Railway Motor Torque Control for Stable Wheel Adhesion
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Solution Overview
Problem
Existing anti-slip/slide control systems for railway vehicles often experience undesired oscillations in wheel effort and speed due to variable torque modulation, which can lead to resonance and mechanical wear, especially when trying to maintain adherence under changing rail conditions.
Innovation Solution
A method for controlling a railway vehicle using a motor controller for an electric machine that calculates a constant reference torque based on real-time measurements and estimates, employing PI or PID control, and adaptive filtering to minimize torque oscillations and optimize wheel speed, thereby reducing mechanical stress and improving adherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If variable torque modulation is used to maintain adherence, then adherence is improved, but wheel effort and speed exhibit undesired oscillations
Solution Approach 1:
The control system dynamically adjusts torque based on real-time wheel speed measurements and adherence conditions, transitioning from static threshold-based control to adaptive dynamic control that responds to changing operational conditions without causing oscillations
Solution Approach 2:
The system implements closed-loop feedback by continuously measuring wheel speed, calculating slip ratio, and adjusting torque accordingly. This feedback mechanism maintains adherence while preventing oscillations through proportional-integral-derivative (PID) control that responds to error signals between desired and actual wheel behavior
2Reliability
If quick torque modulation is applied to cancel slide, then anti-slip control is improved, but resonance of transmissions is excited
Solution Approach 1:
The system applies torque modulation only to the extent necessary to maintain optimal slip ratio within the adherence peak region, avoiding excessive torque changes that would excite transmission resonance while still achieving effective anti-slip control
Solution Approach 2:
The control system deliberately avoids torque modulation frequencies that would resonate with transmission natural frequencies. By operating in the frequency domain away from resonance peaks, the system achieves anti-slip control without amplifying vibrations that could damage transmission components
3Device complexity
If pre-defined thresholds of wheel slip/slide, acceleration and jerk are used, then anti-blocking control is simplified, but wheel effort and speed exhibit undesired oscillations
Solution Approach 1:
The system replaces fixed threshold parameters with dynamically adjusted parameters based on operating conditions. The slip ratio reference, acceleration limits, and jerk thresholds are adapted in real-time according to wheel speed, torque demands, and adherence conditions, eliminating oscillations caused by rigid threshold-based control
Data Source
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AI summary
According to the invention, a method is provided for controlling a railway vehicle (1) comprising a motor controller (7) for an electric machine (5) acting on at least one wheel of the railway vehicle, the method comprising: - receiving torque request from a central controller (9); - determining the actual speed of the railway vehicle (1); - determining the actual wheel rotational speed of the railway vehicle (1); - receiving an estimated torque (Test) from the motor controller (7); - estimating the maximal adherence coefficient based on the wheel rotational speed and the estimated torque (Test) received from the motor controller; - determining a reference torque (Tcontr) based on the estimated adherence coefficient; and - providing the reference torque (Tcontr) to the motor controller (7).