Simple Control Algorithm Research Articles

Enhanced Voltage Switching States for Direct Torque Controlled Open End Winding Permanent Magnet Synchronous Motor Drive

Direct torque control (DTC) is most popular technique used in industries for adjustable speed of drives. It has simple control algorithm without any pulse width modulation technique and vector transformations involvement. Two level voltage source inverter (VSI)-fed permanent magnet synchronous motor (PMSM) operated with DTC has higher torque and flux ripple problems due to the limited voltage vectors availability, which affects the performance of drive. To alleviate these problems, more number of voltage space vectors should be available for DTC of PMSM drive. In this article, DTC for open-end winding PMSM drive (OEW-PMSM) is proposed. A two level dual VSI-fed OEW-PMSM drive configuration attains three level inversion with an equal dc link voltage to VSIs. Similarly four level inversion can also be attained with an unequal dc link voltage of 2:1 ratio given to dual VSIs. Therefore availability voltage space vectors are increased for PMSM drive operation. The effective voltage switching tables for DTC operated OEW-PMSM drive at different speed conditions are proposed to make its performance more satisfactory, thus achieving less torque and flux ripples and also reduced common mode voltage (CMV). To validate this, Simulink/MATLAB and real time experimentation are performed on 3.7 kW PMSM drive.

Active Control of A Piston-Type Absorbing Wavemaker with Fully Reflective Structure

Multiple reflections of the waves between structure and wavemaker in hydraulic flumes could change the frequency content of the desired incident wave or result in resonance. A prominent approach to avoid multiple reflections is active control of the wavemaker. This paper proposes a simple and practical active control algorithm for piston-type wavemaker. The block diagram of the control system is presented in real time domain. It is shown that there is no need to use any transfer function or filter in the feedback and feed forward loops and the use of constant gains can yield acceptable results. In the operating frequency range (0.25–2 Hz), it is revealed that the proposed system is very effective at suppressing the excitation of resonant sloshing for regular wave. In the case of irregular waves, it is depicted that the experimental waves agree quite well with the desired wave elevation in frequency domain. In addition, comparison of the results obtained both with and without absorption discloses the good characteristics in time domain.

A Comprehensive Overview in Control Algorithms for High Switching-Frequency LLC Resonant Converter

An LLC resonant converter has been widely used in various industrial applications because of its high cost-effectiveness, high power conversion efficiency, simple design methodology, and simple control algorithms using a pulse frequency modulation (PFM). In addition, the soft switching capability of the LLC resonant converter is good to obtain high switching frequency operations, which can get the high-power density of the power converter. Over the past years, several studies have been conducted to improve the performance of a high switching frequency LLC resonant converter with resonant tank design, optimal power stage design, and enhanced control algorithms. This paper is the review paper in terms of the control algorithms for the LLC resonant converter. It focuses on the overview of the high switching-frequency LLC resonant converter in terms of the control algorithms. The advanced control algorithm can improve power conversion efficiency, dynamic performance, tight output voltage regulation, and small electro-magnetic interference. The operational principles of the control algorithms are briefly explained to show their own characteristics and advantages. Thereafter, the research issues for the future works will be discussed in the conclusion.

Region-Reaching Control of a Flexible-Joint Manipulator

Abstract This paper addresses the region-reaching control problem for a flexible-joint robotic manipulator which is formulated by Lagrangian dynamics. An adaptive control scheme is proposed for the manipulator system having two constrained regions which are constructed by selecting appropriate objective functions. The two joints of the flexible-joint manipulator can be, respectively, confined in different regions, and this gives more flexibility than the traditional fixed-point tracking control. By performing a straightforward Lyapunov stability analysis, a simple control algorithm is established to provide a solution for the region-reaching control problem. Finally, numerical simulations are given to validate the theoretical results.

