Direct Haar-space control for DC motors

After considering the analysis of a three-phase inverter driving induction motors for railway applications, the authors take into consideration the system formed by a DC motor fed by a chopper. The mathematical analysis has been conducted through Haar functions, a tool based on the general framework of wavelets. The spec advantage consists in being able to solve differential equations by approaching the problem in the Haar domain, instead of adopting a time domain solution. A limited number of Haar coefficients are necessary to perform this task. Especially transient conditions during the starting process can usefully be examined in such a way, putting into evidence specific characteristics of the chopper motor system. An example describing the application of such technique is presented and critically described.