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    A proportional-resonant controller-based wireless control strategy with a reduced number of sensors for parallel-operated UPSs

    , Article IEEE Transactions on Power Delivery ; Volume 25, Issue 1 , 2010 , Pages 468-478 ; 08858977 (ISSN) Hasanzadeh, A ; Caglar Onar, O ; Mokhtari, H ; Khaligh, A ; Sharif University of Technology
    Abstract
    In this paper, a novel droop method to control the power sharing of parallel uninterruptible-power-supply (UPS) systems is presented. In a clear-cut contrast to the previously reported works, the controller is a proportional-resonant controller which ensures good transient response and steady-state objectives. Furthermore, the need for sensing the output current for the power-sharing control is removed by implementing it in a software routine. This brings a less complicated and less expensive structure in which the number of feedback sensors is reduced from three to two. The droop paralleling strategy is based on the drop in the inverter output frequency and amplitude. The application of... 

    A fully linear 5.2 GHz - 5.8 GHz digitally controlled oscillator in 65-nm CMOS technology

    , Article Microelectronics Journal ; Volume 90 , 2019 , Pages 48-57 ; 00262692 (ISSN) Heydarzadeh, S ; Torkzadeh, P ; Sadughi, S ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    A low-power fully linear integrated CMOS LC-based Digitally Controlled Oscillator is presented. The DCO operates in 5.2 GHz to 5.8 GHz range for using in IEEE 802.11a wireless applications. The system has been designed using 65 nm CMOS technology and 1.2 V supply voltage. By applying a proposed filter in DCO architecture −133.41 dBc/Hz phase noise at 1 MHz offset frequency from the fundamental carrier is achieved. The code generator and digital to analog converter designed to provide the high precision voltage required for fine-tuning. The output frequency swept through 10 control bits with 100 KHz resolution. The measured RMS jitter (∑ [1 KHz – 2 GHz]) from 5.8 GHz carrier is 1.65 fs. The... 

    A simplified droop method implementation in parallel UPS inverters with Proportional-Resonant controller

    , Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 33, Issue 2 , 2009 , Pages 163-178 ; 10286284 (ISSN) Hasanzadeh, A ; Mokhtari, H ; Sharif University of Technology
    2009
    Abstract
    In this paper, a simpler implementation of the well-known droop method for the control of parallel Uninterruptible Power Supply (UPS) systems is presented. In this method, in the power-sharing control scheme, the output current is calculated by software without the need for a current sensor, resulting in a simpler and cheaper structure. By doing so, the number of feedback sensors is reduced from three to two. The paralleling strategy uses the droop method in which the control strategy is based on the drop in the inverter output frequency and amplitude. The application of Proportional-Resonant (PR) controllers is also extended to parallel inverter and its superior performance over the...