A Sensorless Current Feedforward Method for Single-Phase AC–DC Converter

The dynamic performance of the dc bus voltage is crucial to the stable operation of the ac–dc converter. However, the dynamic response of the PI regulator used in the closed-loop control of the ac–dc converter is limited. It is difficult for the ac–dc converter to achieve fast dynamic performance under load disturbances. Introducing load current feedforward to the control loop can address this issue, but it will increase the system costs and hardware complexity. To address this problem, a sensorless current feedforward strategy is proposed in this letter. The proposed strategy extracts the bus voltage ripple amplitude through a phase-locked loop based on the third-order generalized integrator. Then, it estimates the current feedforward on this basis. It can effectively reduce the dc bus voltage fluctuations and enhance the dynamic response of the converter under load variations. Furthermore, the effectiveness of the proposed method is verified through experiments.