Virtual admittance control scheme of three-phase PWM rectifier under unbalanced input voltage condition

Unbalanced input voltage leads to the increase of harmonic and loss in three-phase PWM rectifier. As the traditional solutions to it have relatively complex structure and large calculation load, a simplified current control under two-phase stationary frame is proposed, which takes the virtual admittance as the key control variable based on the balanced instantaneous power theory of three-phase PWM rectifier under unbalanced input voltage conditions, and applies the generalized integrator to realize zero-steady state error. The virtual admittance control system is designed accordingly. Matlab simulation and experiments verify that, the control strategy can not only realize no-ripple voltage control and real-time controllable power factor under unbalanced three-phase voltage with its stable performance, but also need not to detect three-phase positive and negative sequence ac currents respectively, resulting in the improvement of system speediness. The introduced generalized integrator also has simple discrete iterative algorithm to greatly reduce calculation time.