Krishneel Kumar

In this article, a V/f control for high-power induction motor drives is analysed. In such uses, low dynamics in terms of speed-loop bandwidth is usually required. However, in some applications, where the load consists of a long shaft with certain mechanical components and with some resonant frequencies, instability and torque oscillations can cause significant damage. For these reasons, open-loop V/f control could be a winning solution, since it avoids resonances and oscillations caused by measurement feedbacks in the control. However, instability may arise also in open-loop V/f control. A stability analysis is here carried out analytically and a new method to overcome oscillations by varying dynamically the V/f ratio is proposed. The stability analysis and the effectiveness of the proposed method are verified with simulation results on a 2.8 kV-7.25 MW induction motor and with experimental tests on a small-scale 380 V-10 kW motor.

Sensorless control of permanent magnet synchronous motors is nowadays used in many industrial, home and traction applications, as it allows the presence of a position sensor to be avoided with benefits for the cost and reliability of the drive. An estimation of the rotor position is required to perform the field-oriented control (FOC), which is the most common control scheme used for this type of motor. Many algorithms have been developed for this purpose, which use different techniques to derive the rotor angle from the stator voltages and currents. Among them, the so-called passive methods have gained increasing interest as they do not introduce additional losses and current distortion associated instead with algorithms based on the injection of high-frequency signals. The aim of this paper is to present a review of the main passive sensorless methods proposed in the technical literature over the last few years, analyzing their main features and principles of operation. An experimental comparison among the most promising passive sensorless algorithms is then reported, focusing on their performance in the low-speed operating region.

In recent years, part of the efforts of the electric drive researcher has been focused on the study of sensorless control algorithms that allow controlling the machine without a speed measure and with ever-fewer measurement devices. This article proposes a possible solution for the submarine application of an asynchronous motor. The motor is designed to drive a petrol pump at a depth of three thousand meters. The motor is fed by an inverter that is located on an offshore platform, and they are connected through a filter and a cable that is 19.74 km long. In this application, it is not suitable to use a speed measurement device; in fact, at this depth it is important to use as few components as possible, in order to increase the system reliability. A control algorithm that only needs available electrical measures is proposed below.

Asynchronous machines are always widely used in most industrial applications due to their reliability, flexibility, and manoeuvrability. To achieve variable speed operations, the quite simple open-loop V/Hz control is largely utilized. Under open-loop V/Hz control, the nonlinear interaction is well known to cause current and torque oscillations while operating at low to medium speeds under light loads. This article presents the stability analysis of induction motors at low–medium frequencies under no-load conditions with the V/Hz control. A system representation in the form of state space is discussed, and the region of instability is plotted against the V/f plane. Two novel and refined methods for the mitigation of oscillations in the region of instability are presented. The two proposed algorithms are finally tested and validated through simulation on an inverter-fed induction motor drive system.

The use of series architecture nowadays is mainly on hybrid buses. In comparison with series-parallel and parallel architectures, which are usually exploited on medium-size cars, the series architecture allows achieving internal combustion engine higher efficiency. The downside of this architecture, due to a double energy conversion (i.e., mechanical energy converted in electrical energy and electrical energy converted again in mechanical energy), is that additional losses are introduced. For this reason, the parallel and the series/parallel architectures were considered more suitable for hybrid medium-size cars. Nevertheless, the use of new technologies can change this scenario. Regarding storage systems, supercapacitors achieved a significant energy density, and they guarantee much higher efficiency than battery storage. Moreover, the use of wide-bandgap components for power electronic converters, such as silicon carbide devices, assure lower losses. In this scenario, the series architecture can become competitive on medium-size cars. This paper shows a review of various studies performed on this topic.

This paper focuses on robust wind disturbance rejection for nonlinear quadrotor models. By leveraging on nonlinear unknown observer theory, it proposes a nonlinear dynamic filter that, using sensors already on-board the aircraft, can estimate in real-time wind gust signals in the three dimensions. The wind disturbance is then treated as input to the PD controller for a quick and robust flight pathway in presence of disturbances. With this scheme, the wind disturbance can be precisely estimated online and compensated in real-time. Hence, the quadrotor can successfully reach its desired attitude and position. To show the effective and desired performance of the method, simulation results are presented in Matlab/Simulink and ROS-enabled Gazebo platform.

Induction machines are always the most used machines in industry, due to the several advantages they offer. The quite simple V/Hz control strategy is one of the most commonly used strategies to control induction motors speed, due to its simplicity and ease of implementation. However, using this strategy for controlling high power induction motors may cause instability in some regions, leading to high oscillations in currents and in motor torque. Therefore, the authors propose an improved version of the V/Hz control strategy, which compensates for these oscillations by correcting the speed reference using the stator current. The results obtained are presented, showing excellent results in compensating for these oscillations in motor currents and torque.

The recent decrease in the price as well as size of semi-conductor logic and due to significant advancements in technologies such as microcontrollers, motors and sensors, the application of quadcopters in several fields has been achieved. However, testing of quadcopter prototypes still has a risk of damage due to faults and unexpected behavior. Hence, a method of testing of quadcopters in simulation mimicking the actual conditions of the real environment in an actual hardware test has been proposed. For this purpose, Gazebo simulator integrated with ROS has been chosen for the simulation of the path of the quadcopter. Moreover, the software Matlab/Simulink has been interfaced with Gazebo in order for the simulation of the quadcopter to be achieved.

This paper presents a new technology for designing, simulation, implementation and validation of a driverless vehicle system with the use of the Arduino microcontroller, ultrasonic sensors and stepper motors are integrated to Lyapunov based control scheme. The goal is specifically to develop a driverless vehicle system which is able to move from an initial to target location in an obstacle free environment in 2D workspace while taking the shortest route to the destination. Mathematical modeling for the vehicle has also been done in order to find the dynamics of the vehicle which would be used in the software simulation of the vehicle and subsequently verified through experimental design. The new methodology for the prototype and validation are presented with interesting scenarios. The final design and the methodology to reach the final design, prototyping, testing and verification and validation of the output will be presented.