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Pulsed power load (PPL) is a special load type in shipboard microgrids (SMGs), which consists of the generation module, energy storage system, and various types of loads. Having a reliable power supply to shipboard loads is a challenge as the SMG operates in islanded mode in most cases. Particularly, the PPLs require high transient power transfer with fast dynamics and strong robustness. Conventional solution to supply for the PPL is based on proportional-integral (PI) control, which can be used by linearizing the system around the equilibrium operation point. However, for a pulsed power supply (PPS) system, the load demand drastically changes in a short time, usually in millisecond level, making the operating point changes when the pulsed power is triggered or terminated. To supply the PPL with fast dynamics and robustness, an improved PPS control method is presented in this paper. By adopting a nonlinear sliding mode control (SMC) method, fast voltage regulation and robust pulse power tracking can be achieved. In the PPS, the PPL power demand is divided into two terms: one is the average power that is supplied by the SMG and the other is the fast pulsed power that is supplied by the storage capacitor. The size and cost of the storage capacitor are reduced as it is intentionally driven to a deep discharge. The PPS system configuration and coordination principle, SMC controllers, and sizing of passive elements in the PPS are analyzed in detail. The effectiveness of the presented PPS is verified by simulation results., Peer Reviewed, Postprint (published version)

The maximum power extraction using single integral sliding mode control scheme is established from the sliding mode control scheme. The sliding mode control (SMC) scheme extracts the maximum power during the partial shading weather conditions using the effective selection sliding surface duty cycle ratio in combination of dc/dc boost converter. This dynamic operation of sliding surface selection operation in partial shading conditions aids to enhance the solar panel efficiency compared to the other existing MPPT schemes. The effective dynamic operation of sliding surface mode control is designed using feedback loop control scheme to diminish the steady state voltage error of the solar panel, further to obtain the higher sliding duty cycle ratio. The dc-to-dc boost converter is made active using sliding duty cycle ratio as input gate signal boost converter switch. Hence, higher efficiency attains at higher sliding surface duty ration. This sliding surface duty ratio is limited in sliding mode MPPT control scheme and requires the necessary advancements to achieve the maximum duty cycle ratio. The single integral sliding mode control scheme offers the maximum duty cycle ratio compared to sliding mode control scheme. Therefore, this paper discusses the single integral sliding mode MPPT control scheme. The proposed method employs the effective dynamic sliding operation using integrated steady state voltage error signal and allows to nullify the lacuna of maximum sliding duty cycle ratio. Also, the projected SISMC scheme improves the effective dynamic sliding surface switching operations compared to sliding control scheme. This allows the system to be stable and reliable switching operations. To validate the proposed MPPT control scheme the MATLAB / Simulink model was designed and verified. Also, the SMC scheme was designed and compared with the present method.

Three-phase voltage source inverters (VSIs) with output LC filter are preferred topologies to provide voltage and frequency support for islanded ac microgrids. This article proposes a finite-set quasi-sliding model predictive control (FS-QSMPC) scheme for LC-filtered VSIs to improve the output-voltage quality. By explicitly including a predictive sliding-mode function into the cost function, reduced steady-state ripple and enhanced robustness are achieved compared to typical FS-MPC. Besides, theoretical analysis of stability and robustness for FS-QSMPC is given. Analytical tuning of the weighting factor is also derived to decrease the tuning effort. Comparative simulations and experiments verify the presented approach.

The robotic manipulation of composite rigid-deformable objects (i.e., those with mixed nonhomogeneous stiffness properties) is a challenging problem with clear practical applications that, despite the recent progress in the field, it has not been sufficiently studied in the literature. To deal with this issue, in this article, we propose a new visual servoing method that has the capability to manipulate this broad class of objects (which varies from soft to rigid) with the same adaptive strategy. To quantify the object's infinite-dimensional configuration, our new approach computes a compact feedback vector of 2-D contour moments features. A sliding mode control scheme is then designed to simultaneously ensure the finite-time convergence of both the feedback shape error and the model estimation error. The stability of the proposed framework (including the boundedness of all the signals) is rigorously proved with Lyapunov theory. Detailed simulations and experiments are presented to validate the effectiveness of the proposed approach. To the best of the author's knowledge, this is the first time that contour moments along with finite-time control have been used to solve this difficult manipulation problem., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Learning & Autonomous Control

