Improvement In Rise Time Research Articles

System Simulation Comparison of Sliding Mode and PID Controller for Buck Converter

In this paper, the performance of the closed loop sliding mode controller (SMC) is compared with the conventional PID controller for DC-DC buck converter. We specifically address the comparison of the two controllers from system simulations point of view by first developing the system model of the DC-to-DC buck converter circuit and designing a suitable SMC controller.Using MATLAB/SIMULINK system simulations, the performance of the SMC controlled buck converter is compared with the PID controller in terms of the overshoot, rise time and settling time of the load voltage and currents. The simulation results demonstrated the high performance of the SMC controlled buck converter in accurately tracking the reference voltage, eliminating the overshoot, improving the settling time but with slower rise time as compared with the PID controller. The transient time response of the SMC controller can be further improved by tuning the system control parameters to attain improved rise time. Such SMC based buck converter can be used for the design of a stable direct current power supply for DC loads such as DC motors used for water pumps or other applications.

A new method for controlling an induction motor using a hybrid discretization model predictive field orientated control.

The dynamic performance of the Model Predictive Control (MPC) of an Induction Motor (IM) relies on the accuracy and computational efficiency of the Discretisation Technique (DT). If the discretisation process is inaccurate or slow approximation, the MPC will exhibit high torque ripple and lower load handling capabilities. Traditionally, Euler’s method is used to discretise the MPC, which merely relies on the predictor to yield a fast, but less accurate system approximation. In contrast, Heun’s method uses a combination of predictor and corrector at alternate sampling intervals to improve the discretisation accuracy; however, the controller response becomes slow due to increased computational intensity of the algorithm. In this study, a new Hybrid Discretisation Technique (HDT) for Model Predictive Field Oriented Control (MPFOC) for IM control systems is presented to achieve robust discretisation with improved accuracy. In the proposed approach, Euler’s method is used to discretise the system at the first nine samples, followed by the predictor-corrector at the tenth sampling interval, accomplishing the desired speed and accuracy of discretisation. This newly proposed HDT in MPFOC is verified with Processor-In-Loop (PIL) for a three-phase IM with bi-directional rotation under varying load conditions. The results indicate that the IM torque ripple is reduced by up to 20%, whereas, the load handling capability is increased by up to 10%. Moreover, the controller gives 20% and 23% improvement in rise time and settling time, respectively, under high loading conditions, as compared to traditional Euler and Heun methods.

Fractional order PID controlled quasi Z-source inverter with front-line semiconductor material made of power electronics switches fed PMSM motor for EV applications

In the area of control theory, conventional PID controller is most commonly used for various applications to bring out the output of the system at higher efficacy. Now due various technological advancements, PID controller is derived into various advanced controllers. In the advancement of PID controller, there is a controller called Fractional Order PID controller which used widely in industrial applications. The advancement o9f classical integer order PID controller is the FOPID controller. This paper deals with the control of PMSM by FOPID controller. In this work, different control strategies such as Proportional Integral (PI) controller, and Fractional Order Proportional Integral Derivative (FOPID) controller is exploited to sustain the constant yield motor speed of the quasi z-source with 3-phase inverter fed PMSM drive. Also, the source disturbance is introduced to analyze the performance of quasi z-source with 3-phase inverter fed PMSM driven by different controllers. The implementation of FOPID controller will gives out the enhanced response in Quazi Z source inverter fed PMSM. The closed loop system with the FOPID controller has reduced steady state error, improved rise time, settling time and the peak time, when compared with the closed loop system with PI controller. The simulation has been done utilizing MATLAB Simulink software. As discussed, outcomes reveal that the quasi z-source with 3-phase inverter fed PMSM driven by the FOPID-FOPID controller has good-performance such as transient response etc., when compared to the PI-PI controller. Material properties affect the performance and efficiency of power electronic switching devices in three phase inverter circuits. These are generally silicon switches. To increase material technology and performance, switching devices employ wide band-gap semiconductors. This paper also examines the optimal semiconductor material utilized in the three-phase inverter circuit's power electronic switches.

