Variable Speed Control Research Articles

Optimization design steering law for VSCMGs with the function of attitude control and energy storage

Control Momentum Gyros (CMGs) have many advantages over other actuators for attitude control of a spacecraft. Compared with Single Gimbal Control Moment Gyroscopes (SGCMGs), the Variable Speed Control Moment Gyros (VSCMGs) can be easily implemented. The VSCMGs have great advantages in performing complex mission of attitude control and easing power shortage of the entire spacecraft. In this paper, the singularity avoidance characteristic of the steering law of Weighted Pseudo-inverse with Null Motion (WPINM) is firstly analyzed by the method of the inner product. A new steering law is designed based on optimization theory, which can satisfy the requirement of attitude control and energy storage. At last, the singular point can be avoided by the new design steering law based on the simulation result.

Composite Decoupling Control of Gimbal Servo System in Double-Gimbaled Variable Speed CMG Via Disturbance Observer

In order to realize the decoupling and disturbance rejection control of the inner and outer gimbal system under two working conditions of a double-gimbaled variable speed control moment gyroscope (DGVSCMG), this paper presents a composite controller based on the disturbance observer and state feedback control. We first developed a dynamic model of a double-gimbal servo system, and analyzed the system characteristics of coupling and mismatched disturbance in CMG and flywheel working modes. Then, we propose a novel decoupling method through regarding the coupling term as systems lumped disturbance. The system disturbance was estimated by the designed disturbance observer and was rejected via the proposed composite controller combining a state feedback method. Finally, we proved the overall system stability by using a Lyapunov approach and derived an estimated upper bound of the state variables to guide controller parameters selection. We concluded from simulation and experimental results that the proposed method was effective in decoupling and disturbance compensation control of the DGVSCMG double-gimbal servo system, and enhanced system disturbance rejection and speed servo performance.

Dynamic analysis of vibratory feeder and their effect on feed particle speed on conveying surface

Abstract The vibratory feeder is a forced vibrating system mostly used in industries to feed material from hoppers, bins, silos and storage piles to belt conveyors. It is used to control the feed rate of material being transported. In this paper, dynamic analysis of the vibratory feeder is conducted theoretically and the obtained results are validated with experimental values corresponding to the various operating frequencies of the feeder unit. Further, speed of feed particles are identified experimentally at various operating frequencies. The actual vibration behavior of the particle on conveying surface is examined experimentally and movement of the particles are shown graphically. The experimental work is conducted on the fabricated vibratory feeder with 1HP motor installed on it with variable speed controller. The instruments used are the B&K 4-channel analyzer, accelerometer and the force transducer. The post processing of data analysis was done in ME’Scope software.

Asymptotic tracking control for wind turbines in variable speed mode

This paper presents a variable speed control strategy for wind turbines in order to capture maximum wind power. Wind turbines are modeled as a two-mass drive-train system with generator torque control. Based on the obtained wind turbine model, variable speed control schemes are developed. Nonlinear tracking controllers are designed to achieve asymptotic tracking for a prescribed rotor speed reference signal so as to yield maximum wind power capture. Due to the difficulty of torsional angle measurement, an observer-based control scheme that uses only rotor speed information is further developed for global asymptotic output tracking. The effectiveness of the proposed control methods is illustrated by simulation results.

VSCMG搭載宇宙機における姿勢制御とバッテリーの長寿命化を考慮した電力マネジメント

This study proposes a power management method for a spacecraft with Variable Speed Control Moment Gyro/Integrated Power and Attitude Control System (VSCMG/IPACS) and Lithium-ion battery, considering the lifetime of the battery. The proposed method achieves the attitude control of the spacecraft through the steering law of the VSCMGs, while the IPACS and battery realize the required power, suppressing the degradation mode of the battery. In the proposed power management method, the total required power is distributed into two references, which should be realized by the battery and the IPACS. In case the thresholds of the state of charge (SOC) or C-rate of the battery are exceeded, the IPACS assists the power output and charging of the battery while considering the saturation of the wheel speed of the IPACS.

Maneuver and Active Vibration Suppression of Free-flying Space Robot

This work studies the maneuver control and vibration suppression of a flexible free-flying space robot using variable-speed control moment gyros as actuators. A novel flexible space manipulator is designed. The dynamics of the flexible multibody system is derived by using Kane method. Based on the singular perturbation approach, the dynamics of the flexible manipulator is decoupled into a slow subsystem and a fast subsystem. The slow subsystem is associated with the rigid motion dynamics, and the fast subsystem is related to the link flexible dynamics. A composite control strategy is proposed as a combination of two controllers for these subsystems. An adaptive sliding mode controller is designed for the slow subsystem, and an adaptive controller is designed for the fast subsystem. Uncertainty estimation can be achieved by the adaptive terms of the composite controller. A weighted robust pseudo-inverse steering law is proposed for the variable-speed control moment gyros. Numerical results demonstrate that the proposed composite controller is robust to parameter uncertainties and external disturbances.

