A novel field-circuit approach for the design and analysis of permanent magnet machines
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A novel field-circuit approach for permanent magnet (PM) machine design and analysis has been developed in this paper. The approach is based on off-line finite element analysis for obtaining flux function curves with designated structure variables of PM machines, such as the thickness of permanent magnet, diameter of stator and rotor, and so on. The curves are then utilized as a database for optimal design and analysis of the PM machines. The approach not only shares the benefits of the field method, such as accuracy and effectiveness, but also maintains the succinctness and quickness of the circuit method. Simulation and experimental results exhibit the validation of the proposed approach.Noise of automotive alternators can be classified into mechanical noise, aerodynamic noise and electro-magnetic noise. which is the same as for electric motors. Previous studies show that the elect ro-magnetic noise takes a maw peak at the rotating frequency multiplied by the number of stator slots. It has not been proved clearly so far, however, that the major peak is wholely due to the stator slots. On the contrary it is well known that noise of motors. which has a mechanism similar to the alternator except that the number of stator slots in automotive alternators is in gene\integer multiple of that of rotor segments, is closely related to the number of rotor slots. Therefore, the statement that only the stator slots is the source of the major peak in the noise spectrum of alternators is suspicious although not easy, to show theoretically, that the statement is incorrect. In this paper. effects of the stator slots on the noise in an automotive alternator are experimentally investigated by intentionally modifying the number of stator slots in such a way that the number of the states is not an integer multiples of the rotor slots. It is shown that both the stator slots are not so much influential as the rotor slots and claimed that the major peak in the noise spectrum of conventional alternators is due to superposition of a component caused by the stator and a higher harmonic component caused by the rotor
Alternator
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The characteristic of rotor and stator vibration signals under run-impact status is studied.Firstly,the characteristic and rules of rotor and stator vibration signals under rub-impact status are studied.Rotor and stator vibration feature with different rotor speed is analyzed through experiment.Through the analysis of stator vibration characteristic,the pulse force from rub-impact may lead to stator resonance,so it can be brought out to diagnose rubimpact faults.Results reveal that the stator resonance signals can indicate rub-impact faults.The conclusions can give basis for the vibration character of the stator and the detection of rub-impact signals for the rotor system.
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This paper addresses itself to the inter-influence on the stator and rotor fault detection in induction motors. The reason why the detection of stator fault is influenced adversely to a certain extent by rotor fault is clearly revealed by study based on the electromagnetic mechanism. Rotor fault results in edge frequency components emerged in stator current. The conventional algorithm of negative sequence component of stator current, which is usually regarded as the most typical indicator of stator fault, gives rise to a false negative sequence component due to the modulation of edge frequency components in stator current, and might influence the detection of stator fault. The problem whether stator fault influences the detection of rotor fault or not is quantitatively discussed on the standpoint of electromagnetic mechanism, and a few interesting conclusions have been drawn. Namely, stator fault indeed results in edge frequency components emerged in stator current, which is usually regarded as the most typical indicator of rotor fault, and thus influence the detection of rotor fault in theory. However, the amplitudes of the edge frequency components derived from incipient even some severe stator fault are rather small with respect to those derived from rotor fault, and not be detectable from the practice’s point of view, and thus do not confuse the indicator of rotor fault.
Wound rotor motor
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Stators for the formerly developed multi-degree-of-freedom ultrasonic motors are not small enough compared with their rotors. In this study, a new type of multi-degree-of-freedom ultrasonic motor, whose stator is relatively small, is developed. First, the stator is designed in detail using a finite element analysis. An outline of the stator is square plate, which has four projections to be in contact with a spherical rotor. The rotor rotates around three perpendicular axes using three natural vibrations of the stator. Second, the designed stator is actually produced, and motion tests of the rotor are conducted. As a result, it is confirmed that the multi-degree-of-freedom motion of the rotor is experimentally produced.
Ultrasonic motor
Degree (music)
Square (algebra)
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Stator and rotor vibration characteristics of generator are analyzed when the rotor winding inter-turn short circuit fault and the imbalance fault occur. The rotor vibration of fundamental frequency increases and the stator vibration of second frequency decreases when the rotor winding inter-turn short circuit fault occurs. But when the imbalance fault occurs, the rotor vibration of fundamental frequency increases and the stator vibration of second frequency increases too, so the stator vibration characteristics are different from that of the rotor winding inter-turn short circuit fault. Considering the differences of the stator vibration, a new diagnosis method of rotor fault, based on stator and rotor vibration characteristics, is developed. Comparing to the traditional method that only considering the rotor vibration signals, the rotor winding inter-turn short circuit fault and imbalance fault can be effectively diagnosed. Finally, the vibration data of a type of SDF-9 generator are measured in the laboratory to verify the theoretical analysis presented above.
Wound rotor motor
Squirrel-cage rotor
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This paper deals with the identification of the stator and rotor resistances. The originality of this work is that it considers both rotor and stator resistances as time-varying parameters. Two schemes for the rotor resistance identification and one scheme for both stator and rotor resistances identification are outlined. The first and the third schemes use the measured stator current, voltage command and rotor speed while the second scheme uses only stator current and voltage commands. All schemes are based on the sliding mode observer and the convergence of the estimates to their true values does not required the persistence of excitation conditions to be satisfied by the input signal.
Identification
Observer (physics)
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Transient (computer programming)
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A vibration apparatus has been designed, manufactured and constructed to study the effects of bearing clearance upon rotor/stator response due to unbalance excitation. Frequency measurements of component sub-systems were taken and reasonable agreement was obtained.To supplement the design, a computer program has been developed to calculate damped rotor/stator response as a function of bearing clearance for both dry and fluid-filled clearances. A comparison of theoretical results, for a dry clearance space, with previous researchers indicates a very good correlation.
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The paper presents the results of investigations concerning choioe of the optimal shape (from the viewpoint of acoustical efficiency) of the holes of the rotor and stator of a dynamic axial generator, the horn and pressure chamber of which are common to all the stator channels.
Compared to the sound power and the efficiency for a generator operating with the rotor preferred hitherto a doubling of the values of the parameters was achieved for a generator which has an approximate rectangular function for the time-dependence of the active surface area of the inlet holes of stator channels.
Electric generator
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