Variable Speed Control Research Articles

Attitude maneuver of spacecraft with a variable-speed double-gimbal control moment gyro

In this paper, two types of computational procedures are presented for a rest-to-rest spacecraft maneuver using a variable-speed double-gimbal control moment gyro (VSDGCMG). The first procedure is a numerical computational procedure in which a quasi-time-optimal trajectory satisfying several physical constraints is obtained by repeating the Newton’s method. The other procedure is an approximate computational procedure in which an analytical solution is obtained by approximately solving a series of linear optimal control problems. The two procedures play complementary roles: the former is suitable for implementation, and the latter can be used to select an initial value for use in the former. The effectiveness of the proposed procedures is demonstrated by plotting the surfaces of maneuvering time for all rotational axes and by plotting time responses for several maneuvering examples.

IMPROVED INDIRECT FIELD-ORIENTED CONTROL OF INDUCTION MOTOR DRIVE BASED PSO ALGORITHM

Optimization techniques are increasingly used in research to improve the control of three-phase induction motor (TIM). Indirect field-oriented control (IFOC) scheme is employed to improve the efficiency and enhance the performance of variable speed control of TIM drives. The space vector pulse width modulation (SVPWM) technique is used for switching signals in a three-phase bridge inverter to minimize harmonics in the output signals of the inverter. In this paper, a novel scheme based on particle swarm optimization (PSO) algorithm is proposed to improve the variable speed control of IFOC in TIM. The PSO algorithm is used to search the best values of parameters of proportional-integral (PI) controller (proportional gain (kp) and integral gain (ki)) for each speed controller and voltage controller to improve the speed response for TIM. An optimal PI controller-based objective function is also used to tune and minimize the mean square error (MSE). Results of all tests verified the robustness of the PSO-PI controller for speed response in terms of damping capability, fast settling time, steady state error, and transient responses under different conditions of mechanical load and speed.

Experimental and Analytical Studies on Variable Speed Control of High-Temperature Superconducting Induction/Synchronous Motor

We try to realize variable speed control technology of superconducting drive motors in order to apply such motors to transportation equipment, i.e., trains, buses, automobiles, etc. Our target motor is the so-called high-temperature superconducting induction/synchronous motor (HTS-ISM). Based on experiments and analyses, we have already shown that the HTS-ISM has prominent performance such as highly efficient synchronous rotation in the steady state. On the other hand, a detailed study for the variable speed control is not carried out yet. In this paper, we first perform a starting test of a 20-kW-class HTS-ISM and then succeed in accelerating the HTS-ISM from 0 to 1500 r/min just for 0.4 s. Second, we succeed in controlling the HTS-ISM for variable speed under the drive mode called standard JC08. Next, we assume that there should be three kinds of rotational modes upon the acceleration of the HTS-ISM, which are expressed by the use of a transfer function. It is shown that the analytical results agree well with the phenomenon in the experiment we conducted. These results indicate that it is possible to accelerate the HTS-ISM under not only the slip mode but also the highly efficient synchronous mode.

RETRACTED: Robust variable air speed control of a nonlinear fan system based on backstepping sliding mode control techniques

A backstepping technique combining the sliding mode control method with an integrator and estimator design for variable air speed control is proposed in this article. The self-build fan-plate system is used to derive the mathematical model for air speed control which builds a direct connection between motor rotation and air speed control. Furthermore, the mathematical model also includes effects arising from modelling uncertainties, parameter variations and external disturbances because of modelling errors, load changing and variable loading shifting, respectively. The Lyapunov theory is employed in the controller design procedure that ensures the stability of the system. The experimental results show the great tracking and convergence ability of the proposed controllers even under the time variations and sharply changing commands.

