Selected practical problems of HSR traction systems

In the construction of modern rail vehicles, power electronics solutions are widely used, such as converters and inverters for locomotive drives, electric multiple units (EMUs), metro trains, trams, and transistorized static converters used to power AC and DC installations in vehicles. The devices are manufactured using modern components – HV IGBT transistors and technological solutions that ensure high reliability and very good operational parameters.AC drive systems
Traction motors are powered by traction inverters, designed for specific vehicles and using modern IGBT components. The inverters are characterized by high efficiency and reliability.
They use FOC SVPWM (Field Orientation Control Space Vector Pulse Width Modulation) control methods.
They provide anti-slip torque control for individual vehicle axles, effective electrodynamic braking across the entire vehicle speed range, emergency braking in the absence of voltage in the overhead line, energy recovery to the grid during braking, with dissipation of excess energy in braking resistors – after exceeding the maximum recuperation voltage value, and operation over a wide range of voltage fluctuations in the overhead line as well as a wide range of ambient temperature changes. Modern solutions meet European standards regarding safety and radio interference. Inverters can be cooled by forced air circulation (maintenance-free solution) or have liquid cooling. The best technical solution is to use one inverter for each traction motor, although solutions with one inverter powering two traction motors are also encountered.
The process of controlling acceleration and braking takes into account the elimination of slip during acceleration and braking, the implementation of cruise control functions, and operation with a set torque – both for acceleration and braking, i.e., ensuring proper acceleration during start-up and deceleration during braking. During electrodynamic braking, a very important issue is ensuring proper cooperation between the pneumatic brake and the electrodynamic brake, especially at low speeds (so-called blending).
To implement control processes, temperature sensors for windings and rotational speed sensors (usually magnetic), built into the traction motor, are used. (…)

Selected practical problems of HSR traction systems – PDF file for download