Adjustable Speed Drives and power quality: Challenges and cost-effective opportunities

Abstract

This paper provides an overview and proposes cost-effective and efficient opportunities in improving power quality in Adjustable Speed Drive (ASD) systems. In particular, use of Electronic Inductor (EI) technique in single drives to overcome the existing challenges in conventional front-end rectifier systems with focus on partial loading conditions is investigated. Moreover, the effectiveness of EI technique along with a phase-shifted current control in terms of improved grid current quality in multi-drive configurations is addressed. Furthermore, a novel DC-link current modulation scheme for multi-drive systems is proposed. Experimental and simulation results verify the effectiveness of the theoretical analysis.

A multi-pulse front-end rectifier system with electronic phase-shifting for harmonic mitigation in motor drive applications

“…6(a), applying the proposed passive control method (L dc+ = L dc-) when one current sensor is used at positive dc-link legs the currents are controlled within the Hysteresis Band (HB) and shared the currents equally between both converters. Conventionally when the firing angle increases the boost converter draws more current in order to adjust the output voltage due to the reduction on the SCR rectified voltage [12]. The proposed configuration overcomes this problem which in return can enhance the harmonic reduction capability of the system.…”

“…1(b) exemplifies the input current waveforms of a conventional ASD system under different loading conditions when the passive filter inductor is placed at the dc-side. In practice the inductance value is selected in the range of 3-5% (e.g., L dc = 2 mH) [12]. Thus, maintaining the THD i and the power factor (λ) independent of the load profile is very beneficial.…”

“…In addition, a current modulation technique at the dc-link using Electronic Inductor (EI) technique is employed which substantially improves the input current quality. The proposed technique is an enhanced method based on previous introduced strategies by the authors in [5]- [8], [12]. The introduction of a common dc-bus in this method makes the performance of the system independent of the load profile.…”