scholarly journals An improved 2-level MPPT scheme for photovoltaic systems using a novel high-frequency learning based adjustable gain-MRAC controller

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pankaj Sahu ◽  
Rajiv Dey
Keyword(s):  
Duty Cycle ◽  
Environmental Conditions ◽  
High Frequency ◽  
Tracking Error ◽  
Fast Convergence ◽  
Lyapunov Theory ◽  
Control Architecture ◽  
Transient Performance ◽  
Adaptive Law ◽  
High Adaptation

AbstractUnder rapidly changing environmental conditions, the model reference adaptive control (MRAC) based MPPT schemes need high adaptation gain to achieve fast convergence and guaranteed transient performance. The high adaptation gain causes high-frequency oscillations in the control signals resulting in numerical instability and inefficient operation. This paper proposes a novel high-frequency learning-based adjustable gain MRAC (HFLAG-MRAC) for a 2-level MPPT control architecture in photovoltaic (PV) systems to ensure maximum power delivery to the load under rapidly changing environmental conditions. In the proposed 2-level MPPT control architecture, the first level is the conventional ripple correlation control (RCC) that yields a steady-state ripple-free optimum duty cycle. The duty cycle obtained from the first level serves as an input to the proposed HFLAG-MRAC in the second level. In the proposed adaptive law, the adaptation gain varies as a function of the high-frequency ripple content of the tracking error. These high-frequency contents are the difference between the tracking error and its low-pass filtered version representing the fluctuations in output due to rapid changes in the environmental conditions. Thus, adjusting the adaptation gain by high-frequency content of the tracking error ensures fast convergence, guaranteed transient performance, and overall system stability without needing high adaptation gain. The adaptive law of the proposed HFLAG-MRAC is derived using the Lyapunov theory. Simulation studies, experimental analysis, and performance comparison with recent similar work validate the effectiveness of the proposed work.

Robust flexible adaptation gain based CRM for guaranteed transient performance

2018 ◽  
Vol 41 (5) ◽  
pp. 1233-1242
Author(s):  
Rajiv Dey ◽  
Sachin K Jain ◽  
Prabin K Padhy
Keyword(s):  
Estimation Error ◽  
System Stability ◽  
Control Input ◽  
Simulation Studies ◽  
Transient Performance ◽  
High Frequency Oscillations ◽  
Adaptive Law ◽  
Flexible Adaptation ◽  
Model Reference Adaptive ◽  
High Adaptation

High adaptation gain in model reference adaptive control (MRAC) with closed-loop reference models (CRMs) is a necessary requirement to ensure guaranteed transient performance with better tracking and fast convergence. The high adaptation gain, however, may excite unmodelled dynamics, leading to instability, making the differential equations of the adaptive law stiff and causing numerical instability. Therefore, it becomes apparent that a compromise is required on either convergence speed and transient performance or system stability. This paper attempts to address these issues with a novel CRM-MRAC architecture with flexible adaptation gain, which varies as a function of the derived parameter estimation error. The proposed adaptive scheme mathematically ensures a designable upper bound of the [Formula: see text] norm; it also ensures the absence of high-frequency oscillations in the control input, thereby making the system more robust and stable. The effectiveness of the proposed work has been validated with simulation studies on a standard numerical example and the performance has been compared with recent similar works.

Wavelet Filter Approach for GPS Attitude Tracking System on Ship

2010 ◽  
Vol 450 ◽  
pp. 552-555
Author(s):  
Ping Wang ◽  
Kai Xue ◽  
Qiu Hong Li
Keyword(s):  
High Frequency ◽  
Tracking System ◽  
Tracking Error ◽  
Low Frequency ◽  
Attitude Measurement ◽  
Visual Effects ◽  
Error Sources ◽  
Attitude Tracking ◽  
Servo Mechanism ◽  
Filter Approach