Mode-Scheduling Steering Law of VSCMGs for Multi-Target Pointing and Agile Maneuver of a Spacecraft

This study proposes a method of selecting a set of gimbal angles in the final state and applies the method to the mode-scheduling steering law of variable-speed control moment gyros intended for multi-target pointing manoeuvres in the three-axis attitude control of a spacecraft. The proposed method selects reference final gimbal angles, considering the condition numbers of the Jacobian matrix of the reaction wheel mode in the final state of a single manoeuvre and that of the constant-speed control moment gyro mode at the start of the upcoming manoeuvre to keep away from the singularities. To improve the reachability of reference final gimbal angles, the nearest set of gimbal angles among nominated sets according to the Euclidean norm is selected as the reference final set at the middle of the single manoeuvre, and then realised by adopting gimbal angle feedback steering logic using null motion. In addition, the manoeuvre profile is designed such that the second half of the single manoeuvre is more gradual and takes longer than the first. Numerical simulation confirms the validity of the proposed method in consecutive manoeuvres.

The parameters optimisation design for variable speed control momentum gyroscopes

ABSTRACTControl momentum gyroscopes (CMGs) have many advantages over other actuators for the attitude control of a spacecraft. Compared with the single-gimbal control moment gyroscopes (SGCMGs), the mass and power of the flywheel of variable-speed control moment gyroscopes (VSCMGs) are greatly increased. In this paper, a new solving strategy of singularity problem is proposed, which concludes the exchangeable momentum and steering law, and the parameters of VSCMGs are designed based on the constraint of singular problem. The configuration characteristics of VSCMGs with the constraint of upper and lower bounds of the flywheel regulation speed are revealed. The steering characteristics of weighted pseudo-inverse with null motion (WPINM) are analysed, then the flywheel torque requirement of WPINM is evaluated based on the geometry theory. At last, the parameter design problem of VSCMGs is cast as multi-objectives and bi-level programming problem. The bi-level programming is transformed into a single-level programming problem by using of the Karush–Kuhn–Tucker condition. Finally, the intelligent algorithm of particle swarm optimisation is presented to solve the nonlinear multi-objective problem.

A new steering approach for VSCMGs with high precision

A new variable speed control moment gyro (VSCMG) steering law is proposed in order to achieve higher torque precision. The dynamics of VSCMGs is established, and two work modes are then designed according to command torque: control momentum gyro (CMG)/reaction wheel (RW) hybrid mode for the large torque case and RW single mode for the small. When working in the CMG/RW hybrid mode, the steering law deals with the gimbal dead-zone nonlinearity through compensation by RW sub-mode. This is in contrast to the conventional CMG singularity avoidance and wheel speed equalization, as well as the proof of definitely hyperbolic singular property of the CMG sub-mode. When working in the RW single mode, the motion of gimbals will be locked. Both the transition from CMG/RW hybrid mode to RW single mode and the reverse are studied. During the transition, wheel speed equalization and singularity avoidance of both the CMG and RW sub-modes are considered. A steering law for the RWs with locked gimbals is presented. It is shown by simulations that the VSCMGs with this new steering law could reach a better torque precision than the normal CMGs in the case of both large and small torques.

Analysis of centrifugal chillers with oil-free magnetic bearings for enhancing building energy performance

This article examines the actual operating performance of centrifugal chillers with oil-free magnetic bearings (hereafter oil-free chillers) to analyze energy saving potentials for commercial buildings. A chiller system retrofit for a shopping arcade involved replacing three existing constant speed water-cooled centrifugal chillers by three oil-free centrifugal chillers of the same capacity. The coefficient of performance was calculated based on operating data logged at 1-h intervals for over 1 year before and after replacement. Oil-free chillers with variable speed control operated at a higher coefficient of performance under part load conditions, reducing the total electricity consumption of the shopping arcade by 9.6%. If the average technical efficiency in data envelopment analysis was improved to 1 from 0.6 in the existing case, the average system coefficient of performance could increase from 6.2 to 10.3. The improvement involved controlling the temperature of supply chilled water at a lower boundary curve and operating an equal percentage of capacity among chillers. It is economically viable to design an all-variable speed chiller system with oil-free chillers instead of the conventional constant speed system for a reference office building in a subtropical climate.

