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An educational studies and understanding about theoretical and practical laboratory in power quality issues. Interline dynamic voltage restorer is used in the proposed system for mitigating voltage sag, swell, harmonics, and interruptions. The conventional topology of dynamic voltage restorer possessing voltage source inverter is modified into a switched coupled inductor inverter which has the clear edge in power transfer over the former one. The versatility of the controller is enhanced in this work by deploying an artificial neural network combined discrete wavelet transform. The artificial neural network and discrete wavelet transform aided pulse width modulation generation enhances the controller performance by mitigating the harmonics considerably. The simulation and experimental results reveal that interline dynamic voltage restorer renders solution for major power quality issues like voltage sag and swell. Interline dynamic voltage restorer-based SCII is implemented with field programmable gate array Spartan 6 controller and signal processing technique such as discrete wavelet transform that mitigates voltage sag and harmonics. Paper is constructed such that the students in Bachelor's and Master's program of Electrical engineering can understand the power quality, various issues, and mitigating the total harmonic distortion value. The equations related to real power transfer are derived which enable the students to clearly understand about the power exchange between the feeders. Further, it is applied in practical laboratory setup facility for understanding about power quality issues to students of both undergraduate and postgraduate courses. [ABSTRACT FROM AUTHOR]

This paper presents the design and experimental results of control of a Shape Memory Alloy (SMA) actuator using Pulse-Width Pulse-Frequency (PWPF) modulation to reduce the energy consumption of the SMA actuator. An SMA wire test stand is used in this research. Based on results of open-loop testing of the SMA wire actuator and parameter analysis of the PWPF modulator, a PWPF modulator is designed to modulate a Proportional plus Derivative (PD) controller. Experiments demonstrate that control of the SMA actuator using PWPF modulation effectively save actuation energy while maintaining same control accuracy as compared to continuous PD control. [ABSTRACT FROM AUTHOR]

The paper develops a new topology for a three phase multilevel inverter with a view to reduce the number of switches in the path of the current. It encompasses a mechanism to reach the desired target voltage and in turn enable the three phase induction motor to operate at the specified speed. The formulation incorporates the theory of an appropriate pulse width modulation strategy to ensure the elimination of higher frequency components of the output voltage. The use of relatively smaller number of carriers in the process of generating the switching pulses serves to enhance the output voltage spectrum. The intriguing merits of the phase disposition over the other modulation schemes enable to arrive at a nearly sinusoidal voltage. The performance obtained from the prototype substantiate the MATLAB based simulation results and establish the ability of the series parallel switched multilevel inverter topology to offer an improved performance for the induction motor. [ABSTRACT FROM AUTHOR]

This paper reports a study aimed at detecting warp breaks in terms of yarn type using a Micro-Electro-Mechanical Systems (MEMS) accelerometer based detection system, which has been described in earlier publications. The MEMS accelerometers were mounted on harness cords of a Jacquard tie. MEMS output acceleration signals were analyzed. The signals were acquired while warp ends were up and at the moment of intentional break with a pair of sharp scissors simulating missing warp ends. The results indicated that MEMS acceleration signals at intentional breaks for continuous filament from standard and high strength fibers could be detected. The break signals of cotton and cotton/polyester spun yarns were undetectable. [ABSTRACT FROM AUTHOR]

This paper investigates the output regulation problem for switched discrete-time systems with output quantization. We adopt the quantized output in feedback controllers and allow each subsystem to have its own quantization density, so that the communication network can be efficiently utilized. By using the different coordinates transformation, the solvability of the output regulation problem is guaranteed under deigned output feedback controllers with the switching signals satisfying a dwell time constraint. In the simulation, a pulse-width modulation driven boost converter model is employed to validate the result. [ABSTRACT FROM AUTHOR]

A new hybrid technique for grid integration of solar photovoltaic system using modified incremental conductance maximum power point tracking algorithm with multi-output converter and multilevel inverter is proposed in the paper. The proposed hybrid technique is the joint execution of improved dolphin echolocation algorithm and gradient boosting decision trees and this way the proposed technique is named as IDE-GBDT technique. The novelty of the proposed work is the dolphin echolocation algorithm, which is integrated by the crossover and the mutation function so it is named as IDE. In the proposed technique, the multi-output converter is the combination of boost converter and switched capacitor function to generate different self-balanced output voltages. The utilization of multilevel inverter in the proposed system provides better quality of output voltage and current waveform thereby reducing the size of passive filters. Also, eliminates the requirement of bulky transformers for grid integration. Multicarrier unipolar phase disposition pulse width modulation technique is employed for triggering the switches of the multilevel inverter. The maximum power point tracking algorithm uses the estimated active power output of the generator as its input and generates command speed so that maximum power is transferred to the dc link. This control system also incorporates a loss minimization approach to minimize the losses in the generator and hence to improve the efficiency of the photovoltaic system. Finally, the performance of the proposed maximum power point tracking control of wind and photovoltaic power generation schemes is executed in Matrix Laboratory/Simulink working platform and the execution is assessed with the existing techniques. The proposed technique is compared with the existing techniques and the observed total harmonic distortion of the proposed technique in all the cases is 0.67%, 0.51%, 0.58%, 0.63%, 0.92%, and 1.03% and the total harmonic distortion is found to be very less compared with existing techniques. [ABSTRACT FROM AUTHOR]