GPS attitude tracking system on the ship is a servo mechanism which could be used for counteracting the effects of the ship’s pitch and roll. But the attitude measurement precision of ship is more important to the tracking precision of the servo mechanism. As one of the major error sources, the noises of GPS attitude measurement bring out the steady tracking error of the tracking servo mechanism. To reduce the steady error due to the noise, the threshold noise removing method of wavelet is used to eliminate the noise. And the better result with the meaning of standard deviation and the better visual effects could be gotten by using the method. The signals of the processed high frequency and the retained low frequency could be reconstructed with the original signals. Therefore, the signals after noise removing could be obtained. The threshold noise removing method of wavelet used to remove the noise of GPS attitude information in the paper is of great value in practice.

Performance of Pulsating High-Frequency Current Injection Based Sensorless Control of PMSM

2013 ◽  
Vol 347-350 ◽  
pp. 610-616
Author(s):  
Jian Min Wang
Keyword(s):  
High Frequency ◽  
Sensorless Control ◽  
Tracking Error ◽  
Position Estimation ◽  
Current Control ◽  
Current Injection ◽  
High Frequency Current ◽  
Position Errors ◽  
Pulsating Current ◽  
Frequency Current

In the paper the principle and performances of the pulsating current injection based sensorless control of permanent magnet synchronous motor (PMSM) are analyzed theoretically and investigated by simulations. In the analyses, the effects of the speed EMF terms and the deviation between the actual d-axis high-frequency current and the command, which results from the limited gain and bandwidth of the current control loop, are all taken into account. It is shown that the pulsating current injection method can achieve stable position estimation in a wide speed range. But appreciable position errors will result at high speeds due to the cross-coupling effects of the speed EMFs and the tracking error between the actual and command carrier current. In order to improve the performance, a modified scheme is proposed. Its validity is confirmed by simulations.

Duty Cycle Measurement Techniques for Adaptive and Resilient Autonomic Systems

2011 ◽  
Vol 2 (3) ◽  
pp. 63-87
Author(s):  
Chiara Taddia ◽  
Gianluca Mazzini ◽  
Riccardo Rovatti
Keyword(s):  
Quality Of Service ◽  
Duty Cycle ◽  
Crucial Role ◽  
Pulse Train ◽  
Measurement Techniques ◽  
Fast Convergence ◽  
Autonomic Systems ◽  
Digital Pulse ◽  
Regular Sampling

When systems are deployed in environments where change is the rule rather than the exception, adaptability and resilience play a crucial role in order to preserve good quality of service. This work analyses methods that can be adopted for the duty cycle measurement of sensor-originated waveforms. These methods start from the assumption that no regular sampling is possible and thus they are naturally thought for an adaptive coexistence with other heterogeneous and variable tasks. Hence, the waveform carrying the information from low-priority sensors can be sampled only at instants that are non-controlled. To tackle this problem, this paper proposes some algorithms for the duty cycle measurement of a digital pulse train signal that is sampled at random instants. The solutions are easy to implement and lightweight so that they can be scheduled in extremely loaded microcontrollers. The results show a fast convergence to the duty cycle value; in particular, a considerable gain with respect to other known solutions is obtained in terms of the average number of samples necessary to evaluate the duty cycle with a desired accuracy is obtained.

scholarly journals Dynamic Modeling and Adaptive Robust Synchronous Control of Parallel Robotic Manipulator for Industrial Application

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-23
Author(s):  
Haiqiang Zhang ◽  
Hairong Fang ◽  
Qi Zou ◽  
Dan Zhang
Keyword(s):  
Trajectory Tracking ◽  
High Frequency ◽  
Parallel Manipulator ◽  
Sliding Mode ◽  
Virtual Work ◽  
Parallel Manipulators ◽  
Adaptive Robust Control ◽  
Lyapunov Theory ◽  
Synchronous Control ◽  
Effective Manner