CFD simulation of a floating offshore wind turbine system using a variable-speed generator-torque controller

Prediction and control of rotor rotational velocity is critical for accurate aerodynamic loading and generator power predictions. A variable-speed generator-torque controller is combined with the two-phase CFD solver CFDShip-Iowa V4.5. The developed code is utilized in simulations of the 5 MW floating offshore wind turbine (FOWT) conceptualized by the National Renewable Energy Laboratory (NREL) for the Offshore Code Comparison Collaboration (OC3). Fixed platform simulations are first performed to determine baseline rotor velocity and developed torque. A prescribed platform motion simulation is completed to identify effects of platform motion on rotor torque. The OC3’s load case 5.1, with regular wave and steady wind excitation, is performed and results are compared to NREL’s OC3 results. The developed code is shown to functionally control generator speed and torque but requires controller calibration for maximum power extraction. Generator speed variance is observed to be a function of unsteady stream-wise platform motions. The increased mooring forces of the present model are shown to keep the turbine in a more favorable variable-speed control region. Lower overall platform velocity magnitudes and less rotor torque are predicted corresponding to lower rotor rotational velocities and a reduction in generated power. Potential improvements and modifications to the present method are considered.

Dynamics and Modal Analysis of Gyroelastic Body With Variable Speed Control Moment Gyroscopes

Gyroelastic body refers to a flexible structure with a distribution of stored angular momentum (called gyricity). In previous studies, it was assumed that each volume element of the structure possesses an infinitesimal spinning rotor so that the distribution of the gyricity is continuous. However, the momentum devices must be discretely distributed in engineering applications; therefore, this paper studies the gyroelastic body formed by directly mounting a set of variable speed control moment gyroscopes (CMGs) on the flexible structure. The detailed dynamics of the CMGs is incorporated to capture the interactions between the CMGs and the structure. The gyroelastic modes and pseudorigid modes are discussed based on the linearized mathematical model. The examples of a gyroelastic beam and a gyroelastic parabolic structure demonstrate several involved concepts and properties.

Load reduction potential of variable speed control approaches for fixed pitch tidal current turbines

The present paper compares control strategies for fixed pitch tidal current turbines and introduces the underspeed control technique. The state of the art approach of overspeed control for fixed pitch turbine increases the tip speed ratio to limit the power output of the turbine. This leads to a high fatigue loading as the number of load cycles increases and requires a specific rotor design not to increase the thrust coefficient as well.The underspeed controller on the other side reduces the tip speed ratio resulting in a reduced thrust coefficient and a reduced number of load cycles. However, this point of operation is unstable based on the characteristic curves of the rotor and needs to be stabilised by the controller. The basic structure of the controller as well as the calculated stability limits will be shown in the paper.Further, the performance of the underspeed controller regarding loads is compared to state of the art fixed and variable pitch controllers. The paper concludes with an analysis of the impacts on the turbine design and further potential and issues arising with the underspeed control approach, especially the stochastic stall.

Passively adaptive tidal turbine blades: Design tool development and initial verification

Fixed pitch passively adaptive tidal turbine blades made of non-homogeneous composite materials have the potential to reduce blade and structural loads, shed power above design conditions, reduce cavitation inception, and reduce the effects of fatigue loading. Due to the flexibility of these blades, a fluid–structure interaction design methodology is required. This paper outlines the development of a coupled finite element (FEM)-blade element momentum theory (BEMT) design tool developed to iterate between the structural (deformation and stresses) and hydrodynamic (power and thrust loads) responses of passively adaptive blades. Such a FEM–BEMT design methodology provides an early stage tool with minimal computational requirements compared to computational fluid dynamics-FEM coupled codes. Both the BEMT and FEM components of the design code have been verified independently, with results presented here. Results using the design tool in a case study of a small-scale turbine with three pre-twisted fixed pitch passively adaptive blades, operated using variable speed control, showed load mitigation and power shedding at flow speeds above design conditions, and increased overall power capture between the cut-in speed and the design speed.

Modelling, control and frequency domain analysis of a tidal current conversion system with onshore converters

To optimise a tidal energy conversion system, the operation, maintenance and power generation aspects have to be taken into account. As a result the key focus of this study is to propose and investigate an alternative method of implementing a tidal energy conversion system using a pitch-regulated turbine and a variable-speed squirrel cage induction generator with long distance converters. The generator power output can be optimised by utilising variable-speed control strategies allowing the system to operate at maximum power coefficient while availability can be increased by reducing the components installed offshore by using long three-phase cables between the generator and onshore voltage source converters. The tidal current energy conversion system is investigated by developing a full resource-to-grid model in MATLAB/SIMULINK and by performing system analysis regarding the effects of harmonics in the long subsea cables. Simulation results show that optimised filter design and the choice of suitable operating frequency for the generator controller can minimise the overvoltages associated with the harmonics and the reflecting voltage waves in the cables.

