TMS320F28335 Digital Signal Processor Research Articles

Experimental design of the adaptive backstepping control technique for single‐phase shunt active power filters

In this study, a cascade two-loop non-linear controller is developed for single-phase shunt active power filters which is robust and stable in a wide range of output current and DC-link voltage changes. A variable structure proportional-integral controller is designed to regulate DC-link voltage in the outer loop. Also filter output current is controlled in the inner loop using adaptive backstepping approach. All of the model uncertain parameters are estimated using designed estimation rules. By introduction of suitable Lyapunov functions, proposed controller stability is investigated using Barbalat lemma. Grid reference current is calculated indirectly using a phase-locked loop circuit according to DC-link voltage error. Designed active power filter has been implemented using TMS320F28335 digital signal processor and practical response of the developed controller is studied in some tests. It is shown that the proposed controller is able to eliminate harmonic components of the local load current with a fast dynamic response. Also, compensation capability of the designed non-linear approach is compared with sliding mode controller in similar conditions.

Modified Synchronous Reference Frame Based Shunt Active Power Filter with Fuzzy Logic Control Pulse Width Modulation Inverter

Harmonic distortion in power networks has greatly reduced power quality and this affects system stability. In order to mitigate this power quality issue, the shunt active power filter (SAPF) has been widely applied and it is proven to be the best solution to current harmonics. This paper evaluates the performance of the modified synchronous reference frame extraction (MSRF) algorithm with fuzzy logic controller (FLC) based current control pulse width modulation (PWM) inverter of three-phase three-wire SAPF to mitigate current harmonics. The proposed FLC is designed with a reduced amount of membership functions (MFs) and rules, and thus significantly reduces the computational time and memory size. Modeling and simulations of SAPF are carried out using MATLAB/Simulink R2012a with the power system toolbox under steady-state condition, and this is followed with hardware implementation using a TMS320F28335 digital signal processor (DSP), Specrum Digital Inc., Stafford, TX, USA. The results obtained demonstrate a good and satisfactory response to mitigate the harmonics in the system. The total harmonic distortion (THD) for the system has been reduced from 25.60% to 0.92% and 1.41% in the simulation study with and without FLC, respectively. Similarly for the experimental study, the SAPF can compensate for the three-phase load current by reducing THD to 5.07% and 7.4% with and without FLC, respectively.

A Refined Self-Tuning Filter-Based Instantaneous Power Theory Algorithm for Indirect Current Controlled Three-Level Inverter-Based Shunt Active Power Filters under Non-sinusoidal Source Voltage Conditions

In this paper, a refined reference current generation algorithm based on instantaneous power (pq) theory is proposed, for operation of an indirect current controlled (ICC) three-level neutral-point diode clamped (NPC) inverter-based shunt active power filter (SAPF) under non-sinusoidal source voltage conditions. SAPF is recognized as one of the most effective solutions to current harmonics due to its flexibility in dealing with various power system conditions. As for its controller, pq theory has widely been applied to generate the desired reference current due to its simple implementation features. However, the conventional dependency on self-tuning filter (STF) in generating reference current has significantly limited mitigation performance of SAPF. Besides, the conventional STF-based pq theory algorithm is still considered to possess needless features which increase computational complexity. Furthermore, the conventional algorithm is mostly designed to suit operation of direct current controlled (DCC) SAPF which is incapable of handling switching ripples problems, thereby leading to inefficient mitigation performance. Therefore, three main improvements are performed which include replacement of STF with mathematical-based fundamental real power identifier, removal of redundant features, and generation of sinusoidal reference current. To validate effectiveness and feasibility of the proposed algorithm, simulation work in MATLAB-Simulink and laboratory test utilizing a TMS320F28335 digital signal processor (DSP) are performed. Both simulation and experimental findings demonstrate superiority of the proposed algorithm over the conventional algorithm.