Light-emitting diode-based lighting systems are now applied in both general lighting and automotive lighting. Time-modulated control methods such as pulse width modulation are frequently applied as a dimming method. This paper presents the characteristics of the visibility of the phantom array effect according to luminance, chromaticity and angular field of view. The threshold frequency of the visibility of the phantom array increases in proportion to the logarithm of the luminance of the light source. As the angular field of view of the light source increases, the threshold frequency of the visibility of the array decreases exponentially over a range from 0.125° to 4° in our experimental conditions. The threshold frequency at which the array is visible depends on chromaticity at high light source modulation frequencies. When designing time-modulated light sources, our findings can be applied so as to minimize the phantom array effect. [ABSTRACT FROM AUTHOR]

The popularity of LED-based luminaires has increased enormously in recent years. Every such luminaire consists of several elements including a polymer-based transparent housing, yet some of the ageing aspects of specific luminaire materials have not been investigated. In this paper, we present research aimed at determining the impact of LED lamp powering mode on polymer material deterioration. In the experiment, three LED lamp operating systems based on two different pulse width modulation units and one DC power source were used to induce deterioration in a polymethyl methacrylate sample. Two types of LEDs, white and ultraviolet, were considered as the most significant in terms of the impact on the material. Observations of the surface's morphological changes were performed to enable non-destructive investigation of the degradation of the exposed samples. In order to obtain high roughness detection sensitivity, atomic force microscopy was used. We observed various ageing ratios of the material, despite the fact that total average optical energy for specific wavelengths was equal for all samples. The importance of these findings for designing modern luminaires is discussed. [ABSTRACT FROM AUTHOR]

This paper presents a control methodology that enables nonlinear model-base control of pulse width modulated (PWM) pneumatic position servo control system of a magnetic resonance (MR) compatible needle insertion robot used for MRI-guided prostate brachytherapy. Sliding mode control with a boundary layer is investigated based on the equivalent continuous-time dynamic model. Considering chattering in sliding mode control applications, especially in motion control of the robot, a fuzzy method is developed to tune the boundary layer of the sliding mode controller. Simulation and experimental results indicate that the controller is effective in both position control and trajectory tracking. With the boundary layer increasing, the steady state error of the response is becoming larger; however the maximum error is less than 0.2 mm. This steady state performance meets the accuracy requirement. [ABSTRACT FROM PUBLISHER]

In this paper, a novel hybrid control scheme is proposed to improve the control performance in a real-time pressure tracking system using fast on-off solenoid valves. In this novel hybrid control scheme, an original approach named Time Interlaced Modulation (TIM) is developed to replace the traditional Pulse Width Modulation (PWM) approach. Besides using TIM, a new switching method which is referred as seven possible control modes is designed to ensure the proper switching states of the valves. Moreover, a controller with field programmable gate array (FPGA) is chosen to guarantee the real-time implementation of the control algorithm. All the simulations and experimental results implemented on FPGA verify the feasibility of the hybrid control scheme. [ABSTRACT FROM AUTHOR]

The paper studies the modes of oscillations in control systems which employ pulse width modulation power dispatch techniques in their loops for a wide class of linear time invariant systems. Particular care is taken of the mode of oscillation under which instability can occur. Both bipolar and unipolar pulse width modulation is considered and conditions which produce chaotic behaviour in the plant response are investigated. [ABSTRACT FROM PUBLISHER]

Pulse width modulation for dimming the light output of LEDs has become common. When pulse width modulation is used at low frequencies unwanted visual artefacts including flicker perception and stroboscopic effects may occur. These artefacts need to be avoided or at least reduced to a minimum in order to obtain high user acceptance. In this paper, an optimized phase-shifted pulse width modulation method is described, implemented and validated in a visual experiment. The method is intended to minimize the stroboscopic effect on a reference surface by first optimizing the LED units of a single LED luminaire and then co-optimizing several of these luminaires. The optimized pulse width modulation waveforms are then compared to standard pulse width modulation dimming methods. In the visual experiment, 13 subjects rated the extent of the stroboscopic effect of standard and optimized waveforms in a white painted experimental room. The results indicate that the optimized waveforms are indistinguishable from constant light. [ABSTRACT FROM AUTHOR]

