| MS Seminar

Name of the Speaker: Mr. PATEL KULDIP VINODKUMAR (EE22S049)
Guide: Dr. Kamalesh Hatua
Online meeting link: http://meet.google.com/bpr-iqpg-gbj
Date/Time: 20th June 2025 (Friday), 2:00 PM
Title: Harmonic Free Improved d-q Current Estimation Technique for High-Power Traction Applications.

Abstract :

The electrification of transportation is one of the most critical technological transitions of our time due to rising environmental concerns and stringent emission regulations. Induction motor drives have emerged as a reliable and cost-effective solution for high-power traction applications. Their rugged construction, reliability, low maintenance requirement, and their ability to operate efficiently over a wide range of speed and load conditions enhance their suitability in a variable speed drive system. One key design consideration in a high-power traction drive is the low switching frequency, typically less than 1 kHz. This reduction in switching frequency reduces the voltage waveform quality and increases harmonic distortion in line current. This harmonic-rich current poses challenges in closed-loop controlled traction drives. To address this limitation, an innovative algorithm was proposed for extracting the fundamental component of line current. The harmonic voltage applied by the inverter is calculated in real-time. This harmonic voltage information is utilized to calculate the ripple current using a high-frequency model of the induction motor, which is subtracted from the sensed line current. This results in a ripple-free fundamental current suitable for closed-loop control schemes. This algorithm is validated through both simulation and experimental studies. Simulations were conducted on a 1.35 kV, 300 kW, two-level VSI-fed induction motor drive model in open-loop V/f control, as well as vector control. Experimental validation is carried out on the laboratory prototype of a 415 V, 5.5 kW induction motor drive in open-loop V/f control.

Traction drives are usually operated in the overmodulation zone to enhance the torque capability and DC bus utilization. However, the inverter output voltage contains lower-order harmonic voltages in the overmodulation zone. These harmonic voltages result in lower-order harmonic currents in the line current, which enter the control loops through the feedback path and deteriorate the performance of the closed-loop drive. Therefore, a suitable fundamental current extraction algorithm is required. The correct motor parameters are necessary to estimate precise fundamental current, which is sometimes difficult to estimate. This article proposes an improved fundamental current estimation algorithm, which estimates the leakage inductance error and updates it in real-time. The proposed algorithm is simulated and verified on an open-loop V/f induction motor model.