An AC MPPT with Active/Reactive Power Control Feature for Single-Stage Three-Phase Grid-Connected Photovoltaic VSIs

This article introduces a new AC MPPT (maximum power point tracking) controller for single-stage three-phase grid-connected photovoltaic (PV) voltage source inverters (VSIs) with active/reactive power control capability. Novelty lies in employing the theory of power transfer in short AC transmission lines to achieve MPPT, where two independent control variables exist: load angle and inverter modulation index. Accordingly, the proposed controller maximizes the capabilities of the single-stage VSI and enables it to control either/both active power or/and reactive power, besides achieving MPPT function. Such contribution opens up avenues in MPPTs world in terms of flexibility, fast performance, and low hardware count/cost. AC refers to Alternate Current since the MPPT is managed in AC terms. Theoretical framework of the proposed controller has been addressed. Moreover, the overall system is simulated in MATLAB (The MathWorks, Natick, Massachusetts, USA) environment, and results have been introduced. Design and implementation of proposed algorithms have been carried out using a fixed-point digital signal processor (DSP)TMS320F2812. Furthermore, a breadboard circuit is built up for experimentally investigating the controller's performance using 3-phase VSI that connects PV with the grid. In addition to that, a comprehensive discussion is conducted for demonstrating results. Moreover, a detailed comparison of proposed work with a number of previously published papers in literature is carried out and addressed in this manuscript. Results reveal that introduced controller achieves satisfactory performance.

Neutral‐point voltage deviation control for three‐level inverter‐based shunt active power filter with fuzzy‐based dwell time allocation

Three-level inverters have emerged as the main alternative to replace the use of standard two-level inverters in current harmonics mitigation. Neutral-point diode clamped (NPC) inverter is the most attractive candidate due to its robustness. However, the inherent neutral-point voltage deviation problems have always been the most troublesome features of NPC inverter. Hence, voltage balancing of DC-link capacitors is highly essential, where it is usually achieved through proper switching control. Space vector pulsewidth modulation is the most desirable switching scheme, where the voltage balancing control is mostly accomplished by decently allocating the dwell time for all the switching states. In this study, a fuzzy logic controller is incorporated to systematically control the dwell time allocation for all the switching states based on the instantaneous voltage of splitting DC-link capacitors. The proposed method is called the fuzzy-based dwell time allocation algorithm. To validate effectiveness and feasibility of the proposed algorithm, simulation work in MATLAB-Simulink and experimental implementation utilising TMS320F28335 digital signal processor (DSP) are performed. Both simulation and experimental results are presented, confirming effectiveness of the proposed algorithm in reducing the inherent voltage deviation problems of NPC inverter to a minimum level.

New parameter for current-sensorless MPPT in grid-connected photovoltaic VSIs

This paper a new quantity for current-sensorless power-angle-based MPPT for single-stage grid-connected photovoltaic voltage-source inverters (VSIs). The proposed tracker eliminates the use of the current sensor by using only the voltage sensor: The current sensor is substituted with a new quantity, which is the sine value of the power-angle (the phase angle between the inverter output voltage and the power grid voltage). A theoretical proof for this quantity is developed and is provided. Then the controller is designed and implemented using a digital signal processor (DSP). Algorithms are configured on a fixed point DSP TMS320F2812. Moreover, a breadboard has been built-up for testing the use of the proposed tracker with a single-stage grid-connected photovoltaic voltage-source inverter. Both of simulation and experimental results show that the proposed tracker attains a satisfactory performance. On the other hand, it requires a good control tool to accurately achieve the arithmetic calculations. A substantial part of the manufacturing cost and complexity burdens of MPPTs involves the use of current sensors. Considering this investigation saves cost, decreases complexity, and therefore increases the power density of the MPPTs.

DSP based current controlled single stage single phase integrated converter with external compensating signal for Class-C & Class-D appliances

AbstractDesign and implementation of a current controlled single stage single phase integrated AC/DC isolated Power Factor Correction (PFC) converter is presented in this paper. With the integrated topology reduces the number control switches. The proposed converter has the advantage of low bulk capacitor voltage and only single control switch hence reduce in complexity in control and cost. Sub-harmonic oscillations which are produced in conventional current controller. By adding an external compensating signal effect of oscillations are reduced and performance of the converter is improved. The proposed scheme is implemented in real time by TMS320F2812 digital signal processor (DSP) board. The performance of converter is verified both experimentally and by simulation at different load and line conditions. The proposed converter is designed for 90–230 V, 50 Hz AC input, 48 V DC output and operating at 100 kHz switching frequency. The Experimental results shows that the DSP-based fuzzy controlled single pha...

