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Modern day manufacturing practices are focusing on maximizing production while actively pursuing ways to mitigate potential failures in their products. With rotating machinery, part of this pursuit requires qualification checkpoints during manufacturing processes. For motor stators, it is essential to perform in-process insulation testing to ensure the dielectric integrity of the system is maintained...
The stator inter-turn faults and stator electrical asymmetries such as stator resistance and inductance unbalance generate similar negative sequence current signatures in the induction machine. Hence the stator inter-turn fault is one of the most difficult faults to discriminate and detect in an induction machine. Discrimination of the stator inter-turn fault from stator electrical asymmetry essentially...
This paper proposes an improved stator ground fault protection scheme for the generator through injecting 20Hz voltage to realize the selectivity of the protection. The insulation resistance value of the generator is firstly calculated to determine whether or not ground fault occurring. When the ground fault happens, the 20Hz differential current between the neutral and terminal of each generator...
One of the main challenging issues in induction motor drives is the lack of knowledge about the actual values of some critical parameters, such as rotor and stator resistances which are subject to large variations during operation. Such problem is difficult to resolve due to the strong interconnection between states and parameters in the nonlinear motor model, besides the unavailability of both rotor...
This paper deals with reduced-order observers with stator-resistance adaptation for motion-sensorless permanent-magnet synchronous motor drives. An analytical solution for the stabilizing observer gain and stability conditions for the stator-resistance adaptation are derived. The proposed observer design is experimentally tested using a 2.2-kW motor drive; stable operation at very low speeds under...
A reduced-order position observer with stator-resistance adaptation is applied for motion-sensorless synchronous reluctance motor drives. A general analytical solution for the stabilizing observer gain and stability conditions for the stator-resistance adaptation are given. The local stability of the position and stator-resistance estimation is guaranteed at every operating point except the zero frequency,...
This paper introduces a novel approach to identifying the ohmic stator resistance Rs of permanent magnet synchronous machines (PMSM) based on low frequency signal injection. The identification does not depend on specific speed or load conditions. Besides the value of Lq(id, iq), no further electrical parameter is needed for the identification algorithm. The proposed stator resistance identification...
This paper describes a robust full-order adaptive stator flux observer is designed for a speed sensorless DTC system and a new speed-adaptive law and a stator resistance adaptive law are given. Furthermore, dynamic neural network is used to design the observer gain matrix and the gain matrix can be adjusted on-line. The stability of observer is guaranteed by the gain matrix in the whole speed range...
Until recently, power plant operators have had very limited options for on-line monitoring of the health of motor and generator rotors, particularly those with brushless excitation systems. Degradation of field winding insulation can lead to ground faults or shorted turns, with little or no warning. Moreover, the capability to monitor local hot spot temperatures on rotor windings in service has not...
The control strategy which the direct self-control was proposed to brushless DC motor system achieved the high performance with its simple structure and the torque control was the center. However, at lower speed, the distortion of stator flux-linkage waveform made the operating performance of brushless DC motor lower as the impact of stator resistance voltage drop. Thus, a new approach was brought...
Semiconducting fiberglass tapes were developed in order to achieve a stable, heat-resistant, chemically homogeneous semiconducting material with electrical resistance, which would be independent of the probability of the distribution of semiconducting fillers (such as carbon-black or SiC) in the dielectric binders, and in order to avoid the influence on the material resistance of the binder thickening...
This paper presents an on-line estimation for the stator resistances of the induction motor in the direct torque controlled drive, using artificial neural networks. The variation of stator resistance due to changes in temperature or frequency degrades the performance of such control strategy. In order to solve this issue, a backpropagation algorithm is used for training of the neural network. The...
Due to quick torque response and robustness against parameter variation, the direct torque control system has been widely utilized in the industrial production. To improve its dynamic performance, a novel approach using wavelet network for identifying stator resistance online is proposed. The wavelet transform can accurately detect and localize signal characteristic in time frequency domains, where...
An average value modeling of synchronous machine-rectifier system considering the stator resistance is derived in this paper. A proper voltage-behind-reactance synchronous machine model is used for the generator that allows effective calculation of commutation displacement angle. Simulation results are compared with experimental results to verify the accuracy of the average model.
Thermal protection is one of the most important aspects of any motor control system. This paper proposes a stator winding temperature estimation method for the thermal protection of inverter-fed electric motors. By modifying the space vector pulse width modulation (SVPWM) in an open-loop motor drive, a dc voltage can be intermittently injected into the motor. The stator temperature can be estimated...
The paper presents an experimental comparison of the efficiency and losses characteristics of 3 hp Premium efficiency and EFF1 induction motors. North American and European motors were tested according to Standard IEEE 112-B. A comparison, at rated operating point, shows that, under the same load conditions, the Premium motor operates with 2 % higher efficiency than EFF1 motor. However, in low voltage...
This paper proposes a method for including both hysteresis losses and eddy current losses in the dynamic space vector model of induction machines. The losses caused by the rotation and magnitude changes of the flux vector are taken into account. The model can be applied, for example, to time-domain simulations and real-time applications such as drive control. Finite element analysis, simulations,...
Nowadays, wind turbines implementing doubly fed induction generators (DFIG) occupy the largest share of the wind power market. These machines incorporate the benefits of variable speed generators in a cost-effective way but are very sensitive to grid disturbances and especially to voltage dips. To prevent the damages that grid disturbances can cause to the converter, the machines are equipped with...
Cradled in Virginia's rugged Allegheny Mountains, the Bath County Pumped Storage Station, which went into operation in 1985, is jointly owned by Dominion and the operating companies of the Allegheny Power System, and managed by Dominion Generation. The facility, which includes six rotating machines, each operating as a synchronous generator or synchronous motor, quietly balances the power demands...
Vector control methods have made accurate and fast control of induction machines possible. The success of indirect rotor-flux-oriented-control (RFOC) depends greatly on the accuracy of the machine parameters, especially the rotor time constant. In this paper, rotor resistance data is extracted from standard current-slip tests and analyzed. The data show that the rotor resistance appears to change...
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