The maximum power extraction using single integral sliding mode control scheme is established from the sliding mode control scheme. The sliding mode control (SMC) scheme extracts the maximum power during the partial shading weather conditions using the effective selection sliding surface duty cycle ratio in combination of dc/dc boost converter. This dynamic operation of sliding surface selection operation in partial shading conditions aids to enhance the solar panel efficiency compared to the other existing MPPT schemes. The effective dynamic operation of sliding surface mode control is designed using feedback loop control scheme to diminish the steady state voltage error of the solar panel, further to obtain the higher sliding duty cycle ratio. The dc-to-dc boost converter is made active using sliding duty cycle ratio as input gate signal boost converter switch. Hence, higher efficiency attains at higher sliding surface duty ration. This sliding surface duty ratio is limited in sliding mode MPPT control scheme and requires the necessary advancements to achieve the maximum duty cycle ratio. The single integral sliding mode control scheme offers the maximum duty cycle ratio compared to sliding mode control scheme. Therefore, this paper discusses the single integral sliding mode MPPT control scheme. The proposed method employs the effective dynamic sliding operation using integrated steady state voltage error signal and allows to nullify the lacuna of maximum sliding duty cycle ratio. Also, the projected SISMC scheme improves the effective dynamic sliding surface switching operations compared to sliding control scheme. This allows the system to be stable and reliable switching operations. To validate the proposed MPPT control scheme the MATLAB / Simulink model was designed and verified. Also, the SMC scheme was designed and compared with the present method.

Sliding mode control (SMC) can be considered for torque regulation of permanent magnet synchronous machines (PMSMs) when fast transient response and/or robustness under parameter uncertainties are required. In some particular applications, a voltage harmonic injection technique that enhances the dc-link voltage utilization should be incorporated into the controller to operate at high speeds. Although this is straightforward for pulsewidth modulated (PWM) drives, a convenient definition of the sliding surfaces and an appropriate injection procedure must be implemented when using SMC. In this work, a novel approach to generate zero-sequence voltage harmonic injection in surface-mounted (SM) PMSM drives controlled by a fixed switching frequency first-order SMC is proposed. A theoretical analysis is provided verifying the sliding mode existence and demonstrating the system stability when the sliding mode is reached. Finally, experimentation is carried out in an off-the-shelf PMSM drive, where two voltage injection patterns are tested. In both cases, the dc-link voltage utilization is extended by a 15%, confirming the validity of the proposal., Peer Reviewed, Postprint (author's final draft)

To address the stability issues aroused by the negative-resistance effect of constant power loads (CPLs), this paper proposes a composite robust discretized quasi-sliding mode control (DQSMC) scheme for stabilization of buck-converter fed dc microgrids with CPLs. In the outer control loop, a robust DQSMC voltage controller is proposed. First, a discrete integral sliding surface is designed to obtain a fast and robust dynamic response of dc-bus voltage. Then, to tackle the varying load disturbances and model uncertainties, a second-order sliding mode disturbance observer is embedded in the voltage controller for disturbance estimation and compensation. The resulting composite DQSMC scheme features enhanced disturbance rejection, inherent chattering suppression, and guaranteed dynamics. Meanwhile, a PI current controller is retained in the inner control loop to realize the current control and limitation. Robustness and stability analysis of the whole composite controller are proved to assure large-signal stability. Simulation and experimental results confirm the superiority of the presented approach.

