http://www.cecube.co.uk/ The latest traction and railway technical information for knowledge propagation and educational support en-gb (C)2007 Cecube Limited UK Transportation http://www.cecube.co.uk/images/eurostar.jpg http://www.cecube.co.uk/ http://www.cecube.co.uk/papers/Inverters-Signalling.pdf The process of PWM design to either avoid or minimise certain harmonic frequencies requires solving non-linear transcendental equations. However, just understanding the results prescribed by the solutions gives good insight into the design principles. With this understanding it has been possible to tune other less mathematical PWM design methods (e.g. Space Vector PWM) to offer solutions close to Harmonic Elimination or Harmonic Minimisation for inverter applications. http://www.cecube.co.uk/papers/Inverters-Signalling.pdf Wed, 17 Oct 2007 10:52:41 GMT http://www.cecube.co.uk/papers/regeneration_5.htm A comparison of lossless algebraic optimum profiles versus the lossy numerical integration solutions is presented. It is shown that for station to station run times with small time margin then the lossless solutions are a close approximation to the model with detailed losses. It is explained how these solutions are applied to Driving Advice Systems and the significant energy savings that can result. http://www.cecube.co.uk/papers/regeneration_5.htm Thu, 07 Jun 2007 17:24:06 GMT http://www.cecube.co.uk/sitemap/sitemap.htm To facilitate linear control system design, such as the servo controls used in railway traction systems, reference to the classical continuous time methods of Bode and Nichols are commonplace. The contour maps and transforms behind these methods are now available at a single convenient location, suitable for downloading. Extension to digital system analysis is also catered for, in the unusual form of a Z plane contour map for second order systems. All located on the link page under HELPFUL HINTS. http://www.cecube.co.uk/sitemap/sitemap.htm Fri, 25 May 2007 15:27:51 GMT http://www.cecube.co.uk/papers/regeneration_4.htm In the previous article the choice of an objective function constructed for minimum energy consumption was defined and mathematical methods necessary to solve for the lossless case investigated. This paper explains how to add realistic loss functions into the equation set, and develops heuristic numerical methods required to obtain a solution for energy lost in a motor-coast-brake cycle. http://www.cecube.co.uk/papers/regeneration_4.htm Fri, 27 Apr 2007 10:39:46 GMT http://www.cecube.co.uk/papers/regeneration_3.htm As explained in the second article, the energy used is a measure of operational cost, and both run time and energy consumed are important factors in choosing the motoring and braking characteristic. Hence, careful weighting of the two objectives is extremely important. This paper defines the choice of an objective function and mathematical methods to solve for minimum energy consumption. http://www.cecube.co.uk/papers/regeneration_3.htm Fri, 16 Mar 2007 21:39:46 GMT http://www.cecube.co.uk/papers/regeneration_2.htm A second article on electrical regeneration deals with the mathematical derivation of consumed energy, and how this varies according to the electrical braking strategy designed into the rolling stock. Whilst failure to provide regenerative capacity is a well understood strategic error, this work shows that relatively small errors in brake performance specification can readily undermine expected environmental and cost benefits. http://www.cecube.co.uk/papers/regeneration_2.htm Fri, 19 Jan 2007 14:04:22 GMT http://www.cecube.co.uk/news/C3_Newsletter_Dec-06.pdf Railway stations, junctions, tunnels and trunk routes frequently involve more than one network resulting in potential interaction, conflicting with EN50121 and NR/GN/SIG/50018. No text book solution exists to realistically calculate coupling effects at these network interfaces, being of varied complexity and individuality. At least two interacting coupling mechanisms are present (conductive and inductive) and conductor impedance paths are highly frequency dependent and non-linear. Over simplification of earth arrangements and failure to account for ground dispersion effects produces poor manually calculated results. TOP-FACE automates the mathematical complexity in a generalised solution, providing short execution time and rapid reconfiguration for addition or removal of features without interface redesign http://www.cecube.co.uk/news/C3_Newsletter_Dec-06.pdf Wed, 27 Dec 2006 12:05:50 GMT http://www.cecube.co.uk/safety/emc_doc_map.htm To appreciate the full complexity of any large system or project is never easy. This is why designs are composed of progressively smaller and more manageable hierarchical sub-systems. Railway EMC is no exception, so we have compiled a pictorial representation of hazards, threats and victim systems to help assimilation of the issues. http://www.cecube.co.uk/safety/emc_doc_map.htm Wed, 27 Dec 2006 11:04:22 GMT http://www.cecube.co.uk/PWM/PWM.htm This technology pseudo-randomly varies the notional PWM switching frequency with time preventing the generated harmonics from being stationary. Since the harmonics change pitch during the course of a measurement period, the effect is to spread the noise emissions into neighbouring bands. This creates a non-tonal characteristic required for not only for EMC compliance but increasingly importantly to satisfy environmental noise pollution via acoustic tonality specifications (EN ISO 3381 & EN ISO 3095). The change in switching structure from inverter cycle to cycle makes the method asynchronous, particularly across the critical low speed range. Applying these principles efficiently and controllably at low switching frequencies is achieved by EPWM technology. http://www.cecube.co.uk/PWM/PWM.htm Mon, 09 Oct 2006 13:34:28 GMT http://www.cecube.co.uk/papers/regeneration_1.htm Concern about the environment and opportunity for carbon trading is raising interest in the regenerative capabilities of modern railway rolling stock. The first in a series of articles shows analytically how a traction equipment designed to save energy may also save time. This mathematical study explores how to specify the performance characteristics of rolling stock to maximise electrical energy saving while retaining the best possible network utilisation. http://www.cecube.co.uk/papers/regeneration_1.htm Thu, 05 Jan 2006 19:01:58 GMT http://www.cecube.co.uk/simulation/simulation.htm A description and video clip demonstration of electronic adhesion control with limited sand application to move a heavy freight Class 60 locomotive on poor condition rail without excessive wheelspin. High tutorial value. http://www.cecube.co.uk/simulation/simulation.htm Wed, 04 Jan 2006 09:52:14 GMT