Control of parallel manipulators is very hard due to their complex dynamic formulations. If part of the complexity is resulting from uncertainties, an effective manner for coping with these problems is adaptive robust control. In this paper, we proposed three types of adaptive robust synchronous controllers to solve the trajectory tracking problem for a redundantly actuated parallel manipulator. The inverse kinematic of the parallel manipulator was firstly developed, and the dynamic formulation was further derived by mean of the principle of virtual work. Furthermore, linear parameterization regression matrix was determined by virtue of command function “equationsToMatrix” in MATLAB. Secondly, the three adaptive robust synchronous controllers (i.e., sliding mode control, high gain control, and high frequency control) are developed, by incorporating the camera sensor technique into adaptive robust synchronous control architecture. The stability of the proposed controllers was proved by utilizing Lyapunov theory. A sequence of simulation tests were implemented to prove the performance of the controllers presented in this paper. The three proposed controllers can theoretically guarantee the errors including trajectory tracking errors, synchronization errors, and cross-coupling errors asymptotically converge to zero for a given trajectory, and the estimated unknown parameters can also approximately converge to their actual values in the presence of unmodeled dynamics and external uncertainties. Moreover, all the simulation comparative results were presented to illustrate that the adaptive robust synchronous high-frequency controller possess a much superior comprehensive performance than two other controllers.

scholarly journals Adaptive output regulation for a class of nonlinear systems with guaranteed transient performance

2019 ◽  
Vol 42 (6) ◽  
pp. 1180-1190
Author(s):  
Weijie Sun ◽  
Zhenhua Zhu ◽  
Jianglin Lan ◽  
Yunjian Peng
Keyword(s):  
Nonlinear Systems ◽  
Tracking Error ◽  
High Gain ◽  
Output Regulation ◽  
Control Law ◽  
Stabilization Problem ◽  
Transient Performance ◽  
Adaptive Stabilization ◽  
Output Tracking ◽  
Output Constraints

This paper is dedicated to adaptive output regulation for a class of nonlinear systems with asymptotic output tracking and guarantee of prescribed transient performance. With the employment of internal model principle, we first transform this problem into a specific adaptive stabilization problem with output constraints. Then, by integrating the time-varying Barrier Lyapunov Function (BLF) technique together with the high gain feedback method, we develop an output-based control law to solve the constrained stabilization problem and consequently confine the output tracking error to a predefined arbitrary region. The output-based control law enables adaptive output regulation in the sense that, under unknown exosystem dynamics, all the closed-loop system signals are bounded whilst the controlled output constraints are not violated. Finally, efficacy of the proposed design is illustrated through a simulation example.

scholarly journals Model Predictive Voltage Control with Optimal Duty Cycle for Three-Phase Grid-Connected Inverter

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Shahrouz Ebrahimpanah ◽  
Qihong Chen ◽  
Liyan Zhang ◽  
Misbawu Adam
Keyword(s):  
Steady State ◽  
Duty Cycle ◽  
Tracking Error ◽  
Voltage Control ◽  
Sampling Period ◽  
Sampling Interval ◽  
Nonlinear Load ◽  
Three Phase ◽  
Switching State ◽  
Steady State Performance

This paper proposes a model predictive voltage control (MPVC) strategy with duty cycle control for grid-connected three-phase inverters with output LCL filter. The model of the system is used to predict the capacitor filter voltage according to the future output current for each possible switching state at each sampling period. Then the cost function for each prediction is determined and the switching state is selected. In the proposed method, two voltage vectors are applied during one sampling interval to achieve better steady-state performance. Finally, the optimal duration of the nonzero voltage vector is defined based on the duty cycle optimization, which is vital to the control system. The proposed strategy offers a better reference tracking error with less THD in linear and nonlinear load situations. The effectiveness of the proposed method has been verified by MATLAB/Simulink and experimental results exhibit a better steady-state performance with less sampling frequency.

Sign in / Sign up

Export Citation Format

Share Document