Robust RST control design based on Multi-Objective Particle Swarm Optimization approach

In this paper, a novel method for the digital two-Degrees-Of-Freedom (2DOF) controller design, called canonical RST structure, is proposed and successfully implemented based on a Multi-Objective Particle Swarm Optimization (MOPSO) approach. This is a polynomial control structure allowing independently the regulation and the tracking of discrete-time systems. An application to the variable speed control of an electrical DC Drive is investigated. The RST design and tuning problem is formulated as a multi-objective optimization problem. The proposed MOPSO algorithm which is based on the Pareto dominance is used to identify the non-dominated solutions. This approach used the leader selection strategy that is called a geographically-based system. In addition, the adaptive grid method is used to produce well-distributed Pareto fronts in the multi-objective formalism. The well known NSGA-II and the proposed MOPSO algorithms are evaluated and compared with each other in terms of several performance metrics in order to show the superiority and the effectiveness of the proposed method. Simulation results demonstrate the advantages of the MOPSO-tuned RST control structure in terms of performance and robustness.

Take-off characteristics and longitudinal controllability of FanWing

Purpose This paper aims to study the short take-off characteristics and longitudinal controllability of FanWing. As a new structural plane, it has achieved great success at the air shows, but the existing literature is mostly on feasibility and prototype study while little on short take-off performance analysis and controllability. Thus, the paper will do some research on those two aspects. Design/methodology/approach This paper focuses on a certain type of a 3.5 kg FanWing and builds the longitudinal model based on its structure characteristics and operation principle. Its take-off process is simulated and the longitudinal control law is designed. Findings The short take-off performance and the large load characteristic are verified. To attain a better short take-off performance, several factors that influence the take-off distance are researched, and the optimal no-load take-off distance 5 m is obtained when the elevator deflection angle is −30°, the center of gravity is 0.42 m and the cross-flow fan rotation speed is 2500 r/min. The longitudinal controllability is verified through simulation. And without variable cross-flow fan rotation speed control, the longitudinal control of FanWing is the same to that of the conventional aircraft. Practical implications The presented efforts provide markers for designing the fan wing aircraft that would have better performances. And the control of FanWing is similar to that of a conventional airplane. Originality/value It is proved that FanWing can offer a better take-off performance through reasonable configuration. The paper also offers a useful reference on the control of FanWing.

Economic analysis of air-cooled chiller with advanced heat rejection

This study analyses economic benefits of an air-cooled chiller retrofitted with advanced heat rejection features. The rated capacity was 282 kW and operating variables were monitored comprehensively to develop random forest models. The top five variables to ensure model accuracy were identified. Electricity savings were predicted by the models with 3 advanced operating modes: variable speed control for condenser fans with an adjustable condensing temperature (the VSD mode), mist precooling of condenser air (the Mist mode), and their composites (the VSD + Mist mode). The integrated part load value (IPLV) was 2.90, 3.31, 2.93 and 3.34 for the normal mode, VSD mode, Mist mode, and the VSD + Mist mode, respectively. For a chiller system serving an office building, the VSD mode gave the highest economic benefit with a simple payback of 10.83 yrs and an internal rate of return of 4.38% over a 15-yr life cycle.

Constrained steering law for VSCMGs with the function of attitude control and energy storage

Variable speed control moment gyros (VSCMGs) cluster with single gimbal have great advantages in performing integrated power/attitude control system. In this paper, the changeable momentum envelop that can satisfy attitude control and energy storage is firstly given. The singularity avoidance characteristic of VSCMGs is firstly analyzed of weighted pseudo-inverse will null motion. A new steering law with constrained momentum envelop is proposed. The new design steering law can reduce the requirement of the flywheel torque and satisfying the requirement of attitude control and energy storage. At last, the simulation result verified that the new steering law can effectively avoided the singularity point and greatly reduced the requirement of flywheel torque.

IoT Based Wind/Solar Hybird Inverter

Paper deals with power control of a wind and solar hybrid generation system for connection operation with electric distribution system. Power control strategy is to extract the maximum energy available from varying condition of wind speed and solar irradiance while maintaining power quality at a safety level. In order to verify the maximum power variable speed control is come for wind turbine and maximum power is applied for PV system. Inverter transfers the energy from the wind turbine and PV array into the grid by keeping common dc voltage constant. To ensure safety these inverters automatically shut down in the event of: High/Low AC-voltage; High/Low frequency; IOT is a key feature in which safety measurement is current and voltage. The results show the control performance and behavior of the wind/PV system .solar and wind are major possible ways were energy level are stored in battery, we implement to ensure that power transmission ways in hybrid pv/wind power are stored properly in batteries. Our aim is to monitor the current and voltage by means of IOT. The wave distribution of voltage and current is checked rapidly by using IOT. Non regular checking of voltage and current leads to total damage. And so we ensure that damage are monitored over IOT, variable power raise and drop are checked over by IOT. PV and wind power.

