Adaptive ac filter parameters identification for voltage-oriented control of three-phase voltage-source rectifiers

Abstract

This paper proposes an adaptive voltage-oriented control (VOC) with online ac filter parameters identification for three-phase voltage-source rectifier (VSR). A new method based on adaptive linear neuron (ADALINE) is first designed to identify the ac filter parameters. For accurate identification, the VSR nonlinearity are included in the ADALINE structure. Thereafter, the developed ADALINE is inserted in the VOC to realize an adaptive VOC. Thus, the decoupled terms and the proportional-integral current controller gains are updated online. Finally, the ADALINE ability to track properly the ac filter parameters is investigated by experimental analysis. It shows that the VSR nonlinearity consideration has significant influence on the resistance identification. Compared to the VOC, the enhancement of the proposed adaptive VOC is experimentally proved. The originality of this paper is the building of a VSR model including VSR nonlinearity that is suitable for implementation with ADALINE. This leads to ease implementation and accurate identification.

Grid Voltages Estimation for Three-Phase PWM Rectifiers Control Without AC Voltage Sensors

“…During the learning process, the weight W is adaptively updated to converge toward X. The weight W is updated using the LMS algorithm with the learning rate η [5], [30], [34] in the following way:…”

“…It consists of a control unit and an estimation unit. The control unit based on VOC maintains a constant DC-link voltage under a UPF operation [5]. The estimated parameters θ est , e d,est and e q,est are obtained from the AN estimator through a phase locked loop (PLL).…”

“…Usually, control scheme of the three-phase grid connected PWM rectifier consist of two control loops; one for tracking AC-line currents, and another to regulate the DC-link voltage [5]. To perform this, at least five sensors are generally required; two grid voltage sensors, one DC-link voltage sensor, and two AC-line current sensors [6]- [11].…”

“…The simple structure of the AN estimator offers low computational burden where only three weights are online updated. This leads to easy implementation in low cost DSPs [5], [30]. In addition, its online adaptation and filtering properties ensure robustness against periodic and time-varying disturbances related to the grid voltages.…”

“…19) where ||•|| is the Euclidian norm in n ℜ . From(5) and(6), the following equality can be assumed:…”