Combination of Modified P&O with Power Management Circuit to Exploit Reliable Power from Autonomous PV-Battery Systems

Energy demand and conservation are two main concerns in distributed generation systems. Recently, lighting loads play a crucial role in these concerns. Nowadays, DC-fed LED lighting provides better solution. The conventional grid needs rectifier to provide DC results at high cost with low efficiency. Hence, a reliable autonomous PV-battery (APVB) system-fed LED load employing power management circuit (PMC) with maximum power point tracking (MPPT) has been presented to overcome these concerns. The undesirable oscillations at MPP associated with conventional perturb and observe algorithm are highly reduced by implementing variable step size-modified P&O algorithm. PMC includes non-isolated bidirectional converter as a charge controller which determines the battery charging and discharging mode depending upon state of charge, solar/converter output power and battery power with regulated DC bus voltage of 36 V. Performance has been analyzed with three MPPT and PMC through simulation. Moreover, to validate the effectiveness of the proposed approach, incremental conductance control is also employed and compared with results. In addition, the same was also tested with experimental setup by using developed prototype model with DSPIC30F2010 controller. Experimental results illustrate that the proposed system yields desired output voltage with superior performance via simplified control algorithm. Results proven that APVB provides stable and balanced power for any desired loads.

A Low-Harmonic Control Method of Bidirectional Three-Phase Z-Source Converters for Vehicle-to-Grid Applications

Three-phase $Z$ -source inverters provide a solution of voltage boosting by a single-stage topology. They are also capable of bidirectional operation as rectifiers, thus have great potential for applications in the field of transportation electrification such as vehicle-to-grid (V2G) chargers. In this article, three new modulation schemes for three-phase $Z$ -source converters are proposed and investigated. The best performed one is further developed to a closed-loop proportional–integral (PI) control method. Although the voltage conversion ratio is flexible, the output voltage total harmonics distortion (THD) is below 3% within the voltage ratio range 0.5–2.5. The effectiveness of the proposed method has been fully validated in MATLAB/Simulink simulations and RT-Lab hardware-in-loop (HIL) experiments based on the real-time simulator OPAL-RT OP4510. Compared to existing control methods, the proposed one performs better with reduced harmonics, flexible voltage gain, and simpler control algorithm.

Analysis and Verification of a Wide Input Voltage PWM Converter with Variable Windings

A three-leg pulse-width modulation converter with auxiliary windings is provided and investigated to realize wide voltage operation and zero voltage switching characteristics on power switches. The presented converter has three converter legs on the input-side and two sets of winding turns on the output-side. Owing to the on/off states of the three converter legs and the two sets of secondary winding turns, the proposed converter can be operated under three different equivalent circuits to have wide input voltage operation from 30V ~ 240V (Vin,max = 8Vin,min). Compared with the multi-stage converters to realize wide input voltage operation, the proposed circuit topology has fewer circuit components and a simple control algorithm. Conventional duty cycle control with phase-shift between each converter leg is adopted to regulate load voltage and also accomplish zero voltage switching on active switches. The presented three-leg converter is tested with a laboratory circuit. Finally, experiments testify to the performance and validity of the presented converter.

Modular Battery Charger for Light Electric Vehicles

Rapid developments in energy storage and conversion technologies have led to the proliferation of low- and medium-power electric vehicles. Their regular operation typically requires an on-board battery charger that features small dimensions, high efficiency and power quality. This paper analyses an interleaved step-down single-ended primary-inductor converter (SEPIC) operating in the discontinuous conduction mode (DCM) for charging of battery-powered light electric vehicles such as an electric wheelchair. The required characteristics are achieved thanks to favourable arrangement of the inductors in the circuit: the input inductor is used for power factor correction (PFC) without additional elements, while the other inductor is used to provide galvanic isolation and required voltage conversion ratio. A modular interleaved structure of the converter helps to implement low-profile converter design with standard components, distribute the power losses and improve the performance. An optimal number of converter cells was estimated. The converter uses a simple control algorithm for constant current and constant voltage charging modes. To reduce the energy losses, synchronous rectification along with a common regenerative snubber circuit was implemented. The proposed charger concept was verified with a developed 230 VAC to 29.4 VDC experimental prototype that has proved its effectiveness.