In this paper, fault detection and an isolation technique for an insulated-gate bipolar transistor open-circuit fault in a voltage source inverter are presented. This technique consists of analysing the pole voltage and providing the detection and the location of simple, simultaneous and multiple faults. Open-circuit faults can be detected by sensing the pole voltage of each leg and comparing it with the theoretical one. To improve the calculation speed and reliability of this technique and to avoid false diagnosis alarms, the fault detection and isolation scheme is based on a novel model of pole voltage taking into account the time delays due to the turn-on and turn-off process of the power switches. This method reduces the detection time and is applied for open-loop or closed-loop faults in a transient or steady state. [ABSTRACT FROM AUTHOR]

This paper describes project work in which students must implement a pre-processing approach founded on the Σ-Δ technique, which is traditionally well suited to signal processing applications, for increasing the effective resolution of the digital pulse-width modulator in a voltagemode controlled Buck converter. Simulations in a MATLAB/Simulink environment are first conducted in order to confirm the effectiveness of the approach. Then, experimental results obtained with a low-cost development board are presented and the educational experience is discussed. [ABSTRACT FROM AUTHOR]

Reviews the theory of pulse-width modulated d.c.-d.c. converters for the standard Buck, Boost, Buck-Boost and Cuk converters. Linearization; Normalization; Pulse-width modulation; Small-signal analysis.

A vacuum pressure tracking system with high-speed on-off valves is a discontinuous system due to the discrete nature of high-speed on-off valves. Chamber pressure changes in the system are determined by the mass flow rates during the processes of charging and discharging. Here, a sliding mode controller with an asymmetric compensator based on average mass flow rate is designed for accurate vacuum pressure tracking. The controller output signal is converted into the duty cycles of the high-speed on-off valves via a pulse width modulation pulsing scheme. Owing to the extreme asymmetry of the processes, an asymmetric structure comprising one high-speed on-off valve in the charging unit and three high-speed on-off valves in the discharging unit is applied to weaken the impact of asymmetry. In addition, an asymmetric compensator is also designed to modify the pulse width modulation pulsing scheme to further eliminate the asymmetry. Experimental results indicate that the proposed controller achieves better performance in pressure tracking with the asymmetric compensator overcoming process asymmetry and enhancing system robustness. [ABSTRACT FROM AUTHOR]

This study proposes a novel digital hydraulic valve system using multiple equal size on/off valves and a circulating switching control, with an aim to increase the resolution and the linearity of the digital hydraulic valve systems. The solution is founded on the equal coded valve system concept which represents a recent development in the digital hydraulic valve technology. The circulating switching control algorithm is used to overcome nonlinearities occurring in the typical noncirculating switching control and to decrease the operating frequency of single on/off valves. As a result, a substantial improvement in tracking control performance is demonstrated with 8+8 parallel connected valves. The results verify that compact, robust, and high-performance valve control can be realized. [ABSTRACT FROM AUTHOR]

In digital fluid power, fast switching valve is a potential digital hydraulic component because of less throttling loss, reliability, low price, and so on. But its outlet flow is usually small and discontinuous. In this article, a two-stage proportional flow control valve is presented, in which the main stage is a flow amplifying valve, and the pilot stage consists of several switching valves with pulse width modulation control strategy. Peak and hold technique is adopted to improve the dynamic performance of the pilot stage. Benefits of the proposed configuration are continuous outlet flow and large flow capacity. The valve performance is investigated by theoretical analysis, simulation, and test. It is shown that both poppet displacement and outlet flow fluctuate around a stable value because of the discontinuous pilot flow, but the average outlet flow as well as poppet displacement of the main stage can be approximately proportionally regulated by changing pulse width modulation duty ratio. Average outlet flow of the main stage is an amplification of that of pilot stage. Increasing the average pressure drop not only increases outlet flow but also increases the severity of flow pulsations because pressure fluctuation becomes more serious as the average pressure difference increases. In theory, higher carrier frequency leads to smoother outflow; however, tested outflow profile of the proposed valve at 50 Hz is not significantly smoother than that at 30 Hz. This phenomenon may be due to the asynchrony of the four switching valves and the pressure fluctuations during the testing process. [ABSTRACT FROM AUTHOR]

A method used to determine the harmonic components of the output waveform of a pulse width modulation (PWM) inverter is presented. The method calculates the Fourier coefficients of individual positive and negative pulses of the output PWM waveform and adds them together using the principle of superposition to calculate the Fourier coefficients of the entire PWM output signal. This method allows direct calculation of harmonic magnitudes and angles without having to use linear approximations, look-up tables, or Bessel functions. The method presented is a general method that can easily be extended to various types of multilevel inverters and PWM schemes. [ABSTRACT FROM PUBLISHER]