sensorless Load Current Feedforward Control Scheme

This paper aims to solve the dynamic performance problem of the totem-pole bridgeless PFC converter when the output voltage or load varies over a wide range, and proposes an improved control strategy to enhance the system's disturbance immunity and dynamic response performance. In order to reduce the hardware complexity and lower the system cost, a second-order sliding mode observer is used to estimate the load current and the stability is proved. The results show that with the addition of the notch filter, the system can effectively suppress the interference of the second harmonic and ensure the dynamic response speed of the voltage loop without affecting the harmonic content of the input current. The dynamic performance of the system against load disturbances is significantly improved by the load current feed-forward control strategy. The application of second-order sliding mode observer simplifies the hardware design, reduces the system cost, and has a good performance in load current estimation. Simulation experimental results verify the effectiveness of the proposed method.