Solar Radiation Pressure Enabled Femtosatellite-Based Earth Remote Sensing

Recent developments in electronics have pushed miniaturized satellites to the femto-scale, with masses between 10 and 100 g. Although femtosatellites have been proven as a feasible concept, most designs are limited in mission capacity and lifetime due to the lack of environmental protection and onboard propellant. In this article, a novel concept for femtosatellites for earth remote sensing is proposed. In particular, a swarm of femtosatellites are used as elements of a sparse array in orbit to receive radar echoes. They also feature active orbit control enabled by solar radiation pressure to extend their lifetime. A simple active orbit control algorithm has been demonstrated. A mission concept based on a sun-synchronous circular orbit is proposed to maximize the benefit for both earth remote sensing and active orbit control. A synthetic aperture radar mission has been used to characterize their performance.

Navigation of a Network of Aerial Drones for Monitoring a Frontier of a Moving Environmental Disaster Area

This article focuses on monitoring of a moving disaster area using aerial drones. The aim is to navigate a network of drones to the frontier of the disaster area so that they are able to monitor the faster moving segment of the frontier. A computationally simple sliding-mode control algorithm for navigation of drones is developed. It is proved that the proposed algorithm tracks the moving frontier of the disaster area and achieves the global maximum in the considered optimization problem. Simulations with real bushfire images are conducted to demonstrate the effectiveness of the proposed method.

A Hardware Implementation of Flexible Attitude Determination and Control System for Two-Axis-Stabilized CubeSat

This paper presents a hardware implementation of flexible and low-cost attitude determination and control system (ADCS) for two-axis-stabilized CubeSat. As small satellite missions are increasing, the CubeSat requires precise ADCS with attitude drift adjustment. This attitude drift if not properly compensated, will cause a slow attitude information loss as the error in attitude rises between the actual and estimated signals. The proposed ADCS comprises two steps; the attitude determination which estimates the current CubeSat’s attitude and a novel simplified intelligent proportional-integral control algorithm that accurately adjusts the attitude. The control algorithm is based on the multi degree-of-freedom controller concept and has no controller gains parameters. The proposed ADCS employs sun sensor, magnetometer, and a micro-electro-mechanical gyroscope sensor to correct the attitude drift by offering a comparative attitude that is utilized for updating the estimated attitude delivered to the Kalman filter for determining the CubeSat’s attitude and angular velocity. The ADCS model verification and validation are accomplished via Matlab/Simulink and hardware implementation. A comparison with other ADCS techniques is presented. The ADCS simulated model demonstrates precision results with error of less than 0.1°.

Retraction Note to: Estimation of contact forces of underactuated robotic finger using soft computing methods

Underactuated robotic finger could be used as adaptive mechanism with simple control algorithm. In this study the main aim was to estimate the robotic finger contact forces by soft computing methods. Soft computing approach was applied in order to overcome high nonlinearity in the finger behavior. Kinetostatic analysis was performed in order to extract the input/output data samples for the soft computing methods. The main goal was to estimate the contact forces based on contact locations with the objects. Seven soft computing methods were applied: genetic programming, support vector machine, support vector machine with firefly algorithm, artificial neural network, support vector machine with wavelet transfer function), extreme learning machine and extreme learning machine with wavelet transfer function. The reliability of these computational models was analyzed based on simulation results. Extreme learning machine with wavelet transfer function shown the best accuracy for the contact forces estimation.

Compliance Control for Robot Manipulation in Contact with a Varied Environment Based on a New Joint Torque Controller

Compliance control is required in the applications of robots for assembling, grinding, polishing and human-robot interface, which needs both position control and force control of robots. The impedance control based on joint torque servo is a promising and practical method to realize compliance control in industrial applications. The performance of a joint torque servo controller is thus crucial to the success of compliance control. However, both nonlinear friction torque of the joint motor and varied dynamics of environmental contact during manipulation increase control difficulty greatly. This paper focuses on the compliance control problem and presents a new joint torque servo controller which is a cascading structure including an inner velocity feedback loop and an outer torque control loop. Due to the high signal-to-noise ratio of the motor velocity, an extended state observer is designed to effectively estimate and compensate for the motor friction torque, varied dynamics of environmental contact and other unknown disturbance. And benefiting from the introduction of the efficient and powerful velocity inner loop, the new torque controller performs very well not only in the rigid but also elastic contact environment. Then a standard PD controller is designed in the outer torque loop to produce the control law. Based on the satisfactory joint torque controller, a simplified impedance control algorithm is designed to achieve the force control. Experiments with three other joint torque controllers on a robot manipulator are conducted to demonstrate the proposed joint torque method and the overall force control framework. These results show the proposed joint torque controller can reduce the steady-state error from 3.07 Nm to 0.21 Nm which indicates the joint actuator friction can be eliminated by more than 99%. And a substantial improvement can also be observed in the experiments of force control based on the new joint torque controller.

