11Renewable Energy Research Center, Faculty of Electrical Engineering, Sahand University of Technology, Tabriz, Iran
22Department of Electrical Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
This paper presents a comparative analysis between two current control strategies, constant source power and generalized Fryze current, used in Active Power Filter (APF) applications having three different modulation methods. The Hysteresis Band (HB) and first-order Delta-Sigma Modulation (DSM) as well as the second-order DSM is applied. The power section of the active power filter is viewed as an Analogue to Digital Converter (ADC), then as a result a three-phase shunt active filter modulator controller which, uses Delta-Sigma analogue to digital converter is presented to improve modulator performance. As a result, using second-order Delta-Sigma modulator makes low switching rate compared with first-order Delta-Sigma and hysteresis modulators under same sampling frequency. So, applying this modulator increases system efficiency and reduces cost of switches. In addition, simulation results on MATLAB software show that by using the Delta-Sigma modulator, Total Harmonic Distortion (THD) can be significantly decreased. Moreover, active filter based on the second-order DSM with constant source power has high efficiency and provides lower source current THD.