Asynchronized (doubly-fed) machines with two (three) excitating winding and reversing excitation system allow to control vector of magnetomotive force. This solution allows separating regulation of the electromagnetic torque (active power) and voltage (reactive power). This paper describes the experience in the development and operation of asynchronized turbogenerators and condensers.

This paper deals with detection of the stator windings shorted turns in an induction motor drive working under open (scalar) and closed loop (Direct Field Oriented DFO) control structures. In order to detect the early stage of stator winding fault, the analysis of symmetrical and principal components of stator voltages and currents is used. Experimental results obtained from a specially prepared induction motor are presented.

The aim of the study described herein was to design, construct and test a demonstrator of a system to control the direction of the resultant thrust vector of a rocket motor to be used in short range anti-tank missiles with a mass of up to 15 kg. The novelty of the system is that the direction of the resultant thrust vector is manipulated by means of moveable jet vanes integrated with a moveable nozzle diffuser through telescopic connectors. The technology demonstrator was built using different materials and different manufacturing processes. The first versions were 3D printed from plastic materials. Minor modifications to the design were made at an early stage. The final version had the main components made of aluminum using CNC machining. The system, with and without jet vanes, was tested on a specially developed test rig equipped with a multi-axis sensor to measure forces and torques. The nozzle performance parameters measured and analyzed in this study were the components of the thrust vector, the moments and the effective vectoring angle. The findings show that the experimental data are in good agreement with the results of earlier simulations and that the demonstrator is fully operational.

The hybrid excitation synchronous motor (HESM), which aim at combining the advantages of permanent magnet motor and wound excitation motor, have the characteristics of low-speed high-torque hill climbing and wide speed range. Firstly, a new kind of HESM is presented in the paper, and its structure and mathematical model are illustrated. Then, based on a space voltage vector control, a novel flux-weakening method for speed adjustment in the high speed region is presented. The unique feature of the proposed control method is that the HESM driving system keeps the q-axis back-EMF components invariable during the flux-weakening operation process. Moreover, a copper loss minimization algorithm is adopted to reduce the copper loss of the HESM in the high speed region. Lastly, the proposed method is validated by the simulation and the experimental results.

Among all control methods for induction motor drives, Direct Torque Control (DTC) seems to be particularly interesting being independent of machine rotor parameters and requiring no speed or position sensors. The DTC scheme is characterized by the absence of PI regulators, coordinate transformations, current regulators and PWM signals generators. In spite of its simplicity, DTC allows a good torque control in steady state and transient operating conditions to be obtained. However, the presence of hysteresis controllers for flux and torque could determine torque and current ripple and variable switching frequency operation for the voltage source inverter. This paper is aimed to analyze DTC principles, the strategies and the problems related to its implementation and the possible improvements.

This article discusses the most important issues regarding the implementation of digital algorithms for control and drive technology in industrial machines, especially in open mining machines. The article presents the results of tests in which the algorithm and drive control parameter settings were not selected appropriately for voltage-fed induction motors, and where the control speed was not verified by any of the available motoring or simulation methods. We then show how the results can be improved using field-oriented control algorithms and deep parameters analysis for sensorless field-oriented performance.

The paper proposes a newrobust fuzzy gain adaptation of the sliding mode (SMC) power control strategy for the wind energy conversion system (WECS), based on a doubly fed induction generator (DFIG), to maximize the power extracted from the wind turbine (WT). The sliding mode controller can deal with any wind speed, ingrained nonlinearities in the system, external disturbances and model uncertainties, yet the chattering phenomenon that characterizes classical SMC can be destructive. This problem is suitably lessened by adopting adaptive fuzzy-SMC. For this proposed approach, the adaptive switching gains are adjusted by a supervisory fuzzy logic system, so the chattering impact is avoided. Moreover, the vector control of the DFIG as well as the presented one have been used to achieve the control of reactive and active power of the WECS to make the wind turbine adaptable to diverse constraints. Several numerical simulations are performed to assess the performance of the proposed control scheme. The results show robustness against parameter variations, excellent response characteristics with a reduced chattering phenomenon as compared with classical SMC.