© 2013 IEEE. This paper proposes a modular photovoltaic (PV) dc-Nanogrid (dc-NG) architecture for residential applications. The proposed architecture is based on the Loss-Free Resistor (LFR) concept. The dc distribution bus is supplied by PV panels, ac utility and a storage battery. The storage battery is connected to the main dc bus through a dc-dc bidirectional converter (BDC). This battery has also an important role to ensure uninterruptible power supply to the critical loads and controls the power flow in the dc-NG. A mathematical model of the system is first derived and a stability analysis is carried out showing that the stability is guaranteed under certain mild conditions. Numerical simulations of a case study for two PV panels corroborate the theoretical predictions which have been finally confirmed by experimental measurements.

Operators of forest machinery suffer from intensive whole body vibrations, which are big threats to their health. Therefore, it is important to investigate effective seat undercarriages and control methods for vibration reduction. This paper addresses the control problem of a novel seat undercarriage with pneu-matic actuators customized for forest machinery. A two-layer cascade controlstructure is developed, where the top layer consists of a group of proportional controllers to regulate the position of pneumatic actuators and the bottom layeris a sliding mode controller for force and stiffness tracking. The advantage ofthe sliding mode control is to achieve robust control performance with coarse system models. The paper demonstrates that the proposed control structure is better than a traditional PID controller. The robust stability of the sliding mode controller is proved by the Lyapunov's method. Experiments show its capability of reducing at least 20% amplitude of seat vibrations from 0.5 to 1 Hz., QC 20190118

Motivation: Upper-limb motor impairment is one of the most common consequences after Stroke. Limited capability for performing reaching and grasping movements hinders the execution of most activities of daily living. Consequently, the quality lives of the affected individuals are severely compromised. Due to these facts, the recovery of the upper limb functional capabilities is currently one of the keystones of the rehabilitation therapy. Background: Researchers are developing new methods and technologies to boost the outcomes of rehabilitation therapy. A hybrid robotic system has been proposed as a promising rehabilitation technology that combines a passive device (Armeo Spring exoskeleton) to support the arm weight against gravity with a Functional Electrical Stimulation (FES) system to execute the reaching task. This system provides to patients the possibility of training specifically and intensive exercises. Objective: The main objective of this paper is to investigate the performance and robustness of a Feedback Error learning (FEL) scheme mixed with sliding mode control (SMC) to control the FES. Methods: We implemented a nonlinear model describing the muscle response to FES and the dynamic behavior of the elbow joint. Using this model we carried out a simulation study to compare four control strategies: computed torque control (CTC), sliding mode Control (SMC), and adaptive feedback control using FEL: ANN+ CTC and FEL: ANN+SMC. We tested these controllers in two different simulation conditions: In the absence and presence of fatigue. To check the performance of the controllers, we compared the root means square (RMSE) of tracking error and the Normalized RMS of muscle stimulation for various range of movement (ROM). Results: All four controllers achieved good tracking performance in the absence of perturbations. When introducing muscle fatigue, good tracking performance is given essentially by the adaptive control ANN+SMC. Conclusion: Among the proposed approa

© 2019 by the authors. A comparative analysis of the dynamic features of a step-up microinverter based on the cascade connection of two synchronized boost stages and a full-bridge is presented in this work. In the conventional approach the output of the cascaded boost converter is a 350–400 DC voltage that supplies the full-bridge that makes the DC-AC conversion. Differently from the classical approach, in this work, the cascaded boost converter delivers a sinusoidal rectified voltage of 230 Vrms to the full-bridge converter that operates as unfolding stage. This stage changes the voltage sign of one of every two periods of the rectified sinusoidal signal providing the final output AC waveform. In contrast to a classical full-bridge inverter, the unfolding stage lacks output filter, and has zero order dynamics. Thus, the approach presented here implies a second order dynamics reduction that will be increased applying sliding motions to control the system. After introducing the inverter circuit, two sliding control alternatives, input current mode and pseudo-oscillating mode, are presented. Both alternatives are analyzed, simulated, and verified experimentally. Furthermore, detailed description of the microinverter power stage and control circuits are also given.