Adaptive Active Noise Suppression Using Multiple Model Switching Strategy

Active noise suppression for applications where the system response varies with time is a difficult problem. The computation burden for the existing control algorithms with online identification is heavy and easy to cause control system instability. A new active noise control algorithm is proposed in this paper by employing multiple model switching strategy for secondary path varying. The computation is significantly reduced. Firstly, a noise control system modeling method is proposed for duct-like applications. Then a multiple model adaptive control algorithm is proposed with a new multiple model switching strategy based on filter-u least mean square (FULMS) algorithm. Finally, the proposed algorithm was implemented on Texas Instruments digital signal processor (DSP) TMS320F28335 and real time experiments were done to test the proposed algorithm and FULMS algorithm with online identification. Experimental verification tests show that the proposed algorithm is effective with good noise suppression performance.

A Comprehensive Analysis and Hardware Implementation of Control Strategies for High Output Voltage DC-DC Boost Power Converter

Classical DC-DC converters used in high voltage direct current (HVDC) power transmission systems, lack in terms of efficiency, reduced transfer gain and increased cost with sensor (voltage/current) numbers. Besides, the internal self-parasitic behavior of the power components reduces the output voltage and efficiency of classical HV converters. This paper deals with extra high-voltage (EHV) dc-dc boost converter by the application of voltage-lift technique to overcome the aforementioned deficiencies. The control strategy is based on classical proportional-integral (P-I) and fuzzy logic closed-loop controller to get high and stable output voltage. Complete hardware prototype of EHV is implemented and experimental tasks are carried out with digital signal processor (DSP) TMS320F2812. The control algorithms P-I, fuzzy logic and the pulse-width modulation (PWM) signals for N-channel MOSFET device are performed by the DSP. The experimental results provided show good conformity with developed hypothetical predictions. Additionally, the presented study confirms that the fuzzy logic controller provides better performance than classical P-I controller under different perturbation conditions.

A low-cost and highly integrated control system for lower limb rehabilitation robot

This paper presents a lower limb rehabilitation control system designed to train stroke patients by providing variable damping on the knee joint. The hardware based on the controller TMS320F28335 digital signal processor (DSP) and the software based on the DSP/BIOS embedded operation system are designed. The effective control of brushless DC (BLDC) motor can be implemented by combining with the upper impedance control algorithms and the underlying field-oriented control (FOC) control algorithm, which improves the performance of rehabilitation robot control system. The proposed integrated control system has robustness, dependability and works in real-time, and is easy to be upgraded and expanded.

A low-cost and highly integrated control system for lower limb rehabilitation robot

This paper presents a lower limb rehabilitation control system designed to train stroke patients by providing variable damping on the knee joint. The hardware based on the controller TMS320F28335 digital signal processor (DSP) and the software based on the DSP/BIOS embedded operation system are designed. The effective control of brushless DC (BLDC) motor can be implemented by combining with the upper impedance control algorithms and the underlying field-oriented control (FOC) control algorithm, which improves the performance of rehabilitation robot control system. The proposed integrated control system has robustness, dependability and works in real-time, and is easy to be upgraded and expanded.

A Control Methodology of Bidirectional Converter for Grid Connected Systems

Objectives This paper proposes a control methodology of bidirectional Converter for grid connected systems. Methods/ Statistical Analysis: The bidirectional converter is used for converting the DC-AC power by using decoupled current control strategy in stationary reference frame. The simulations of the proposed system are carried out in PSIM software. An experimental prototype of Bidirectional converter has been built in the laboratory. A TMS320F28335 digital signal processor (DSP) is used for generating the control pulses for the Converter. Findings: The control of grid converter along with battery backup would provide support to the grid. Thus the proposed control strategy could independently control active and reactive power and also able to avoid grid failures. Application/Improvements: Reduction of operating switching frequency, improved dynamics as well as robustness against grid impedance variation are some of the improvements of proposed system.