A novel technology for control of variable speed pumped storage power plant

Variable speed pumped storage machines are used extensively in wind power plant and pumped storage power plant. This paper presents direct torque and flux control (DTFC) of a variable speed pumped storage power plant (VSPSP). By this method both torque and flux have been applied to control the VSPSP. The comparison between VSPSP’s control strategies is studied. At the first, a wind turbine with the capacity 2.2 kW and DTFC control strategies simulated then a 250 MW VSPSP is simulated with all of its parts (including electrical, mechanical, hydraulic and its control system) by MATLAB software. In all of simulations, both converters including two-level voltage source converter (2LVSC) and three-level voltage source converter (3LVSC) are applied. The results of applying 2LVSC and 3LVSC are the rapid dynamic responses with better efficiency, reducing the total harmonic distortion (THD) and ripple of rotor torque and flux.

Time-Optimal Path Planning for a Kinematic Car with Variable Speed

This paper investigates the minimum-time path-planning problem for a kinematic car with variable speed and turn rate controls. The speed is strictly positive, ranging from a lower to an upper limit, and the turn rate limits are symmetric about zero. The minimum principle is used to characterize the extremal controls and, using additional geometric arguments, a finite and sufficient set of candidate optimal controls is derived. It is found that, in addition to straight and maximum rate turning segments at maximum-speed, minimum-time paths may include “cornering” turns at the minimum forward speed and the maximum turn rate. A procedure is proposed for solving the path synthesis problem of constructing the minimum-time path between two “oriented points” in the plane.

Optimal and energy efficient operation of conveyor belt systems with downhill conveyors

Downhill conveyors are important potential energy sources within conveyor belt systems (CBSs). Their energy can be captured using regenerative drives. This paper presents a generic optimisation model for the energy management of CBSs that have downhill conveyors. The optimisation model is able to optimally schedule three configurations of a case-study CBS that is connected to the grid and operated under a time-of-use tariff. The three suggested drive configurations showcase potential energy savings/incomes that can be obtained from implementing: (a) variable speed control, (b) internal use of downhill conveyor energy and (c) the export of energy to the grid. The results show that a CBS with a daily energy consumption of 924 kWh can be reconfigured and controlled to reduce consumption by 53 or 100 % or be made to generate 1984 kWh, depending on the configuration. Analysis of the investment in each of the three configurations is assessed using a life-cycle cost and payback period (PBP). The daily operation simulation results show that the use of regenerative drives and variable speed control is able to provide energy savings in CBSs. The cost analysis shows that the configuration that enables sale of energy to the grid is the most profitable arrangement, for the case study plant under consideration. The sensitivity analysis indicates that the PBPs are more sensitive to the annual electricity price increases than changes in the discount rate. Combining regenerative drives and optimal operation of CBS generates energy savings that give attractive PBPs of less than 5 years.

Variable Speed Control Using Fuzzy-PID Controller for Two-phase Hybrid Stepping Motor in Robotic Grinding

In a robotic grinding process, a light-weight grinder is held by an intelligible robot arm. Material removal is carried out by the rotating grinding tool while the end effector of robot guarantees that the tool follows a programmed path in order to work on complex curved surfaces. Grinding tool is driven by Two-Phase Hybrid Stepping motor derive. This work aims to develop a controller based on fuzzy logic to improve the speed control performance of Two-Phase Hybrid Stepping motor derive in order to achieve a controller that provides grinding with higher quality. The analysis and design of PID-Fuzzy controller to improve the response of the motor speed were studied. This paper simulates six motor speed input conditions. The simullink package of the MATLAB. Comparison between the conventional PID controller and Fuzzy-PID output was done on the basis of the simulation result obtained by MATLAB. The simulation results demonstrate that the designed Fuzzy-PID controller realize a good dynamic behavior of the Two-Phase Hybrid Stepping motor, a perfect speed tracking with less rise and settling time, minimum overshoot, minimum steady state error and give better performance compared to conventional PID controller.

Improved variable speed control of series‐connected DC wind turbines for offshore wind power collection to high‐voltage direct current system

DC wind farm (DCWF) with series-connected DC wind turbines (DCWTs) is proved to be a potential solution of offshore wind power collection. The coupling behaviour of series-connected DCWTs is described in detail. Possible wind energy curtailment during the period of wind turbine voltage limitation and its key impact factors are firstly quantitatively derived. A novel variable speed control strategy is proposed under voltage limiting condition of the DCWT to improve its wind energy capture. This control algorithm can be implemented in the local DCWT controller without the communication need. The specific variable speed control strategy of the DCWT is realised in a generalised averaged model. Dynamic simulation cases under different operation conditions have been conducted to evaluate the effectiveness of the proposed control strategy. It is found that the proposed control strategy might be a solution for wind energy curtailment, which will significantly improve the performance of the series-connected DCWTs between the time scale above seconds and below minutes.