Traction control for railway vehicles

So far the traction drive-train was not considered in the traction control software as all mechanical parameters were unknown. The latter are subject to significant wheelset wear and ageing of rubber elastic joints during the drive-train’s operational life. The known vibration behavior of the drivetrain, namely the mode shapes, facilitates an ingenious and simple parameter identification scheme. As a result, an appropriate three-inertia virtual model is derived which is applied for parameter estimation, for system monitoring and for control. Based on this model, virtual sensors are introduced for all relevant signals of the drive-train. The signals are analyzed by the use of histograms to mainly determine both utilization of the wheel-rail contact and load cycle spectrum of the wheelset shaft. The wearless virtual sensors outmatch their physical counterpart in means of reliability, robustness, cost and space requirements. Further for anti-vibration control, two state of the art control schemes, namely the standard and the passive readhesion controller, are discussed and improved regarding their anti-windup and prevention performance. Then a novel modal state control scheme is derived in the time domain with its feedforward controllers. Subsequently, an equivalent scheme is developed in the frequency domain. A simple starting procedure of this novel active anti-vibration controller from any standard controller is proposed to raise its acceptance and applicability in the traction application. Due to a low quality of the speed sensor signal, the active anti-vibration controller is designed to be capable of damping slip-stick vibrations up to a certain limit. Beyond this limit, a passive readhesion controller is additionally coupled and intervenes until the active anti-vibration controller can cope with the vibrations. Using the synergy of the active and the passive controllers, the stable operating range of the traction drive is significantly increased without any loss of traction force. To simplify the commission complexity and to further increase the damping performance, a virtual absorber feedback controller with minimized sensor noise amplification is introduced based on the standard speed controller. The absorber is virtually mounted on the indirect-driven wheel of any traction drive-train and for its starting is faded in from the standard control scheme. Its parameters are continuously adapted to wheelset wear and to rubber joint ageing circumventing all drawbacks known from the fixed mechanical absorber installation. On the basis of the virtual absorber, more universally valid virtual filters are applied to the traction drive-train to protect the structure from the vibrational intake as well as to increase the tractive effort utilization. The latter effect is only achieved by active virtual readhesion where on the other hand, the well-known passive approach comes along with a loss of traction force. Virtual protection is obtained by all virtual filters which are mutually exclusively applied to all three inertias of the virtual model. To implement such a multi-feedback controller scheme, a looping state machine is introduced to handle the activation of the several controllers according to the desired state