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Clock signal and its attribute for agriculture
Published in Govind Singh Patel, Amrita Rai, Nripendra Narayan Das, R. P. Singh, Smart Agriculture, 2021
A PLL is an electronic circuit used to produce a signal that maintains the phase in synchronization to the phase reference clock. This device (PLL) consists of a variable frequency generation setup, namely voltage-controlled oscillator, a phase locator, charge pump and clock divider in the feedback path. The phase locator produces a comparison between the input signal and the phase of the reference signal received from the oscillator. The phase locator output is fed into the charge pump circuit, which steps down the charging direction. The production of charge pump goes up for high input and low for low information (Weste and Harris 2011; Prakash and Hiremath 2017; Pahlevan et al. 2019). The analog output of the charge pump provides an initial voltage to generate frequency. Frequency of VCO oscillator automatically adjusts the frequency of the oscillator to keep both in phase.
Distributed Generation and Microgrids
Published in Vinod Kumar, Ranjan Kumar Behera, Dheeraj Joshi, Ramesh Bansal, Power Electronics, Drives, and Advanced Applications, 2020
Vinod Kumar, Ranjan Kumar Behera, Dheeraj Joshi, Ramesh Bansal
The PLL involves the phase detector, loop filter, and voltage-controlled oscillator. The system descriptions are as follows: Phase detector (PD): The PD is used to detect the phase of the signal. The PD compares the input signal and the reference signal, which generates the proportional output signal. This output signal of PD is a high-frequency sinusoidal component that appears with the DC phase-angle difference signal.Loop filter (LF): The main work of the LF is to provide a low-pass filtering characteristic to attenuate the output signal of the PD. Moreover, the LF block constitutes a PI controller or first-order low-pass filter.Voltage-controlled oscillator (VCO): The VCO generates the oscillated AC signal whose oscillation frequency is controlled by the output of the LF signal.
A wide-tuning frequency range DLL-based clock generator
Published in Artde D.K.T. Lam, Stephen D. Prior, Siu-Tsen Shen, Sheng-Joue Young, Liang-Wen Ji, Smart Science, Design & Technology, 2019
Almost all electronic systems have a clock generator [1], and the clock generator determines the speed of the whole system, a good clock generator can greatly improve the performance and adaptability of the system. There are two ways to implement the general clock generator. One is to use the crystal oscillator. The other is to use the circuit technique and the crystal oscillator to realize the high speed and wide-tuning range of the clock generator. The crystal oscillator only generates a single frequency, which is only suitable for low-speed and simple systems. Generally, circuit techniques are used to improve output frequency of the crystal oscillator in order to make the system more high-speed and flexible. The circuit implementations are mostly divided into two methods .One is Phase Locked Loop (PLL)[2-3] the other is realized by using Delay-Locked Loop (DLL)[4-6] .The implementation of PLL has the advantages of high speed, easy to change the output frequency, and has many applications. Compared with the PLL-based clock generator, the DLL has many advantages, such as smaller area, faster locking time, unconditional loop stability and better performance of clock jitter. Therefore, in recent years, DLL is often used to replace PLL.
Photovoltaic generator coupled on the electrical grid via an inverter
Published in International Journal of Ambient Energy, 2022
Hajer Khabou, Mansour Souissi, Abdelouhab Aitouche
To synchronise the PV inverter with the grid and make them in same phase angle, a phase locked loop (PLL) controller is the most widely used synchronisation technique [Golestan, Monfared, and Freijedo 2013]. This PLL has a quadratic voltage of the utility grid as an input and a phase angle as an output which can be used in Park transform to generate d-q components. As shown in Figure 2, a basic PLL consists of three building blocks: a phase detector (PD) which represents the main difference among the proposed PLLs in literature, a loop filter (LF) and a voltage-controlled oscillator (VCO) [Golestan, Monfared, and Freijedo 2013; Tsai, Tu, and Su 2008]. The PLL uses a feed-back PI-control loop to eliminate the phase error between the PLL output and the grid phase [Kamarzaman and Tan 2014].
Multi-stage Fractional-order Controller for Frequency Mitigation of EV-based Hybrid Power System
Published in IETE Journal of Research, 2022
Zahid Farooq, Asadur Rahman, Shameem Ahmad Lone
PLL is a control system that creates an output signal with the same phase as an input signal. Frequency measurement is a big concern in the power system that can be attained by phase-locked loop. PLL is modelled mathematically by a first- or second-order transfer function model [35], presented in Figure 4. PLL is made up of (i) phase detector (PD), which produces an output based on the phase variance among the input and the PLL produced signals; (ii) loop filter (LF), which helps reduce high-frequency from AC signals; and (iii) voltage-controlled-oscillator (VCO) that creates AC output signal and deviates its frequency from nominal frequency which is an LF function. The PD and VCO gains are taken as unitary values, which leads to the transfer function for open loop and closed loop given as (2) and (3) [35], The normalized form of Equation (3) can be written as (4) follows [35]: where is the natural frequency and is the damping coefficient.
Performance Analysis of Maximum Power Point Tracking for Two Techniques with Direct Control of Photovoltaic Grid -Connected Systems
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Bahaa Saleh, Ali M. Yousef, Farag K. Abo-Elyousr, Moayed Mohamed, Saad A. Mohamed Abdelwahab, Ahmed Elnozahy
PLL is the instantaneous phase angles detected by synchronizing the PLL rotating reference frame to the utility voltage vector. The PLL is a control system that generates an output signal whose phase is related to the phase of an input signal. There are several different types of PLL circuits; the simplest is an electronic circuit consisting of a variable frequency oscillator and a phase detector in a feedback loop. The oscillator generates a periodic signal, and the phase detector compares the phase of that signal with the phase of the input periodic signal, adjusting the oscillator to keep the phases matched. To control the voltage at the inverter via the PI and H∞C, a current regulator and VDC regulator (voltage source control) are employed as presented in Figure 10c and 10d, respectively.