Single Current Measurement Research Articles

Adaptive sensorless PMSM mechanical fault detection with varying speeds

In this paper, we propose to improve an OSG (Orthogonal Signal Generator) based technique in order to extract mechanical faults from a PMSM (Permanent Magnet Synchronous Motor) with variable mechanical speed. This technique is part of the MCSA (Motor Current Signal Analysis) family. In this particular case, we use a single current measurement. The technique can be used on-line and without a mechanical speed sensor. A stability analysis of the adaptive OSG method is presented in this paper. Order tracking extraction is added to ensure robust analysis and detection of variable speed faults. A comparison is made with the Concordia and TKEO (Teager Kaiser Enregy Operator) methods on an experimental bench with a mechanical fault emulator. A statistical study of the fault detection is conducted based on the experimental results

Model-Based Sensorless Torque Control of SRM Drive Using Single Current Sensor

Switched reluctance motor (SRM) is been considered for electric drive applications because of its low cost and robustness. Nevertheless, the power electronics needed to operate the drive increases its cost and volume, and also reduces its running reliability. Hence, the number of switches, diodes, and sensors involved are needed to be reduced by improving the power converter topology. Therefore, sensorless torque control of SRM using a single current sensor Resistor-Dump (R-Dump) converter is proposed in this study. An R-Dump converter is proposed in this study because it has minimal power components compared with mostly use converters like an asymmetric half-bridge converter (AHBC). The sensorless control is developed based on a new sliding mode observer (SMO) that is defined to only use a single current measurement and an inductance model to estimate the rotor position of the SRM. Furthermore, the proposed drive is simulated in MATLAB/SIMULINK and compared with a conventional SMO based senseless SRM drive. Results from the simulation show that the proposed converter topology, torque control, and position estimation methods can significantly reduce the size and cost of the SRM drive with a negligible increase in torque ripple compared to the conventional methods.

A Tacholess Order Analysis Method for PMSG Mechanical Fault Detection with Varying Speeds

This article deals with the detection of mechanical faults in synchronous machines from single current measurement at variable speed. The proposed approach is based on an order tracking method in which the analysis signal is sampled as a function of the mechanical angle. In this case, the spectral components become independent of the speed and the frequency analysis can be exploited. Order tracking is generally implemented from a position measurement. In this work we present a method that allows us to estimate this position and the analysis signal from only one current measurement. The proposed approach allows an intuitive adjustment of the algorithm parameters. Secondly, a statistical method is used to finalize the diagnosis. At variable speed, this type of method is difficult to implement and we show that order tracking makes it possible to simplify the analysis. The procedure is tested in simulation and on a experimental test bench.

Mechanical Fault Diagnostic in PMSM from Only One Current Measurement: A Tacholess Order Tracking Approach

This article presents a mechanical fault diagnosis methodology in synchronous machines using only a single current measurement in variable speed conditions. The proposed methodology uses order tracking in order to sample the analysis signal as a function of the rotor angle. The spectrum of the signal is then independent of speed and it could be employed in frequency analysis. Order tracking is usually applied using rotor position measurement. In this work, the proposed method uses one current measurement to estimate the position as well as the analysis signal (rotation speed). Furthermore, a statistical approach is used to create a complete diagnosis protocol. At variable speed and with only one current measurement the diagnosis is challenging. However, order tracking will allow simpler analysis. The method is proved in simulations and experimental set-up.

Querying a quasi-classical Oracle: One-bit function identification problem implemented in a single atom transistor

We show that a single atom transistor (SAT) addressed by a pulsed gate voltage is a physical realization of an Oracle that can calculate the four one-bit Boolean functions, the logical output being encoded in a measurable current. The algorithm relies on the quasi-classical parallelism that arises from the linearity of the kinetic scheme used to describe incoherent electron transport through two levels of the SAT. We demonstrate that one of the four one-bit Boolean functions can be identified by a single current measurement. The generalization of the algorithm to n bit functions is also discussed.

A technique for accurate measurements of ion beam current density using a Faraday cup

We have performed measurements of the spatial distribution of current in various alkali and reactive ion beams over the energy range 5–600 eV using a Faraday cup. Ion beam current densities have been extracted from these measurements using a simple deconvolution procedure. Our results reveal that the beams are Gaussian in shape with a constant width, σ, for energies greater than approximately 75 eV and for all ion species investigated. This width is consistent with that determined from the distribution of oxygen on a Cu(001) crystal after an O+ ion beam deposition, measured using Auger electron spectroscopy. Using the measurement technique outlined in this article, together with the linear relationship between current density and Faraday cup current, it is possible to determine the beam current density using a single current measurement.

Current measurement in three-phase brushless DC drives

The problem of estimating the currents in the windings of a three phase brushless DC machine from measurements of a single drive input current is discussed in this paper. The proposed solution involves the application of a state observer, which uses errors between the actual and estimated drive input currents to update its estimates of winding currents. Such estimation is possible only if the winding currents are observable (i.e. knowledge of the drive input currents is sufficient to derive the winding currents), and it is shown that observability depends on drive operating condition, PWM switching strategy and machine winding connection. All of these factors are discussed for the case of current measurement in the DC link and a novel measurement strategy involving the measurement of total switching device current. An important advantage of the single current measurement method is that measurements are made equally on all three phases of the machine, so that the effects of sensor imbalance are eliminated.

Oceanography of Mississippi Delta Sedimentary Environments

Oceanography of Mississippi Delta Sedimentary Environments