Modern dynamo electric machinery

Advanced optimization of gas turbine aero-engine transient performance using linkage-learning genetic algorithm: Part II, optimization in flight mission and controller gains correlation development

A stable gain scheduled controller for a gas turbine engine that drives a variable pitch propeller is developed and described. A stability proof is developed for gain scheduled closed-loop system using global linearization and linear matrix inequality (LMI) techniques. Using convex optimization tools, a single quadratic Lyapunov function is computed for multiple linearizations near equilibrium and nonequilibrium points of the nonlinear closed-loop system. This approach guarantees stability of the closed-loop gas turbine engine system. To verify the stability of the closed-loop system on-line, an optimization problem is proposed, which is solvable using convex optimization tools. Simulation results show that the developed gain scheduled controller is capable to regulate a turboshaft engine for large thrust commands in a stable fashion with proper tracking performance.

: Synthesis procedures for nonlinear stochastic feedback control of gas turbine engines were developed and evaluated. Modern estimation and control procedures based upon separating the stochastic and deterministic aspects of the control problem were employed. The resulting closed-loop control consists of nonlinear deterministic feedback control logic designed using piecewise-linear/piecewise-optimal techniques, and an estimator designed using nonlinear filtering logic. Engine variables estimated from noise-corrupted measurements are fed back through the deterministic control logic to generate commanded inputs to the engine. Mode-switching logic was developed to provide smooth transition between small-signal regulation and large-signal transient modes of estimator/controller operation.

Safe operation of Gas Turbine Engines (GTEs) is one of the paramount missions in the GTE industry. Ensuring reliable operation and control performance is a challenging task that involves optimizing engine performance across various operating points. The Model Predictive Control (MPC) technique is a powerful approach that provides an optimization framework to meet the management and control requirements of GTEs during their operation. This work presents a systematic control framework to efficiently control a GTE. The proposed control algorithm employs an adaptive MPC methodology that ensures both safe and efficient engine operation. The MPC structure is adapted across varying operating points, and its parameters are optimized to provide control inputs that ensure best engine performance during both transient and steadystate engine operation. To enhance control reliability, the MPC is systematically coupled with min-max limiters to maintain critical variables within allowable bounds, ultimately to prevent engine surge, flame-out, and exceeding unsafe variable limits. Through this approach, the aim is to achieve a superior level of safety and operability for GTE control and management. Simulation results on a generic commercial turbofan engine with a 40,000-pound thrust show that the proposed algorithm outperforms a gain-scheduled PI controller with min-max limiters, and demonstrate enhanced performance in engine management and control.

In this article, robust attitude control schemes are proposed for the near-space vehicle with the backlash-like hysteresis and the time-varying unknown disturbance using backstepping technique. In the robust attitude control design, the backlash-like hysteresis is described by a dynamic equation which is decomposed as a linear term and a nonlinear term. To handle the nonlinear term in the dynamic equation of the backlash-like hysteresis and the time-varying unknown disturbance, they are treated as a compounded disturbance and the nonlinear disturbance observer is designed to estimate them. Based on the developed nonlinear disturbance observer, the robust backstepping attitude control is firstly developed for the near-space vehicle. Then, the robust sliding mode attitude control scheme is presented for the near-space vehicle to further enhance the robust attitude control performance. The convergence of all closed-loop signals is rigorously proved via Lyapunov analysis method under the developed robust attitude control schemes. Finally, simulation results are presented to illustrate the effectiveness of the proposed attitude control approaches.

The Navy Landing Craft Air Cushion (LCAC) Service Life Extension Program (SLEP) upgrades the current TF40B gas turbine engine and analog control system on the LCAC to an Enhanced TF40B (ETF40B) gas turbine with a Full Authority Digital Engine Control (FADEC) system. This upgrade and enhancement will provide additional engine horsepower, increased engine reliability, and modern digital engine control equipment to the LCAC. The success of the ETF40B engine development program has been an ongoing effort between the Navy, the LCAC craft builder Textron Marine & Land Systems (TM&LS), and the engine manufacturer Honeywell Engine and Systems. This paper will document and outline the differences between the TF40B and ETF40B and the efforts of the ETF40B 150 hour endurance qualification test.

In this paper, a new robust position controller is proposed for Series Elastic Actuators (SEAs) by using Sliding Mode Control (SMC) and a second order Disturbance Observer (DOb). The latter estimates not only disturbances but also their first and second order successive derivatives. A simple yet efficient dynamic model of the position control system is derived by using the analogy of a two-mass-spring-damper system. It is of fourth order and suffers from collocated and non-collocated disturbances. The former is directly cancelled by feeding-back its estimation through control input. The latter is suppressed by treating the estimations of disturbances and their first and second order time derivatives in the design of the SMC-based robust position controller. By cancelling disturbances via their estimations, not only the robustness of the position control system is improved but also the control signal chattering is lowered. The proposed robust controller significantly improves the position control performance of SEAs by suppressing plant uncertainties and external disturbances, such as friction, backlash, inertia variation and load. The validity of the proposed robust position controller is verified by giving experimental results of an SEA.

Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors (LATMs), which are primarily used to position first-stage valves in electrohydraulic servosystems. This paper presents a high reliability axial-flux slotted LATM with quasi-Halbach array for torque performance improvement including constant torque range (CTR) and output torque. Firstly, the structure with two sets of windings and the operation principle of the proposed slotted LATM is analyzed. Secondly, a brief design procedure is presented, the structure selections of open slot and double-stator single-rotor (DSSR) interior rotor with surface mounted quasi-Halbach permanent magnet (PM) array are illustrated, and the geometric parameters are optimized to obtain the optimal design of the proposed slotted LATM. Then, 3-D finite-element method (FEM) is employed to compare the proposed slotted LATM with the conventional surface mounted PM slotted LATM in terms of cogging torque, no-load back EMF, and output torque, and the results show that the proposed LATM with quasi-Halbach array has a 10% improvement in output torque and a 25% improvement in CTR. Meanwhile, the flux linkages and torque performance of the two sets of windings under various conditions verify good magnetic isolation. Finally, prototypes of two different rotor types are manufactured and a series of experiments are performed to validate the analysis.

Based on the success of gas turbine and automotive engine control system designs, a single lever power control (SLPC) model for aircraft piston engines has been developed utilizing fuzzy logic controllers. To permit development and refinement of the SLPC controllers, a propulsion simulation workbench has been developed for simulation of light aircraft piston engine applications. The objective of the workbench is to provide a platform on which the aircraft engine control system modeling and development can occur. The workbench is an integrated set of Matlab Simulink/sup (R)/ models of a piston aircraft engine, variable pitch propeller, and controller. In addition, an atmospheric model simulates the ambient conditions as they change with aircraft altitude. Results of simulated aircraft missions show dynamic and steady state characteristics of both the propulsion system model and single lever power control system to be acceptable for this application, and demonstrate the utility of the engine/propeller simulation.

New Approach To The Formation Of The Adequate Diagnostic Matrix Of The Gas Turbine Engine

Computer numerical simulations for accelerated design of rare earth permanent magnet motors in renewable energy applications: A review

Unmanned aerial vehicle (UAV) applications have evolved to a wide range of fields in the last decade. One of the main challenges in autonomous tasks is the UAV stability during maneuvers. Thus, attitude and position control play a crucial role in stabilizing the vehicle in the desired orientation and path. Many control techniques have been developed for this. However, proportional integral derivative (PID) controllers are often used due their structure and efficiency. Despite PID’s good performance, different requirements may be present at different mission stages. The main contribution of this research work is the development of a novel strategy based on a fuzzy-gain scheduling mechanism to adjust the PID controller to stabilize both position and altitude. This control strategy must be effective, simple, and robust to uncertainties and external disturbances. The Robot Operating System (ROS) integrates the proposed system and the flight control unit. The obtained results showed that the proposed approach was successfully applied to the trajectory tracking and revealed a good performance compared to conventional PID and in the presence of noises. In the tests, the position controller was only affected when the altitude error was higher, with an error of 2% lower.

Comparison of control strategies for hysteresis attenuation in electromechanical actuators subject to dispersion

Parallel processing is often employed in real-time control systems to reduce execution times. The paper, however, investigates the potential of parallel processing, and one device, in particular, the Inmos transputer, in the design of a fault-tolerant high-integrity computer module for gas-turbine engine control. Introducing multiple processors into a control system has the potential to render that system less reliable in an operational sense, than a conventional single processor implementation. However, attention to system design can, in fact, exploit parallel-processing capability to result in improved reliability. While three-lane voting systems are commonly favoured in avionics systems, owing to hardware implementation constraints, gas-turbine engine controllers are generally realised as two-lane systems. Transputer system configurations are devised in an attempt to overcome this constraint. In particular, an ‘overlapping triad’ topology is investigated in detail, and both strength and weaknesses of the present transputer architecture are revealed.

In this chapter, an introduction to gas turbine engine operation and control is given. The chapter starts by emphasising engine control in general through a brief survey of conventional control strategies. Engines need to attain high levels of overall efficiency. A number of high-level efficiency criteria are introduced and the use of optimisation within the design cycle is considered. The chapter concludes with a section considering examples of on-line optimisation from a number of different viewpoints to maximise: range at cruise condition, specific fuel consumption and thrust. The aim is to globally optimise the engines overall performance through selection of appropriate control strategies.KeywordsSpecific Fuel ConsumptionShaft SpeedTransient OperationAero EngineMaximum ThrustThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.