Phase-locked Loop Technique Research Articles

£60M goes to engineering automation

The contribution of solar photovoltaic (PV) in the electrical power sector is increasing expeditiously. Recent interest in the integration of solar PV into the grid raises concerns about the synchronization technique. Continuous research has successfully replaced the small stand-alone system with a grid-tied PV system. A grid-tied PV system is popular due to the abundance of solar light and advanced power electronics techniques. This paper helps to provide a basic conceptual framework to develop a superior grid-tied system. Synchronization is a crucial problem in grid-tied inverters operation and control research indicates that frequency, phase, and amplitude of voltage are the most crucial parameters that need to be measured and controlled for grid-tied application. This paper presents the state of the art of various synchronization methods for both single-phase and three-phase units. A phase-locked loop (PLL) is a popular grid synchronization approach, which needs to sustain power system oscillations as its vulnerability influences the produced reference signal. Traditional PLL catches the frequency and phase through feedback loop-filter (LF) to improve steady-state capability during adverse grid conditions. The review paper focuses on the power stages architecture of PV fed grid synchronization along with a comparison of various PLL techniques based on their merits and demerits. This paper will be the one-stop reference for the researchers in the area of PV-fed grid.

An inexpensive digital crystal thickness monitor

A simple digital type quartz crystal thickness monitor with high sensitivity and good resolution has been designed and fabricated. In the same design another method using the phase-locked loop technique has been provided for the measurement of thickness of the films which can be compared with the value obtained by the digital frequency counter. Both these methods can simultaneously be used for the accurate measurement of the rate of deposition and the total thickness of the films.

Automatic NMR field-frequency lock—pulsed phase locked loop approach

A self-contained deuterium frequency-field lock scheme for a high-resolution NMR spectrometer is described. It is based on phase locked loop techniques in which the free induction decay signal behaves as a voltage-controlled oscillator. By pulsing the spins at an offset frequency of a few hundred hertz and using a digital phase-frequency discriminator this method not only eliminates the usual phase, rf power, offset adjustments needed in conventional lock systems but also possesses the automatic pull-in characteristics that dispense with the use of field sweeps to locate the NMR line prior to closure of the lock loop.

Digital Speed Control of a DC Motor With Phase-Locked Loop Regulation

This paper describes a digital speed control method of a rectifier-fed separately excited dc motor incorporating phase-locked loop technique. The converter uses cosine-wave crossing method, the digital version of which is generated by programming a set of read-only-memories (ROM). The smooth control of firing angle in the range of 0° to 180° permits motoring and regeneration in the full range, and four-quadrant operation is possible by reversing to motor field. A complete speed control system employing a 3/4-hp motor has been designed and tested in the laboratory and the experimental results agree wel1 with the theory. The principle can be easily extended to a three-phase system and higher horse power drives.

A Modular Michelson Interferometer for Fourier Transform Spectrochemical Measurements from the Mid-Infrared to the Ultraviolet

A versatile Michelson interferometer system capable of Fourier transform spectrochemical measurements from the uv to the mid-ir has been developed in our laboratory. Laser fringe referencing is used in the interferometer system to sequence digitization and the velocity of the air bearing mirror drive system is controlled with the laser fringe signal using phase-locked loop techniques. Interferograms can be time averaged under white light interferogram control. The modular design of the interferometer is such that the detector, beamsplitter, and source can all be changed and the interferometer realigned in a matter of a few minutes. Interferograms are acquired and transformed with a PDP 11 minicomputer. This system is described in detail and its application to spectrochemical measurements in the mid-ir and uv-visible is briefly illustrated.

Phase-locked loop techniques applied to ultrasonic Doppler signal processing

A new method of measuring blood flow velocity and acceleration using analogue and phase locked loop techniques is described. Instantaneous peak velocity, instantaneous mean velocity and acceleration can be obtained on-line and displayed on simple recording systems.

A Phase-Locked Loop Motor Control System

This paper describes a motor control circuit for a dc motor using phase-locked loop techniques. The purpose of such a control loop is to provide very accurate speed control, repeatability, and synchronization capability.

Comparison Of Physical Modelling And CADRepresentation Of Compensated RailwaySystems

Comparison Of Physical Modelling And CADRepresentation Of Compensated RailwaySystems

Frequency-selective integrated circuits using phase-lock techniques

A system-oriented approach to the design of inductorless tuned integrated circuits is described. This design method uses the phase-locked loop (PLL) techniques to obtain the desired tuning and interference-rejection characteristics. The PLL approach does not require tight control of component tolerances, and offers a higher selectivity and frequency capability than the corresponding active-RC synthesis methods. In this paper, basic design parameters for phase-locked integrated circuits are given, and two separate design examples are described. First is a high- frequency (1 to 25 MHz) FM amplifier/detector, which forms a monolithic replacement for the IF strip and the detector sections of a conventional FM receiver or TV sound system. The second is an integrated FM multiplex receiver for multi-channel telemetry applications, which has the selectivity of a 6-pole bandpass filter and can be tuned by means of an external resistor or capacitor from a fraction of a cycle to over 300 kHz.

A proposed spacecraft-to-earth communications link: The unified carrier approach

Unified carrier, range tracking and communications system using phase-locked loop techniques for coherent spacecraft-to-Earth communications