Performance enhancement of ZnGa2O4 Schottky type deep-ultraviolet photodetectors by oxygen supercritical fluid treatment

For semiconductor device applications such as FinFET, MEMS, 2D materials, and wide bandgap materials, reliability is one of the most powerful key factors for commercialization in the industry. ZnGa2O4 deep ultraviolet (DUV) photodetectors (PDs) have been studied for their reliability and hence have been examined using the accelerated life test (ALT), which has shown the poor reliability of the device and device degradation such as high leakage current and poor rise time falling time (Tr/Tf) ratios. Therefore, in this paper, we proposed a method to enhance device performance by a non-destructive post-treatment method with low temperature and high-pressure oxygen supercritical fluid (SCF-O) for DUV photodetectors. This method not only improved the device performance but allowed it to perform even better than the as-grown sample. X-ray photoelectron spectroscopy, X-ray diffraction, and atomic force microscope analyses corroborated better crystallinity with a smaller number of interstitial defects followed by mathematical modelling using density functional theory. The on/off ratio increased from 102 to 105 and had an improved rise time and fall time ratio (Tr/Tf). The responsivity for the SCF-O treated ZnGa2O4 PDs (@240 nm) increased to 639 A/W as compared with that (486 A/W) of as-grown sample. The first-principles DFT-GGA calculations were used to explain the relationship between the formation energies of defects in the oxygen treatment on the ZnGa2O4 epitaxial layers and agreed well with the experiment results. As per our knowledge, our study was the first to present this post-treatment method for DUV photodetectors, which could increase the lifetime of semiconductor devices.

Interferometric measurements of supersonic projectile acoustic signatures

Supersonic projectiles cause disturbances in the air that propagate and coalesce to form acoustic signatures. In the far-field, these signatures approach ideal N-waves. However, near the projectile these signatures are closely related to the projectile's shape. To study the generation and formation of acoustic signatures from supersonic projectiles, an experiment was conducted using optical methods. A z-type schlieren imaging system and laser interferometer were used in conjunction with acoustic sensors to measure the pressure field surrounding supersonic projectiles of various sizes and shapes. The rate of change of the phase difference recorded by the interferometer is inverted to obtain the ballistic pressure field by assuming cylindrical symmetry and using an inverse Abel transform. The accuracy of these reconstructed time series is evaluated by comparing N-wave parameters, such as period and peak pressure, with analytical results derived from the Whitham F-function. Improved rise time resolution obtained from the interferometric measurement is demonstrated by comparison with recordings from standard condenser microphones. Advantages of measuring acoustic signatures near the projectile by interferometric methods are discussed.

An Agile Supply Modulator With Improved Transient Performance for Power Efficient Linear Amplifier Employing Envelope Tracking Techniques

This article presents an agile supply modulator with optimal transient performance that includes improvement in rise time, overshoot and settling time for the envelope tracking supply in linear power amplifiers. For this purpose, we propose an on-demand current source module: the bang–bang transient performance enhancer (BBTPE). Its objective is to follow fast variations in input signals with reduced overshoot and settling time without deteriorating the steady-state performance of the buck regulator. The proposed approach enables fast system response through the BBTPE and an accurate steady-state output response through a low switching ripple and power efficient dynamic buck regulator. Fast output response with the help of the added module induces a slower rise of inductor current in the buck converter that further helps the proposed system to reduce both overshoot and settling time. This article also introduces an efficient selective tracking of envelope signal for linear PAs. To demonstrate the feasibility of the proposed solution, extensive simulations and experimental results from a discrete system are reported. The proposed supply modulator shows 80% improvement in rise time along with 60% reduction in both overshoot and settling time compared to the conventional dynamic buck regulator-based solution. Experimental results using the LTE 16-QAM 5 MHz standard shows improvement of 7.68 dB and 65.1% in adjacent channel power ratio (ACPR) and error vector magnitude (EVM), respectively.

HYBRID ITERATIVE LEARNING CONTROL FOR POSITION TRACKING OF AN ELECTRO HYDRAULIC SERVO SYSTEM

Accurate position control of an electro hydraulic servo system (EHSS) is a challenging task due to inherent system nonlinearities, parametric variations and un-modelled dynamics. Since feedback controllers alone cannot provide perfect tracking control, an integration of feedback and feed forward controller is required. A cascaded iterative learning control (ILC) technique for position control of EHSS is proposed in this paper. ILC is a feed forward controller which modifies the reference signal for a feedback fractional order proportional-integral-derivative (PID) controller by learning through current control input and previous error obtained through trails. Unlike other feed forward controllers, ILC works on signal instead of system which eliminates the need of complete knowledge of the system. As compared to other controllers, the proposed technique provides fast convergence without the need of reconfiguring the existing control loop. Simulation and experiments revealed the effectiveness of the proposed technique for EHSS. The obtained results indicated eight percent improvement in rise time and nearly twenty one percent improvement in the settling time.

