Direct power control with virtual flux estimation for three-phase PWM rectifiers

A new method of virtual flux (VF) based instantaneous power estimation without line voltage sensors is proposed. The new solution is employed in the direct power control (DPC) of three-phase PWM rectifiers. Theoretical principles, steady-state operation and dynamic performance of the DPC with VF-based power estimation are presented and compared with the conventional voltage-based estimation. Both power estimators are investigated under purely sinusoidal as well as unbalanced and distorted line voltages. Computer simulations and laboratory experiments have shown that the new method offers significant advantages. In particular, it results in a sinusoidal current even when the supply voltage is far from ideal.