Mode Extremum Seeking Research Articles

EXPERIMENTAL INVESTIGATIONS OF MPPT IN A SMALL SCALE PHOTOVOLTAIC ENERGY SYSTEM BASED ON EXTREMUM SEEKING CONTROL

This study carried out experimental validation based on the simulation analysis results of Yau and Wu [1], and compared the MPPT situations of three kinds of extremum seeking control. It was proved that the sliding mode extremum seeking control has better transient response and steady-state characteristic, and changes the sunshine intensity to test the performance of algorithm, thus proving that the system can track the maximum power point rapidly in the environment with rapid atmospheric changes.

Sliding Mode Extremum Seeking Control Scheme Based on PSO for Maximum Power Point Tracking in Photovoltaic Systems

An extremum seeking control (ESC) scheme is proposed for maximum power point tracking (MPPT) in photovoltaic power generation systems. The robustness of the proposed scheme toward irradiance changes is enhanced by implementing the ESC scheme using a sliding mode control (SMC) law. In the proposed approach, the chattering phenomenon caused by high frequency switching is suppressed by means of a sliding layer concept. Moreover, in implementing the proposed controller, the optimal value of the gain constant <svg style="vertical-align:-3.3907pt;width:31.1875px;" id="M1" height="16.4125" version="1.1" viewBox="0 0 31.1875 16.4125" width="31.1875" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,12.138)"><path id="x28" d="M300 -147l-18 -23q-106 71 -159 185.5t-53 254.5v1q0 139 53 252.5t159 186.5l18 -24q-74 -62 -115.5 -173.5t-41.5 -242.5q0 -130 41.5 -242.5t115.5 -174.5z" /></g><g transform="matrix(.017,-0,0,-.017,5.944,12.138)"><path id="x1D448" d="M751 650l-6 -28q-53 -1 -69 -12.5t-24 -38.5q-23 -85 -43 -192l-13 -69q-34 -181 -130 -262q-79 -65 -185 -65t-171 57q-87 77 -54 258l42 232q12 58 0.5 73t-75.5 19l8 28h263l-6 -28q-63 -5 -78 -18t-26 -74l-41 -226q-25 -135 22 -201t139 -66q99 0 161.5 68t91.5 217&#xA;l11 57q28 149 28 193q0 28 -19 38t-79 12l6 28h247z" /></g> <g transform="matrix(.012,-0,0,-.012,18.912,16.212)"><path id="x30" d="M241 635q53 0 94 -28.5t63.5 -76t33.5 -102.5t11 -116q0 -58 -11 -112.5t-34 -103.5t-63.5 -78.5t-94.5 -29.5t-95 28t-64.5 75t-34.5 102.5t-11 118.5q0 58 11.5 112.5t34.5 103t64.5 78t95.5 29.5zM238 602q-32 0 -55.5 -25t-35.5 -68t-17.5 -91t-5.5 -105&#xA;q0 -76 10 -138.5t37 -107.5t69 -45q32 0 55.5 25t35.5 68.5t17.5 91.5t5.5 105t-5.5 105.5t-18 92t-36 68t-56.5 24.5z" /></g> <g transform="matrix(.017,-0,0,-.017,25.25,12.138)"><path id="x29" d="M275 270q0 -296 -211 -440l-19 23q75 62 116.5 174t41.5 243t-42 243t-116 173l19 24q211 -144 211 -440z" /></g> </svg> is determined using a particle swarm optimization (PSO) algorithm. The experimental and simulation results show that the proposed PSO-based sliding mode ESC (SMESC) control scheme yields a better transient response, steady-state stability, and robustness than traditional MPPT schemes based on gradient detection methods.

Energy harvesting from the FC stack that operates using the MPP tracking based on modified extremum seeking control

In this paper, a Maximum Power Point (MPP) tracking technique is proposed for the Fuel Cell (FC) stacks based on a modified Extremum Seeking (mES) control that slightly improves the performances of the classical ES control schemes. A higher value of the search speed obtained for the same tracking accuracy is demonstrated for the proposed mES control in comparison with the classical ES control schemes. The analysis made for the mES control in frequency domain reveals interesting relationships to design the control parameters, the values of closed loop gain and the dither amplitude, to obtain the imposed performance related to the search speed and tracking accuracy. The search speed will increase proportionally with the product of both control parameters, so it is practically limited for safe reasons. Finally, in the dynamical operation of the FC stack, a higher loop gain means a shorter time to catch the next MPP. Simulations show that the performances mentioned above are effective for the mES control based on a band pass filter scheme.

Source Seeking With Very Slow or Drifting Sensors

Slow sensors arise in many applications, including sensing chemical concentrations in tracking of contaminant plumes. Slow sensors are often the cause of poor performance and a potential cause of instability. In this paper, we design a modified extremum seeking scheme to account and exploit slow sensor dynamics. We also consider the worst case, which is sensor dynamics governed by a pure integrator. We provide stability results for several distinct variations of an extremum seeking scheme for one-dimensional optimization. Then we develop a design for source seeking in a plane using a fully actuated vehicle, prove its closed-loop convergence, and present simulation results. We use metal oxide microhotplate gas sensors as a real world example of slow sensor dynamics, model the sensor based on experimental data, and employ the identified sensor model in our source seeking simulations.

Automatic Controller Gain Tuning of a Multiple Joint Robot Based on Modified Extremum Seeking Control

AbstractNonlinear programming (NLP) is a field in mathematics that focuses on iteratively decreasing an arbitrary cost function. In this paper, a NLP approach based on extremum seeking control (ESC) is modified for the purpose of autonomously tuning the controller gains of robots. The effectiveness and flexibility of the approach is demonstrated through experimental results on a six degrees-of-freedom (DOF) industrial robot. Both single joint, and multiple joint tuning experiments were performed.

Design of Extremum Seeking Control with PD Accelerator and its Application to Monod and Williams-Otto Models

In this paper, we are concerned with the design and its simulation studies of a modified extremum seeking control for nonlinear systems. A standard extremum seeking control has a simple structure, but it takes a long time to reach an optimal operating point. We consider a modification of the standard extremum seeking control which is aimed to reach the optimal operating point more speedily than the standard one. In the modification, PD acceleration term is added before an integrator making a principal control, so that it enables the objects to be regulated to the optimal point smoothly. This proposed method is applied to Monod and Williams-Otto models to investigate its effectiveness. Numerical simulation results show that this modified method can improve the time response to the optimal operating point more speedily than the standard one. Keywords—Extremum seeking control, Monod model, WilliamsOtto model, PD acceleration term, Optimal operating point.