AC Voltage and Current Sensorless Control of Three-Phase PWM Rectifiers

In this paper, a novel control scheme of three-phase PWM rectifiers eliminating both the ac input voltage and current sensors is proposed. The phase angle and the magnitude of the source voltage are estimated by controlling the deviation between the rectifier current and its model current to be zero. The input currents can be reconstructed from switching states of the PWM rectifier and the measured dc link currents. To eliminate the calculation time delay effect of the microprocessor, the currents ahead one sampling period are estimated by a state observer and then are used for feedback control. The proposed control scheme reduces the system cost and improves its reliability. The feasibility of the proposed ac sensorless technique for three-phase PWM rectifiers has been verified through experiments using a high performance DSP chip.