Abstract
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.
Highlights
The availability of railway traction units can be improved by implementing condition-based maintenance (CBM) [1]
The discontinuous term is given by Equation (6), where p is a gain that should be higher than the maximum sum of sensor faults and uncertainties, in order to achieve the sliding motion, sat is the bound of the sliding surface and ez = [ez1 ez2 ] = ẑ − z, ẑ being the estimated states and z the bound of the sliding surface and
In the case recommended to apply a fault detection and isolation (FDI) to the motor phase current sensors to avoid a false evaluation of in the the catenary voltage sensor, the available sensor redundancy in other traction units should be checked in catenary current sensor due to the effect in the control strategy of a high gain fault in any motor phase order to distinguish and catenary voltage sensor faults
Summary
The availability of railway traction units can be improved by implementing condition-based maintenance (CBM) [1]. An on-board model-based sensor fault diagnosis is proposed and implemented in a commercial traction control unit (TCU) for a railway application. Similar to the model of the input filter, previous studies have used the model of a PWM rectifier [20,21] for DC-link voltage and catenary current sensor fault diagnosis. The solution proposed for sensor fault diagnosis is based on a sliding mode observer (SMO). [21], SMO-based FDI approaches for DC-link voltage and catenary current sensors are presented. In contrast to previous publications, in this article, a fault reconstruction based on a SMO for DC-link voltage and catenary current sensor faults is proposed. 4 proposes a fault diagnosis and reconstruction approach for DC-link voltagethe and catenary and current sensors.
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