DC-link sensor Fault Detection and isolation for railway traction electric drives

This article presents the design and the implementation of a fault detection and isolation strategy for sensors in variable speed drives. Electric drives use several current and voltage sensors for control and protection. The principal objective of the strategy is to detect faults in DC-Link sensors, since the conclusion of a preliminary study showed that in some applications many functionalities in the control strategy depend on it. Although it was mainly designed for DC-Link sensors, thanks to the FDI structure presented here, the algorithm is able to detect faults in other sensors. The strategy is based on state observers and has been validated through real time simulations in a Hardware-in-the-Loop platform. The principal components of the platform are an OPAL-RT real time simulator and a commercial traction control unit

DC-Link Voltage and Catenary Current Sensors Fault Reconstruction for Railway Traction Drives

Due to the importance of sensors in control strategy and safety, early detection of faults in sensors has become a key point to improve the availability of railway traction drives. The presented sensor fault reconstruction is based on sliding mode observers and equivalent injection signals, and it allows detecting defective sensors and isolating faults. Moreover, the severity of faults is provided. The proposed on-board fault reconstruction has been validated in a hardware-in-the-loop platform, composed of a real-time simulator and a commercial traction control unit for a tram. Low computational resources, robustness to measurement noise, and easiness to tune are the main requirements for industrial acceptance. As railway applications are not safety-critical systems, compared to aerospace applications, a fault evaluation procedure is proposed, since there is enough time to perform diagnostic tasks. This procedure analyses the fault reconstruction in the steady state, delaying the decision-making in some seconds, but minimising false detections

Novel approach to fault-tolerant control of inter-turn short circuits in permanent magnet synchronous motors for UAV propellers

This paper deals with the development of a novel fault‐tolerant control technique aiming at the diagnosis and accommodation of inter‐turn short circuit faults in permanent magnet synchronous motors for lightweight UAV propulsion. The reference motor is driven by a four‐leg converter, which can be reconfigured in case of a phase fault by enabling the control of the central point of the motor Y‐connection. A crucial design point entails the development of fault detection and isolation (FDI) algorithms capable of minimizing the failure transients and avoiding the short circuit extension. The proposed fault‐tolerant control is composed of two sections: the first one applies a novel FDI algorithm for short circuit faults based on the trajectory tracking of the motor current phasor in the Clarke plane; the second one implements the fault accommodation, by applying a reference frame transformation technique to the post‐fault commands. The control effectiveness is assessed via nonlinear simulations by characterizing the FDI latency and the post‐fault performances. The proposed technique demonstrates excellent potentialities: the FDI algorithm simultaneously detects and isolates the considered faults, even with very limited extensions, during both stationary and unsteady operating conditions. In addition, the proposed accommodation technique is very effective in minimizing the post‐fault torque ripples

Fault Tolerant Power Converter Topologies for Sensor-less Speed Control of PMSM Drives

This paper exhibits a sensor-less speed control method based MRAS observer applied to a fault-tolerant PMSM drive system. So, this paper proposes a rapid method of fault switch detection in the power converters aiming to make sure the continuity of service even though the fault presence of an opening phase. In fact, the MRAS observer is used to replace the mechanical sensor and a redundant inverter leg is equally employed to replace the faulty leg. The proposed fast fault diagnosis method has the features of simple algorithm, independence of the transient states and being simply integrated without any additional sensors

Automatic detection test of current sensor faults for induction motor drives at standstill

This paper proposes an automatic detection test of gain faults in current sensors. An offline test is applied when the machine is not operating. The designed test operates at standstill without being necessary to disconnect the machine from the application. Current sensors are part of a commercial induction motor drive composed by a bilevel inverter, an induction motor and an electronic control unit. Therefore, in the selection of the approach, memory usage, computational cost and real-time implementation have been carefully considered. The algorithm, based on the model of the motor, uses the parameter aLs of the machine as a fault indicator. In order to estimate that parameter, firstly, precalculated width voltage pulses are injected into the motor using the inverter. Secondly the generated current slope is measured. Finally the estimation is compared to its nominal value. Once the theoretical basis is explained, the execution sequence of the test and the simulation results are presented. In addition, some enhancements are proposed to improve the resolution and accuracy of the approach, because the real conditions of the test do not follow exactly some of the theoretical assumptions

