AC current sensorless control of three-phase three-wire PWM rectifiers under the unbalanced source voltage

This paper proposes an AC current sensorless control strategy for a PWM rectifier under the unbalanced source voltage. In the unbalanced system, if we use the traditional control scheme, it will yield large input current harmonics and dc-link voltage ripples due to the effect of the negative components. Meanwhile, in the ordinary control methods, at least two current sensors are needed to test the phase current, which increases the system's cost and reliability. This paper's control objective is to balance the input current and minimize the dc-link voltage ripples of the three-phase three-wire boost rectifier without the AC current sensors in the case of the unbalanced situation. The control is implemented in the positive SRF, and notch filters will be applied. The two AC current sensors will be replaced by only one current sensor, which is expected to test the dc-link current. The feasibility of the method has been confirmed through computer simulations.