Adaptive optimal pulse-width modulation for the line-side converter of electric locomotives

Two methods of generating synchronous online optimal PWM sequences for the line-side converter of electrical locomotives are described. The properties of the feeding supply line render the system oscillatory at multiple resonance frequencies, which are time-variable functions of the railway track topography and of the respective locations of traction vehicles. The prevailing topographic conditions define a time-variable virtual model of the overhead line, the harmonic energy of which is the optimum criterion to be minimized. The 176 switching instants of a nine-level PWM converter voltage are optimized using an online algorithm. The necessary computations are performed in the time intervals between two commutations. The performance is illustrated by measurements obtained from a real-time multiprocessing model of an extended railway track topography, including substations and locomotives. The developed hardware structure is designed for the implementation in a railway traction vehicle