Real-Time Fault Diagnosis of Permanent Magnet Synchronous Motor and Drive System

Permanent Magnet Synchronous Motors (PMSMs) have gained massive popularity in industrial applications such as electric vehicles, robotic systems, and offshore industries due to their merits of efficiency, power density, and controllability. PMSMs working in such applications are constantly exposed to electrical, thermal, and mechanical stresses, resulting in different faults such as electrical, mechanical, and magnetic faults. These faults may lead to efficiency reduction, excessive heat, and even catastrophic system breakdown if not diagnosed in time. Therefore, developing methods for real-time condition monitoring and detection of faults at early stages can substantially lower maintenance costs, downtime of the system, and productivity loss. In this dissertation, condition monitoring and detection of the three most common faults in PMSMs and drive systems, namely inter-turn short circuit, demagnetization, and sensor faults are studied. First, modeling and detection of inter-turn short circuit fault is investigated by proposing one FEM-based model, and one analytical model. In these two models, efforts are made to extract either fault indicators or adjustments for being used in combination with more complex detection methods. Subsequently, a systematic fault diagnosis of PMSM and drive system containing multiple faults based on structural analysis is presented. After implementing structural analysis and obtaining the redundant part of the PMSM and drive system, several sequential residuals are designed and implemented based on the fault terms that appear in each of the redundant sets to detect and isolate the studied faults which are applied at different time intervals. Finally, real-time detection of faults in PMSMs and drive systems by using a powerful statistical signal-processing detector such as generalized likelihood ratio test is investigated. By using generalized likelihood ratio test, a threshold was obtained based on choosing the probability of a false alarm and the probability of detection for each detector based on which decision was made to indicate the presence of the studied faults. To improve the detection and recovery delay time, a recursive cumulative GLRT with an adaptive threshold algorithm is implemented. As a result, a more processed fault indicator is achieved by this recursive algorithm that is compared to an arbitrary threshold, and a decision is made in real-time performance. The experimental results show that the statistical detector is able to efficiently detect all the unexpected faults in the presence of unknown noise and without experiencing any false alarm, proving the effectiveness of this diagnostic approach.publishedVersio

Dynamics and Stability Analysis of IPMSM Position Sensorless Control for xEV Drive System

芝浦工業大学2019年

Sensorless position estimation in fault-tolerant permanent magnet AC motor drives with redundancy.

Safety critical applications are heavily dependent on fault-tolerant motor drives being capable of continuing to operate satisfactorily under faults. This research utilizes a fault-tolerant PMAC motor drive with redundancy involving dual drives to provide parallel redundancy where each drive has electrically, magnetically, thermally and physically independent phases to improve its fault-tolerant capabilities. PMAC motor drives can offer high power and torque densities which are essential in high performance applications, for example, more-electric airplanes. In this thesis, two sensorless algorithms are proposed to estimate the rotor position in a fault-tolerant three-phase surface-mounted sinusoidal PMAC motor drive with redundancy under normal and faulted operating conditions. The key aims are to improve the reliability by eliminating the use of a position sensor which is one of major sources of failures, as well as by offering fault-tolerant position estimation. The algorithms utilize measurements of the winding currents and phase voltages, to compute flux linkage increments without integration, hence producing the predicted position values. Estimation errors due measurements are compensated for by a modified phase-locked loop technique which forces the predicted positions to track the flux linkage increments, finally generating the rotor position estimate. The fault-tolerant three-phase sensorless position estimation method utilizes the measured data from the three phase windings in each drive, consequently obtaining a total of two position estimates. However, the fault-tolerant two-phase sensorless position estimation method uses measurements from pairs of phases and produces three position estimates for each drive. Therefore, six position estimates are available in the dual drive system. In normal operation, all of these position estimates can be averaged to achieve a final rotor angle estimate in both schemes. Under faulted operating conditions, on the other hand, a final position estimate should be achieved by averaging position estimates obtained with measurements from healthy phases since unacceptable estimation errors can be created by making use of measured values from phases with failures. In order to validate the effectiveness of the proposed fault-tolerant sensorless position estimation schemes, the algorithms were tested using both simulated data and offline measured data from an experimental fault-tolerant PMAC motor drive system. In the healthy condition, both techniques presented good performance with acceptable accuracies under low and high steady-state speeds, starting from standstill and step load changes. In addition, they had robustness against parameter variations and measurement errors, as well as the ability to recover quickly from large incorrect initial position information. Under faulted operating conditions such as sensor failures, however, the two-phase sensorless method was more reliable than the threephase sensorless method since it could operate even with a faulty phase.Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 201

Large Grid-Connected Wind Turbines

This book covers the technological progress and developments of a large-scale wind energy conversion system along with its future trends, with each chapter constituting a contribution by a different leader in the wind energy arena. Recent developments in wind energy conversion systems, system optimization, stability augmentation, power smoothing, and many other fascinating topics are included in this book. Chapters are supported through modeling, control, and simulation analysis. This book contains both technical and review articles