Acquisition of the Feedback Signals
Closed-loop performance of grid-side inverters and electrical drives depend on the closed-loop bandwidth of digital current controllers, which are used as inner control loop in vast number of cases. The current control is organized on the feedback principles. Thus, it is necessary to measure the output currents for the purpose of closing the feedback and also for the purpose of overcurrent protection. The feedback acquisition chain comprises analogue and digital devices and filters. Their purpose is producing the digital word that represents the output current with the least possible delay and error. The digital word resides within RAM of the digital controller, and it is used for the feedback and protection purposes.