A Simplified Synchronous Reference Frame for Indirect Current Controlled Three-level Inverter-based Shunt Active Power Filters

This paper presents a new simplified harmonics extraction algorithm based on the synchronous reference frame (SRF) for an indirect current controlled (ICC) three-level neutral point diode clamped (NPC) inverter-based shunt active power filter (SAPF). The shunt APF is widely accepted as one of the most effective current harmonics mitigation tools due to its superior adaptability in dynamic state conditions. In its controller, the SRF algorithm which is derived based on the direct-quadrature (DQ) theory has played a significant role as a harmonics extraction algorithm due to its simple implementation features. However, it suffers from significant delays due to its dependency on a numerical filter and unnecessary computation workloads. Moreover, the algorithm is mostly implemented for the direct current controlled (DCC) based SAPF which operates based on a non-sinusoidal reference current. This degrades the mitigation performances since the DCC based operation does not possess exact information on the actual source current which suffers from switching ripples problems. Therefore, three major improvements are introduced which include the development of a mathematical based fundamental component identifier to replace the numerical filter, the removal of redundant features, and the generation of a sinusoidal reference current. The proposed algorithm is developed and evaluated in MATLAB / Simulink. A laboratory prototype utilizing a TMS320F28335 digital signal processor (DSP) is also implemented to validate effectiveness of the proposed algorithm. Both simulation and experimental results are presented. They show significant improvements in terms of total harmonic distortion (THD) and dynamic response when compared to a conventional SRF algorithm.

Robust flat filtering DSP based control of the boost converter

The article deals with the design and implementation of a flat filter tracking digital controller for a boost DC-DC power converter. A highly perturbed switched boost converter circuit is shown to be efficiently controlled, in a trajectory tracking task for its non-minimum phase output, by means of a suitable linear filter, here addressed as a flat filter. Flat filtering is a natural robust version of generalized proportional integral control (GPIC) by which the effects of arbitrary time varying exogenous disturbances, unknown endogenous nonlinearities and un-modeled dynamics can be jointly attenuated in a conceptually similar fashion to observer-based active disturbance rejection control (ADRC) and algebraic identification based model free control (MFC) but: a) without using extended state observers and b) respecting the original system order in a time-varying simplified model while avoiding algebraic estimation techniques. The proposed control technique based on the TMS320F28335 digital signal processor chip is tested by means of realistic simulations and experimental setup.

Power Quality Improvement for Grid Connected Inverters under Distorted and Unbalanced Grids

A power quality improvement scheme for grid connected inverters, even in the presence of the disturbances in grid voltages due to harmonic distortions and three-phase imbalance, is presented for distributed generation (DG) power systems. The control objective is to force the inverter currents to follow their references with robustness even under external disturbances in grid voltages. The proposed scheme is realized by a disturbance observer (DOB) based current control scheme. Since the uncertainty in a system can be effectively canceled out using an estimated disturbance by the DOB, the resultant system behaves like a closed-loop system consisting of a disturbance-free nominal model. For experimental verification, a 2 kVA laboratory prototype of a grid connected inverter has been built using a digital signal processor (DSP) TMS320F28335. Through comparative simulations and experimental results under grid disturbances such as harmonic distortion and imbalance, the effectiveness of the proposed DOB based current control scheme is demonstrated.

DC-Link Capacitor Voltage Regulation for Three-Phase Three-Level Inverter-Based Shunt Active Power Filter with Inverted Error Deviation Control

A new control technique known as inverted error deviation (IED) control is incorporated into the main DC-link capacitor voltage regulation algorithm of a three-level neutral-point diode clamped (NPC) inverter-based shunt active power filter (SAPF) to enhance its performance in overall DC-link voltage regulation so as to improve its harmonics mitigation performances. In the SAPF controller, DC-link capacitor voltage regulation algorithms with either the proportional-integral (PI) or fuzzy logic control (FLC) technique have played a significant role in maintaining a constant DC-link voltage across the DC-link capacitors. However, both techniques are mostly operated based on a direct voltage error manipulation approach which is insufficient to address the severe DC-link voltage deviation that occurs during dynamic-state conditions. As a result, the conventional algorithms perform poorly with large overshoot, undershoot, and slow response time. Therefore, the IED control technique is proposed to precisely address the DC-link voltage deviation. To validate effectiveness and feasibility of the proposed algorithm, simulation work in MATLAB-Simulink and experimental implementation utilizing a TMS320F28335 Digital Signal Processor (DSP) are performed. Moreover, conventional algorithms with PI and FLC techniques are tested too for comparison purposes. Both simulation and experimental results are presented, confirming the improvement achieved by the proposed algorithm in terms of accuracy and dynamic response in comparison to the conventional algorithms.

