Real-time Controller Board Research Articles

QCASBC: An algorithm for hardware-in-the-loop simulation of 3-link RRR robotic manipulator

In this paper, a quick convergence adaptive structure is proposed for trajectory tracking of an articulated type robotic manipulator using the Hardware in the Loop (HIL) simulation technique. A novel Nonlinear Quick Convergence Adaptive Sliding Backstepping Control (QCASBC) algorithm is implemented on a C2000 real-time controller board. The performance of the proposed control algorithm is inspected concerning the sliding mode PID (SM-PID) control technique to estimate its correlation with the proposed algorithm. The experimental part of the HIL simulation tests has been carried out on a simulated model of a three-link serial robot manipulator. A dynamic model of the robotic manipulator has been developed using Matlab Simulink software and its performance is analyzed using the HIL technique via a C2000 real-time controller for tracking the desired trajectory. Results show that the speed of convergence while tracking the desired trajectory of the manipulator is better in the proposed algorithm. It is also estimated that the positional error of the QCASBC algorithm is superior to the SM-PID control algorithm. The observed average angle error is improved by 14% and the average response time error is improved by 11% by using the proposed QCASBC algorithm compared to the SM-PID approach.

An improved predictive current control for IM drives

In Finite Control Set-Model Predictive Control (FCS-MPC), the model of the induction machine (IM) is expressed in the α-β or d-q reference frame, and then the back-EMF is estimated based on the applied voltage vectors. In this work, the d-q reference frame is used but unlike the existing method, the estimated back-EMF is calculated by filtering the voltage vectors. Moreover, the work studies the importance of the discretization method on the predictive control behavior of IM. It has been demonstrated that the mentioned enhancements lead to an efficient Total Harmonic Distortion value for stator current (THDi) and torque ripple reduction compared to the conventional methods. The proposed Predictive Current Controller (PCC) has been validated experimentally by using a commercial IM of 7.5[kW] controlled by a dSpace 1103 real-time control board running with sample frequencies from 10[kHz]to 80[kHz]. The test results validate the developed controller’s ability to meet the control objectives in a whole range of speeds, loads, and sampling frequencies.

Experimental Evaluation of MPPT algorithms: A Comparative Study

Photovoltaic (PV) energy is among the most used renewable sources. Grid-connected PV systems should yield as much energy as possible. However, external influencers such as irradiance and temperature impose a non-linear characteristic of the PV system, which hinder its operation at the maximum power point. Additionally, other factors, such as shading or internal degradation, can change this characteristic by making local maximums appear, which makes it difficult to extract the maximum available power. There are several techniques for maximum power point tracking (MPPT) and very diverse algorithms for this purpose. There are also some published works with comparative studies. However, in most of these works, the comparison is based on a literature review or on simulation. An experimental evaluation of MPPT techniques, from the simplest to the most complex, remains relevant . Thus, this paper presents an experimental analysis of five MPPT algorithms: two of the simplest and widely used (Perturb & Observe and Incremental Conductance) and three of the most complex (Fuzzy Logic Controller, Kalman Filter and Particle Swarm Optimization). The experimental tests were carried out under real test conditions, using Simulink and the dSPACE 1103 real-time controller board. The results show that the five MPPT algorithms are able to track the MPP with a difference of less than 2% in their efficiency under normal operating conditions. This difference increases under shadow effect. The PSO algorithm was the only one able to find the global MPP under the effect of partial shading.

Modeling and frequency control of community micro-grids under stochastic solar and wind sources

The Community Micro-Grid (CMG) is a coordinated local grid area served by one or more distribution substations supported by local renewable and other distributed energy resources (DER). In an islanded mode, the CMG stability reduces due to low inertia of the equivalent system and stochastic nature of renewable energy sources (RESs). To study the frequency stability of the islanded CMG system, this paper explores the mathematical modeling aspects of different sources in the CMG and the robust control design for the community microgrid model. The robust design using a fixed structure H∞ synthesis method has been presented to compensate for the effect of modeling uncertainty. The uncertainty in the CMG model results in parametric perturbation which degrades its performance and stability. This paper explores the existing mathematical models of CMG’s and different control techniques applied for frequency regulation. Robust controller design for CMG is proposed that can handle the stochastic input disturbances like a sudden change in power coming from solar and wind sources and also the model uncertainty that results in the parametric perturbations. The complete model is simulated using MATLAB Simulink platform and results of frequency deviation obtained by robust and PID controller are compared. The controller hardware in loop (C-HIL) validation of the robust control method for CMG has been done using a real-time controller board (DS1104). This CHIL system also implements the CMG plant-controller model and analyzes the frequency deviation against load and renewable power fluctuations. The oscillations in frequency deviation are analyzed for sudden rise or fall in the renewable power coming from the solar and wind sources. A reduction of 30% is achieved in frequency overshoot and settling time using a robust controller than the PID controller. The controller developed and implemented using H∞ synthesis has robust stability and performance for the perturbed CMG model and also shows a better time response, unlike the PID controller.