Translucent Photodetector with Blended Nanowires-Metal Oxide Transparent Selective Electrode Utilizing Photovoltaic and Pyro-Phototronic Coupling Effect.

ZnO is a potential candidate for photodetection utilizing the pyroelectric effect. Here, a self-biased and translucent photodetector with the configuration of Cu4 O3 /ZnO/FTO/Glass is designed and fabricated. In addition, the pyroelectric effect is effectively harvested using indium tin oxide (ITO), silver nanowires (AgNWs), and a blend of AgNWs-coated ITO as the transparent selective contact electrode. The improved rise times are observed from 1400 µs (bare condition; without the selective electrode) to 69, 60, 7 µs, and fall times from 720 µs (bare condition) to 80, 70, 10 µs for corresponding ITO, AgNWs, and AgNWs-coated ITO contact electrodes, respectively. Similarly, the responsivity and detectivity are enhanced by about 4.39 × 107 and 5.27 × 105 %, respectively. An energy band diagram is proposed to explain the underlying working mechanism based on the workfunction of the ITO (4.7 eV) and AgNWs (4.57 eV) as measured by Kelvin probe force microscopy, which confirms the formation of type-II band alignment resulting in the efficient transport of photogenerated charge carriers. The functional use of the transparent selective contact electrode can effectively harness the pyro-phototronic effect for next-generation transparent and flexible optoelectronic applications.

Rise-Time Improvement in Bipolar Pulse Solid-State Marx Modulators

This paper presents the effect of stray capacitances in bipolar (negative and/or positive) pulses generated by the two different topologies of the solid-state Marx modulators. According to the analysis, the stray capacitances influence the energy transfer from the Marx modulator capacitors to the load affecting the bipolar (negative and/or positive) pulse rise time. This paper deals with the structure design to reduce the influence of the stray capacitance and to improve the pulse rise time of these bipolar solid-state Marx modulators. A four-stage laboratory prototype of the two topologies has been assembled using 1200-V insulated gate bipolar transistors and diodes, operating with 1000-V dc input voltage and 1-kHz frequency, producing 4-kV bipolar pulses, with 5-μs pulse duration and 120-ns rise time, into a resistive load.

Speed Control of Permanent Magnet Brushless DC Motor Using Hybrid Fuzzy Proportional plus Integral plus Derivative Controller

The main core of this work is to investigate two different digital controllers (Conventional PID Controller and Hybrid Fuzzy PID) on closed loop control of Permanent Magnet Brush Less Direct Current (PMBLDC) Motor. The application of intelligent control (fuzzy logic) technique is attempted in a Proportional –Integral- Derivative (PID) controller for tuning their parameters automatically in an online process. In-order to achieve desired speed, Hybrid Fuzzy-PID provides the finest set of solutions. The conventional PID controller and Hybrid Fuzzy-PID controller performances are analyzed both in steady state and dynamic operating condition with various set point speeds. The rise time, dead time, settling time and steady state error are the parameters considered for comparison. The results prove that, the Hybrid Fuzzy-PID controller offers better performance (Improvement in rise time, Reduction in settling time, No steady sate error) over the conventional PID controller. The simulation makes use of LabVIEW Fuzzy–PID tool and it is implemented in real time through NI-DAQ 6009 with PMBLDC motor which is rated at 36V, 4A, 4000 RPM.

Intelligent Control of Electroactive Polymer Actuators Based on Fuzzy and Neurofuzzy Methodologies

Conjugated conducting polymer actuators, especially those based on polypyrrole (PPy), possess enormous potential for the creation of biomimetic devices, single-cell manipulators, numerous biomedical applications as well as robotics and prosthetics. This is due to their low actuation voltage, ability to operate at the macro- or microscale, large force-to-weight ratio, biocompatibility, low cost and their operation in aqueous and nonaqueous environments. This paper experimentally investigates the potential of intelligent control methodologies to improve the positional accuracy and response speed of trilayer PPy actuators. Two intelligent control techniques were designed and implemented—fuzzy logic PD+I control and neurofuzzy adaptive neural fuzzy inference system (ANFIS) control, which are fundamentally model-free control techniques. The performance of these controllers was compared to that of a conventional proportional integral derivative (PID) controller. It was found that the two intelligent control schemes significantly outperformed the conventional PID controller in both step and dynamic responses, with an improvement in rise time of at least 18 times and in settling time of at least two times. This study is the first to implement and compare fuzzy logic PD+I and neurofuzzy ANFIS PD+I intelligent control methodologies with a classical PID controller to the emerging field of conducting polymer PPy actuators and lays the groundwork for their use in functional devices.