LUT-Based Focal Beamforming System Using 2-D Adaptive Sequential Searching Algorithm for Microwave Power Transfer

This paper presents a look-up table (LUT)-based focal beamforming system that can effectively transmit RF power up to mid-range distances (≤ 3 m) including when the Rx is in the near-field zones. The Tx elements control and radiate signals for the Rx even at the near-field zone ensuring the received signals are in-phase. Since the proposed system uses a LUT for storing the phase sets of the signals for the Tx elements, it requires only very simple hardware and a very simple adaptive control algorithm compared to conventional retroreflective method. In order to track the moving Rx, a 2-D adaptive sequential searching algorithm is proposed. The system can find the optimum phase set by sequentially searching the phase sets for a pre-determined 2-D area. The LUT of the phase sets are generated using geometric analysis over the entire 2-D area where the Rx could be located. To verify the proposed method, a 5.2 GHz mid-range (≤ 3 m) MPT system composed of a 4 × 8 Tx array and a 2 × 3 Rx array was designed and implemented. Using the proposed 2-D adaptive sequential searching algorithm, the optimum phase set for focal beamforming can be quickly found for a given position of the Rx. In our experiments, the results showed an RF power level of 177.8 mW was received at the Rx with a distance of 1 m with a total radiated RF power of 16W. Since the measured received power levels for various Rx positions agree well with the simulation results, the proposed system was proved to be an excellent candidate for the practical application.

A Unique Single Source Nine Level Inverter with Reduced Switching Devices for Single Phase AC Applications

In recent times there is a huge demand in reduced switched multilevel inverter. The multilevel inverter is one of the attractive features in harmonics elimination. This paper proposes single source nine level inverter with reduced switching devices for single phase AC applications. The conventional cascaded and other multilevel inverter comprises of more number of switches, passive components as well as sources. This makes the system larger in size, weight as well as less cost effective. The proposed multilevel inverter has the ability of producing nine levels with reduced number of switches and source. In addition to that the single source nine level inverter utilizes the simplified control algorithm which reduces the complexity. The Sinusoidal Pulse Width Modulation (SPWM) scheme is one of the most common control techniques which have the simple structure. The operation of the circuit and control algorithm is discussed in detail. The results are verified by the Matlab/Simulink which shows the value and righteousness of the system.

Development of automatic control system of motion of an unmanned surface ships with a sailing installation

The object of research is an unmanned surface ship with a sailing installation. One of the problems in controlling a sailing ship using automatic systems is the almost infinite number of static and dynamic states of traditional sails, which are difficult to detect and difficult to predict. In addition, the ability of traditional sails to twist and engage is known, and all operations with sails are performed through the operation of a running and standing rigging, that is, indirectly. Given the need for continuous deployment and cleaning of conventional sails, building an automatic control system for them will obviously be an extremely difficult task.The paper considers an alternative to the traditional sail – a rigid sail-wing. For unmanned surface ships, the sail-wing is proposed to be made on the basis of symmetrical aerodynamic profiles. Such a sail-wing will simplify such a procedure as cleaning the sail, that is, ensuring its inactivity, as well as simplify the procedure for the transition of a sailing ship by moving the right or left tacks.The study presents relatively simple control algorithms that are possible when using symmetrical aerodynamic profiles for rigid sails. Such sails will make it relatively easy to implement the modes of motion of unmanned ships with tacks, as well as the mode of inactivity of the sail. Also shown is the need to build a system that combines the functions of controlling the angle of attack of the wing-sail and course control. In this case, the control system of the angle of attack does not depend on the heading control system, and the heading control system must take into account the sailing mode. Overcoming the critical transition points of the ship from one tack to another is possible using an additional propulsion device. The control of the sail-wing can be carried out using one single electric drive returns it relative to the wind at a given angle of attack, which ensures its driving force.