Rapid Tracking of Grid Variables Using Prefiltered Synchronous Reference Frame PLL

For synchronization applications, synchronous reference frame (SRF) phase-locked loop (PLL) is widely deployed. Its performance is excellent when the input voltage consists of only fundamental positive sequence (FPS) component. If the grid voltage is unbalanced or polluted with harmonics and dc offset, its performance degrades. Many modifications were proposed to address this issue. However, the removal of dc offset and fundamental negative sequence (FNS) component without compromising the dynamic performance still remains a challenging task. To this end, this paper presents a rapid Type-1 SRF PLL scheme with preloop filtering stage for tracking the attributes of grid voltage FPS component. Fixed sampling period sliding discrete Fourier transform (SDFT) and instantaneous symmetrical components method are employed in the preloop stage. With this modification, the dc offset, harmonics and the FNS component are rejected and only the FPS component enters the PLL. As a result, transients vanish quickly. However, when the grid frequency drifts, SDFT causes amplitude and phase errors, and Type-1 PLL introduces a steady-state tracking error in phase. These errors are compensated with the help of an error correction criteria. Robustness and the improved transient response of the proposed scheme are demonstrated with an experimental study involving real-time controller board (dSPACE DS1104) and three-phase programmable power source.

Single-Phase Grid Voltage Attributes Tracking for the Control of Grid Power Converters

Grid interfacing power converters are indispensable for renewable energy conversion schemes. Fast and precise detection of grid signal parameters is essential for effective operation and control of these converters. For such applications, synchronous reference frame phase-locked loop (SRF PLL) involving two orthogonal signals (OS) is widely deployed. For the single-phase system, this requires another signal orthogonal to the input. In this paper, single-phase SRF PLL with fixed sampling period sliding discrete Fourier transform (SDFT) filter as OS generator is proposed. Additionally, this filter is capable of rejecting dc offset and harmonics present in the grid voltage. With this arrangement, the loop filter of PLL need not be equipped with filtering capability. Therefore, PLL could be designed with larger bandwidth, which will result in better transient performance. However, SDFT output will be erroneous with asynchronous sampling, under grid frequency drift. With suitable study, relation between those errors and deviation of frequency from nominal value is established. Using this relation, error compensation at any grid frequency can be achieved. To validate the proposed method, various grid abnormalities are emulated with the aid of programmable power source and dSPACE real-time controller board. The effectiveness of the proposed scheme is demonstrated through experimental investigations.

Digital Control of a Shunt Hybrid Power Filter Adopting a Nonlinear Control Approach

This paper proposes a nonlinear derivative-less control approach for controlling a three-phase shunt hybrid power filter (SHPF). The dynamic model of the SHPF system is first elaborated in the stationary frame and then transformed into a “dq” reference frame. The control system is divided into two separate loops, namely the two current dynamics inner loop and the dc voltage dynamic outer loop. The exact feedback linearization technique is used to decouple the inner loop variables. Proportional-integral controllers are utilized to control the SHPF input currents and dc-bus voltage. The proposed nonlinear control is first simulated and then validated on a 2.5-kVA laboratory prototype supported by the DS 1104 digital real-time controller board of dSPACE. Satisfactory results, such as low-ac-current total harmonic distortion, fast step response, and high robustness under load variation, are obtained. Significantly high correlation between the experimental results and the theoretical model, implemented with SIMULINK/Matlab, is obtained.

Cascade fuzzy logic control of a single-link flexible-joint manipulator

This paper presents the design and control of a single-link flexible-joint robot manipulator. A cascade fuzzy logic controller (FLC) was used to remove link vibrations and to obtain fast trajectory tracking performance. The cascade FLC structure includes 3 different FLCs. The input variables of the first and the second FLCs are the motor rotation angle error, its derivative, and the end-point deflection error its derivative, respectively. The outputs of these controllers are the inputs of the third FLC, which yields the control signal to the flexible robot arm. All of the FLCs were embedded in a DS1103 real-time control board. Several experiments were conducted to verify the controller performance. In the step-response experiments, the error of motor rotation angle was obtained as less than 0.12° and there was no steady-state error in the end-point deflection. In trajectory tracking experiments with the same FLC structure, small errors and phase shifts in the system variables occurred. Model parameters of the flexible arm such as link length and spring stiffness were changed to test the robustness of the FLC. It was seen that the FLCs were very robust to internal and external disturbances. Considering the results of the experiments, the proposed FLC structure shows efficient control performance in flexible robot arms.

