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Efficiency of induction machines can be determined using international efficiency test standards such as the IEEE standard 112, IEC 60034-2-1 and JEC 37. The methods presented in these standards involve tests such as the no-load test, lock rotor test and a dynamometer test. Performing the no-load test is simple with fewer requirements in terms of equipment. The dynamometer test and the locked rotor...
The paper deals with brushless DC motors (BLDC) operated in high speed region without any speed or position sensor. A six-step commutation technique is used to control the BLDC motor, utilizing the disconnected motor phase for sensing the induced voltage. The main goal of the paper is to describe the limitation of the conventional 6-step commutation control in sensorless mode at high speeds and to...
This paper presents a sensorless starting procedure for a soft starter driven IE4 direct on line permanent magnet synchronous motor (PMSM). First, the initial position of the rotor is determined using a pulsating current space vector. Subsequently, the motor is started from standstill by the soft starter from a known position. The following firing sequences are calculated on the basis of the flux...
The paper presents the possibility of using a two-dimensional field-circuit model of a squirrel cage induction motor for qualitative tests of the axial leakage flux course used in non-invasive diagnostics of induction machines. The study considered the reduction of leakage fluxes associated with the stator and rotor winding to the zero component of the symmetric components system. A qualitative comparison...
This paper presents a sensorless starting procedure for a soft starter driven IE4 direct on line permanent magnet motor (PMSM). After determining the initial position of the motor using a pulsating current space vector, the motor is started from standstill by the soft starter from a known position. The following firing angles can be calculated based on the measured back-emf voltage of the motor. The...
This paper presents an experimental evaluation of the voltage unbalances effects in the efficiency of induction motors. In that sense, two distinct National Electrical Manufacturers Associations (NEMA) design were evaluated to seek the changes on their performance. The voltage unbalance was assessed using the Complex Voltage Unbalance Factor (CVUF). The experimental methodology consisted in a segregation...
In the vector control strategy of induction machines (IMs) fed by inverter, core loss information is critical to accurate determination of rotor magnetic field orientation and dynamic response control. However, methods introduced in IEEE-112 standard to separate the core loss on-line from the total loss are not available. This paper presents a novel real-time core loss determination approach considering...
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...
There is considerable demand for reducing the losses, the stray load loss, in particular, in three-phase 4-pole squirrel-cage induction motors (IMs) in order to realize high efficiency. A better understanding of the harmonic fluxes in the stray load loss factors is also required. This paper presents the frequency analyzed results of the search coil voltage for a few gap lengths, the driven frequencies...
The article considers rotor speed estimation method without speed or position sensor for double-fed motor option. In this case there is a possibility to directly measure instantaneous phase currents and voltages in stator and rotor circuits and to control the frequency ratio of stator and rotor currents depending on the shaft speed. Simulation results are presented.
A method for identification of induction motor parameters with the use of instantaneous power components balance equations is proposed in the paper. A dependence for nonlinear resistance in the rotor current function is obtained.
The determination of induction machine torque and current speed characteristics relies on methods based on either direct testing or calculation, using machine equivalent circuit. Both methods may lead to significant errors. The paper discusses the challenges encountered using these methods and an approach is presented in the paper to overcome the inherent challenges. The proposed approach considers...
A typical challenge for electric drivetrains is to reduce the number of sensors required for control action or system monitoring. This is particularly important for electric motors operating in offshore conditions, since they work in hostile environment which often damages data acquisition systems. Therefore, this paper deals with verification and validation of the extended Kalman filter (EKF) for...
This paper discusses the risks of ignition sources which may appear due to the utilisation of electrical drives in areas at risk of explosive atmospheres. The main goal is to present the traditional approach to mitigation of those risks, as well as to identify its disadvantages. The option to introduce technical diagnostics in the field of explosion protection presents the central part of this paper...
The paper presents a sensorless sliding mode observer for the flux magnitude of the induction motor (IM) drive. In order to implement a vector control scheme for the IM, the angle of the rotor flux and the flux magnitude are needed. To obtain them, it is typical to use a stationary frame flux observer - once the α, β flux components have been estimated, they are used to compute the flux angle and...
This paper presents a novel algorithm for in-situ full-load efficiency estimation of induction motors operating under unbalanced voltages. The goal of this research work is to design a reliable in-situ efficiency estimation tool that can be used in industry to derate induction motors operating with unbalanced voltages. The proposed technique utilizes the genetic algorithm, IEEE Form F2-Method F1 calculations...
Induction motor drives are at the heart of modern industrial and commercial applications. With conventional control techniques, induction motor drives have shown less than expected dynamic performance. With vector control techniques emerging as potential replacement in induction motor drives, this paper aims at highlighting various vector control strategies. Direct and indirect vector controls along...
Transferring motor loads from one bus to another bus, due to a source disconnection from a Main-Tie-Main arrangement, is not a trivial action. The transfer is dependent on detection of breakers' status, switch positions, and accurate measurements of line and bus voltages.
This paper deals with monitoring and diagnosis of stator windings damages in vector-controlled induction motor (IM) drive. The article proposes a simple method of shorted turns detection using only virtual control and decoupling signals from the classical Direct Field Oriented Control (DFOC) method. The diagnosis of the stator windings faults is based on the analysis of twice the fundamental frequency...
A synthetic test bench with two different voltage sources is described to investigate bearing currents, based on a lumped element model of an electrical motor. The aim of this synthetic test bench is to reproduce the voltage and current wave form at the bearing, which actually happen in bearings of inverter-fed motors, to investigate the influence of these electric quantities on bearing failures.
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