Bioreactor profile control by a nonlinear auto regressive moving average neuro and two degree of freedom PID controllers

This paper presents the use of nonlinear auto regressive moving average (NARMA) neuro controller for temperature control and two degree of freedom PID (2DOF-PID) for pH and dissolved oxygen (DO) of a biochemical reactor in comparison with the industry standard anti-windup PID (AWU-PID) controllers. The process model of yeast fermentation described in terms of temperature, pH and dissolved oxygen has been used in this study. Nonlinear auto regressive moving average (NARMA) neuro controller used for temperature control has been trained by Levenberg–Marquardt training algorithm. The 2DOF-PID controllers used for pH and dissolved oxygen have been tuned by MATLAB's auto tune feature along with manual tuning. Random training data with input varying from 0 to 100l/h have been obtained by using NARMA graphical interface. The data samples used for training, validation and testing are 20,000, 10,000 and 10,000 respectively. Random profiles have been used for simulation. The NARMA neuro controller and the 2DOF-PID controllers have shown improvement in rise time, residual error and overshoot. The proposed controllers have been implemented on TMS320 Digital Signal Processing board using code composure studio. Arduino Mega board has been used for input/output interface.

Intelligent Control of Twin-Rotor MIMO System Using Fuzzy Inference Techniques

The flight control system of helicopter is difficult to control for their performance of high-order unstable, nonlinear, and multiple-inputs multiple-outputs (MIMO) system. The behavior of two degree-of-freedom (2-DOF) helicopter has significant cross-coupling between pitch and yaw directional motions. This study presents a control system for a 2-DOF helicopter plant which more specific presented as twin-rotor MIMO system by using fuzzy logic technique. Fuzzy logic controller (FLC) is designed by using MATLAB to improve the performance of flight control system. Thus, the designed pitch and yaw controller are tuned by adjusting the range of membership function of input variable and the number of fuzzy rules used. The designed FLC are implemented and the results of the simulation are compared with LQR controller. The proposed pitch fuzzy controller shows improvement in rise time from 0.607sec to 0.458s, settling time from 7.188s to 1.866s, and percent overshoot from 38.1% to 0% over the existing pitch LQR controller. Meanwhile, the proposed yaw fuzzy controller shows improvement in rise time from 1.361s to 0.828s, settling time from 9.120sec to 2.517 s, and percent overshoot from 23.51% to 2.86% over the existing yaw LQR controller. Hence, the simulation results show that FLC has great potential than LQR controller for the flight control system.

CONVERSION OF IMPULSE VOLTAGE GENERATOR INTO STEEP WAVE IMPULSE TEST-EQUIPMENT

This paper demonstrates the alternative measures to generate the Steep wave impulse by using Impulse Voltage Generator (IVG) for high voltage testing of porcelain insulators. The modification of IVG by incorporating compensation of resistor, inductor, and capacitor has been achieved and further performance of the modified system has been analyzed by applying the generated lightning impulse and analyzing the electrical characteristics of impulse waves under standard lightning and fast rise multiple lightning waveform to determine the effect to improve rise time. The advantageous results have been received and being reported such as increase in overshoot compensation, increase in capacitive and inductive load ranges. Such further reduces the duration of oscillations of standard impulse voltages. The reduction in oscillation duration of steep front impulse voltages may be utilized in up gradation of Impulse Voltage Generator System. Stray capacitance could further be added in order to get the minimized difference of measurement between simulation and the field establishment.

Real-time implementation of grey fuzzy terminal sliding mode control for PWM DC–AC converters

Classical terminal sliding mode control (TSMC) has finite system state convergence time and is insensitive to disturbances and uncertainties within expected limits. However, TSMC may chatter when uncertainty values are overestimated or may exhibit a steady-state error when uncertainty values are underestimated. An improved TSMC is proposed by the use of a mathematically simple and computationally fast grey prediction (GP) methodology, which is then fine-tuned by the use of fuzzy control methodology for PWM DC–AC converters. First, GP methodology is employed to deal with classical TSMC chattering and steady-state error problems. Fuzzy control is then used to tune the GP forecasting value for improved rise time and overshoot characteristics. The system is evaluated by simulation and also by real experiment. Both evaluation methods confirm that the proposed controller achieves low total harmonic distortion under non-linear loading conditions and fast dynamic response under transient loading conditions. Because the proposed grey-fuzzy TSMC methodology is simpler to implement than prior methods and offers more efficient computation, it will be of interest to designers of related control systems.

