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Doubly fed induction generator (DFIG) is the most implemented electric machine in wind energy conversion systems (WECS) due to reduced size converter, active and reactive power control and economic factors. However, the power electronic stage needs an accurate controller that allows to follow the stator power regulation. As a result, Sliding-Mode Control (SMC) has been successfully implemented in...
The paper presents a method to estimate the inverse of the rotor time constant of the induction motor. The estimation is done using a sliding mode observer under the assumption that the stationary frame fluxes are known. These fluxes are first obtained using a voltage model observer; they are also used for field orientation. With measured voltages, currents, known fluxes and speed, the rotor time...
The paper presents a method to estimate the rotor position, speed and load torque of the PMSM drive. Estimation is based on an extended dynamic model of the PMSM and is done using sequential observers. A first observer estimates the EMFs of the motor; these are used to compute the rotor position angle. The EMFs along with the angle are used as inputs to a second observer which estimates the speed...
Dual stator winding induction generator, being brush-less and magnet-less, has been found to be suitable for remotely located wind-electrical systems where maintenance becomes a key issue. Since this generator has a squirrel cage rotor and two distributed stator windings, manufacturing process is simple and system becomes rugged. Both the windings may contribute active and reactive power when operated...
Inter-turn insulation failure in induction motor results in complete or developing winding short circuit. Stator winding fault leads to an unbalance in the three phases of the motor leading to a faulty induction motor with increased time and space harmonics of flux. This can lead to uneven distribution of air gap flux and increase in torque ripple. The condition is worsened due to an unbalance in...
In this paper a novel position sensorless scheme named Back EMF Zero Difference Point (ZDP) detection has been proposed for six-switch VSI converter fed permanent magnet BLDC motor. This technique is based on the comparison of back EMFs and detection of the points in the back EMF waveforms where they cross each other or in other words they are equal. Commutation point is achieved exactly at the same...
The synchronous reluctance motor (SynRM) is gaining popularity for general purpose drivers, where the sensorless operation is important. It is well known that, at low-speed, the saliency of these machines can be exploited for sensorless control down to stand-still through high-frequency (HF) signal injection. Nevertheless, the use of a separate HF model makes more complex the integration with the...
This paper proposes a contact force control system for a dual-rotor helicopter. Force control of a helicopter allows for achieving aerial tasks that include contact motions with objects. Although one-degree-of-freedom force control systems have been already developed, multi-degree-of-freedom systems have not been achieved yet. Therefore, in this paper, a force control system for a dual-rotor helicopter...
For a safe and efficient operation of large variable-pitch wind turbines, the controller plays a vital role. Below the rated wind speed, there is a power-optimal rotor speed for a given wind speed, achieved by designing a generator torque control. Pitch control is appropriate above the rated wind speed, to keep the rotor speed constant. In order to deal with nonlinearities and uncertainties, in this...
Real-time simulation of an electrical vehicle (EV) with hardware-in-the-loop is a cost-effective approach in evaluating the behavior of electrical vehicles and its controllers before applying them in a real system. This paper demonstrates a nonlinear approach of a real-time induction motor model implemented in a National Instrument real-time platform. Many studies have been conducted concerning on...
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