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Phase Locked Loop Design
Published in Mike Golio, Commercial Wireless Circuits and Components Handbook, 2018
The phase detector produces an output signal that is proportional to the phase difference between the reference input, ϕref, and the phase of the divided down VCO signal, ϕo/N. The most commonly used phase detector is a phase-frequency detector. In an out-of-lock condition, the output of the phase-frequency detector latches (i.e., the AC component is removed), thereby the error signal goes to the low or high rail, depending upon the direction of phase error. The phase detector having the ability to perform frequency discrimination has greatly simplified the complexity of the PLL circuitry. In much of the literature written on PLL design, the analog phase detector is addressed. With the advent of VLSI design, the digital phase detector is most favored. There are three basic types of digital phase-frequency detectors: (1) the charge pump, (2) the proportional or pulse width modulated, and (3) the pseudo-differential.
AC/DC Grid Interface Based on the Three-Phase Voltage Source Converter
Published in Dorin O. Neacsu, Switching Power Converters, 2017
Let us consider a synchronization scheme based on a PLL circuit. A generic PLL circuit schematic is shown in Figure 13.45 and it is composed of a voltage-controlled oscillator (VCO) working at a frequency multiple of N times the detected frequency. In power converters, it makes sense to select the VCO frequency equal to the sampling frequency of the PWM pattern (Figure 13.46). The resulting train of pulses is divided by N resulting in a logic signal with a frequency comparable with the sensed voltage. A phase detector compares the phase of the sensed and feedback voltages and it increases or decreases the control voltage accordingly. This control voltage is used as a reference for the VCO that modifies its frequency based on the phase difference. The goal of this closed-loop approach is to align the sensed signal with the generated one. If the frequency or phase of the sensed signal varies for any reason, this control loop acts as a filter and the feedback signal does not jitter. The feedback signal can further be used as a reference for the generation of the PWM pattern. Usually, the same counter is used both for closing the PLL loop and for counting the angular coordinate of the PWM pattern.
Distortion and Modulation Effects in RF Power Amplifiers
Published in Abdullah Eroglu, Linear and Switch-Mode RF Power Amplifiers, 2017
When two signals of identical frequencies are applied to a mixer, it produces a DC component at the output, which has a sinusoidal relationship to the phase difference of the two signals as shown in Figure 8.16. This, in essence, corresponds to using mixer as a phase detector. DC component produced at the output of the mixer depends on magnitudes and relative phase of two sinusoids. In the proposed system, the sum product will be filtered off; so the DC component is the wanted product. Therefore, the resulting DC component seen at IF port is a function of both the phase and magnitude of the driving signals. As the phase of one of signal is swept, the resulting DC values at the IF port will trace out a sinusoid as shown in Figure 8.17.
Mixed third-fourth order generalised integrator based PLL for grid integration of solar photovoltaic systems
Published in International Journal of Ambient Energy, 2023
Ojaswini A. Sharma, Amit V. Sant
The a-b-c to d-q-0 and d-q-0 to a-b-c transformations are the crucial part of the VOC. The information regarding the instantaneous phase angle of the fundamental positive sequence component of the grid voltage, ω1t, measured at the PCC is essential to carry out these transformations. The use of PLLs to extract this information is very common (Chung 2000). PLL is a closed-loop control system that consists of three basic components, (i) phase detector, (ii) loop filter, and (iii) voltage-controlled oscillator. The phase detector compares and generates the error signal by comparing the desired and measured phases. The error signal is then provided to the loop filter, where the control signal for minimising the error is generated. This control signal is then supplied to the voltage-controlled oscillator, causing the output waveform to be in-phase with the desired waveform. Lately, SOGIs are widely being employed for the extraction of ω1t. Compared to other PLLs, SOGIs offer the benefits of computational simplicity and ease of implementation. The SOGIs work on the principle of generalised integrators to determine the quadrature component of the signal. GI leverages the simple concept of phase shift associated with integration. MTFOGI-PLL, developed based on SOGI, is reported in this paper. A detailed discussion on MTFOGI-PLL is provided in the following sections.
Design and Development of FM and PM Receivers Using Autocorrelation Technique
Published in IETE Journal of Research, 2022
Tosicul Wara, Karri V. R. Dinesh Kumar Reddy, Usha Bhandiwad
For FM signal:For PM signal: The frequency mixer which acts as a phase detector may be either unipolar type or bipolar type. For a bipolar phase detector, the detector gain, , may be either positive or negative depending on the operating or quiescent value of the input phase difference, . Consequently, the detector output voltage may also be positive or negative. Therefore, the recovered baseband signal, , at such receiver output will be either in phase or out of phase of the original baseband signal, Consequently, the amplitudes of the demodulated signal, i.e. the baseband signal at the receiver’s output, could be re-written as follows:
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.