High‐frequency harmonic suppression method for interleaved traction converters based on synchronous sampling

Abstract

High‐frequency resonance in traction power supply systems (TPSSs) is of great concern because of its potential to cause great damage to the safety and stable operation of railroad systems; it has been demonstrated that when a locomotive generates a harmonic current with the resonant frequency of the series impedance on the traction network, a large amount of high‐frequency harmonic voltage is generated. This paper proposes a high‐frequency harmonic suppression method based on synchronous sampled carrier phase‐shift PWM modulation strategy (SSCPS‐PWM), which has the advantage of not only considering the consistency of sampling the analogue signal by multiple controllers, but also further optimising the precise synchronization between multiple converter pulses. This method generates lower high‐frequency harmonic content and is particularly suitable for the field of high‐power, low switching frequency, multi‐controller locomotive traction converters. The proposed method was simulated and compared with the traditional method for the harmonics injected by the locomotive, and a real railway line with a harsh power supply condition was selected and field tests were conducted in four sections by a 7200kW 6‐axle electric locomotive. The test results showed that the proposed method effectively reduced the high‐frequency harmonic current of the locomotive and reduced the high‐frequency resonant overvoltage in the TPSS.

Simulation of a direct torque control system in the presence of winding asymmetry in induction motor

“…The most common type of protection in the event of emergency modes of both the inverter [31][32][33] and the traction motor [34][35][36] is based on the maximum current protection algorithm. That is, disconnection of the damaged element of the traction drive occurs when some specified value of the phase current is exceeded with a time delay after diagnosis.…”