Optimal Fuzzy Control Design Using Simulated Annealing and Application to Feedwater Heater Control

A methodology for designing membership functions for fuzzy controllers has been developed and demonstrated with application to feedwater heater level control. This method, namely simulated annealing, assumes that the rule base is determined by an expert who is knowledgeable about the process to be controlled. Although this method is applicable to any type of fuzzy controller, max-min center-average fuzzy controllers with triangular and trapezoidal membership functions were used due to the ease of implementation of this combination. This method essentially performs a random search for the parameters of the membership functions that yield the minimum squared error between the plant outputs and their setpoints for a given test signal as a disturbance. A major dimensionality reduction is accomplished through the identification of some requirements on membership functions. A significant improvement is made in handling membership function constraints that allows the use of every generated solution in the search process. The proposed methodology was applied to the control of cascade-arranged feedwater heaters that are currently controlled by individual pneumatic proportional-only controllers. An optimal fuzzy control system was developed for controlling the levels in this system for a typical load-following transient. The optimal fuzzy controller was found to improve rise time and settling time and to decrease the overshoot in the desired level.

Time-Optimal Negative Input Shapers

Input shaping reduces residual vibration in computer controlled machines by convolving a sequence of impulses with a desired system command. The resulting shaped input is then used to drive the system. The impulse sequence has traditionally contained only positively valued impulses. However, when the impulses are allowed to have negative amplitudes, the rise time can be improved. Unfortunately, excitation of unmodeled high modes and overcurrenting of the actuators may accompany the improved rise time. Solutions to the problem of high-mode excitation and overcurrenting are presented. Furthermore, a simple look-up method is presented that facilitates the design of negative input shapers. The performance of negative shapers is evaluated experimentally on two systems; one driven by a piezo actuator and the other equipped with DC motors.

The Delay Line Readout Technique Applied to Proportional Chambers Using Electronegative Gas Mixtures

The delay line readout technique was adapted to proportional chambers using electronegative gas mixtures. This requires lines with improved rise time, but allows somewhat shorter delays; at the same time, we improved the two-pulse resolution. Our new line is 55cm long, has a delay to rise time ratio of 50 for a delay of 2.1 μs; two pulse resolution in the middle of the line is of the order of 15mm for equal amplitude pulses. We also investigated aluminum core and printed circuit delay lines. We found that the first ones are well suited for low to medium delays with medium two pulse resolution; the second ones are adapted to low delays and may have extremely good delay to rise time ratio in the differential stripline configuration.

A transistorized potentiostat with very fast rise time for impulse techniques.

The need for rapidly charging the double layer, in some electrode process studies, calls for a fast rise-time potentiostat, which, in turn, means a high-gain wide-band amplifier. Parasitic oscillations can occur within the closed loop feedback system: potentiostat + electrodes, when more than one RC product inside the amplifier is of the same order as the time constant resulting from the cell capacity (typically some μs or more). It is thus necessary to bring the other transition frequencies up to the 10–100 Mc/s region, to keep the phase shift sufficiently low to avoid instability. These requirements have been fulfilled with a one-stage modified “bootstrap”) amplifier (gain ∼1500, frequency response linear up to several hundreds kc/s) in which the major time constant is located, followed by a unity-gain amplifier, driving high frequency power transistors (complementary symmetry emitter followers). The regulated d.c. power supply is current-limited to ensure protection against overload. To improve rise time with highly reactive loads, a corrective RC network is associated with the anode resistor of the first stage. Depending upon the load, rise time ranges from 0·25 μs (purely resistive) to 20–25 μs (C = 50 μF). The output voltage is 0 ± 20 V (± 1 to 2 A).

Design of ACP Tunnel-Diode-Coupled Circuits

The performance of the Advanced Circuit Program (ACP) circuits described by D. H. Chung and J. A. Palmieri can be improved by replacing the coupling resistor with a pair of tunnel diodes. The low impedance and power gain properties of the tunnel diode increase the fan-power and provide better control of signal levels. In addition, the improved rise times increase circuit speeds to the extent that delays of less than 1 nsec per logic function have been demonstrated. Since the tunnel diode pair can be designed to perform AND, OR, or majority logic functions, the logic flexibility of these circuits is greater than that of the resistor-coupled circuits. The design techniques which lead to a consistent set of logic circuits and to binary full adders are discussed. The very fast rise times generated by the tunnel diode pair require the use of transmission lines as the interconnection medium. The techniques used to minimize the effects of noise and reflections on circuit performance are discussed.