Research and Development of High-speed Laser Scanning Galvanometer System

This study developed and controlled laser scanning mechanism and circuit design, in order to reduce the vibratory magnitude resulted from high-speed operation. The principle of mechanism design is that the output end mirror can swing within ± 3° when the laser scanning mechanism is in operation, the accuracy value is ± 0.2°. The static simulation and dynamic measurement were carried out for mutual validation. The vibration generated in the operation of machine causes dynamic unbalance, influencing the stability of machine. In order to overcome and improve the dynamic unbalance generated when the mechanism is in motion, different solutions were proposed, such as changing the output end mass, to add elastic material in or to change constant speed control of input end motor to variable speed control.

逆運動学に基づく単一の可変速二軸ジンバルコントロールモーメントジャイロの駆動則

逆運動学に基づく単一の可変速二軸ジンバルコントロールモーメントジャイロの駆動則

可変速2軸ジンバルCMGの特異点の回避／通過則について

Attitude control of a spacecraft using a variable-speed double-gimbal control moment gyro is considered in this paper. A steering law of this type of actuator has singular points where the rotation axis of the wheel coincides with that of the outer gimbal. Either the avoidance or passage of the singular states can be adopted in the steering law. In this paper, the steering law that selects the avoidance or passage of the singular states from the outer gimbal motion in the vicinity of the singular states is proposed. The usefulness of the steering law is examined by the ground experiments as well as the numerical simulations.

テザーの速度可変式巻取り制御に関する研究

テザーの速度可変式巻取り制御に関する研究

Integrated Power and Attitude Control Design of Satellites Based on a Fuzzy Adaptive Disturbance Observer Using Variable-Speed Control Moment Gyros

To satisfy the requirements for small satellites that seek agile slewing with peak power, this paper investigates integrated power and attitude control using variable-speed control moment gyros (VSCMGs) that consider the mass and inertia of gimbals and wheels. The paper also details the process for developing the controller by considering various environments in which the controller may be implemented. A fuzzy adaptive disturbance observer (FADO) is proposed to estimate and compensate for the effects of equivalent disturbances. The algorithms can simultaneously track attitude and power. The simulation results illustrate the effectiveness of the control approach, which exhibits an improvement of 80 percent compared with alternate approaches that do not employ a FADO.

Variable Sampling Effect for BLDC Motors using Fuzzy PI Controller

Background/Objectives: The variable sampling effect the response time taken to attain its speed of the motor is low whereas, response time is high. Methods/Statistical Analysis: The simulation tool includes three parts, the first is continuous time model of BLDC motors, the second is variable sampling trigger, and the next is the discrete time speed and variable sampling time constant estimator. Findings: Variable sampling systems describe a class of systems whose sensor outputs are obtainable only at some situations not specified by the sampling mechanism. In our proposed work, a fuzzy PI controller based on variable sampling for BLDC motor drives with low resolution position sensors (Hall sensors). It is not only easy to understand as the conventional PI controller, but also more robust in variable speed control. We use three PI controller based on different sampling time at the same time, a fuzzy logic controller to calculate command. The only input variable of our fuzzy logic is rotor speed of the BLDC motor, because the sampling time thus becomes a variable according to the motor speed and the response time is high. Application/Improvements: This type method used for air-conditioner, fans etc.

Analysis of a Dual-Winding Fault-Tolerant Permanent Magnet Machine Drive for Aerospace Applications

With the increasing development of aircraft and helicopter, new electric drive system for aerospace applications have attracted more and more attentions in the aviation sector [1]-[2]. The common hydraulic drive helicopter winch is replaced by the electric drive helicopter winch gradually, due to the fact that the electric drive system can not only improve the system efficiency and the flexibility of variable speed control, but also reduce the weight and volume of the system [2]-[3]. However, in the electric drive helicopter winch systems, where continuous operation must be ensured, high reliability and strong fault tolerance become a critical requirement [2]-[4]. The purpose of this paper is to propose a new electric drive helicopter winch system based on a six-phase ten-pole dual-winding fault-tolerant permanent magnet (DFPM) machine. The DFPM machine, which incorporates the merits of high power density and high efficiency of permanent magnet (PM) machine and high fault-tolerance of dual-winding machine, consists of optimal surface-mounted permanent magnet rotor and 12 slots stator with two sets of independent three-phase concentrated armature windings on alternate teeth. To achieve the fault-tolerant performance, the redundant fault-tolerant control strategy based on speed, current, voltage three-loop control is proposed and analyzed. Then, the electromagnetic performances of the DFPM machine drive with an open-circuit fault under load hoisting and dropping conditions have been verified by experiments. The research results showing the effectiveness of the proposed fault-tolerant control strategy and the high performance of the fault-tolerant characteristic of the proposed DFPM machine drive.

