Abstract
Digital current controllers have the key impact on the performance of grid-side converters and ac drives. The voltage disturbances are commonly suppressed by enhancing the controller with an inner active resistance feedback. In cases where the switching noise and parasitic oscillations introduce sampling errors, conventional sampling is replaced by the oversampling-based error-free feedback acquisition which derives the average of the measured currents over the past switching period. The time delay introduced into the feedback path creates difficulties in designing the current controller with the active resistance. In this paper, we introduce a novel structure of the current controller, which includes the error-free sampling and the active resistance feedback. Devised structure improves the disturbance rejection by extending the range of permissible values of the active resistance. Controller structure is based on the internal model principles, and it maintains the input step response unaffected. This paper comprises analytical design, the gain setting procedure, computer simulation, and experimental results obtained from an experimental setup with a three-phase inverter, digital controller, and a permanent-magnet synchronous motor.
Highlights
Digital current controllers represent an important part of the inner control loop of both vector-controlled high-performance ac drives [1] and grid-connected inverters and their influence on the overall control system characteristics is profound [2], [3]
The above analysis of the pulse transfer function WORA implies that the introduction of error-free feedback acquisition with improved task scheduling does not reduce the range of applicable active resistance gains
The paper shows that application of active resistance feedback in conjunction with the conventional sampling leads to excessive noise and current ripple in current controlled inverter applications
Summary
Digital current controllers represent an important part of the inner control loop of both vector-controlled high-performance ac drives [1] and grid-connected inverters and their influence on the overall control system characteristics is profound [2], [3]. Disturbance rejection can be significantly improved by using an active resistance feedback [8], at the expense of worsening the input step response This can be circumvented to some extent by increasing the controller integral gain [8]. The final result is a digital current controller which (1) is free of sampling error, (2) contains active resistance feedback, improving the disturbance rejection, and (3) is characterized with a bandwidth commensurate with the current state-of-the-art controllers, without overshoot, and without negative impact of the active resistance feedback on the input step response.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