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works, This paper describes the design of an interleaved sliding mode control for a multiphase synchronous buck converter, which inherits the properties of sliding mode control, operates with fixed switching frequency in the steady-state, and ensures current equalization among phases. Moreover, a power management algorithm is added in order to decide the number of active phases as function of the power load demand, thus optimizing the converter efficiency. The system uses a Master-Slave structure where each phase can actuate as the Master one in such a way that the overall system reliability is improved. Experimental results in a 1.5 kW eight-phase synchronous buck converter show that interleaving operation, robust output voltage regulation, phase current equalization, switching frequency regulation, and power management are achieved., Peer Reviewed, Postprint (author's final draft)

Traditionally, the vector operation technique has been used to control three-phase converters using one cycle control. In this paper, a three-phase active power filter large-signal model with vector operation technique in a new coordinate system is presented. By using the vector operation technique, only two phase-legs are switching at high frequency, thus reducing the switching losses. This paper not only covers the literature gap about the modeling of three-phase converters using vector operation, but also presents a sliding mode control for this converter. The con- trol scheme consists of a nonlinear matrix transformation in order to obtain the voltages and currents in a new two- dimensional frame, ¿¿-frame, a sliding mode controller de- signed in these coordinates, and a modulator to obtain the control signals in natural frame. The sliding mode control is designed with the help of the presented large signal model assuring sinusoidal grid currents in phase with the grid voltages. This controller, provides a fast transient response against sudden load changes with a good current tracking capability and a reduction of the switching losses. A stability analysis is performed in order to validate the control parameters. Experimental results are provided using a fully-digital control system in order to validate the performances of the proposed controller., Peer Reviewed, Postprint (published version)

This paper presents a new concept in active damping techniques using a reduced model of a LCL-filtered grid connected inverter. The presence of the LCL filter complicates the design of the inverter control scheme, particularly when uncertainties in the system parameters, especially in the grid inductance, are considered. The proposed control algorithm is addressed to overcome such difficulties using a reduced model of the inverter in a state observer. In this proposal, two of the three state variables of the system are obviated from the physical inverter model and only the inverter side current is considered. Therefore, the inverter side current can be estimated emulating the case of an inverter with only one inductor, thus eliminating the resonance problem produced by the LCL filter. Besides, in the case of a distorted grid, the method allows to estimate the voltages at the point of common coupling free of noise and distortion without using any PLL-based synchronization. To complete the control scheme, a theoretical stability analysis is developed considering the effect of the observer, the system discretization and the system parameters deviation. Experimental and comparative evaluation results are presented to validate the effectiveness of the proposed control scheme, Postprint (published version)

© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works, Fixing the switching frequency is a key issue in sliding mode control implementations. This paper presents a hysteresis band controller capable of setting a constant value for the steady-state switching frequency of a sliding mode controller in regulation and tracking tasks. The proposed architecture relies on a piecewise linear modeling of the switching function behavior within the hysteresis band, and consists of a discrete-time integral-type controller that modifies the amplitude of the hysteresis band of the comparator in accordance with the error between the desired and the actually measured switching period. For tracking purposes, an additional feedforward action is introduced to compensate the time variation of the switching function derivatives at either sides of the switching hyperplane in the steady state. Stability proofs are provided, and a design criterion for the control parameters to guarantee closed-loop stability is subsequently derived. Numerical simulations and experimental results validate the proposal., Accepted version

With increasing number of on-road transportationvehicles, the demand for passenger safety and comfort isinevitable. This inspired to develop technologically sophisticatedautomobiles with active safety systems that provide improvedvehicle handling during critical driving situations. Yaw stabilitycontroller prevents the vehicle from spinning and drifting-outunder loss of traction during a turning maneuver. This paperpresents a controller design based on sliding mode principle withtwo-stage sliding surfaces considering yaw rate and body sideslip angle errors as primary and secondary surfaces respectively.A simplified model of the vehicle during a turning (Slalom +DLC) maneuver is been considered and the dynamic equationsof the desired states were summed up and used to design thesliding surface. Computer simulations have been conducted toverify the proposed approach, with results indicating itseffectiveness and robustness for yaw stability control.