2개의 가변속 제어모멘트자이로를 이용한 인공위성의 자세제어

For the attitude control of spacecraft, two variable-speed control moment gyros are proposed as main actuators in the article. Since a variable-speed control moment gyro (VSCMG) makes two control torques (gyroscopic torque and reaction torque), two VSCMGs are sufficient for controlling 3-axes attitude. Additionally, there are no singular conditions for two non-parallel VSCMGs. Since gyroscopic torque is usually much greater than reaction torque, the control performances of approximately 3 axes may not be the same. However, several missions can be accomplished by controlling two axes. For such missions, a selective axes control method is proposed. The method selects two axes for a certain task and controls the attitude of the selected axes. For the remaining axis, angular speed is controlled for stabilization. A hardware-in-the-loop simulation has been used to test VSCMG modules and to verify the proposed method. Two VSCMGs can be alternative actuators for small satellites.

Adaptive hill-climb searching method for MPPT algorithm based DFIG system using fuzzy logic controller

This paper proposes a variable speed control algorithm for a grid connected doubly-fed induction generator system. The main objective is to track the maximum power point by using an adaptive hill climb searching (HCS) technique based on fuzzy logic controller (FLC), and compare it with the conventional optimal torque control method for large inertia wind turbines. The role of the FLC is to adapt the step-size of the HCS method according to the operating point. The control system has two sub-systems for the rotor side and the grid side converters (RSC, GSC). Active and reactive power control of the back-to-back converters has been achieved indirectly by controlling q-axis and d-axis current components. The main function of the RSC controllers is to track the maximum power through controlling the rotational speed of the wind turbine. The GSC controls the DC-link voltage, and guarantees unity power factor between the GSC and the grid regardless of the magnitude and direction of the slip power. The proposed system is developed and tested in MATLAB/SimPowerSystem environment.

Energy Efficient Blower Control Strategy for the Ventilation System of a Metropolitan Subway Station

This paper proposes an energy efficient blower motor control strategy for the ventilation system in the metropolitan subway station based on an electrical energy saving simulator. This ventilation energy saving simulator considers the energy saving effect when the control method for an induction blowermotor is changed from simple on/off control to a variable speed control method. In addition, it also provides energy saving information when the blower induction motor is changed to a synchronous reluctance blower motor with the variable speed control method. The ventilation energy saving calculator in this paper was built by MATLAB. Based on a comparative study, it can be concluded that the variable speed control method with a blower induction motor has 71% of energy saving effect and that the blower motor replacement from an induction motor to a SynRM has 73% of energy saving effect.

Attitude tracking of a rigid spacecraft using two internal torques

The attitude-tracking control of a rigid spacecraft using only two internal torques is addressed. First, a given reference trajectory is classified as feasible or unfeasible according to the preservation or violation of the momentum conservation law. The dynamics of the attitude-tracking error is then formulated on the attitude manifold SO(3) with the angular momentum of the actuators as inputs. Given the Lie group structure of SO(3), the transverse function approach is utilized to design an attitude-tracking law ensuring asymptotically ultimately bounded tracking error for any reference trajectory. For feasible reference trajectories satisfying certain persistence conditions, asymptotic tracking is achieved by constructing an asymptotically stable zero dynamics for the closed-loop system. To deliver control torques to the actuator command signals, steering laws are designed for two reaction wheels, two single-gimbal control moment gyros mounted in parallel, and one variable-speed control moment gyro, respectively. The resulting control law can be applied to a spacecraft with different kinds of momentum actuators but underactuated for tasks ranging from bounded tracking of a generic trajectory, three-axis earth pointing to line-of-sight pointing, etc. Numerical examples are presented to verify the effectiveness of the proposed method.