120,138 research outputs found
Different Virtual Stator Winding Configurations of Open-End Winding Five-Phase PM Machines for Wide Speed Range without Flux Weakening Operation
No full textThis paper presents a specific control strategy of double-ended inverter system for wide-speed range of open-winding five phase PM machines. Different virtual winding configurations (star, pentagon, pentacle and bipolar) can be obtained by choosing the appropriated switching sequences of two inverters. The motor’s speed range is thus increased.Projet MHYGALE/ADEM
Frequency Domain Modeling of High Voltage Transformers Using a Nonlinear Least-Square Estimation Technique
No full textThe development of transformer models can be achieved based on experimental frequency response measurements providing access to the windings is available and the physical dimensions are known in order to calculate R, L and C parameter values. Of interest are methods that allow the generation of a suitable model if the R, L and C parameters are unknown and access is restricted to the external terminals of the winding only. Using a lumped parameter model and the measured frequency response across the whole winding, it is possible to estimate the intermediary winding responses. Knowledge of the intermediary winding frequency responses facilitates the development of condition monitoring tools that are capable of locating the source of partial discharge activity or winding deformation within a faulty transformer [1]. This paper includes a full description of the developed modeling technique, along with experimental results from a model winding system that validates the proposed approach
A measurements-based discharge location algorithm for plain disc winding power transformers
No full textA measurements-based electrical method for locating partial discharges (PD) in transformers is described in the paper. This location method relies on the series resonance frequencies of the signals produced at the transformer terminals by a discharge on the winding. Based on the equivalent circuit of plain disc type winding which consists of series inductance (L), series capacitance (K) and shunt capacitance to earth (C) of the winding, an analytical location algorithm is derived which gives the relationship between the location of a discharge and its terminal response's series resonance frequencies. LKC parameters of the equivalent circuit can be estimated using the series resonance frequencies of a calibration signal measured at the bushing tap during PD calibration. The PD location algorithm was tested on 11 kV transformer winding using signals produced by a discharge simulator and real discharges, and the results confirm its validity with a location accuracy of better than 10% of the winding length. However, blind area where this location algorithm is not applicable does exist near the neutral of the winding and far away from the measuring terminal. Since this location algorithm uses the series resonance frequencies below 500 kHz, it can be implemented with conventional PD measuring circuitry and instruments to detect and locate discharges in power transformers
General Analytical Model of Magnet Average Eddy-Current Volume Losses for Comparison of Multi-phase PM Machines with Concentrated Winding
No full textthis paper studies magnet eddy-current losses in permanent magnet (PM) machines with concentrated winding. First of all, space harmonics of magnetomotive force (MMF) and their influence on magnet losses in electrical machines are investigated. Secondly, analytical model of magnet volume losses is developed by studying the interaction between MMF harmonics wavelengths and magnet pole dimensions. Different cases of this interaction are exhibited according to the ratio between each harmonic wavelength and magnet pole width. Then various losses sub-models are deduced. Using this analytical model, magnet volume losses for many Slots/Poles combinations of 3, 5, and 7 phase machines with concentrated winding are compared. This comparison leads to classify combinations into different families depending on their magnet losses level. Finally, in order to verify the theoretical study, Finite Element models are built and simulation results are compared with analytical calculationsProjet MHYGALE/ADEM
Simulation of a transformer winding for partial discharge propagation studies
No full textA simulation model of a continuous disc type 6.6 kV transformer winding was used to study the propagation behaviour of partial discharge (PD) pulses. The model based on multi-conductor transmission line theory uses a single turn as a circuit element with the capacitance, inductance, and losses calculated as distributed parameters. Transfer functions that describe how the location of the PD source affects the current signals measured at the terminals of the winding were calculated. The paper shows how the position of the zeros in the frequency response of the measured current signals can be used to locate the source of the discharge. Sensitivity studies on the parameters of the model were used to investigate the effect of inaccuracies in the model on the position of the zeros and hence the location of the discharge
An electrical PD location method applied to a continuous disc type transformer winding
