Analysis of Front and Rear Asymmetric Wheelset Applying Switch Control of Individual Motor and Active Coupler to Improve Running Performance of Independently Rotating Wheel Type Railway Vehicle

Abstract

The low floor tram, which has been recently introduced, uses an independently rotating wheelset to achieve 100% low-floor structure and improve the running performance of curves. The independently rotating wheelset is designed to allow smooth curve driving by allowing the left and right wheels to rotate freely, allowing the outer wheels to rotate faster during sharp curves. As the rotational constraints on the left and right wheels disappeared, the lateral restoring force, which is inherent to railroad wheels, also decreased. Lack of resistance to disturbance may cause continuous flange contact or, in severe cases, zigzag driving while repeatedly impacting the left and right flanges. To overcome these shortcomings, research on guide mechanisms and steering mechanisms has been carried out, but there are few cases in which actual vehicles have been applied due to many operational problems with the attachment of additional devices or complicated systems. Considering the superior running characteristics of rigid wheels when driving straight and the characteristics of independently rotating wheels when running on curves, front and rear asymmetric bogies using a combination of two types of wheelsets have also been proposed. The front and rear asymmetric bogie must be able to improve the driving performance only when the front shaft is a rigid wheel, and on the contrary, the stability is worse. In this paper, the performance of the front and rear asymmetric bogies is verified through analysis and small-scale roller rig test. In order to improve the shortcomings of the fixed asymmetric bogies, the switch control method of the individual motor control is applied to the motor bogie and the switch control method using active coupler for the trailer bogie were proposed. The performance improvement effect of switch control was verified through analysis and test. The switch control is a practical control method that can be applied directly to a real vehicle by applying a very simple and effective control method and plans to verify the performance improvement effect through actual vehicle test in the future.