PROJECT TITLE :

AC Current Controller with Error-Free Feedback Acquisition System

ABSTRACT:

During this paper, we tend to introduce an improved ac current controller with robustness against the noise in the feedback path. This 3-phase current controller is suited for inverter equipped ac machines and grid-connected power converters. Standard solutions create use of symmetric pulse-width modulation (PWM) techniques with feedback sampling in the center of the voltage pulses. Single-sample-based feedback acquisition gets stricken by the noise and parasitic phenomena. We perform a radical analytical and experimental study on feedback errors with conventional sampling, and we tend to contemplate the impact of the lockout time, motor cables, winding capacitance, and anti-aliasing filters. In order to suppress a vital spectral content in the area of low-order harmonics, we apply an improved acquisition technique, that uses a amount-average and removes any PWM noise from the feedback signals. Both anti-aliasing filter and proposed period-average filter introduce delays, that impair the control-loop performance. The standard current controller is then extended to suppress the effects of the delays. Parameter setting procedure is devised to attain each the bandwidth and therefore the robustness against the parameter changes. Analytical and experimental studies prove that the proposed feedback acquisition technique improves the robustness within the presence of variable delays and switching transients. Experimental tests show that the extended current controller with amount-average feedback acquisition reaches the identical bandwidth and robustness because the state-of-the-art controller.