No full textA 6.6 kV continuous disc type winding of a distribution transformer is used to investigate the propagation of partial discharges (PD) with the aim of location. The winding was modelled, as multiconductor transmission lines with each turn represented by a transmission line. This approach results in the model being valid up to a few MHz in frequency. The validity of the model was confirmed by impedance measurements on the winding. The transfer functions calculated between probable PD source locations to winding terminals showed that the troughs (or zeros) change in frequency with the location of PD source and hence can be used for the location of PD. Transfer functions obtained experimentally using a discharge calibrator as the PD source, showed very good agreement with the calculations
General modeling of the windings for multi-phase ac machines
No full textThis paper, which deals with the winding modeling of ac multi-phase machines with a regular distribution of the stator slots, details an original matrix modeling of the stator winding. First, the properties of the balanced multi-phase windings (with integral-slot and fractional-slot patterns) are analysed. The winding function approach, one of the most common way to model the winding distribution effects on the stator rotating field, is then introduced. For multi-phase machines, it will be shown that the pole number generated by the winding distribution depends on a new parameter: the circularity index. The discrete nature of the winding, imposed by the stator slots, leads to the development of a discrete modeling of the winding obtained from sampling the winding function: two matrices, the winding function matrix and the distribution function matrix, are introduced to characterize the multi-phase winding. This matrix approach is thus a concise way to calculate the winding factors and to estimate the set of self and mutual stator inductances for smooth air gap multi-phase machines. A particularly original method of obtaining an analytical expression for the leakage mutual inductance is described. The results are validated with two experimental 5-phase PM machines by using experimental measurements and numerical simulations
New 5-Phase Concentrated Winding Machine with Bi-Harmonic Rotor for Automotive Application
No full textFor a power range from 10 to 30 kW, 5-phase machines are well adapted to low-voltage (48V) supply thanks to their reduced current per phase. For three-phase machines but with higher voltages (>120V), machines with a number of slots per pole and per phase spp equal to 0.5 (as the 12slots/8poles combination) are widely used in hybrid automotive applications when a wide speed range is required. The reason is that the value of spp=0.5 guarantees no sub-harmonics and thus induces low level of permanent magnet rotor losses. In this paper a 20slots/8poles/5phases machine is chosen. With a winding factor of only 0.588 for the first harmonic, this machine is only interesting if its high third harmonic winding factor (0.951) is used. Thus, a new bi-harmonic rotor structure is presented. Thanks to adequate control with flux-weakening and ratio r between first and third harmonic currents, the maximum torque versus speed characteristic is determined.Projet ADEME/MHYGAL
Analytical Model of Magnet Eddy-Current Volume Losses in Multi-phase PM Machines with Concentrated Winding
No full textThanks to IEEE. The original PDF of the article can be found at: http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6342330&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6342330 MHYGALE, project managed by VALEO-EEMthis paper studies magnet eddy-current losses in permanent magnet (PM) machines with concentrated winding. First of all, space harmonics of magnetomotive force (MMF) and their influence on magnet losses in electrical machines are investigated. Secondly, analytical model of magnet volume losses is developed by studying the interaction between MMF harmonics wavelengths and magnet pole dimensions. Different cases of this interaction are studied according to the ratio between each harmonic wavelength and magnet pole width (following flux density variation). Then various losses sub-models are deduced. Finally, using this analytical model, magnet volume losses for many slots/poles combinations of 3, 5, and 7 phase machines with concentrated winding are compared. This comparison leads to classify combinations into different families depending on their magnet losses level. Besides, in order to validate the theoretical study, Finite Element models are built and simulation results are compared with analytical calculations.MHYGALE/ADEM
Method to evaluate winding trajectories in robotized filament winding
No full textRobotized filament winding technology involves the deposition of a tape according to a planned robot trajectory and its polymerisation in a furnace for thermoset resin matrix. In this way it is possible to wind asymmetric or complex parts. The winding trajectory is a critical aspect of the robotized filament winding process, since the mechanical performances and the winding time of the manufac- tured composite part change according to winding trajectory geometry. This work presents an original method to optimize and to compare alternative winding trajectories for robotized filament winding. The proposed method uses a set of geometric parameters that characterize the winding process and, in the same time, that are easy to measure. Therefore, the implemented method is quick and user friendly. The designed method has been implemented and tested on two different trajectories that have been planned to wind a same composite part
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