Simplified Adaptive Linear Neuron Harmonics Extraction Algorithm for Dynamic Performance of Shunt Active Power Filter

This paper presents a single-phase shunt active power filter with artificial intelligence based algorithms by introducing a new Simplified Adaptive Linear Neuron (ADALINE) algorithm for harmonics extraction. The proposed harmonics extraction is an innovative work over the established algorithm, known as Modified Widrow-Hoff ADALINE algorithm. Three significant major improvements are made by modifying weight updating technique which leads to introduction of fundamental active current updating technique, removing cosine component according to symmetrical theory of periodic signal, and minimizing large average square error by removing sum of elements. The SAPF with the proposed harmonics extraction algorithm was simulated in MATLAB/Simulink. For practical validation, the experimental laboratory prototype was also developed, and the algorithm was implemented using Digital Signal Processor TMS320F28335. Both simulation and experimental tests cover different types of nonlinear loads and dynamic operation of loads. From simulation and experimental results, significant improvements in terms of Total Harmonic Distortion and response time are shown together with comparison analysis with the established algorithm.

Fuzzy logic controller for partial shaded photovoltaic array fed modular multilevel converter

This study presents the control and modelling of modular multilevel converter (MMC) with grid-connected photovoltaic system. Synchronisation is an important issue in grid-connected system. Even though conventional proportional–integral (PI) controller used for synchronisation provides adequate performance, it yields poor transient response of the system because of poor tuning of controller gain values. In this study, the fuzzy tuned PI controller is designed and implemented to overcome this problem. The fuzzy logic controller refrains the controller gains based on the operating point of the system. The improved performance parameters such as faster transient response, tracking of the reference current with low overshoot and short settling time with system parameter changes under partial shading of the proposed controller are validated. The results are compared with conventional PI controlled grid-connected MMC with various PI gains. The developed controller algorithm is implemented through TMS320F28335 digital signal processor.

Modeling, Digital Control, and Implementation of a Three-Phase Four-Wire Power Converter Used as a Power Redistribution Device

This paper presents a power electronic converter used to redistribute the power among the phases in unbalanced power systems, which is supposed to be designed based on the involved degree of unbalance. A bidirectional converter is chosen for this purpose, whose modeling is presented in the dq0 system. This solution can be considered as part of a unified control system, where conventional active power filters may be solely responsible for compensating harmonics and/or the tuning of passive filters becomes easier, with consequent reduction in involved costs in a decentralized approach. The adopted control strategy is implemented in digital signal processor TMS320F2812, while experimental results obtained from an experimental prototype rated at 17.86 kVA are properly discussed considering that the converter is placed at the secondary side of a transformer supplying three distinct single-phase loads. It is effectively shown that the converter is able to balance the currents in the transformer phases, thus leading to the suppression of the neutral current.

Fundamental Active Current Adaptive Linear Neural Networks for Photovoltaic Shunt Active Power Filters

This paper presents improvement of a harmonics extraction algorithm, known as the fundamental active current (FAC) adaptive linear element (ADALINE) neural network with the integration of photovoltaic (PV) to shunt active power filters (SAPFs) as active current source. Active PV injection in SAPFs should reduce dependency on grid supply current to supply the system. In addition, with a better and faster harmonics extraction algorithm, the SAPF should perform well, especially under dynamic PV and load conditions. The role of the actual injection current from SAPF after connecting PVs will be evaluated, and the better effect of using FAC ADALINE will be confirmed. The proposed SAPF was simulated and evaluated in MATLAB/Simulink first. Then, an experimental laboratory prototype was also developed to be tested with a PV simulator (CHROMA 62100H-600S), and the algorithm was implemented using a TMS320F28335 Digital Signal Processor (DSP). From simulation and experimental results, significant improvements in terms of total harmonic distortion (THD), time response and reduction of source power from grid have successfully been verified and achieved.