Structure Rotation and Pull-in Voltage Control of MEMS Lateral Comb Resonators Under Fault Conditions

Lateral comb resonators (LCRs) theoretically possess a symmetric structure; therefore, the electrostatic force is effective only along the axis of displacement and is neutralized elsewhere. This force is not a function of the distance between the stationary and the moving (shuttle) plates in the direction of the movement. However, manufacturing imperfections and fault conditions make the device operate asymmetrically and cause rotation of the shuttle structure in a lateral gap-closing direction, putting the device in an unstable region of operation (pull-in voltage limit). In this region, the rotated structure experiences an extra force which pulls the device into the region of instability beyond the pull-in voltage limits. This paper illustrates the application of variable structure controllers to correct such behavior and to compensate for the uncertainties that exist in the microsystem parameters. The controller is equipped with a self-tuning parameter estimation block and is designed to control the LCRs under both normal and fault conditions. The controller utilizes through-wafer optical monitoring to provide the position feedback signal. The controller is implemented in a real-time control board and is experimentally verified to demonstrate the effectiveness of the control method under different operating conditions.

Implementation of a New Linear Control Technique Based on Experimentally Validated Small-Signal Model of Three-Phase Three-Level Boost-Type Vienna Rectifier

In this paper, the design and implementation of a new multiple-input-multiple-output linear control technique based on a theoretically established and experimentally validated small- signal model for the three-phase three-level boost-type ac/dc Vienna converter are presented. Averaging and local linearization techniques are used to derive the dynamic model expressed in the dqo reference frame. The resulted transfer functions are discretized for the sake of a digital controller design. Multiple-loop control strategy is adopted and consists of inner current feedback loops, which are based on the straightforward looping technique that neglects interactions between the dq components of control inputs and currents, respectively, and of an outer voltage loop, which is designed to ensure dc voltage regulation by adjusting the magnitude of the references for the inner current loops. The output dc voltage unbalance is also controlled in the inner loops. The proposed modeling and control approaches are first simulated and then validated on a 1.5-kW laboratory prototype supported by the DS 1104 digital real-time controller board of dSPACE. The obtained results prove the accuracy of the proposed new small-signal model and, therefore, its reliability for dynamic analysis and control design purposes. It is also proved that a judicious choice of controller parameters, as well as an adequate rating of boost inductors, allows one to meet the IEEE standard requirements in terms of ac line-current total harmonic distortion and power factor. The efficiency of the proposed control technique is maintained in case of disturbances occurring on both source and load sides.

Small-signal perturbation technique used for DSP-based identification of a three-phase three-level boost-type Vienna rectifier

New small-signal-modelling technique and validation procedures are applied to a three-phase three-level boost-type AC/DC Vienna converter. The adopted methodology consists of three steps: the first one is to elaborate the converter steady state and dynamic models that are derived by means of a local linearisation around the nominal operating point from the state space-averaged model, initially expressed in abc physical variables and then transformed into dqo synchronous reference frame. Twenty transfer functions relating the inputs to the outputs of the system are therefore obtained. The second step is the numerical verification using the averaged state space model and the converter model built in SIMULINK/MATLAB. Finally, an experimental validation of the transfer functions is carried out using a 1.5 kW laboratory prototype on the basis of the DS 1104 real-time controller board of dSPACE. The results are quantified and compared as magnitude and phase Bode graphs. It is confirmed that the proposed new small-signal model represents rather accurately the real system and is therefore reliable for further tasks such as dynamic characteristic analysis, numerical simulation as well as controller design purposes.

Compensation of the Non-Sinusoidal Electromotive Force with Multiple-Frequency Resonant Controller for a PMLSM

This paper presents how to compensate for the non-sinusoidal electromotive force (EMF) of the permanent magnet linear synchronous motor (PMLSM) with a multiple-frequency resonant controller. After the modeling of the non-sinusoidal EMF in a PMLSM, the multiple-frequency resonant controller is proposed to control the PMLSM in order to compensate for the negative influence of such EMF. After explaining the discrete resonant controller theory, the effectiveness of the suggested method is verified on a test bench equipped with a Rexroth LSP120C linear motor and a dSPACE DS1005 real-time controller board.

Application of Finite-Element Method to a PMLSM with Non-Sinusoidal Electromotive Force

An accurate thrust control of permanent magnet linear synchronous motors (PMLSM) is more efficient with a fine knowledge of the harmonics value of the electromotive force (EMF). This is often difficult to obtain experimentally for a PMLSM. As a consequence, this paper deals with the study of the non-sinusoidal EMF of a PMLSM using the 3D Finite-Element Method (FEM). Two potential formulations are used to consider several cases. Afterwards, for the same accuracy, the computation times are examined. The results of the FEM are compared to those given by the measurements from a test bench composed of a Siemens LIMES400/120 linear motor and a dSPACE DS1005 real-time controller board. Finally, the advantages and the limitations of the FE Analysis will be discussed.