Torque control for induction motors under the scheme of indirect field-oriented control (IFOC) considering rotor resistance perturbations is analyzed via linear approximations. Several important characteristics of IFOC are elucidated, leading to the design of linear, robust, and performance-based torque, speed, and position controllers. In particular, the resulting controllers are of a low order, robust to rotor resistance perturbations, and are designed according to classical performance specifications, which is a combination of characteristics that have been historically difficult to achieve. General control design guidelines valid for any induction motor are presented. In addition, the stability and minimum phase conditions of the IFOC torque controller are fully derived for any induction motor. These conditions are of prime importance when designing fixed linear speed or position controllers. A case study for a typical motor, including the design of a series of robust controllers and real-time experimental results, is presented. The proposed approach makes use of well-known classical control methods that allow the results presented here to be further extended using any linear single-input-single-output controller design tool, such as H∞ and quantitative feedback theory.

This paper focuses on the aerodynamics and design of an unmanned aerial vehicle (UAV) based on solar cells as a main power source. The procedure includes three phases: the conceptual design, preliminary design, and a computational fluid dynamics analysis of the vehicle. One of the main disadvantages of an electric UAV is the flight time; in this sense, the challenge is to create an aerodynamic design that can increase the endurance of the UAV. In this research, the flight mission starts with the attempt of the vehicle design to get at the maximum altitude; then, the UAV starts to glide and battery charge recovery is achieved due to the solar cells. A conceptual design is used, and the aerodynamic analysis is focused on a UAV as a gliding vehicle, with the calculations starting with the estimation of weight and aerodynamics and finishing this stage with the best glide angle. In fact, the aerodynamic analysis is obtained for a preliminary design; this step involves the wing, fuselage, and empennage of the UAV. In order to achieve the preliminary design, an estimation of aerodynamic coefficients, along with computational fluid dynamics analysis, is performed.

The adequate control of stator currents is a fundamental requirement for several high-performance induction motor (IM) control schemes. In this context, classical linear controllers remain widely employed due to their simplicity and success in industrial applications. However, the models and methods commonly used for control design lack valuable information, which is fundamental to guarantee robustness and high performance. Following this line, the design and existence of linear fixed controllers is examined using individual channel analysis and design. The studies presented here aim to establish guidelines for the design of simple (time invariant, low order, stable, minimum phase, and decentralized) yet robust and high-performance linear controllers. Such characteristics ease the implementation task and are well suited for engineering applications, making the resulting controllers a good alternative for the stator current control required for high-performance IM schemes such as field-oriented, passivity-based, and intelligent control. Illustrative examples are presented to demonstrate the analysis and controller design of an IM, with results validated in a real-time experimental platform. It is shown that it is possible to completely decouple the stator current subsystem without the use of additional decoupling elements.