Impact of Wheel Polygonal Wear on the Operational Performance of Electric Traction Drive Systems in Locomotives

The stability of electric traction drive systems is crucial for the safe operation of electric locomotives. Polygonal wear (PW) on wheels induces wheel-rail impacts that propagate through the closed-loop feedback of the traction drive system, causing significant fluctuations in key electrical parameters. However, the existing research on this issue is limited, particularly in terms of theoretical support and the consideration of motor control. This article systematically derives the theoretical impact of PW on electrical parameters, accounting for the complete structure of the traction drive system. First, this article analyzes the propagation of the excitations caused by PW and investigates the resulting characteristics of electrical parameters. Next, an electromechanical coupling model of the traction drive system, incorporating gear meshing and wheelset flexibility, is established to investigate the impacts of ideal and measured PW on electrical parameters and verify the theoretical derivations. Finally, the theoretical findings and simulation results are further validated based on HIL platform. Results indicate that PW with an excitation frequency of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}_{\mathbf {pw}}$ </tex-math></inline-formula> introduces <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \textrm {nf}_{\textit {pw}}~\pm ~{f}_{{0}}\vert $ </tex-math></inline-formula> harmonic in the stator current, resulting in harmonic torques of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textrm {nf}_{\textit {pw}}$ </tex-math></inline-formula>. Additionally, PW causes wideband harmonics in the stator current when locomotives operate at a continuously variable speed.