Efficient Predictive Torque Control for Induction Motor Drive

Finite control set model predictive control is an emerging technique for the control of power electronic converters. This paper introduces a simple and efficient predictive torque control (PTC) algorithm for induction motor drive. The proposed technique eliminates the need for flux-weighting factor for the conventional PTC. As a result, tedious offline tuning is no longer required. At the same time, the proposed technique ensures that the relative importance between torque and flux ripples is determined in an online fashion. Moreover, unlike the conventional method that needs to evaluate the cost function seven times (for two-level three-phase inverter case), the proposed method needs only to test four voltage vectors at each control sample which leads to a significant reduction in the computation time and switching frequency without sacrificing the performance. The effectiveness of the proposed method is demonstrated by both simulation and experimental results with comprehensive comparisons with the reported literature.

Two-leg Modular Multilevel Cascade Converter as Active Power Filter - Control Improvement

This paper analyses the use of a simplified ac-side current control algorithm strategy, independent of the number of submodules, applied to a Modular Multilevel Cascade Converter acting as an Active Power Filter (MMCC-APF) with a reduced hardware structure. Here, Model Predictive Control (MPC) with a reduced number of states is used for both ac-side current control and submodules' capacitor voltage balancing algorithm. Furthermore, analytical criteria are developed, to define the minimum number of states required for current control. This approach improves the control strategy, thus reducing computational effort for MMCC in APF applications. For the calculation of APF compensating currents, two main strategies are addressed, in order to assess ac-side currents control limitations: (i) total and (ii) specific frequencies harmonic compensation. The system analyzed in this paper consists of a nine-level MMCC connected to a medium voltage distribution grid, compensating the harmonics drained by a diode rectifier. All the analyses are conducted in the environment of circuit simulation PSIM.

Real-time nonlinear speed control of an induction motor based on a new advanced integral backstepping approach

This work proposes a robust control scheme of a three-phase induction motor using a new Backstepping approach based on variable gains. Because of the saturation blocks that are essential to protect the control system, the use of conventional integral Backstepping could lead to a modest performance represented by overshooting and strong vibrations in transitional regimes that cause overcurrent. To develop an efficient and simple control algorithm, the variable gains propriety is used in the speed controller to offer a quick response without overshooting with good robustness against external disturbances. The same property has been introduced in current regulation by a different mean in order to develop a new solution to solve obstacles related to very low-speed operations. The asymptotic stability of the global control is proven by Lyapunov theory. The improvement of the new version compared with the classical one was verified by a brief comparative study based on simulation results. The proposed algorithm has been implemented in a dSPACE DS 1104 card, to analyze the real-time motor performance, and to test control sensitivity against parametric variations. The obtained results show a remarkable improvement of the new control concerning rapidity and stability of transient regimes, overtaking elimination and reduction of starting current, with a low algorithm sensitivity against parametric variations. We have also been able to confirm that the new current control method can guarantee optimal regulation in order to achieve a high-performance operation at very low-speed zones, in the presence of various internal and external disturbances.

PV and Grid interfaced Plug-in EV Battery Charger operating in P-VG, P-V and V-G Modes

The proposed system facilitates uninterruptable charging of a photovoltaic (PV) fed plug-in electric vehicle (EV) battery charging system irrespective of solar irradiation conditions by integrating utility grid to the battery charging system. The system employs bidirectional cycloconverter (BDCC) in order to use utility grid as source or sink during different modes of operation which depends on the availability of solar power. During low irradiation condition, the utility grid acts as a backup source in order to facilitate uninterruptable charging of the EV battery. When surplus power is generated from the PV panel, it is fed to the utility grid, which acts as sink in this mode. For uninterruptable EV battery charging, the controller operates the switches and relays in the proposed system corresponding to solar irradiation level. The available literatures define complex control strategies which are solved in this proposed system by adopting a simple dynamic control algorithm. The simulation of the proposed system has been carried out using PSIM simulation software and experimental prototype has been designed, developed and tested for different modes of operations to validate the efficacy of the proposed system.